perlguts - Perl API の紹介 This document attempts to describe how to use the Perl API, as well as to provide some info on the basic workings of the Perl core. It is far from complete and probably contains many errors. Please refer any questions or comments to the author below. このドキュメントでは Perl API の使い方、および Perl コアの基本的な動作に 関するいくばくかの情報を提供しようとしています。 完璧からは程遠いものですし、間違いも多いと思います。 疑問点やコメントは後述する著者に対して行なってください。 (変数) (データ型) Perl has three typedefs that handle Perl's three main data types: Perl では、主となる三つのデータ型を扱うために三つの型定義を行なっています: Each typedef has specific routines that manipulate the various data types. それぞれの typedef には様々なデータ型を操作するための特別なルーチンが 用意されています。 ("IV" ってなに?) Perl uses a special typedef IV which is a simple signed integer type that is guaranteed to be large enough to hold a pointer (as well as an integer). Additionally, there is the UV, which is simply an unsigned IV. Perl では、符号付き整数でもポインタでも十分に入れることのできる特別な typedef である IV を使います。 更に、単に符号なしの IV である UV もあります。 Perl also uses two special typedefs, I32 and I16, which will always be at least 32-bits and 16-bits long, respectively. (Again, there are U32 and U16, as well.) They will usually be exactly 32 and 16 bits long, but on Crays they will both be 64 bits. Perl はまた、二つの特殊な typedef である I32 と I16 を使っています。 これらはそれぞれ、常に最低 32bit、16bit の長さを持っているものです。 (再び、同様に U32 と U16 もあります。) これらは普通は正確に 32 ビットと 16 ビットですが、Cray では両方とも 64 ビットです。 (SV に対する作業) An SV can be created and loaded with one command. There are five types of values that can be loaded: an integer value (IV), an unsigned integer value (UV), a double (NV), a string (PV), and another scalar (SV). SV は、1 つのコマンドで生成し、値をロードすることができます。 ロードできる値の型には、整数 (IV)、符号なし整数 (UV)、 倍精度 (NV)、文字列 (PV)、その他のスカラ (SV) があります。 The seven routines are: これらを行なう、7 つのルーチンは: STRLEN is an integer type (Size_t, usually defined as size_t in config.h) guaranteed to be large enough to represent the size of any string that perl can handle. STRLEN は perl が扱えるどんな文字列のサイズも表現するのに十分なだけの 大きさを持つことが保証されている整数型(Size_t, 普通は config.h で size_t として定義されています)。 In the unlikely case of a SV requiring more complex initialisation, you can create an empty SV with newSV(len). If len is 0 an empty SV of type NULL is returned, else an SV of type PV is returned with len + 1 (for the NUL) bytes of storage allocated, accessible via SvPVX. In both cases the SV has value undef. あまりなさそうですが、SV がもっと複雑な初期化を必要とする場合、 newSV(len) で空の SV も作成できます。 もし len が 0 なら、NULL 型の空の SV が返され、さもなければ PV 型の SV は、SvPVX でアクセスできる len + 1 (NUL のため) バイトの領域を 割り当てられて返されます。 両方の場合で、SV の値は未定義値です。 To change the value of an already-existing SV, there are eight routines: 既に存在する スカラの値を変更するために 8 つのルーチンがあります: Notice that you can choose to specify the length of the string to be assigned by using sv_setpvn, newSVpvn, or newSVpv, or you may allow Perl to calculate the length by using sv_setpv or by specifying 0 as the second argument to newSVpv. Be warned, though, that Perl will determine the string's length by using strlen, which depends on the string terminating with a NUL character. 代入すべき文字列の長さを sv_setpvn や newSVpv、あるいは newSVpv を使って指定することもできますし、sv_setpv を使ったり newSVpv の第二引数に 0 を指定することによって、Perl 自身に 文字列の長さを計算させることもできます。 ただし Perl は、NUL 文字で終了することに依存している strlen を使って長さを計算しているということに注意してください。 The arguments of sv_setpvf are processed like sprintf, and the formatted output becomes the value. sv_setpvf の引数は sprintf と同じように処理され、書式化された 出力が値となります。 sv_vsetpvfn is an analogue of vsprintf, but it allows you to specify either a pointer to a variable argument list or the address and length of an array of SVs. The last argument points to a boolean; on return, if that boolean is true, then locale-specific information has been used to format the string, and the string's contents are therefore untrustworthy (see perlsec). This pointer may be NULL if that information is not important. Note that this function requires you to specify the length of the format. sv_vsetpvfn は vsprintf と同じようなものですが、 可変引数リストに対するポインタか SV の配列のアドレスと長さのいずれかを指定することができます。 最後の引数はブール値を指し示します。 関数から返ってきたときに これが true であれば、フォーマット文字列としてロカール固有の 情報が使われているのでその文字列の内容は信頼するできないことを 表わしています(perlsec を参照)。 ロカールに関する情報が重要でないのなら、 このポインタは NULL であってもかまいません。 この関数はフォーマットの長さを要求していることに注意してください。 The sv_set*() functions are not generic enough to operate on values that have "magic". See Magic Virtual Tables later in this document. sv_set*() 関数群は“magic”を持っている値に対する 操作に対して充分に一般化されたものではありません。 後述する Magic Virtual Tables を参照してください。 All SVs that contain strings should be terminated with a NUL character. If it is not NUL-terminated there is a risk of core dumps and corruptions from code which passes the string to C functions or system calls which expect a NUL-terminated string. Perl's own functions typically add a trailing NUL for this reason. Nevertheless, you should be very careful when you pass a string stored in an SV to a C function or system call. すべてのSV は、必須と言うわけではありませんが NUL キャラクターで 終端されているべきです。 この終端の NUL が無かった場合、コアダンプしたり文字列を (文字列が NUL で終端されていることを期待している) C 関数やシステムコールに 渡すコードをおかしくする危険があります。 Perl 自身の典型的な関数は、この理由により終端に NUL を追加します。 そうであったとしても、あなたが SV に格納されている文字列を C の関数や システムコールに渡す時には十二分に気をつけるべきなのです。 To access the actual value that an SV points to, you can use the macros: SV が指し示す実際の値をアクセスするには、以下のマクロを使えます: which will automatically coerce the actual scalar type into an IV, UV, double, or string. これは実際のスカラの型を自動的にに IV や UV や倍精度や文字列にします。 In the SvPV macro, the length of the string returned is placed into the variable len (this is a macro, so you do not use &len). If you do not care what the length of the data is, use the SvPV_nolen macro. Historically the SvPV macro with the global variable PL_na has been used in this case. But that can be quite inefficient because PL_na must be accessed in thread-local storage in threaded Perl. In any case, remember that Perl allows arbitrary strings of data that may both contain NULs and might not be terminated by a NUL. SvPV マクロでは、返される文字列の長さは、変数 len に格納されます (これはマクロですから、&len と しないで ください)。 もしデータの長さを気にしないのであれば、SvPV_nolen マクロを 使ってください。 歴史的に、この場合にはグローバル変数 PL_na に SvPV マクロが 使われてきました。 しかしこれは可能ですが効率は良くありません; なぜなら PL_na はスレッド化した Perl ではスレッドローカルな 領域にアクセスしなければならないからです。 いずれの場合にも、Perl は NUL を含んでいる文字列と NUL で 終端されていないような文字列の両方を扱うことができるということを 覚えておいてください。 Also remember that C doesn't allow you to safely say foo(SvPV(s, len), len);. It might work with your compiler, but it won't work for everyone. Break this sort of statement up into separate assignments: 同様に、Cで SvPV(s, len), len) とすることが安全ではないことを 忘れないでください。 これはあなたの使うコンパイラによってはうまくいきますが、 いつでもそうだとは限らないのです。 そこで、こういったステートメントは以下のように分割します: If you want to know if the scalar value is TRUE, you can use: 単にスカラ値が真かどうかを知りたいだけならば、 Although Perl will automatically grow strings for you, if you need to force Perl to allocate more memory for your SV, you can use the macro Perl は、SV にもっとメモリを割り当てて欲しいときには自動的に文字列を 大きくしてくれますが、さらにメモリを割り当てさせることが必要であれば which will determine if more memory needs to be allocated. If so, it will call the function sv_grow. Note that SvGROW can only increase, not decrease, the allocated memory of an SV and that it does not automatically add a byte for the a trailing NUL (perl's own string functions typically do SvGROW(sv, len + 1)). というマクロが使えます。 もし必要なら、このマクロが sv_growを呼びます。 SvGROW は SV に割り当てたメモリを増やすだけで、減らすことは できないということと、終端の NUL の分のバイトが自動的に加算されない (perl自身の文字列関数は 大概 SvGROW(sv, len + 1) としています)と いうことに注意してください。 If you have an SV and want to know what kind of data Perl thinks is stored in it, you can use the following macros to check the type of SV you have. 手元にある SV の、 Perl から見たデータの種類を知りたいときには、 その SV の型をチェックするのに You can get and set the current length of the string stored in an SV with the following macros: SV に納められた文字列の現在の長さを取得したり設定したりするのに は以下のマクロが使えます。 You can also get a pointer to the end of the string stored in the SV with the macro: 同様に、SV に格納されている文字列の終端へのポインタを以下のマクロを 使って得ることができます。 But note that these last three macros are valid only if SvPOK() is true. ただし、これらは SvPOK() が真のときだけ有効だということに気を つけてください。 If you want to append something to the end of string stored in an SV*, you can use the following functions: SV* に格納されている文字列の末尾になにかを追加したいときに以下のような 関数が使えます。 The first function calculates the length of the string to be appended by using strlen. In the second, you specify the length of the string yourself. The third function processes its arguments like sprintf and appends the formatted output. The fourth function works like vsprintf. You can specify the address and length of an array of SVs instead of the va_list argument. The fifth function extends the string stored in the first SV with the string stored in the second SV. It also forces the second SV to be interpreted as a string. 最初の関数は strlen を使って追加する文字列の長さを計算します。 二番目の関数では、関数を使用する人が文字列の長さを指定します。 三番目の関数はその引数を sprintf の様に処理し、整形された結果を 追加します。 四番目の関数は vsprintf のように動作します。 va_list 引数の代わりに、SV の配列のアドレスと長さを指定することが できます。 五番目の関数は最初の SV にある文字列を二番目の SV にある文字列で 拡張します。 また、この関数は二番目の SV を強制的に文字列として解釈します。 The sv_cat*() functions are not generic enough to operate on values that have "magic". See Magic Virtual Tables later in this document. sv_cat*() 関数群は“magic”を持っている値に対する 操作に対して充分に一般化されたものではありません。 後述する Magic Virtual Tables を参照してください。 If you know the name of a scalar variable, you can get a pointer to its SV by using the following: スカラ変数の名前がわかれば、その SV へのポインタは This returns NULL if the variable does not exist. を使って得ることができます。 その変数が存在しない場合には NULL が返されます。 If you want to know if this variable (or any other SV) is actually defined, you can call: その変数 (もしくは他の任意の SV) が、実際に 定義されているか を 知りたいならば、 The scalar undef value is stored in an SV instance called PL_sv_undef. スカラの undef 値は、PL_sv_undef という SV のインスタンスに 納められています。 Its address can be used whenever an SV* is needed. Make sure that you don't try to compare a random sv with &PL_sv_undef. For example when interfacing Perl code, it'll work correctly for: そのアドレスは、SV* が必要とされるところで使用することができます。 任意の sv を &PL_sv_undef を比較しようとしないように気をつけてください。 例えば、Perl コードとのインターフェースで、以下は正しく動きます: But won't work when called as: しかし、以下のように呼び出すと動作しません: So to repeat always use SvOK() to check whether an sv is defined. 従って、sv が定義されているかをチェックするために、毎回繰り返して SvOK() を使ってください。 Also you have to be careful when using &PL_sv_undef as a value in AVs or HVs (see AVs, HVs and undefined values). また、AV や HV の値として &PL_sv_undef を使うときにも 注意しなければなりません (AVs, HVs and undefined values を 参照してください)。 There are also the two values PL_sv_yes and PL_sv_no, which contain boolean TRUE and FALSE values, respectively. Like PL_sv_undef, their addresses can be used whenever an SV* is needed. ブール値の真と偽を表わす、PL_sv_yes や PL_sv_no という値もあります。 PL_sv_undef と同様に、これらのアドレスも SV* が必要なところで 使うことができます。 Do not be fooled into thinking that (SV *) 0 is the same as &PL_sv_undef. Take this code: (SV *0) と &PL_sv_undef が同じであると考えて、だまされてはいけません。 次のようなコードを見てください: This code tries to return a new SV (which contains the value 42) if it should return a real value, or undef otherwise. Instead it has returned a NULL pointer which, somewhere down the line, will cause a segmentation violation, bus error, or just weird results. Change the zero to &PL_sv_undef in the first line and all will be well. このコードは、実値を返さなければならないときには、(値として 42 を 持つ) 新しい SV を返そうとし、さもなくば undef を返そうとします。 ですが、どこかの行でナルポインタを返して、セグメントバイオレーションが 起こるか、何かおかしな結果になってしまいます。 最初の行の 0 を &PL_sv_undef に変えれば、すべてがうまくいきます。 To free an SV that you've created, call SvREFCNT_dec(SV*). Normally this call is not necessary (see Reference Counts and Mortality). 生成した SV を解放するためには、SvREFCNT_dec(SV*) を呼びます。 普通は、この呼び出しは必要ありません。 Reference Counts and Mortality を参照してください。 (オフセット) Perl provides the function sv_chop to efficiently remove characters from the beginning of a string; you give it an SV and a pointer to somewhere inside the PV, and it discards everything before the pointer. The efficiency comes by means of a little hack: instead of actually removing the characters, sv_chop sets the flag OOK (offset OK) to signal to other functions that the offset hack is in effect, and it puts the number of bytes chopped off into the IV field of the SV. It then moves the PV pointer (called SvPVX) forward that many bytes, and adjusts SvCUR and SvLEN. Perl provides the function sv_chop to efficiently remove characters from the beginning of a string; you give it an SV and a pointer to somewhere inside the PV, and it discards everything before the pointer. The efficiency comes by means of a little hack: instead of actually removing the characters, sv_chop sets the flag OOK (offset OK) to signal to other functions that the offset hack is in effect, and it puts the number of bytes chopped off into the IV field of the SV. It then moves the PV pointer (called SvPVX) forward that many bytes, and adjusts SvCUR and SvLEN. (TBT) Hence, at this point, the start of the buffer that we allocated lives at SvPVX(sv) - SvIV(sv) in memory and the PV pointer is pointing into the middle of this allocated storage. Hence, at this point, the start of the buffer that we allocated lives at SvPVX(sv) - SvIV(sv) in memory and the PV pointer is pointing into the middle of this allocated storage. (TBT) This is best demonstrated by example: これは例による最良の実演です: Here the number of bytes chopped off (1) is put into IV, and Devel::Peek::Dump helpfully reminds us that this is an offset. The portion of the string between the "real" and the "fake" beginnings is shown in parentheses, and the values of SvCUR and SvLEN reflect the fake beginning, not the real one. Here the number of bytes chopped off (1) is put into IV, and Devel::Peek::Dump helpfully reminds us that this is an offset. The portion of the string between the "real" and the "fake" beginnings is shown in parentheses, and the values of SvCUR and SvLEN reflect the fake beginning, not the real one. (TBT) Something similar to the offset hack is performed on AVs to enable efficient shifting and splicing off the beginning of the array; while AvARRAY points to the first element in the array that is visible from Perl, AvALLOC points to the real start of the C array. These are usually the same, but a shift operation can be carried out by increasing AvARRAY by one and decreasing AvFILL and AvLEN. Again, the location of the real start of the C array only comes into play when freeing the array. See av_shift in av.c. Something similar to the offset hack is performed on AVs to enable efficient shifting and splicing off the beginning of the array; while AvARRAY points to the first element in the array that is visible from Perl, AvALLOC points to the real start of the C array. These are usually the same, but a shift operation can be carried out by increasing AvARRAY by one and decreasing AvFILL and AvLEN. Again, the location of the real start of the C array only comes into play when freeing the array. See av_shift in av.c. (TBT) (SV に実際に格納されているものは何ですか?) Recall that the usual method of determining the type of scalar you have is to use Sv*OK macros. Because a scalar can be both a number and a string, usually these macros will always return TRUE and calling the Sv*V macros will do the appropriate conversion of string to integer/double or integer/double to string. 自分で保持しているスカラの型を決定する通常の方法は、マクロ Sv*OK を 使うものでした。 スカラは数値にも文字列にもなり得ますから、普通、 これらのマクロはいつも真を返します。 そして Sv*V マクロを呼ぶことで、 文字列から整数/倍精度、整数/倍精度から文字列への変換を行ないます。 If you really need to know if you have an integer, double, or string pointer in an SV, you can use the following three macros instead: もし、本当に SV にあるのが整数か、倍精度か、文字列ポインタかを 知りたいのであれば、 These will tell you if you truly have an integer, double, or string pointer stored in your SV. The "p" stands for private. というマクロを代わりに使うことができます。 これらのマクロは、実際に SV に入っているものが整数か、倍精度か、 文字列ポインタかを教えてくれます。 The are various ways in which the private and public flags may differ. For example, a tied SV may have a valid underlying value in the IV slot (so SvIOKp is true), but the data should be accessed via the FETCH routine rather than directly, so SvIOK is false. Another is when numeric conversion has occurred and precision has been lost: only the private flag is set on 'lossy' values. So when an NV is converted to an IV with loss, SvIOKp, SvNOKp and SvNOK will be set, while SvIOK wont be. The are various ways in which the private and public flags may differ. For example, a tied SV may have a valid underlying value in the IV slot (so SvIOKp is true), but the data should be accessed via the FETCH routine rather than directly, so SvIOK is false. Another is when numeric conversion has occurred and precision has been lost: only the private flag is set on 'lossy' values. So when an NV is converted to an IV with loss, SvIOKp, SvNOKp and SvNOK will be set, while SvIOK wont be. (TBT) In general, though, it's best to use the Sv*V macros. しかし一般的には、Sv*V マクロを使うだけにした方が良いでしょう。 (AV に対する作業) There are two ways to create and load an AV. The first method creates an empty AV: AV を生成して値を設定するのには、二つの方法があります。 最初の方法は、単に空の AV を作るものです: The second method both creates the AV and initially populates it with SVs: ふたつめの方法は、AV を生成した上で、初期値として SV の値を入れます: The second argument points to an array containing num SV*'s. Once the AV has been created, the SVs can be destroyed, if so desired. 二番目の引数は num 個の SV* の配列を指しています。 AV が生成されてしまえば、SV は(それを望むのなら)破棄することができます。 Once the AV has been created, the following operations are possible on AVs: いったん AV が生成されると、AV に対して、 These should be familiar operations, with the exception of av_unshift. This routine adds num elements at the front of the array with the undef value. You must then use av_store (described below) to assign values to these new elements. といった操作が行えます。 これらは、av_unshift を除いては、お馴染みの演算でしょう。 av_unshift は、配列の先頭に num 個の undef 値の要素を付け加えます。 その後で、(後述する) av_store を使って新しい要素に値を 代入しなければなりません。 Here are some other functions: 他にもいくつか関数があります: The av_len function returns the highest index value in array (just like $#array in Perl). If the array is empty, -1 is returned. The av_fetch function returns the value at index key, but if lval is non-zero, then av_fetch will store an undef value at that index. The av_store function stores the value val at index key, and does not increment the reference count of val. Thus the caller is responsible for taking care of that, and if av_store returns NULL, the caller will have to decrement the reference count to avoid a memory leak. Note that av_fetch and av_store both return SV**'s, not SV*'s as their return value. 関数 av_len は配列における最高位の添え字を(ちょうど Perl の $#array と 同じように)返します。 もし配列が空であれば、-1 を返します。 関数 av_fetch は添え字 key の位置にある値を返しますが、lval が 非ゼロであれば、av_fetch はその位置に undef を格納しようとします。 関数 av_store は添え字 key の位置に値 val を格納し、val の 参照カウントをインクリメントしません。 従って、呼び出し側はこの振る舞いに注意して対処し、av_store が NULL を返した場合には、メモリリークを防ぐために参照カウントの デクリメントを行う必要があるでしょう。 av_fetch と av_store の両方ともがその戻り値として SV* ではなく、SV** を返すということに注意してください。 The av_clear function deletes all the elements in the AV* array, but does not actually delete the array itself. The av_undef function will delete all the elements in the array plus the array itself. The av_extend function extends the array so that it contains at least key+1 elements. If key+1 is less than the currently allocated length of the array, then nothing is done. 関数 av_clear は、配列 AV* にあるすべての要素を削除しますが、 配列自身の削除は行いません。 関数 av_undef は配列にあるすべての要素に加え、配列自身の削除も行います。 関数 av_extend は配列を key+1 要素だけ拡張します。 key+1 が配列のその時点での長さより短ければ、何も行なわれません。 If you know the name of an array variable, you can get a pointer to its AV by using the following: 配列変数の名前がわかっているのであれば、次のようにしてその配列に 対応する AV へのポインタを得ることができます。 This returns NULL if the variable does not exist. これは変数が存在していない場合には NULL を返します。 See Understanding the Magic of Tied Hashes and Arrays for more information on how to use the array access functions on tied arrays. tie された配列における配列アクセス関数の使い方についての詳細は Understanding the Magic of Tied Hashes and Arrays を参照してください。 (HV に対する作業) To create an HV, you use the following routine: HV を生成するには、 Once the HV has been created, the following operations are possible on HVs: というルーチンを使います。 いったん HV が生成されると HV に対して、 The klen parameter is the length of the key being passed in (Note that you cannot pass 0 in as a value of klen to tell Perl to measure the length of the key). The val argument contains the SV pointer to the scalar being stored, and hash is the precomputed hash value (zero if you want hv_store to calculate it for you). The lval parameter indicates whether this fetch is actually a part of a store operation, in which case a new undefined value will be added to the HV with the supplied key and hv_fetch will return as if the value had already existed. という操作が行えます。 引数 klen は、渡される key の長さです (Perl にキーの長さを計算させるために、klen> の値として 0 を渡すことは できないということに注意してください)。 引数 val は、設定されるスカラへの SV ポインタを入れ、hash は、 あらかじめ計算したハッシュ値 (hv_store に計算させる場合には、 ゼロ) です。 引数 lval で、このフェッチ操作が実はストア操作の一部であるかどうかを 示します。 ストア操作であれば、新たなundefind value が与えられた キーを伴って HV に追加され、hv_fetch はその値が既に 存在していたかのようにリターンします。 Remember that hv_store and hv_fetch return SV**'s and not just SV*. To access the scalar value, you must first dereference the return value. However, you should check to make sure that the return value is not NULL before dereferencing it. hv_store や hv_fetch は、SV** を返すもので、SV* ではないことに 注意してください。 スカラ値をアクセスするには、まず戻り値の参照外し(dereference)をする 必要があります。 しかし、その前に返却値が NULL でないことを確認すべきです。 These two functions check if a hash table entry exists, and deletes it. ハッシュテーブルのエントリが存在するかをチェックし、削除を行う 関数があります。 If flags does not include the G_DISCARD flag then hv_delete will create and return a mortal copy of the deleted value. flag に G_DISCARD フラグが含まれていなければ、hv_delete は 削除された値の揮発性のコピー(mortal copy)を生成し、それを返します。 And more miscellaneous functions: さらに様々な関数があります: Like their AV counterparts, hv_clear deletes all the entries in the hash table but does not actually delete the hash table. The hv_undef deletes both the entries and the hash table itself. 引数に AV を取る似たような関数と同様、hv_clear はハッシュテーブルにある すべてのエントリーを削除しますがハッシュテーブル自身は削除しません。 hv_undef はエントリーとハッシュテーブル自身の両方を削除します。 Perl keeps the actual data in linked list of structures with a typedef of HE. These contain the actual key and value pointers (plus extra administrative overhead). The key is a string pointer; the value is an SV*. However, once you have an HE*, to get the actual key and value, use the routines specified below. Perl は実際のデータを HE と typedef された構造体のリンクリストを使って 保持しています。 これらは実際のキーと値のポインタ(それに加えて管理のための ちょっとしたもの)を保持しています。 キーは文字列へのポインタであり、値は SV* です。 しかしながら、一度 HE* を持てば、実際のキーと値とを取得するためには 以下に挙げるようなルーチンを使います。 If you know the name of a hash variable, you can get a pointer to its HV by using the following: 配列変数の名前がわかるのであれば、 This returns NULL if the variable does not exist. を使えば、その変数の HV へのポインタが得られます。 その変数が存在しない場合には NULL を返します。 The hash algorithm is defined in the PERL_HASH(hash, key, klen) macro: ハッシュアルゴリズムは PERL_HASH(hash, key, klen) というマクロで 定義されています。 > 5); /* after 5.6 */ ]]> The last step was added in version 5.6 to improve distribution of lower bits in the resulting hash value. 最後のステップは、結果となるハッシュ値の低位ビットの分散を改良するために バージョン 5.6 で追加されました。 See Understanding the Magic of Tied Hashes and Arrays for more information on how to use the hash access functions on tied hashes. tie されたハッシュに対するハッシュアクセス関数の使い方に 関する詳細は、Understanding the Magic of Tied Hashes and Arrays を 参照してください。 (ハッシュ API 拡張) Beginning with version 5.004, the following functions are also supported: バージョン 5.004 から、以下の関数がサポートされました。 Note that these functions take SV* keys, which simplifies writing of extension code that deals with hash structures. These functions also allow passing of SV* keys to tie functions without forcing you to stringify the keys (unlike the previous set of functions). これらの関数が、ハッシュ構造を扱うエクステンションの記述を単純にする SV* キーを引数にとることに注意してください。 これらの関数はまた、SV* キーを(先に挙げた関数群とは異なり) 文字列化することなしに tie 関数に渡すことを許しています。 They also return and accept whole hash entries (HE*), making their use more efficient (since the hash number for a particular string doesn't have to be recomputed every time). See perlapi for detailed descriptions. これらの関数はまた、ハッシュエントリー全体 (HE*) を返したり受け付けて、 より効率良く使用します(特定の文字列に対するハッシュ番号は 毎回計算しなおす必要はないからです)。 詳しくは perlapi を参照してください。 The following macros must always be used to access the contents of hash entries. Note that the arguments to these macros must be simple variables, since they may get evaluated more than once. See perlapi for detailed descriptions of these macros. 以下に挙げるマクロは、ハッシュエントリーの内容にアクセスするのに 常に使わなければならないものです。 これらのマクロはその引数を二度以上評価する可能性があるので、マクロに 対する引数は単純な変数でなければならないということに注意してください。 これらのマクロに関する詳細は perlapi を参照してください。 These two lower level macros are defined, but must only be used when dealing with keys that are not SV*s: 低レベルマクロが二つ定義されていますが、これらは SV* ではないキーを 扱うときにのみ使わなければならないものです。 Note that both hv_store and hv_store_ent do not increment the reference count of the stored val, which is the caller's responsibility. If these functions return a NULL value, the caller will usually have to decrement the reference count of val to avoid a memory leak. hv_store と hv_store_ent の両方ともが、val に格納されている 参照カウントのインクリメントをしないということに注意してください。 それは呼び出し側の責任です。 これらの関数が NULL を返した場合、 呼び出し側はメモリリークを防ぐために、val の参照カウントの デクリメントを行う必要が一般にはあるでしょう。 (AV, HV と未定義値) Sometimes you have to store undefined values in AVs or HVs. Although this may be a rare case, it can be tricky. That's because you're used to using &PL_sv_undef if you need an undefined SV. AV や HV に未定義値を保管しなければならないこともあります。 これは珍しい場合ですが、手の込んだものになります。 なぜなら、未定義の SV が必要なら、&PL_sv_undef を使うことになるからです。 For example, intuition tells you that this XS code: 例えば、直感ではこの XS コードは: is equivalent to this Perl code: 以下の Perl コードと等価です: Unfortunately, this isn't true. AVs use &PL_sv_undef as a marker for indicating that an array element has not yet been initialized. Thus, exists $av[0] would be true for the above Perl code, but false for the array generated by the XS code. 残念ながら、これは正しくありません。 AV は、配列要素がまだ初期化されていないことを示すための印として &PL_sv_undef を使います。 従って、上述の Perl コードは exists $av[0] は真ですが、 XS コードによって生成された配列では偽です。 Other problems can occur when storing &PL_sv_undef in HVs: HV に &PL_sv_undef を保管する時にも別の問題が起こりえます: This will indeed make the value undef, but if you try to modify the value of key, you'll get the following error: 実際これは undef 値を作りますが、key の値を変更しようとすると、 以下のようなエラーが出ます: In perl 5.8.0, &PL_sv_undef was also used to mark placeholders in restricted hashes. This caused such hash entries not to appear when iterating over the hash or when checking for the keys with the hv_exists function. In perl 5.8.0, &PL_sv_undef was also used to mark placeholders in restricted hashes. This caused such hash entries not to appear when iterating over the hash or when checking for the keys with the hv_exists function. (TBT) You can run into similar problems when you store &PL_sv_true or &PL_sv_false into AVs or HVs. Trying to modify such elements will give you the following error: You can run into similar problems when you store &PL_sv_true or &PL_sv_false into AVs or HVs. Trying to modify such elements will give you the following error: (TBT) To make a long story short, you can use the special variables &PL_sv_undef, &PL_sv_true and &PL_sv_false with AVs and HVs, but you have to make sure you know what you're doing. To make a long story short, you can use the special variables &PL_sv_undef, &PL_sv_true and &PL_sv_false with AVs and HVs, but you have to make sure you know what you're doing. (TBT) Generally, if you want to store an undefined value in an AV or HV, you should not use &PL_sv_undef, but rather create a new undefined value using the newSV function, for example: Generally, if you want to store an undefined value in an AV or HV, you should not use &PL_sv_undef, but rather create a new undefined value using the newSV function, for example: (TBT) (リファレンス) References are a special type of scalar that point to other data types (including references). リファレンスは、(リファレンスを含む) 他のスカラ型を指す特別な スカラ型です。 To create a reference, use either of the following functions: リファレンスを生成するには、 The thing argument can be any of an SV*, AV*, or HV*. The functions are identical except that newRV_inc increments the reference count of the thing, while newRV_noinc does not. For historical reasons, newRV is a synonym for newRV_inc. thing には、SV*, AV*, HV* のいずれかを置くことができます。 これら二つの関数は、newRV_inc が thing の参照カウントを インクリメントするが newRV_noinc はインクリメントしないという点を 除き、同一です。 歴史的な理由により、newRV は newRV_inc の同義語となっています。 Once you have a reference, you can use the following macro to dereference the reference: リファレンスができれば、以下のマクロを使ってリファレンスの参照外し (dereference)ができます。 then call the appropriate routines, casting the returned SV* to either an AV* or HV*, if required. というマクロが使うことができ、返された SV* を AV* か HV* に キャストして、適切なルーチンを呼ぶことになります。 To determine if an SV is a reference, you can use the following macro: SV がリファレンスであるかどうかを確認するために、 以下のマクロを使うことができます。 To discover what type of value the reference refers to, use the following macro and then check the return value. リファレンスが参照している型を見つけるために、以下のマクロを 使いその戻り値をチェックします。 The most useful types that will be returned are: 戻り値として返される型で有益なものは以下の通りです。 (bless されたリファレンスとクラスオブジェクト) References are also used to support object-oriented programming. In perl's OO lexicon, an object is simply a reference that has been blessed into a package (or class). Once blessed, the programmer may now use the reference to access the various methods in the class. リファレンスはオブジェクト指向プログラミングをサポートするためにも 使われます。 perl のオブジェクト指向用語では、オブジェクトとはパッケージ (もしくはクラス)に bless された単純なリファレンスです。 一度 bless されれば、プログラマーはそのリファレンスをクラスにおける様々な メソッドにアクセスするために使うことができます。 A reference can be blessed into a package with the following function: 以下の関数を使って、リファレンスをパッケージに bless することができます。 The sv argument must be a reference value. The stash argument specifies which class the reference will belong to. See Stashes and Globs for information on converting class names into stashes. 引数 sv はリファレンス値でなければなりません。 引数 stash はリファレンスが属するクラスを指定します。 クラス名のstashへの変換についての詳細は Stashes and Globs を 参照してください。 /* Still under construction */ /* Still under construction */ Upgrades rv to reference if not already one. Creates new SV for rv to point to. If classname is non-null, the SV is blessed into the specified class. SV is returned. まだ存在していなければ、rv をリファレンスにアップグレードします。 rv が指し示すための新たな SV を生成します。 classname がナルでなければ、SV は指定されたクラスに bless され、 SV が返されます。 Copies integer, unsigned integer or double into an SV whose reference is rv. SV is blessed if classname is non-null. 整数、符号なし整数、倍精度実数を rv が参照している SV へコピーします。 SV は classname がナルでなければblessされます。 Copies the pointer value (the address, not the string!) into an SV whose reference is rv. SV is blessed if classname is non-null. ポインタ値(アドレスであって、文字列ではありません!)を rv が 参照しているSVへコピーします。 SV は classname がナルでなければ bless されます。 Copies string into an SV whose reference is rv. Set length to 0 to let Perl calculate the string length. SV is blessed if classname is non-null. 文字列を rv が参照している SV へコピーします。 length に 0 を設定すると、Perl が文字列の長さを計算します。 SV は classname がナルでなければ bless されます。 Tests whether the SV is blessed into the specified class. It does not check inheritance relationships. SV が特定のクラスに bless されているかどうかを検査します。 これは継承の関係のチェックはしません。 Tests whether the SV is a reference to a blessed object. SV が bless されたオブジェクトのリファレンスであるかどうかを検査します。 Tests whether the SV is derived from the specified class. SV can be either a reference to a blessed object or a string containing a class name. This is the function implementing the UNIVERSAL::isa functionality. SV が特定のクラスから派生したものがどうかを検査します。 SV は bless されたオブジェクトのリファレンスでも、 クラス名を保持している文字列であってもかまいません。 これは UNIVERSAL::isa の機能を実装している関数です。 To check if you've got an object derived from a specific class you have to write: ある特定のクラスの派生オブジェクトを受け取ったかどうか検査するには、 以下のように書く必要があります。 (新しい変数の作成) To create a new Perl variable with an undef value which can be accessed from your Perl script, use the following routines, depending on the variable type. undef という値を持つあなたの Perl スクリプトからアクセスできる新たな Perl の変数を生成するには、以下に示すルーチンを変数の型に応じて 使います。 Notice the use of TRUE as the second parameter. The new variable can now be set, using the routines appropriate to the data type. 二番目のパラメータとして TRUE を使っているということに注意してください。 新しい変数はここでデータ型に対する適切なルーチンを使うことで 設定することができます。 There are additional macros whose values may be bitwise OR'ed with the TRUE argument to enable certain extra features. Those bits are: TRUE 引数とビット和を取って、幾つかの追加機能を有効とするような 二つのマクロがあります。 GV_ADDMULTI Marks the variable as multiply defined, thus preventing the: 変数に多重定義 (multiply defined) であると印を付け: used only once: possible typo ]]> warning. 警告を防ぎます。 GV_ADDWARN Issues the warning: 以下の警告を: unexpectedly ]]> if the variable did not exist before the function was called. 変数が、その関数の呼び出し以前に存在してなかった場合に発生させます。 If you do not specify a package name, the variable is created in the current package. パッケージ名を指定しなかった場合、変数はカレントパッケージで 生成されます。 (参照カウントと揮発性) Perl uses a reference count-driven garbage collection mechanism. SVs, AVs, or HVs (xV for short in the following) start their life with a reference count of 1. If the reference count of an xV ever drops to 0, then it will be destroyed and its memory made available for reuse. Perl は参照カウント駆動(reference count-driven)のガベージコレクション 機構を使用しています。 SV、AV、そしてHV(以下 xV と省略します) はその一生を参照カウント 1 から始めます。 xV の参照カウントが0まで落ちた場合、そのリファレンスは破棄されて、 それが使っていたメモリは 再利用できるようにされます。 This normally doesn't happen at the Perl level unless a variable is undef'ed or the last variable holding a reference to it is changed or overwritten. At the internal level, however, reference counts can be manipulated with the following macros: これは、Perl レベルにおいては、変数が undef されるとかリファレンスを 保持している最後の変数が変更されたとか上書きされるということがない限りは 起こりません。 しかし内部的には、参照カウントは以下に挙げるマクロを使って 操作することができます。 However, there is one other function which manipulates the reference count of its argument. The newRV_inc function, you will recall, creates a reference to the specified argument. As a side effect, it increments the argument's reference count. If this is not what you want, use newRV_noinc instead. その引数の参照カウントを操作する別の関数が一つあります。 newRV_inc という関数がそれです。 これは指定された引数の参照を生成して、その副作用として引数の 参照カウントをインクリメントします。 もしこの副作用が邪魔であれば、newRV_noinc を代わりに使ってください。 For example, imagine you want to return a reference from an XSUB function. Inside the XSUB routine, you create an SV which initially has a reference count of one. Then you call newRV_inc, passing it the just-created SV. This returns the reference as a new SV, but the reference count of the SV you passed to newRV_inc has been incremented to two. Now you return the reference from the XSUB routine and forget about the SV. But Perl hasn't! Whenever the returned reference is destroyed, the reference count of the original SV is decreased to one and nothing happens. The SV will hang around without any way to access it until Perl itself terminates. This is a memory leak. たとえば、XSUB 関数からリファレンスを返したいと思ったとしましょう。 XSUB ルーチンの中で、初期値として参照カウント 1 を持つ SV を生成します。 それから今作成した SV を引数にして newRV_inc を呼びます。 これは新たな SV としての参照を返しますが、newRV_inc に引数として渡した SV の参照カウントは 2 にインクリメントされます。 ここで XSUB ルーチンからそのリファレンスを戻り値として返し、SV のことは 忘れましょう。 けれども Perl は忘れてません! 戻り値で返されたリファレンスが破棄されたときにはいつも、元々の SV の 参照カウントが 1 へと減じられ、そして何事もおこりません。 その SV は、Perl 自身が終了するまではそれにアクセスするなんの手段も 持たずに中ぶらりんになります。 The correct procedure, then, is to use newRV_noinc instead of newRV_inc. Then, if and when the last reference is destroyed, the reference count of the SV will go to zero and it will be destroyed, stopping any memory leak. ここでの正しい手順は、newRV_inc ではなく newRV_noinc を 使うということです。 これによって、最後のリファレンスが破棄されたときに SV のリファレンスカウントは0となってその SV が破棄されて、メモリ リークを食い止めます。 There are some convenience functions available that can help with the destruction of xVs. These functions introduce the concept of "mortality". An xV that is mortal has had its reference count marked to be decremented, but not actually decremented, until "a short time later". Generally the term "short time later" means a single Perl statement, such as a call to an XSUB function. The actual determinant for when mortal xVs have their reference count decremented depends on two macros, SAVETMPS and FREETMPS. See perlcall and perlxs for more details on these macros. xV を破棄するのを助けるような便利な関数が幾つかあります。 これらの関数は「揮発性」(mortality) のコンセプトを導入します。 ある揮発性の xV はその参照カウントをデクリメントするようにマークしますが、 実際には「ちょっと後」(a short time later)までデクリメントが 行なわれません。 一般的には、「ちょっと後」とは、XSUB 関数の呼び出しのような Perl の一つの文です。 揮発性の xV が持っている参照カウントの デクリメントを行うタイミングの決定は二つのマクロ、SAVETMPS と FREETMPS に依存しています。 これら二つのマクロについての説明は perlcall と perlxs を参照してください。 "Mortalization" then is at its simplest a deferred SvREFCNT_dec. However, if you mortalize a variable twice, the reference count will later be decremented twice. 「揮発化」("Mortalization") はそれから、SvREFCNT_dec に決定権を委ねます。 しかし、ある変数を二度揮発的にした場合、その参照カウントは後で 二度デクリメントされます。 "Mortal" SVs are mainly used for SVs that are placed on perl's stack. For example an SV which is created just to pass a number to a called sub is made mortal to have it cleaned up automatically when it's popped off the stack. Similarly, results returned by XSUBs (which are pushed on the stack) are often made mortal. 「揮発性」SVs は主に、perl のスタックに置かれる SV に対して使われます。 For example an SV which is created just to pass a number to a called sub is made mortal to have it cleaned up automatically when it's popped off the stack. Similarly, results returned by XSUBs (which are pushed on the stack) are often made mortal. (TBT) To create a mortal variable, use the functions: 揮発性の変数を生成するには、以下の関数を使います: The first call creates a mortal SV (with no value), the second converts an existing SV to a mortal SV (and thus defers a call to SvREFCNT_dec), and the third creates a mortal copy of an existing SV. Because sv_newmortal gives the new SV no value,it must normally be given one via sv_setpv, sv_setiv, etc. : 最初のものは(値のない)揮発性の SV を生成し、ふたつめは既にある SV を 揮発性の SV に変換します(そして、このために SvREFCNT_dec を呼び出しを 遅らせます)。 三つめは、既に存在する SV の揮発性のコピーを生成します。 sv_newmortal は値のない新しい SV を作るので、普通は sv_setpv, sv_setiv などを使って作らなければなりません: As that is multiple C statements it is quite common so see this idiom instead: これは C の複数文なので、代わりにこの慣用法がとても一般的です: You should be careful about creating mortal variables. Strange things can happen if you make the same value mortal within multiple contexts, or if you make a variable mortal multiple times. Thinking of "Mortalization" as deferred SvREFCNT_dec should help to minimize such problems. For example if you are passing an SV which you know has high enough REFCNT to survive its use on the stack you need not do any mortalization. If you are not sure then doing an SvREFCNT_inc and sv_2mortal, or making a sv_mortalcopy is safer. 揮発性の変数を生成するに当たっては十分注意すべきです。 もし、同じ変数を複合コンテキストの中で揮発性にしたり、ある変数を複数回 揮発性にしてしまったりすればおかしな自体が起こるかもしれません。 Thinking of "Mortalization" as deferred SvREFCNT_dec should help to minimize such problems. For example if you are passing an SV which you know has high enough REFCNT to survive its use on the stack you need not do any mortalization. If you are not sure then doing an SvREFCNT_inc and sv_2mortal, or making a sv_mortalcopy is safer. (TBT) The mortal routines are not just for SVs -- AVs and HVs can be made mortal by passing their address (type-casted to SV*) to the sv_2mortal or sv_mortalcopy routines. 揮発性のルーチンは、単に SV のためだけではありません。 AV や HV も、sv_2mortal や sv_mortalcopy ルーチンに、アドレスを (SV* にキャストして) 渡すことで、揮発性にすることができます。 (スタッシュとグロブ) A stash is a hash that contains all variables that are defined within a package. Each key of the stash is a symbol name (shared by all the different types of objects that have the same name), and each value in the hash table is a GV (Glob Value). This GV in turn contains references to the various objects of that name, including (but not limited to) the following: スタッシュ ("stash")とは、パッケージ内で定義された全ての変数が 入っているハッシュのことです。 ハッシュテーブルにあるそれぞれの key は、(同じ名前のすべての異なる型の オブジェクトで共有される) シンボル名で、ハッシュテーブルの個々の 値は、(グローバル値のための) GV と呼ばれます。 GV には、以下のものを含む (これらに限りませんが)、その名前の様々な オブジェクトへのリファレンスが次々に入ることになります。 There is a single stash called PL_defstash that holds the items that exist in the main package. To get at the items in other packages, append the string "::" to the package name. The items in the Foo package are in the stash Foo:: in PL_defstash. The items in the Bar::Baz package are in the stash Baz:: in Bar::'s stash. main パッケージにあるアイテムを保持する PL_defstash と呼ばれる スタッシュがあります。 他のパッケージにあるアイテムを取得するため には、パッケージ名に「::」を付加します。 Foo というパッケージにあるアイテムは Foo:: という PL_defstash の中にあります。 パッケージ Bar::Baz にあるアイテムは Bar:: のスタッシュの中の Baz:: のスタッシュの中にあります。 To get the stash pointer for a particular package, use the function: 特定のパッケージの HV ポインタの入手には、以下の関数が使えます: The first function takes a literal string, the second uses the string stored in the SV. Remember that a stash is just a hash table, so you get back an HV*. The flags flag will create a new package if it is set to GV_ADD. 最初の関数が、リテラル文字列をとり、二番目が SV に入れた文字列を使います。 stash は単なるハッシュなので、HV* を受け取るということを 忘れないでください。 flags フラグが GV_ADD にセットされている場合には新たなパッケージを 生成します。 The name that gv_stash*v wants is the name of the package whose symbol table you want. The default package is called main. If you have multiply nested packages, pass their names to gv_stash*v, separated by :: as in the Perl language itself. gv_stash*v が要求する name はシンボルテーブルを手に入れようとする パッケージの名前です。 デフォルトのパッケージは、main というものです。 多重にネストしたパッケージであれば、Perl での場合と同様に、 :: で区切って gv_stash*v に名前を渡すのが正しい方法です。 Alternately, if you have an SV that is a blessed reference, you can find out the stash pointer by using: あるいは、もし bless されたリファレンスである SV があれば、 以下のようにしてを使ってもスタッシュポインタを探すことができ: then use the following to get the package name itself: パッケージ名自身は、以下のようにして得られます: If you need to bless or re-bless an object you can use the following function: Perl スクリプトへ bless された値を返す必要があれば、以下の関数が使えます: where the first argument, an SV*, must be a reference, and the second argument is a stash. The returned SV* can now be used in the same way as any other SV. 最初の引数 SV* はリファレンスで、二番目の引数がスタッシュです。 返された SV* は、他の SV と同様に使うことができます。 For more information on references and blessings, consult perlref. リファレンスと bless についてのより詳しい情報は perlref を 参照してください。 (二重型 SV) Scalar variables normally contain only one type of value, an integer, double, pointer, or reference. Perl will automatically convert the actual scalar data from the stored type into the requested type. スカラ変数は通常、整数、倍精度、ポインタ、リファレンスのうちの いずれか一つの型をとります。 Perl は実際のデータに対して、蓄積されている型から要求されている型へ、 自動的に変換を行ないます。 Some scalar variables contain more than one type of scalar data. For example, the variable $! contains either the numeric value of errno or its string equivalent from either strerror or sys_errlist[]. ある種のスカラ変数は、複数の型のスカラデータを持つようになっています。 たとえば変数 $! は、errno の数値としての値と、 strerror や sys_errlist[] から得たのと同値な文字列を持っています。 To force multiple data values into an SV, you must do two things: use the sv_set*v routines to add the additional scalar type, then set a flag so that Perl will believe it contains more than one type of data. The four macros to set the flags are: SV に複数のデータ値を入れるようにするには、二つのことを しなくてはなりません。 スカラ型を別に追加するために sv_set*v ルーチンを使用すること。 それから、フラグを設定して Perl に複数のデータを 持っていることを知らせることです。 フラグを設定するための四つのマクロは以下のものです: The particular macro you must use depends on which sv_set*v routine you called first. This is because every sv_set*v routine turns on only the bit for the particular type of data being set, and turns off all the rest. 使用するマクロは、最初にどの sv_set*v ルーチンを呼ぶのかに 関わってきます。 これは、sv_set*v ルーチンはすべて特定のデータ型のビットだけを 設定して、他をクリアしてしまうからです。 For example, to create a new Perl variable called "dberror" that contains both the numeric and descriptive string error values, you could use the following code: たとえば、"dberror" という新しい Perl 変数を作って、エラー値を数値と メッセージ文字列で持つようにするには、以下のように書きます: If the order of sv_setiv and sv_setpv had been reversed, then the macro SvPOK_on would need to be called instead of SvIOK_on. sv_setiv と sv_setpv の順序が逆であった場合、SvIOK_on マクロの 代わりに SvPOK_on マクロを呼ばなければなりません。 (マジック変数) [This section still under construction. Ignore everything here. Post no bills. Everything not permitted is forbidden.] [This section still under construction. Ignore everything here. Post no bills. Everything not permitted is forbidden.] (TBT) Any SV may be magical, that is, it has special features that a normal SV does not have. These features are stored in the SV structure in a linked list of struct magic's, typedef'ed to MAGIC. すべての SV は magical、つまり、通常の SV が持っていないような特殊な 属性を持つようにすることができます。 これらの属性は MAGIC として typedef されている struct magic の リンクリストにある SV 構造体に格納されます。 Note this is current as of patchlevel 0, and could change at any time. これは、パッチレベル 0 の時点でのものです。 変更される可能性があります。 (マジックの代入) Perl adds magic to an SV using the sv_magic function: Perl は sv_magic 関数を使った SV にマジックを追加します。 The sv argument is a pointer to the SV that is to acquire a new magical feature. 引数 sv は、新たにマジック機能を獲得する SV へのポインタです。 If sv is not already magical, Perl uses the SvUPGRADE macro to convert sv to type SVt_PVMG. Perl then continues by adding new magic to the beginning of the linked list of magical features. Any prior entry of the same type of magic is deleted. Note that this can be overridden, and multiple instances of the same type of magic can be associated with an SV. sv がまだマジカルでなければ、Perl は sv を SVt_PVMG に変換 するために SvUPGRADE を使います。 Perl はそれから、マジック機能のリンクリストの先頭にそれを追加します。 以前に存在していた同じタイプのマジックは削除されます。 これはオーバーライドすることができ、 複数の同じ型のマジックのインスタンスを一つの SV に 結び付けることができるということに注意してください。 The name and namlen arguments are used to associate a string with the magic, typically the name of a variable. namlen is stored in the mg_len field and if name is non-null then either a savepvn copy of name or name itself is stored in the mg_ptr field, depending on whether namlen is greater than zero or equal to zero respectively. As a special case, if (name && namlen == HEf_SVKEY) then name is assumed to contain an SV* and is stored as-is with its REFCNT incremented. 引数 name と namlen はある文字列と magic とを結び付けるために 使われます。 典型的には変数の名前です。 namlen は mg_len フィールドに格納され、name がヌルなら、 name の savepvn コピーか、name 自身 is stored in the mg_ptr field, depending on whether namlen is greater than zero or equal to zero respectively. As a special case, if (name && namlen == HEf_SVKEY) then name is assumed to contain an SV* and is stored as-is with its REFCNT incremented. (TBT) The sv_magic function uses how to determine which, if any, predefined "Magic Virtual Table" should be assigned to the mg_virtual field. See the Magic Virtual Tables section below. The how argument is also stored in the mg_type field. The value of how should be chosen from the set of macros PERL_MAGIC_foo found in perl.h. Note that before these macros were added, Perl internals used to directly use character literals, so you may occasionally come across old code or documentation referring to 'U' magic rather than PERL_MAGIC_uvar for example. 関数 sv_magic は how を、あらかじめ定義されている マジック仮想テーブル("Magic Virtual Table") のどれを mg_virtual フィールドに設定するかを決定するのに使います。 See the Magic Virtual Tables section below. The how argument is also stored in the mg_type field. The value of how should be chosen from the set of macros PERL_MAGIC_foo found in perl.h. Note that before these macros were added, Perl internals used to directly use character literals, so you may occasionally come across old code or documentation referring to 'U' magic rather than PERL_MAGIC_uvar for example. (TBT) The obj argument is stored in the mg_obj field of the MAGIC structure. If it is not the same as the sv argument, the reference count of the obj object is incremented. If it is the same, or if the how argument is PERL_MAGIC_arylen, or if it is a NULL pointer, then obj is merely stored, without the reference count being incremented. 引数 obj は MAGIC 構造体の mg_obj フィールドに格納されます。 これが sv 引数と同じでなかった場合、obj の参照カウントは インクリメントされます。 同じであった場合、もしくは引数 how が PERL_MAGIC_arylen かナルポインタであった場合には、obj は 参照カウントのインクリメントをさせることなく格納されます。 See also sv_magicext in perlapi for a more flexible way to add magic to an SV. SV にマジックを追加する、より柔軟な方法については perlapi の sv_magicext も参照してください。 There is also a function to add magic to an HV: 同様に HV にマジックを付加する関数があります。 This simply calls sv_magic and coerces the gv argument into an SV. これは単純に sv_magic を呼び出し、引数 gv を強制的に SV にします。 To remove the magic from an SV, call the function sv_unmagic: SV からマジックを取り除くには、sv_unmagic という関数を呼び出します。 The type argument should be equal to the how value when the SV was initially made magical. 引数 type は、SV が magical にされたときの how の値と同じに なるようにすべきです。 (マジック仮想テーブル) The mg_virtual field in the MAGIC structure is a pointer to an MGVTBL, which is a structure of function pointers and stands for "Magic Virtual Table" to handle the various operations that might be applied to that variable. MAGIC 構造体の mg_virtual フィールドは MGVTBL へのポインタで、 これは関数ポインタの構造体であり、また対応する変数に対して 適用される可能性のあるさまざまな操作を扱うための 「マジック仮想テーブル」("Magic Virtual Table") を意味しています。 The MGVTBL has five (or sometimes eight) pointers to the following routine types: MGVTBL は、以下に挙げる 5 種類(あるいは時々 8 種類)の ポインタを持っています。 This MGVTBL structure is set at compile-time in perl.h and there are currently 19 types (or 21 with overloading turned on). These different structures contain pointers to various routines that perform additional actions depending on which function is being called. この MGVTBL は perl.h の中でコンパイル時に設定され、現在 19 の型 (オーバーロード込みで 21)があります。 これらの異なった構造体は、関数が呼び出されたときに依存して 追加動作を行うような様々なルーチンへのポインタを保持しています。 For instance, the MGVTBL structure called vtbl_sv (which corresponds to an mg_type of PERL_MAGIC_sv) contains: たとえば、vtbl_sv (PERL_MAGIC_sv の mg_type に対応します)と 呼ばれる MGVTBL 構造体の内容は以下の様になっています。 Thus, when an SV is determined to be magical and of type PERL_MAGIC_sv, if a get operation is being performed, the routine magic_get is called. All the various routines for the various magical types begin with magic_. NOTE: the magic routines are not considered part of the Perl API, and may not be exported by the Perl library. したがって、ある SV がマジカルであると決定されてその型が PERL_MAGIC_sv であったとき、操作が実行されたならば、magic_get が 呼び出されます。 マジカル型に対するルーチンはすべて、magic_ で始まります。 NOTE: マジックルーチンは Perl API の一部として扱われず、 Perl ライブラリによってエクスポートされません。 The last three slots are a recent addition, and for source code compatibility they are only checked for if one of the three flags MGf_COPY, MGf_DUP or MGf_LOCAL is set in mg_flags. This means that most code can continue declaring a vtable as a 5-element value. These three are currently used exclusively by the threading code, and are highly subject to change. The last three slots are a recent addition, and for source code compatibility they are only checked for if one of the three flags MGf_COPY, MGf_DUP or MGf_LOCAL is set in mg_flags. This means that most code can continue declaring a vtable as a 5-element value. These three are currently used exclusively by the threading code, and are highly subject to change. (TBT) The current kinds of Magic Virtual Tables are: 現時点でのMagic Virtual Tables の種類は以下の通りです。 When an uppercase and lowercase letter both exist in the table, then the uppercase letter is typically used to represent some kind of composite type (a list or a hash), and the lowercase letter is used to represent an element of that composite type. Some internals code makes use of this case relationship. However, 'v' and 'V' (vec and v-string) are in no way related. テーブル中で大文字小文字の両方が存在していた場合、大文字は典型的には複合型 (リストもしくはハッシュ)の種類を表わすのに使われ、小文字はその複合型の 要素を表わすのに使われます。 内部コードにはこの大文字小文字の関係を使っているものもあります。 しかし、'v' と 'V' (ベクタと v-文字列) は全く関係がありません。 The PERL_MAGIC_ext and PERL_MAGIC_uvar magic types are defined specifically for use by extensions and will not be used by perl itself. Extensions can use PERL_MAGIC_ext magic to 'attach' private information to variables (typically objects). This is especially useful because there is no way for normal perl code to corrupt this private information (unlike using extra elements of a hash object). マジック型 PERL_MAGIC_ext と PERL_MAGIC_uvar は エクステンションから使われ、Perl 自身からは使われないように特別に 定義されています。 エクステンションは PERL_MAGIC_ext マジックを、 プライベート情報を変数(典型的なオブジェクト)に「アタッチ」(attach) するために使うことができます。 これは、通常の perl コードが(ハッシュオブジェクトの要素を使うのとは違って) そのプライベート情報を壊す恐れがないのでとても便利です。 Similarly, PERL_MAGIC_uvar magic can be used much like tie() to call a C function any time a scalar's value is used or changed. The MAGIC's mg_ptr field points to a ufuncs structure: Similarly, PERL_MAGIC_uvar magic can be used much like tie() to call a C function any time a scalar's value is used or changed. The MAGIC's mg_ptr field points to a ufuncs structure: (TBT) When the SV is read from or written to, the uf_val or uf_set function will be called with uf_index as the first arg and a pointer to the SV as the second. A simple example of how to add PERL_MAGIC_uvar magic is shown below. Note that the ufuncs structure is copied by sv_magic, so you can safely allocate it on the stack. When the SV is read from or written to, the uf_val or uf_set function will be called with uf_index as the first arg and a pointer to the SV as the second. A simple example of how to add PERL_MAGIC_uvar magic is shown below. Note that the ufuncs structure is copied by sv_magic, so you can safely allocate it on the stack. (TBT) Attaching PERL_MAGIC_uvar to arrays is permissible but has no effect. PERL_MAGIC_uvar を配列にアタッチすることは可能ですが、何の意味も ありません。 For hashes there is a specialized hook that gives control over hash keys (but not values). This hook calls PERL_MAGIC_uvar 'get' magic if the "set" function in the ufuncs structure is NULL. The hook is activated whenever the hash is accessed with a key specified as an SV through the functions hv_store_ent, hv_fetch_ent, hv_delete_ent, and hv_exists_ent. Accessing the key as a string through the functions without the ..._ent suffix circumvents the hook. See Hash::Util::Fieldhash/Guts for a detailed description. For hashes there is a specialized hook that gives control over hash keys (but not values). This hook calls PERL_MAGIC_uvar 'get' magic if the "set" function in the ufuncs structure is NULL. The hook is activated whenever the hash is accessed with a key specified as an SV through the functions hv_store_ent, hv_fetch_ent, hv_delete_ent, and hv_exists_ent. Accessing the key as a string through the functions without the ..._ent suffix circumvents the hook. See Hash::Util::Fieldhash/Guts for a detailed description. (TBT) Note that because multiple extensions may be using PERL_MAGIC_ext or PERL_MAGIC_uvar magic, it is important for extensions to take extra care to avoid conflict. Typically only using the magic on objects blessed into the same class as the extension is sufficient. For PERL_MAGIC_ext magic, it may also be appropriate to add an I32 'signature' at the top of the private data area and check that. 複数のエクステンションが PERL_MAGIC_ext や PERL_MAGIC_uvar マジックを 使う可能性があるので、エクステンションがそれを扱うには気をつけることが 重要であることに注意してください。 典型的には、これはオブジェクトをエクステンションが扱えるように同じクラスに bless するときにのみ使います。 PERL_MAGIC_ext マジックでは、これはまた、プライベートなデータ領域の 先頭においてそれをチェックするために I32「シグネチャ」(signature) を 付加するのに適切なものです。 Also note that the sv_set*() and sv_cat*() functions described earlier do not invoke 'set' magic on their targets. This must be done by the user either by calling the SvSETMAGIC() macro after calling these functions, or by using one of the sv_set*_mg() or sv_cat*_mg() functions. Similarly, generic C code must call the SvGETMAGIC() macro to invoke any 'get' magic if they use an SV obtained from external sources in functions that don't handle magic. See perlapi for a description of these functions. For example, calls to the sv_cat*() functions typically need to be followed by SvSETMAGIC(), but they don't need a prior SvGETMAGIC() since their implementation handles 'get' magic. sv_set*() と sv_cat*() といった関数群はそのターゲットに対して 'set' マジックを 起動しない ということにも注意してください。 これには、ユーザーが svSETMAGIC マクロを呼び出した後でこれらの関数を 呼び出すか、あるいは sv_set*_mg() か sv_cat*_mg() の何れかの関数を使わなければなりません。 同様に、一般的な C コードは、 それがマジックを扱っていないような関数から得られた SV を使っているのであれば、 'get' マジックを起動するために SvGETMAGIC を呼び出さなければなりません。 これらの関数については perlapi を参照してください。 例えば、sv_cat*() 関数群の 呼び出しは通常引き続いて SvSETMAGIC() を呼び出す必要がありますが、 SvGETMAGIC が先行している必要はありません; なぜなら、その実装は 'get' マジックを扱うからです。 (マジックを見つけだす) This routine returns a pointer to the MAGIC structure stored in the SV. If the SV does not have that magical feature, NULL is returned. Also, if the SV is not of type SVt_PVMG, Perl may core dump. このルーチンは SV に格納されている MAGIC 構造体へのポインタを 返します。 SV がマジカル機能を持っていなければ、NULL が返されます。 また、SV が Svt_PVMG の型でなければ Perl はコアダンプするかもしれません。 This routine checks to see what types of magic sv has. If the mg_type field is an uppercase letter, then the mg_obj is copied to nsv, but the mg_type field is changed to be the lowercase letter. このルーチンは sv が持っているマジックの型を検査します。 mg_type フィールドが大文字であれば、mg_obj が nsv にコピーされますが、 mg_type フィールドは小文字に変更されます。 (tie されたハッシュと配列のマジックを理解する) Tied hashes and arrays are magical beasts of the PERL_MAGIC_tied magic type. tie されたハッシュと配列は PERL_MAGIC_tied マジック型の magical beast です。 WARNING: As of the 5.004 release, proper usage of the array and hash access functions requires understanding a few caveats. Some of these caveats are actually considered bugs in the API, to be fixed in later releases, and are bracketed with [MAYCHANGE] below. If you find yourself actually applying such information in this section, be aware that the behavior may change in the future, umm, without warning. 警告: リリース 5.004 以降、配列やハッシュに対するアクセス 関数の正しい使い方は、幾つかの注意点を理解していることを要求しています。 これら幾つかの注意点は実際には API におけるバグとして みなされるものであって、将来のリリースにおいては修正されます。 また、注意点は [MAYCHANGE] というブラケットで囲まれています。 このセクションにある情報をあなたが実際に使おうというのであれば、 将来それらは警告なしに変わる可能性があることに注意してください。 The perl tie function associates a variable with an object that implements the various GET, SET, etc methods. To perform the equivalent of the perl tie function from an XSUB, you must mimic this behaviour. The code below carries out the necessary steps - firstly it creates a new hash, and then creates a second hash which it blesses into the class which will implement the tie methods. Lastly it ties the two hashes together, and returns a reference to the new tied hash. Note that the code below does NOT call the TIEHASH method in the MyTie class - see Calling Perl Routines from within C Programs for details on how to do this. perl の tie 関数は、ある変数と GET、SET 等といった様々なメソッドを 実装しているオブジェクトとを結び付けるものです。 XSUB から perl の tie 関数と等価な働きをさせるには、 ちょっとしたオマジナイをしなければなりません。 以下の例が必要なステップです。 まず最初にハッシュを作り、それから tie メソッドを実装するクラスに bless した二番目のハッシュを作ります。 最後に二つのハッシュを tie し、新たに生成した tie されたハッシュに対する リファレンスを返します。 以下の例では MyTie クラスの中で TIEHASH を呼び出していないということに 注意してください。 この件に関する詳細は Calling Perl Routines from within C Programs を 参照してください。 The av_store function, when given a tied array argument, merely copies the magic of the array onto the value to be "stored", using mg_copy. It may also return NULL, indicating that the value did not actually need to be stored in the array. [MAYCHANGE] After a call to av_store on a tied array, the caller will usually need to call mg_set(val) to actually invoke the perl level "STORE" method on the TIEARRAY object. If av_store did return NULL, a call to SvREFCNT_dec(val) will also be usually necessary to avoid a memory leak. [/MAYCHANGE] tie された配列を引数に与えられたときの av_store 関数は、単に配列の magic を mg_copy を使って「保管」されるように値をコピーするだけです。 この関数は、その値が実際には配列に格納する必要のないものであることを 示す NULL を返す可能性があります。 [MAYCHANGE] tie された配列に対して av_store を呼び出した後、呼び出し側は TIEARRAY オブジェクトに対して Perl レベルの "STORE" メソッドを起動するために av_store を呼び出すことが通常は必要となります。 av_store が NULL を返したならば、メモリリークを防ぐために SvREFCNT_dec(val) を呼び出すことが必要となります。 [/MAYCHANGE] The previous paragraph is applicable verbatim to tied hash access using the hv_store and hv_store_ent functions as well. 先のパラグラフの説明は、tie されたハッシュにアクセスするのに使用する hv_store と hv_store_ent についても同様です。 av_fetch and the corresponding hash functions hv_fetch and hv_fetch_ent actually return an undefined mortal value whose magic has been initialized using mg_copy. Note the value so returned does not need to be deallocated, as it is already mortal. [MAYCHANGE] But you will need to call mg_get() on the returned value in order to actually invoke the perl level "FETCH" method on the underlying TIE object. Similarly, you may also call mg_set() on the return value after possibly assigning a suitable value to it using sv_setsv, which will invoke the "STORE" method on the TIE object. [/MAYCHANGE] av_fetch と、対応するハッシュ関数 hv_fetch および hv_fetch_ent は 実際には mg_copy を使って初期化が行なわれている未定義の揮発値を返します。 返された値はすでに揮発性なので、解放する必要がないことに注意してください。 [MAYCHANGE] しかし、TIE オブジェクトに対応した perl レベルの "FETCH" メソッドを実行するには、返されたその値に対して mg_get() を呼び出す必要があるでしょう。 同様に、TIE オブジェクトに対する "STORE" メソッドの起動である sv_setsv を使って適切な値を代入した後で、返された値に対して mg_set() を呼び出すことができます。 [/MAYCHANGE] [MAYCHANGE] In other words, the array or hash fetch/store functions don't really fetch and store actual values in the case of tied arrays and hashes. They merely call mg_copy to attach magic to the values that were meant to be "stored" or "fetched". Later calls to mg_get and mg_set actually do the job of invoking the TIE methods on the underlying objects. Thus the magic mechanism currently implements a kind of lazy access to arrays and hashes. [MAYCHANGE] 言い換えれば、配列やハッシュをフェッチしたりストアする関数は、 tie されている配列やハッシュに対する場合には実際に値をフェッチしたり 保管したりするわけではないということです。 それらの関数は「保管」されたり「フェッチ」された値に対してマジックを 付加するために、単に mg_copy を呼び出すだけです。 Currently (as of perl version 5.004), use of the hash and array access functions requires the user to be aware of whether they are operating on "normal" hashes and arrays, or on their tied variants. The API may be changed to provide more transparent access to both tied and normal data types in future versions. [/MAYCHANGE] 現在(バージョン 5.004)、ハッシュや配列に対するアクセス関数を使用する 際には、ユーザーが「通常の」ハッシュや配列なのか、あるいはそれが tie されたものであるのかを気をつけることが要求されています。 将来のバージョンでは、この API は tie されたデータに対するアクセスと 通常のデータに対するアクセスをより透過的にするために変更されるかも しれません。 [/MAYCHANGE] You would do well to understand that the TIEARRAY and TIEHASH interfaces are mere sugar to invoke some perl method calls while using the uniform hash and array syntax. The use of this sugar imposes some overhead (typically about two to four extra opcodes per FETCH/STORE operation, in addition to the creation of all the mortal variables required to invoke the methods). This overhead will be comparatively small if the TIE methods are themselves substantial, but if they are only a few statements long, the overhead will not be insignificant. TIEARRAY や TIEHASH といったインターフェースが、統一的な ハッシュ/配列構文を使うための perl メソッドを起動をするための単なる 砂糖であることを良く理解したことでしょう。 これらの砂糖の使用はいくらかのオーバーヘッド(通常、FETCH/STORE 操作 当たり二つから四つの余分なオペコード、それに加えてメソッドを 起動するために必要なすべての揮発性変数の生成)を招きます。 このオーバーヘッドは TIE メソッド自身がしっかりしたものであれば、ほぼ 同等なくらい小さなものでしかありませんが、ほんの少し文が長いだけでも オーバーヘッドは無視できないものになります。 (変更をローカル化する) Perl has a very handy construction Perl には非常に便利な構造があります。 This construction is approximately equivalent to この構造は以下のものと ほぼ 同じです The biggest difference is that the first construction would reinstate the initial value of $var, irrespective of how control exits the block: goto, return, die/eval, etc. It is a little bit more efficient as well. 両者の最も大きな違いは、最初のものが goto、return、die/eval など どのようにブロックから脱出しようとも、 $var の元々の値を復帰するということです。 効率といった面では大きな違いはありません。 There is a way to achieve a similar task from C via Perl API: create a pseudo-block, and arrange for some changes to be automatically undone at the end of it, either explicit, or via a non-local exit (via die()). A block-like construct is created by a pair of ENTER/LEAVE macros (see perlcall/"Returning a Scalar"). Such a construct may be created specially for some important localized task, or an existing one (like boundaries of enclosing Perl subroutine/block, or an existing pair for freeing TMPs) may be used. (In the second case the overhead of additional localization must be almost negligible.) Note that any XSUB is automatically enclosed in an ENTER/LEAVE pair. Perl API を通して C から同様の処理を行う方法もあります。 擬似ブロック(pseudo-block)を生成し、そのブロックの最後で自動的に 復帰するような幾つかの変更を行います。 ブロックから抜けるのは、明示的に抜けるための指示があっても良いし、 非局所的な脱出(die() を使ったもの)でもかまいません。 ブロックに似たこの構造は ENTER/LEAVE マクロのペアによって 生成されます(perlcall/"Returning a Scalar" を参照してください)。 このような構造ではなにか重要なローカル化された タスクのための特別なものを作成したり、あるいは 既に存在しているもの(Perl のサブルーチン/ブロックに束縛されたものとか、 あるいは解放する一時変数のペア)を使うことも可能です (二番目のケースでは、ローカル化するためのオーバーヘッドはほとんど 無視できるものです)。 すべての XSUB は自動的に ENTER/LEAVE の ペアによって囲まれているということに注意してください。 Inside such a pseudo-block the following service is available: このような 擬似ブロック の中では以下のサービスが利用可能です: SAVEINT(int i) SAVEIV(IV i) SAVEI32(I32 i) SAVELONG(long i) These macros arrange things to restore the value of integer variable i at the end of enclosing pseudo-block. これらのマクロはそれを囲む 擬似ブロック において 整数変数 i の値をリストアするようにします。 SAVESPTR(s) SAVEPPTR(p) These macros arrange things to restore the value of pointers s and p. s must be a pointer of a type which survives conversion to SV* and back, p should be able to survive conversion to char* and back. これらのマクロは、ポインタsもしくは p の値を リストアします。 s は SV* に対する型変換をできるポインタでなければなりません。 p は char* への型変換が可能であるべきものです。 SAVEFREESV(SV *sv) The refcount of sv would be decremented at the end of pseudo-block. This is similar to sv_2mortal in that it is also a mechanism for doing a delayed SvREFCNT_dec. However, while sv_2mortal extends the lifetime of sv until the beginning of the next statement, SAVEFREESV extends it until the end of the enclosing scope. These lifetimes can be wildly different. 擬似ブロック の終端において sv の参照カウントは デクリメントされます。 これは、遅延した SvREFCNT_dec を行うための機構という意味で sv_2motral に似たものです。 However, while sv_2mortal extends the lifetime of sv until the beginning of the next statement, SAVEFREESV extends it until the end of the enclosing scope. These lifetimes can be wildly different. (TBT) Also compare SAVEMORTALIZESV. また、SAVEMORTALIZESV を比較します。 SAVEMORTALIZESV(SV *sv) Just like SAVEFREESV, but mortalizes sv at the end of the current scope instead of decrementing its reference count. This usually has the effect of keeping sv alive until the statement that called the currently live scope has finished executing. Just like SAVEFREESV, but mortalizes sv at the end of the current scope instead of decrementing its reference count. This usually has the effect of keeping sv alive until the statement that called the currently live scope has finished executing. (TBT) SAVEFREEOP(OP *op) The OP * is op_free()ed at the end of pseudo-block. OP * は 擬似ブロック の終端において op_free() されます。 SAVEFREEPV(p) The chunk of memory which is pointed to by p is Safefree()ed at the end of pseudo-block. p によって指し示されているメモリの塊は 擬似ブロック の終端で Safefree() されます。 SAVECLEARSV(SV *sv) Clears a slot in the current scratchpad which corresponds to sv at the end of pseudo-block. 擬似ブロック の終端において、 sv に対応している カレントのスクラッチパッドにおけるスロットをクリアします。 SAVEDELETE(HV *hv, char *key, I32 length) The key key of hv is deleted at the end of pseudo-block. The string pointed to by key is Safefree()ed. If one has a key in short-lived storage, the corresponding string may be reallocated like this: 擬似ブロック の終端で hv にあるキー key は削除されます。 key によって指し示されている文字列は Safefree() されます。 short-lived storageにある key を持っているものがあった場合には 以下のようにして対応する文字列が再割り当てされます。 SAVEDESTRUCTOR(DESTRUCTORFUNC_NOCONTEXT_t f, void *p) At the end of pseudo-block the function f is called with the only argument p. 擬似ブロック の終端において関数 f が呼び出されます。 この関数 f は p のみを引数に取ります。 SAVEDESTRUCTOR_X(DESTRUCTORFUNC_t f, void *p) At the end of pseudo-block the function f is called with the implicit context argument (if any), and p. 疑似ブロック の最後に、関数 f が(もしあれば)暗黙のコンテキスト 引数と p で呼び出されます。 SAVESTACK_POS() The current offset on the Perl internal stack (cf. SP) is restored at the end of pseudo-block. 擬似ブロック の終端において Perl の内部スタック(SP)のカレント オフセットがリストアされます。 The following API list contains functions, thus one needs to provide pointers to the modifiable data explicitly (either C pointers, or Perlish GV *s). Where the above macros take int, a similar function takes int *. 以下の API リストは、変更可能なデータを指し示すポインタ (C のポインタか、Perl 的な GV * のいずれか) を必要とする関数群です。 前述の int を引数に取るマクロに似て、 int * を引数に取る関数があります。 SV* save_scalar(GV *gv) Equivalent to Perl code local $gv. Perl コード local $gv と等価です。 AV* save_ary(GV *gv) HV* save_hash(GV *gv) Similar to save_scalar, but localize @gv and %gv. save_scalar に似ていますが、@gv と %gv の局所化を行います。 void save_item(SV *item) Duplicates the current value of SV, on the exit from the current ENTER/LEAVE pseudo-block will restore the value of SV using the stored value. It doesn't handle magic. Use save_scalar if magic is affected. SV のカレントの値を複製し、カレントの ENTER/LEAVE 擬似ブロック を抜けるときに SV の保存した値を復帰します。 マジックを扱いません。 マジックを有効にしたい場合は save_scalar を使ってください。 void save_list(SV **sarg, I32 maxsarg) A variant of save_item which takes multiple arguments via an array sarg of SV* of length maxsarg. 複数の引数を長さ maxarg の SV* の配列 sarg として取る save_item の複数の値を取るバリエーションです。 SV* save_svref(SV **sptr) Similar to save_scalar, but will reinstate an SV *. save_scalar に似ていますが、SV * の復帰を行います。 void save_aptr(AV **aptr) void save_hptr(HV **hptr) Similar to save_svref, but localize AV * and HV *. save_svref に似ていますが、AV * と HV * のローカル化を行います。 The Alias module implements localization of the basic types within the caller's scope. People who are interested in how to localize things in the containing scope should take a look there too. Alias モジュールは 呼び出し側のスコープ 中での基本型のローカル化を 実装します。 スコープを持った何かのローカル化に興味のある人は そこに何があるかも見ておいた方が良いでしょう。 (XSUB と引数スタック) The XSUB mechanism is a simple way for Perl programs to access C subroutines. An XSUB routine will have a stack that contains the arguments from the Perl program, and a way to map from the Perl data structures to a C equivalent. XSUB の仕組みは、Perl プログラムが C のサブルーチンを アクセスするための単純な方法です。 XSUB には、Perl プログラムからの引数を入れるスタックと、Perl のデータ 構造を C の等価なものにマッピングする方法を用意しています。 The stack arguments are accessible through the ST(n) macro, which returns the n'th stack argument. Argument 0 is the first argument passed in the Perl subroutine call. These arguments are SV*, and can be used anywhere an SV* is used. スタック引数は ST(n) というマクロを使ってアクセスできます。 これは、n 番目のスタック引数を返すものです。 引数 0 は、Perl のサブルーチン呼び出しで渡された最初の引数です。 これらの引数は SV* で、SV* が使われるところであればどこでも 使うことができます。 Most of the time, output from the C routine can be handled through use of the RETVAL and OUTPUT directives. However, there are some cases where the argument stack is not already long enough to handle all the return values. An example is the POSIX tzname() call, which takes no arguments, but returns two, the local time zone's standard and summer time abbreviations. ほとんどの場合には、C ルーチンからの出力は RETVAL 指示子と OUTPUT 指示子を使って扱うことができます。 しかし、引数スタックのスペースがすべての返却値を扱うのに十分で なくなる場合があります。 例としては、引数をとらないでローカルなタイムゾーンと夏時間の省略形の 二つの返却値を返す、POSIX の tzname() の呼び出しがあります。 To handle this situation, the PPCODE directive is used and the stack is extended using the macro: このような状況を扱うためには、PPCODE ディレクティブを使い、さらに スタックを以下のマクロを使って拡張します: where SP is the macro that represents the local copy of the stack pointer, and num is the number of elements the stack should be extended by. ここで SP はスタックポインタで、num はスタックを拡張すべき 要素の数です。 Now that there is room on the stack, values can be pushed on it using PUSHs macro. The pushed values will often need to be "mortal" (See /Reference Counts and Mortality): スタック上に場所を確保したら、PUSHs マクロを使って値をスタックへ プッシュします。 The pushed values will often need to be "mortal" (See /Reference Counts and Mortality): (TBT) And now the Perl program calling tzname, the two values will be assigned as in: これで、tzname を呼ぶ Perl プログラムでは、二つの値は 以下のように代入できます。 An alternate (and possibly simpler) method to pushing values on the stack is to use the macro: スタックに値を積む、別の (おそらくはより簡単な) 方法は、 以下のマクロを使うことです。 This macro automatically adjust the stack for you, if needed. Thus, you do not need to call EXTEND to extend the stack. こちらのマクロは、必要ならば自動的にスタックを調整してくれます。 このため、EXTEND をスタックを拡張するために呼ぶ必要はありません。 Despite their suggestions in earlier versions of this document the macros (X)PUSH[iunp] are not suited to XSUBs which return multiple results. For that, either stick to the (X)PUSHs macros shown above, or use the new m(X)PUSH[iunp] macros instead; see /Putting a C value on Perl stack. Despite their suggestions in earlier versions of this document the macros (X)PUSH[iunp] are not suited to XSUBs which return multiple results. For that, either stick to the (X)PUSHs macros shown above, or use the new m(X)PUSH[iunp] macros instead; see /Putting a C value on Perl stack. (TBT) For more information, consult perlxs and perlxstut. より詳しい情報は、perlxs と perlxstut を参照してください。 (CプログラムからのPerlルーチンの呼び出し) There are four routines that can be used to call a Perl subroutine from within a C program. These four are: C プログラムから Perl サブルーチンを呼び出すために使用することのできる ルーチンが 四つあります。 その四つは: The routine most often used is call_sv. The SV* argument contains either the name of the Perl subroutine to be called, or a reference to the subroutine. The second argument consists of flags that control the context in which the subroutine is called, whether or not the subroutine is being passed arguments, how errors should be trapped, and how to treat return values. 最もよく使われるはずのものは、call_sv です。 引数 SV* には呼び出される Perl サブルーチンの名前か、その サブルーチンへのリファレンスが含まれます。 二番目の引数には、そのサブルーチンが呼び出されたコンテキストを制御する フラグが置かれます。 これはサブルーチンに引数が渡されたか渡されていないか、エラーを どのようにトラップすべきなのか、どのように戻り値を返すのかを 制御するものです。 All four routines return the number of arguments that the subroutine returned on the Perl stack. 四つのルーチンはいずれも、サブルーチンが Perl スタック上に返した 引数の数を返します。 These routines used to be called perl_call_sv, etc., before Perl v5.6.0, but those names are now deprecated; macros of the same name are provided for compatibility. These routines used to be called perl_call_sv, etc., before Perl v5.6.0, しかしこれらの名前は現在では非推奨です; 同じ名前のマクロが互換性のために 提供されています。 (TBT) When using any of these routines (except call_argv), the programmer must manipulate the Perl stack. These include the following macros and functions: これらのルーチンを使うときには(call_argv を除いて)、プログラマが Perl スタックを操作しなくてはなりません。 以下のマクロと関数が用意されています: For a detailed description of calling conventions from C to Perl, consult perlcall. C から Perl を呼び出す約束ごとについての詳しい記述は perlcall を参照してください。 (メモリ割り当て) (割り当て) All memory meant to be used with the Perl API functions should be manipulated using the macros described in this section. The macros provide the necessary transparency between differences in the actual malloc implementation that is used within perl. Perl API 関数と共に使うような全てのメモリはこのセクションで 説明されているマクロを使って扱うべきです。 マクロは実際の malloc の 実装と、perl で使われているものとの差を透過的にします。 It is suggested that you enable the version of malloc that is distributed with Perl. It keeps pools of various sizes of unallocated memory in order to satisfy allocation requests more quickly. However, on some platforms, it may cause spurious malloc or free errors. Perl と一緒に配布されていて、あなたがこれを使うことを推奨されている malloc の変種です。 これは様々な大きさの未割り付けのメモリをプールしておき、 より早く割り付け要求に応えようとするものです。 しかしながら一部のプラットフォームでは、これは不法なmallocエラーや freeエラーを引き起こす可能性があります。 The following three macros are used to initially allocate memory : これら三つのマクロはメモリの割り付けのために使われます: The first argument pointer should be the name of a variable that will point to the newly allocated memory. 1 番目の引数 pointer は、新たにメモリを割り付けられる変数の 名前にします。 The second and third arguments number and type specify how many of the specified type of data structure should be allocated. The argument type is passed to sizeof. The final argument to Newxc, cast, should be used if the pointer argument is different from the type argument. 3 番目と 4 番目の引数 number と type は、指定された構造体を どれだけ割り付けるのかを指定します。 引数 type は sizeof に渡されます。 Newxcに対する最後の引数 castは、引数 pointer が 引数 type と異なるときに使うべきものです。 Unlike the Newx and Newxc macros, the Newxz macro calls memzero to zero out all the newly allocated memory. Newx や Newxc とは異なり、Newxz は割り付けたメモリのすべてを ゼロで埋めるために memzero を呼び出します。 These three macros are used to change a memory buffer size or to free a piece of memory no longer needed. The arguments to Renew and Renewc match those of New and Newc with the exception of not needing the "magic cookie" argument. 上記の三つのマクロは、メモリのバッファーサイズを変更したりもう 使わなくなったメモリ領域を解放するために使われます。 Renew と Renewc の引数は、“魔法のクッキー”引数が必要ないということを 除きそれぞれ New と Renewc に一致します。 These three macros are used to move, copy, or zero out previously allocated memory. The source and dest arguments point to the source and destination starting points. Perl will move, copy, or zero out number instances of the size of the type data structure (using the sizeof function). この三つのマクロは、それぞれ割り付けたメモリ領域に対する移動、 複写、ゼロで埋めるといったことに使われます。 source と dest という引数は、転送元と転送先の開始番地への ポインタです。 Perl は、構造体 type の大きさ (sizeof 関数を使います)のインスタンスの number 個分だけ、移動、複写、ゼロ埋めを行います。 The most recent development releases of Perl has been experimenting with removing Perl's dependency on the "normal" standard I/O suite and allowing other stdio implementations to be used. This involves creating a new abstraction layer that then calls whichever implementation of stdio Perl was compiled with. All XSUBs should now use the functions in the PerlIO abstraction layer and not make any assumptions about what kind of stdio is being used. 最新リリースの Perl の開発では、Perl の「通常の」標準入出力ライブラリに 依存している部分を取り除くことと、Perl で別の標準入出力の実装が 使えるようにすることが試みられました。 これにより必然的に、Perl と共にコンパイルされた標準入出力の実装を 呼び出すような新しい抽象層が作られました。 すべての XSUB は、今では PerlIO 抽象層の関数を使うべきで、 これまで使っていた標準入出力に関してのすべての仮定はすべきではありません。 For a complete description of the PerlIO abstraction, consult perlapio. PerlIO 抽象化に関する詳しい記述は perlapio を参照してください。 (C での値を Perl スタックに入れる) A lot of opcodes (this is an elementary operation in the internal perl stack machine) put an SV* on the stack. However, as an optimization the corresponding SV is (usually) not recreated each time. The opcodes reuse specially assigned SVs (targets) which are (as a corollary) not constantly freed/created. たくさんのオペコード(これは内部的な perl スタックマシンでの基本的な 操作です)が SV をスタックに置きます。 しかしながら、SV に対する最適化のようなものは(通常は)毎回 行なわれるわけではありません。 オペコードは解放されたり、生成されることのない特別に割り当てられた SVs (targets) を再利用します。 Each of the targets is created only once (but see Scratchpads and recursion below), and when an opcode needs to put an integer, a double, or a string on stack, it just sets the corresponding parts of its target and puts the target on stack. それぞれの targets は、一度だけ生成して(ただし、後述する Scratchpads and recursion を参照のこと)、オペコードがスタックに 整数値、倍精度実数値、文字列といったものを置くことを必要とするときに、 スタックに target を置きます。 The macro to put this target on stack is PUSHTARG, and it is directly used in some opcodes, as well as indirectly in zillions of others, which use it via (X)PUSH[iunp]. この target をスタックに置くためのマクロが PUSHTARG です。 このマクロは、他の多くのマクロが (X)PUSH[iunp] を通じて間接的に 使っているのと同様に、幾つかのオペコードで直接使われています。 Because the target is reused, you must be careful when pushing multiple values on the stack. The following code will not do what you think: Because the target is reused, you must be careful when pushing multiple values on the stack. The following code will not do what you think: (TBT) This translates as "set TARG to 10, push a pointer to TARG onto the stack; set TARG to 20, push a pointer to TARG onto the stack". At the end of the operation, the stack does not contain the values 10 and 20, but actually contains two pointers to TARG, which we have set to 20. This translates as "set TARG to 10, push a pointer to TARG onto the stack; set TARG to 20, push a pointer to TARG onto the stack". At the end of the operation, the stack does not contain the values 10 and 20, but actually contains two pointers to TARG, which we have set to 20. (TBT) If you need to push multiple different values then you should either use the (X)PUSHs macros, or else use the new m(X)PUSH[iunp] macros, none of which make use of TARG. The (X)PUSHs macros simply push an SV* on the stack, which, as noted under /XSUBs and the Argument Stack, will often need to be "mortal". The new m(X)PUSH[iunp] macros make this a little easier to achieve by creating a new mortal for you (via (X)PUSHmortal), pushing that onto the stack (extending it if necessary in the case of the mXPUSH[iunp] macros), and then setting its value. Thus, instead of writing this to "fix" the example above: If you need to push multiple different values then you should either use the (X)PUSHs macros, or else use the new m(X)PUSH[iunp] macros, none of which make use of TARG. The (X)PUSHs macros simply push an SV* on the stack, which, as noted under /XSUBs and the Argument Stack, will often need to be "mortal". The new m(X)PUSH[iunp] macros make this a little easier to achieve by creating a new mortal for you (via (X)PUSHmortal), pushing that onto the stack (extending it if necessary in the case of the mXPUSH[iunp] macros), and then setting its value. Thus, instead of writing this to "fix" the example above: (TBT) you can simply write: you can simply write: (TBT) On a related note, if you do use (X)PUSH[iunp], then you're going to need a dTARG in your variable declarations so that the *PUSH* macros can make use of the local variable TARG. See also dTARGET and dXSTARG. On a related note, if you do use (X)PUSH[iunp], then you're going to need a dTARG in your variable declarations so that the *PUSH* macros can make use of the local variable TARG. See also dTARGET and dXSTARG. (TBT) (スクラッチパッド) The question remains on when the SVs which are targets for opcodes are created. The answer is that they are created when the current unit -- a subroutine or a file (for opcodes for statements outside of subroutines) -- is compiled. During this time a special anonymous Perl array is created, which is called a scratchpad for the current unit. 残っている疑問は、オペコードに対する targets である SV をいつ 生成するのかということでしょう。 その答えは、カレントユニット -- サブルーチンもしくは(サブルーチンの 外側にある文のためのオペコードのための)ファイル -- が コンパイルされたときです。 この間、特別な無名配列が生成されます。 これはカレントユニットのためのスクラッチパッド (scrachpad) と 呼ばれるものです。 A scratchpad keeps SVs which are lexicals for the current unit and are targets for opcodes. One can deduce that an SV lives on a scratchpad by looking on its flags: lexicals have SVs_PADMY set, and targets have SVs_PADTMP set. スクラッチパッドはカレントユニットのためのレキシカルやオペコードの ための target である SV を保持します。 SV があるスクラッチパッドを、 SV のフラグを見ることによって推測することができます。 レキシカルでは SVs_PADMY されていて、targets では SVs_PADTMP が セットされています。 The correspondence between OPs and targets is not 1-to-1. Different OPs in the compile tree of the unit can use the same target, if this would not conflict with the expected life of the temporary. オペコードと targets の間の対応は一対一ではありません。 あるユニットの翻訳木 (compile tree)にある異なるオペコードは、 これが一時変数の expected life と衝突していなければ同じ target を使うことが できます。 (スクラッチパッドと再帰) In fact it is not 100% true that a compiled unit contains a pointer to the scratchpad AV. In fact it contains a pointer to an AV of (initially) one element, and this element is the scratchpad AV. Why do we need an extra level of indirection? コンパイルされたユニットがスクラッチパッド AV へのポインタを 保持しているということは、100% 本当のことではありません。 実際は、(初期値では)一要素の AV へのポインタを保持していて、この要素が スクラッチパッド AV なのです。 なぜ、こういう余計な間接レベルを必要としているのでしょう? The answer is recursion, and maybe threads. Both these can create several execution pointers going into the same subroutine. For the subroutine-child not write over the temporaries for the subroutine-parent (lifespan of which covers the call to the child), the parent and the child should have different scratchpads. (And the lexicals should be separate anyway!) その答えは 再帰 と、おそらく スレッド です。 これら二つは同じサブルーチンに対する別々の実行ポインタを 生成しようとするかもしれません。 子サブルーチンが(呼び出す子サブルーチンを覆っている寿命を持つ) 親サブルーチンの一時変数を上書きしてしまわないように、 親と子では、異なるスクラッチパッドを持つようにすべきです (かつ、レキシカルは分けておくべきなのです!)。 So each subroutine is born with an array of scratchpads (of length 1). On each entry to the subroutine it is checked that the current depth of the recursion is not more than the length of this array, and if it is, new scratchpad is created and pushed into the array. 各サブルーチンは、スクラッチパッドの(長さが 1 の)配列を伴って生成されます。 サブルーチンに対する各エントリーはその時点での再帰の深さが この配列の長さよりも大きくないことをチェックします。 そして、もしそうであれば、新たなスクラッチパッドが生成されて配列へと プッシュされます。 The targets on this scratchpad are undefs, but they are already marked with correct flags. このスクラッチパッドにある targets は undef ですが、これらはすでに 正しいフラグによってマークされています。 (コンパイルされたコード) (コード木) Here we describe the internal form your code is converted to by Perl. Start with a simple example: ここで、Perl によって変換されたプログラムの内部形式を説明しましょう。 簡単な例から始めます。 This is converted to a tree similar to this one: これは次のような木構造へ変換されます(実際にはもっと複雑です)。 (but slightly more complicated). This tree reflects the way Perl parsed your code, but has nothing to do with the execution order. There is an additional "thread" going through the nodes of the tree which shows the order of execution of the nodes. In our simplified example above it looks like: この木構造は、Perl があなたのプログラムを解析したやり方を 反映していますが、実行の順序については反映していません。 ノードの実行順序を表わす木構造のノードを辿ろうとする別の 「スレッド」(thread) があります。 先の簡単な例では、次のようになります。 $c ---> + ---> $a ---> assign-to ]]> But with the actual compile tree for $a = $b + $c it is different: some nodes optimized away. As a corollary, though the actual tree contains more nodes than our simplified example, the execution order is the same as in our example. しかし、$a = $b + $c に対する実際の解析木はこれと異なります。 一部のノードが最適化されています。 その結果として、実際の木構造が私たちの単純な例よりも多くのノードを 持っていたとしても、その実行順序は同じになります。 (木を検査する) If you have your perl compiled for debugging (usually done with -DDEBUGGING on the Configure command line), you may examine the compiled tree by specifying -Dx on the Perl command line. The output takes several lines per node, and for $b+$c it looks like this: perl をデバッグ用にコンパイルした(通常は Configure のコマンドラインで -DDEBUGGING を使って行います)場合、Perl のコマンドラインで -Dx を指定することによって解析木を検査することができます。 その出力はノード毎に数行を取り、$b+$c は以下のようになります。 6 TARG = 1 FLAGS = (SCALAR,KIDS) { TYPE = null ===> (4) (was rv2sv) FLAGS = (SCALAR,KIDS) { 3 TYPE = gvsv ===> 4 FLAGS = (SCALAR) GV = main::b } } { TYPE = null ===> (5) (was rv2sv) FLAGS = (SCALAR,KIDS) { 4 TYPE = gvsv ===> 5 FLAGS = (SCALAR) GV = main::c } } ]]> This tree has 5 nodes (one per TYPE specifier), only 3 of them are not optimized away (one per number in the left column). The immediate children of the given node correspond to {} pairs on the same level of indentation, thus this listing corresponds to the tree: この木には五つのノード(TYPE 毎にひとつ)があって、そのうちの 三つだけが最適化されないものです(左側に数字のあるもの)。 与えられたノードのすぐ下にある子供は同じレベルのインデントにある {} の ペアに対応します。 したがって、このリストは以下の木に対応します。 The execution order is indicated by ===> marks, thus it is 3 4 5 6 (node 6 is not included into above listing), i.e., gvsv gvsv add whatever. 実行順序は ===> マークによって表わされますから、3 4 5 6 (ノード 6は、上にあるリストには含まれません)となります。 つまり、gvsv gvsv add whatever ということになります。 Each of these nodes represents an op, a fundamental operation inside the Perl core. The code which implements each operation can be found in the pp*.c files; the function which implements the op with type gvsv is pp_gvsv, and so on. As the tree above shows, different ops have different numbers of children: add is a binary operator, as one would expect, and so has two children. To accommodate the various different numbers of children, there are various types of op data structure, and they link together in different ways. Each of these nodes represents an op, a fundamental operation inside the Perl core. The code which implements each operation can be found in the pp*.c files; the function which implements the op with type gvsv is pp_gvsv, and so on. As the tree above shows, different ops have different numbers of children: add is a binary operator, as one would expect, and so has two children. To accommodate the various different numbers of children, there are various types of op data structure, and they link together in different ways. (TBT) The simplest type of op structure is OP: this has no children. Unary operators, UNOPs, have one child, and this is pointed to by the op_first field. Binary operators (BINOPs) have not only an op_first field but also an op_last field. The most complex type of op is a LISTOP, which has any number of children. In this case, the first child is pointed to by op_first and the last child by op_last. The children in between can be found by iteratively following the op_sibling pointer from the first child to the last. The simplest type of op structure is OP: this has no children. Unary operators, UNOPs, have one child, and this is pointed to by the op_first field. Binary operators (BINOPs) have not only an op_first field but also an op_last field. The most complex type of op is a LISTOP, which has any number of children. In this case, the first child is pointed to by op_first and the last child by op_last. The children in between can be found by iteratively following the op_sibling pointer from the first child to the last. (TBT) There are also two other op types: a PMOP holds a regular expression, and has no children, and a LOOP may or may not have children. If the op_children field is non-zero, it behaves like a LISTOP. To complicate matters, if a UNOP is actually a null op after optimization (see /Compile pass 2: context propagation) it will still have children in accordance with its former type. There are also two other op types: a PMOP holds a regular expression, and has no children, and a LOOP may or may not have children. If the op_children field is non-zero, it behaves like a LISTOP. To complicate matters, if a UNOP is actually a null op after optimization (see /Compile pass 2: context propagation) it will still have children in accordance with its former type. (TBT) Another way to examine the tree is to use a compiler back-end module, such as B::Concise. Another way to examine the tree is to use a compiler back-end module, such as B::Concise. (TBT) The tree is created by the compiler while yacc code feeds it the constructions it recognizes. Since yacc works bottom-up, so does the first pass of perl compilation. この木構造は、yacc が perl プログラムを読み込んでその構造を解析している 間にコンパイラによって生成されます。 yacc はボトムアップで動作するので、perl によるコンパイルの最初のパスで 行なわれます。 What makes this pass interesting for perl developers is that some optimization may be performed on this pass. This is optimization by so-called "check routines". The correspondence between node names and corresponding check routines is described in opcode.pl (do not forget to run make regen_headers if you modify this file). perl 開発者にとって興味深いのは、このパスで行なわれるいくつかの 最適化でしょう。 これは、"check routines" とも呼ばれる最適化です。 ノード名と対応するチェックルーチンとの間の対応は opcode.pl に 記述されています(このファイルを修正した場合には、make regen_headers を 実行することを忘れないでください)。 A check routine is called when the node is fully constructed except for the execution-order thread. Since at this time there are no back-links to the currently constructed node, one can do most any operation to the top-level node, including freeing it and/or creating new nodes above/below it. チェックルーチンは、ノードが実行順序スレッドを除いて完全に 構築されたときに呼び出されます。 この時点では、構築されたノードに対する back-line が存在しないので、 トップレベルノードに対して、新たなノードを生成したりノードを 解放したりすることを含めて、ほとんどの操作を行うことができます。 The check routine returns the node which should be inserted into the tree (if the top-level node was not modified, check routine returns its argument). このチェックルーチンは木に挿入すべきノードを返します(トップレベルの ノードが変更されていなければ、チェックルーチンはその引数を返します)。 By convention, check routines have names ck_*. They are usually called from new*OP subroutines (or convert) (which in turn are called from perly.y). 規約により、チェックルーチンは ck_* のような名前を持ちます。 これらは通常サブルーチン new*OP (もしくは convert) から 呼び出されます(これらのサブルーチンは perly.y から呼び出されます)。 (コンパイルパス1a: 定数の畳み込み) Immediately after the check routine is called the returned node is checked for being compile-time executable. If it is (the value is judged to be constant) it is immediately executed, and a constant node with the "return value" of the corresponding subtree is substituted instead. The subtree is deleted. チェックルーチンが呼び出された直後に、返されたノードはコンパイル時 実行のためのチェックが行なわれます。 もしそうであれば(値が定数であると判定された)、そのノードは即座に 実行されて、「戻り値」に対応する部分木は 定数 ノードで置換され、 部分木が削除されます。 If constant folding was not performed, the execution-order thread is created. 定数の畳み込み(constant folding)が働かなければ、実行順序スレッドが 生成されます。 (コンパイルパス2: コンテキスト伝播) When a context for a part of compile tree is known, it is propagated down through the tree. At this time the context can have 5 values (instead of 2 for runtime context): void, boolean, scalar, list, and lvalue. In contrast with the pass 1 this pass is processed from top to bottom: a node's context determines the context for its children. 解析木の一部分のコンテキストがわかっているとき、それは木の末端へ 伝播します。 このとき、コンテキストは(実行時コンテキストの二種類ではなく) 無効、真偽値、スカラ、リスト、左辺値の五種類の値を持つことができます。 パス 1 とは対照的に、このパスではトップから末端へと処理が進みます。 あるノードのコンテキストは、その下にある部分のコンテキストを決定します。 Additional context-dependent optimizations are performed at this time. Since at this moment the compile tree contains back-references (via "thread" pointers), nodes cannot be free()d now. To allow optimized-away nodes at this stage, such nodes are null()ified instead of free()ing (i.e. their type is changed to OP_NULL). コンテキストに依存した最適化はこのときに行なわれます。 この動作では解析木が(“スレッド”ポインタを通じて)後方参照を 含んでいるので、ノードをこの時に free() することはできません。 このステージでノードを最適化するのを許すために、対象となるノードは free() されるかわりに null() されます(つまり、そのノードの型が OP_NULL に変えられるということ)。 (コンパイルパス 3: 覗き穴最適化) After the compile tree for a subroutine (or for an eval or a file) is created, an additional pass over the code is performed. This pass is neither top-down or bottom-up, but in the execution order (with additional complications for conditionals). These optimizations are done in the subroutine peep(). Optimizations performed at this stage are subject to the same restrictions as in the pass 2. サブルーチン(もしくは eval かファイル)に対する解析木が生成された後で、 そのコードに対する追加パスが実行されます。 このパスはトップダウンでもボトムアップでもなく、(条件に対する 複雑さを伴った)実行順序です。 これらの最適化はサブルーチン peep() で行なわれます。 このステージで行なわれる最適化はパス 2 でのものと同じ制限に従います。 The compile tree is executed in a runops function. There are two runops functions, in run.c and in dump.c. Perl_runops_debug is used with DEBUGGING and Perl_runops_standard is used otherwise. For fine control over the execution of the compile tree it is possible to provide your own runops function. The compile tree is executed in a runops function. There are two runops functions, in run.c and in dump.c. Perl_runops_debug is used with DEBUGGING and Perl_runops_standard is used otherwise. For fine control over the execution of the compile tree it is possible to provide your own runops function. (TBT) It's probably best to copy one of the existing runops functions and change it to suit your needs. Then, in the BOOT section of your XS file, add the line: It's probably best to copy one of the existing runops functions and change it to suit your needs. Then, in the BOOT section of your XS file, add the line: (TBT) This function should be as efficient as possible to keep your programs running as fast as possible. This function should be as efficient as possible to keep your programs running as fast as possible. (TBT) To aid debugging, the source file dump.c contains a number of functions which produce formatted output of internal data structures. To aid debugging, the source file dump.c contains a number of functions which produce formatted output of internal data structures. (TBT) The most commonly used of these functions is Perl_sv_dump; it's used for dumping SVs, AVs, HVs, and CVs. The Devel::Peek module calls sv_dump to produce debugging output from Perl-space, so users of that module should already be familiar with its format. The most commonly used of these functions is Perl_sv_dump; it's used for dumping SVs, AVs, HVs, and CVs. The Devel::Peek module calls sv_dump to produce debugging output from Perl-space, so users of that module should already be familiar with its format. (TBT) Perl_op_dump can be used to dump an OP structure or any of its derivatives, and produces output similar to perl -Dx; in fact, Perl_dump_eval will dump the main root of the code being evaluated, exactly like -Dx. Perl_op_dump can be used to dump an OP structure or any of its derivatives, and produces output similar to perl -Dx; in fact, Perl_dump_eval will dump the main root of the code being evaluated, exactly like -Dx. (TBT) Other useful functions are Perl_dump_sub, which turns a GV into an op tree, Perl_dump_packsubs which calls Perl_dump_sub on all the subroutines in a package like so: (Thankfully, these are all xsubs, so there is no op tree) Other useful functions are Perl_dump_sub, which turns a GV into an op tree, Perl_dump_packsubs which calls Perl_dump_sub on all the subroutines in a package like so: (Thankfully, these are all xsubs, so there is no op tree) (TBT) and Perl_dump_all, which dumps all the subroutines in the stash and the op tree of the main root. and Perl_dump_all, which dumps all the subroutines in the stash and the op tree of the main root. (TBT) The Perl interpreter can be regarded as a closed box: it has an API for feeding it code or otherwise making it do things, but it also has functions for its own use. This smells a lot like an object, and there are ways for you to build Perl so that you can have multiple interpreters, with one interpreter represented either as a C structure, or inside a thread-specific structure. These structures contain all the context, the state of that interpreter. The Perl interpreter can be regarded as a closed box: it has an API for feeding it code or otherwise making it do things, but it also has functions for its own use. This smells a lot like an object, and there are ways for you to build Perl so that you can have multiple interpreters, with one interpreter represented either as a C structure, or inside a thread-specific structure. These structures contain all the context, the state of that interpreter. (TBT) One macro controls the major Perl build flavor: MULTIPLICITY. The MULTIPLICITY build has a C structure that packages all the interpreter state. With multiplicity-enabled perls, PERL_IMPLICIT_CONTEXT is also normally defined, and enables the support for passing in a "hidden" first argument that represents all three data structures. MULTIPLICITY makes mutli-threaded perls possible (with the ithreads threading model, related to the macro USE_ITHREADS.) One macro controls the major Perl build flavor: MULTIPLICITY. The MULTIPLICITY build has a C structure that packages all the interpreter state. With multiplicity-enabled perls, PERL_IMPLICIT_CONTEXT is also normally defined, and enables the support for passing in a "hidden" first argument that represents all three data structures. MULTIPLICITY makes mutli-threaded perls possible (with the ithreads threading model, related to the macro USE_ITHREADS.) (TBT) Two other "encapsulation" macros are the PERL_GLOBAL_STRUCT and PERL_GLOBAL_STRUCT_PRIVATE (the latter turns on the former, and the former turns on MULTIPLICITY.) The PERL_GLOBAL_STRUCT causes all the internal variables of Perl to be wrapped inside a single global struct, struct perl_vars, accessible as (globals) &PL_Vars or PL_VarsPtr or the function Perl_GetVars(). The PERL_GLOBAL_STRUCT_PRIVATE goes one step further, there is still a single struct (allocated in main() either from heap or from stack) but there are no global data symbols pointing to it. In either case the global struct should be initialised as the very first thing in main() using Perl_init_global_struct() and correspondingly tear it down after perl_free() using Perl_free_global_struct(), please see miniperlmain.c for usage details. You may also need to use dVAR in your coding to "declare the global variables" when you are using them. dTHX does this for you automatically. Two other "encapsulation" macros are the PERL_GLOBAL_STRUCT and PERL_GLOBAL_STRUCT_PRIVATE (the latter turns on the former, and the former turns on MULTIPLICITY.) The PERL_GLOBAL_STRUCT causes all the internal variables of Perl to be wrapped inside a single global struct, struct perl_vars, accessible as (globals) &PL_Vars or PL_VarsPtr or the function Perl_GetVars(). The PERL_GLOBAL_STRUCT_PRIVATE goes one step further, there is still a single struct (allocated in main() either from heap or from stack) but there are no global data symbols pointing to it. In either case the global struct should be initialised as the very first thing in main() using Perl_init_global_struct() and correspondingly tear it down after perl_free() using Perl_free_global_struct(), please see miniperlmain.c for usage details. You may also need to use dVAR in your coding to "declare the global variables" when you are using them. dTHX does this for you automatically. (TBT) To see whether you have non-const data you can use a BSD-compatible nm: To see whether you have non-const data you can use a BSD-compatible nm: (TBT) If this displays any D or d symbols, you have non-const data. If this displays any D or d symbols, you have non-const data. (TBT) For backward compatibility reasons defining just PERL_GLOBAL_STRUCT doesn't actually hide all symbols inside a big global struct: some PerlIO_xxx vtables are left visible. The PERL_GLOBAL_STRUCT_PRIVATE then hides everything (see how the PERLIO_FUNCS_DECL is used). For backward compatibility reasons defining just PERL_GLOBAL_STRUCT doesn't actually hide all symbols inside a big global struct: some PerlIO_xxx vtables are left visible. The PERL_GLOBAL_STRUCT_PRIVATE then hides everything (see how the PERLIO_FUNCS_DECL is used). (TBT) All this obviously requires a way for the Perl internal functions to be either subroutines taking some kind of structure as the first argument, or subroutines taking nothing as the first argument. To enable these two very different ways of building the interpreter, the Perl source (as it does in so many other situations) makes heavy use of macros and subroutine naming conventions. All this obviously requires a way for the Perl internal functions to be either subroutines taking some kind of structure as the first argument, or subroutines taking nothing as the first argument. To enable these two very different ways of building the interpreter, the Perl source (as it does in so many other situations) makes heavy use of macros and subroutine naming conventions. (TBT) First problem: deciding which functions will be public API functions and which will be private. All functions whose names begin S_ are private (think "S" for "secret" or "static"). All other functions begin with "Perl_", but just because a function begins with "Perl_" does not mean it is part of the API. (See /Internal Functions.) The easiest way to be sure a function is part of the API is to find its entry in perlapi. If it exists in perlapi, it's part of the API. If it doesn't, and you think it should be (i.e., you need it for your extension), send mail via perlbug explaining why you think it should be. First problem: deciding which functions will be public API functions and which will be private. All functions whose names begin S_ are private (think "S" for "secret" or "static"). All other functions begin with "Perl_", but just because a function begins with "Perl_" does not mean it is part of the API. (See /Internal Functions.) The easiest way to be sure a function is part of the API is to find its entry in perlapi. If it exists in perlapi, it's part of the API. If it doesn't, and you think it should be (i.e., you need it for your extension), send mail via perlbug explaining why you think it should be. (TBT) Second problem: there must be a syntax so that the same subroutine declarations and calls can pass a structure as their first argument, or pass nothing. To solve this, the subroutines are named and declared in a particular way. Here's a typical start of a static function used within the Perl guts: Second problem: there must be a syntax so that the same subroutine declarations and calls can pass a structure as their first argument, or pass nothing. To solve this, the subroutines are named and declared in a particular way. Here's a typical start of a static function used within the Perl guts: (TBT) STATIC becomes "static" in C, and may be #define'd to nothing in some configurations in future. STATIC becomes "static" in C, and may be #define'd to nothing in some configurations in future. (TBT) A public function (i.e. part of the internal API, but not necessarily sanctioned for use in extensions) begins like this: A public function (i.e. part of the internal API, but not necessarily sanctioned for use in extensions) begins like this: (TBT) pTHX_ is one of a number of macros (in perl.h) that hide the details of the interpreter's context. THX stands for "thread", "this", or "thingy", as the case may be. (And no, George Lucas is not involved. :-) The first character could be 'p' for a prototype, 'a' for argument, or 'd' for declaration, so we have pTHX, aTHX and dTHX, and their variants. pTHX_ is one of a number of macros (in perl.h) that hide the details of the interpreter's context. THX stands for "thread", "this", or "thingy", as the case may be. (And no, George Lucas is not involved. :-) The first character could be 'p' for a prototype, 'a' for argument, or 'd' for declaration, so we have pTHX, aTHX and dTHX, and their variants. (TBT) When Perl is built without options that set PERL_IMPLICIT_CONTEXT, there is no first argument containing the interpreter's context. The trailing underscore in the pTHX_ macro indicates that the macro expansion needs a comma after the context argument because other arguments follow it. If PERL_IMPLICIT_CONTEXT is not defined, pTHX_ will be ignored, and the subroutine is not prototyped to take the extra argument. The form of the macro without the trailing underscore is used when there are no additional explicit arguments. When Perl is built without options that set PERL_IMPLICIT_CONTEXT, there is no first argument containing the interpreter's context. The trailing underscore in the pTHX_ macro indicates that the macro expansion needs a comma after the context argument because other arguments follow it. If PERL_IMPLICIT_CONTEXT is not defined, pTHX_ will be ignored, and the subroutine is not prototyped to take the extra argument. The form of the macro without the trailing underscore is used when there are no additional explicit arguments. (TBT) When a core function calls another, it must pass the context. This is normally hidden via macros. Consider sv_setiv. It expands into something like this: When a core function calls another, it must pass the context. This is normally hidden via macros. Consider sv_setiv. It expands into something like this: (TBT) This works well, and means that XS authors can gleefully write: This works well, and means that XS authors can gleefully write: (TBT) and still have it work under all the modes Perl could have been compiled with. and still have it work under all the modes Perl could have been compiled with. (TBT) This doesn't work so cleanly for varargs functions, though, as macros imply that the number of arguments is known in advance. Instead we either need to spell them out fully, passing aTHX_ as the first argument (the Perl core tends to do this with functions like Perl_warner), or use a context-free version. This doesn't work so cleanly for varargs functions, though, as macros imply that the number of arguments is known in advance. Instead we either need to spell them out fully, passing aTHX_ as the first argument (the Perl core tends to do this with functions like Perl_warner), or use a context-free version. (TBT) The context-free version of Perl_warner is called Perl_warner_nocontext, and does not take the extra argument. Instead it does dTHX; to get the context from thread-local storage. We #define warner Perl_warner_nocontext so that extensions get source compatibility at the expense of performance. (Passing an arg is cheaper than grabbing it from thread-local storage.) The context-free version of Perl_warner is called Perl_warner_nocontext, and does not take the extra argument. Instead it does dTHX; to get the context from thread-local storage. We #define warner Perl_warner_nocontext so that extensions get source compatibility at the expense of performance. (Passing an arg is cheaper than grabbing it from thread-local storage.) (TBT) You can ignore [pad]THXx when browsing the Perl headers/sources. Those are strictly for use within the core. Extensions and embedders need only be aware of [pad]THX. You can ignore [pad]THXx when browsing the Perl headers/sources. Those are strictly for use within the core. Extensions and embedders need only be aware of [pad]THX. (TBT) dTHR was introduced in perl 5.005 to support the older thread model. The older thread model now uses the THX mechanism to pass context pointers around, so dTHR is not useful any more. Perl 5.6.0 and later still have it for backward source compatibility, but it is defined to be a no-op. dTHR was introduced in perl 5.005 to support the older thread model. The older thread model now uses the THX mechanism to pass context pointers around, so dTHR is not useful any more. Perl 5.6.0 and later still have it for backward source compatibility, but it is defined to be a no-op. (TBT) When Perl is built with PERL_IMPLICIT_CONTEXT, extensions that call any functions in the Perl API will need to pass the initial context argument somehow. The kicker is that you will need to write it in such a way that the extension still compiles when Perl hasn't been built with PERL_IMPLICIT_CONTEXT enabled. When Perl is built with PERL_IMPLICIT_CONTEXT, extensions that call any functions in the Perl API will need to pass the initial context argument somehow. The kicker is that you will need to write it in such a way that the extension still compiles when Perl hasn't been built with PERL_IMPLICIT_CONTEXT enabled. (TBT) There are three ways to do this. First, the easy but inefficient way, which is also the default, in order to maintain source compatibility with extensions: whenever XSUB.h is #included, it redefines the aTHX and aTHX_ macros to call a function that will return the context. Thus, something like: There are three ways to do this. First, the easy but inefficient way, which is also the default, in order to maintain source compatibility with extensions: whenever XSUB.h is #included, it redefines the aTHX and aTHX_ macros to call a function that will return the context. Thus, something like: (TBT) in your extension will translate to this when PERL_IMPLICIT_CONTEXT is in effect: in your extension will translate to this when PERL_IMPLICIT_CONTEXT is in effect: (TBT) or to this otherwise: or to this otherwise: (TBT) You have to do nothing new in your extension to get this; since the Perl library provides Perl_get_context(), it will all just work. You have to do nothing new in your extension to get this; since the Perl library provides Perl_get_context(), it will all just work. (TBT) The second, more efficient way is to use the following template for your Foo.xs: The second, more efficient way is to use the following template for your Foo.xs: (TBT) Note that the only two changes from the normal way of writing an extension is the addition of a #define PERL_NO_GET_CONTEXT before including the Perl headers, followed by a dTHX; declaration at the start of every function that will call the Perl API. (You'll know which functions need this, because the C compiler will complain that there's an undeclared identifier in those functions.) No changes are needed for the XSUBs themselves, because the XS() macro is correctly defined to pass in the implicit context if needed. Note that the only two changes from the normal way of writing an extension is the addition of a #define PERL_NO_GET_CONTEXT before including the Perl headers, followed by a dTHX; declaration at the start of every function that will call the Perl API. (You'll know which functions need this, because the C compiler will complain that there's an undeclared identifier in those functions.) No changes are needed for the XSUBs themselves, because the XS() macro is correctly defined to pass in the implicit context if needed. (TBT) The third, even more efficient way is to ape how it is done within the Perl guts: The third, even more efficient way is to ape how it is done within the Perl guts: (TBT) This implementation never has to fetch the context using a function call, since it is always passed as an extra argument. Depending on your needs for simplicity or efficiency, you may mix the previous two approaches freely. This implementation never has to fetch the context using a function call, since it is always passed as an extra argument. Depending on your needs for simplicity or efficiency, you may mix the previous two approaches freely. (TBT) Never add a comma after pTHX yourself--always use the form of the macro with the underscore for functions that take explicit arguments, or the form without the argument for functions with no explicit arguments. Never add a comma after pTHX yourself--always use the form of the macro with the underscore for functions that take explicit arguments, or the form without the argument for functions with no explicit arguments. (TBT) If one is compiling Perl with the -DPERL_GLOBAL_STRUCT the dVAR definition is needed if the Perl global variables (see perlvars.h or globvar.sym) are accessed in the function and dTHX is not used (the dTHX includes the dVAR if necessary). One notices the need for dVAR only with the said compile-time define, because otherwise the Perl global variables are visible as-is. If one is compiling Perl with the -DPERL_GLOBAL_STRUCT the dVAR definition is needed if the Perl global variables (see perlvars.h or globvar.sym) are accessed in the function and dTHX is not used (the dTHX includes the dVAR if necessary). One notices the need for dVAR only with the said compile-time define, because otherwise the Perl global variables are visible as-is. (TBT) If you create interpreters in one thread and then proceed to call them in another, you need to make sure perl's own Thread Local Storage (TLS) slot is initialized correctly in each of those threads. If you create interpreters in one thread and then proceed to call them in another, you need to make sure perl's own Thread Local Storage (TLS) slot is initialized correctly in each of those threads. (TBT) The perl_alloc and perl_clone API functions will automatically set the TLS slot to the interpreter they created, so that there is no need to do anything special if the interpreter is always accessed in the same thread that created it, and that thread did not create or call any other interpreters afterwards. If that is not the case, you have to set the TLS slot of the thread before calling any functions in the Perl API on that particular interpreter. This is done by calling the PERL_SET_CONTEXT macro in that thread as the first thing you do: The perl_alloc and perl_clone API functions will automatically set the TLS slot to the interpreter they created, so that there is no need to do anything special if the interpreter is always accessed in the same thread that created it, and that thread did not create or call any other interpreters afterwards. If that is not the case, you have to set the TLS slot of the thread before calling any functions in the Perl API on that particular interpreter. This is done by calling the PERL_SET_CONTEXT macro in that thread as the first thing you do: (TBT) Just as PERL_IMPLICIT_CONTEXT provides a way to bundle up everything that the interpreter knows about itself and pass it around, so too are there plans to allow the interpreter to bundle up everything it knows about the environment it's running on. This is enabled with the PERL_IMPLICIT_SYS macro. Currently it only works with USE_ITHREADS on Windows. Just as PERL_IMPLICIT_CONTEXT provides a way to bundle up everything that the interpreter knows about itself and pass it around, so too are there plans to allow the interpreter to bundle up everything it knows about the environment it's running on. This is enabled with the PERL_IMPLICIT_SYS macro. Currently it only works with USE_ITHREADS on Windows. (TBT) This allows the ability to provide an extra pointer (called the "host" environment) for all the system calls. This makes it possible for all the system stuff to maintain their own state, broken down into seven C structures. These are thin wrappers around the usual system calls (see win32/perllib.c) for the default perl executable, but for a more ambitious host (like the one that would do fork() emulation) all the extra work needed to pretend that different interpreters are actually different "processes", would be done here. This allows the ability to provide an extra pointer (called the "host" environment) for all the system calls. This makes it possible for all the system stuff to maintain their own state, broken down into seven C structures. These are thin wrappers around the usual system calls (see win32/perllib.c) for the default perl executable, but for a more ambitious host (like the one that would do fork() emulation) all the extra work needed to pretend that different interpreters are actually different "processes", would be done here. (TBT) The Perl engine/interpreter and the host are orthogonal entities. There could be one or more interpreters in a process, and one or more "hosts", with free association between them. The Perl engine/interpreter and the host are orthogonal entities. There could be one or more interpreters in a process, and one or more "hosts", with free association between them. (TBT) All of Perl's internal functions which will be exposed to the outside world are prefixed by Perl_ so that they will not conflict with XS functions or functions used in a program in which Perl is embedded. Similarly, all global variables begin with PL_. (By convention, static functions start with S_.) All of Perl's internal functions which will be exposed to the outside world are prefixed by Perl_ so that they will not conflict with XS functions or functions used in a program in which Perl is embedded. Similarly, all global variables begin with PL_. (By convention, static functions start with S_.) (TBT) Inside the Perl core, you can get at the functions either with or without the Perl_ prefix, thanks to a bunch of defines that live in embed.h. This header file is generated automatically from embed.pl and embed.fnc. embed.pl also creates the prototyping header files for the internal functions, generates the documentation and a lot of other bits and pieces. It's important that when you add a new function to the core or change an existing one, you change the data in the table in embed.fnc as well. Here's a sample entry from that table: Inside the Perl core, you can get at the functions either with or without the Perl_ prefix, thanks to a bunch of defines that live in embed.h. This header file is generated automatically from embed.pl and embed.fnc. embed.pl also creates the prototyping header files for the internal functions, generates the documentation and a lot of other bits and pieces. It's important that when you add a new function to the core or change an existing one, you change the data in the table in embed.fnc as well. Here's a sample entry from that table: (TBT) The second column is the return type, the third column the name. Columns after that are the arguments. The first column is a set of flags: The second column is the return type, the third column the name. Columns after that are the arguments. The first column is a set of flags: (TBT) A This function is a part of the public API. All such functions should also have 'd', very few do not. This function is a part of the public API. All such functions should also have 'd', very few do not. (TBT) p This function has a Perl_ prefix; i.e. it is defined as Perl_av_fetch. This function has a Perl_ prefix; i.e. it is defined as Perl_av_fetch. (TBT) d This function has documentation using the apidoc feature which we'll look at in a second. Some functions have 'd' but not 'A'; docs are good. This function has documentation using the apidoc feature which we'll look at in a second. Some functions have 'd' but not 'A'; docs are good. (TBT) Other available flags are: Other available flags are: (TBT) s This is a static function and is defined as STATIC S_whatever, and usually called within the sources as whatever(...). This is a static function and is defined as STATIC S_whatever, and usually called within the sources as whatever(...). (TBT) n This does not need a interpreter context, so the definition has no pTHX, and it follows that callers don't use aTHX. (See perlguts/Background and PERL_IMPLICIT_CONTEXT.) This does not need a interpreter context, so the definition has no pTHX, and it follows that callers don't use aTHX. (See perlguts/Background and PERL_IMPLICIT_CONTEXT.) (TBT) r This function never returns; croak, exit and friends. This function never returns; croak, exit and friends. (TBT) f This function takes a variable number of arguments, printf style. The argument list should end with ..., like this: This function takes a variable number of arguments, printf style. The argument list should end with ..., like this: (TBT) M This function is part of the experimental development API, and may change or disappear without notice. This function is part of the experimental development API, and may change or disappear without notice. (TBT) o This function should not have a compatibility macro to define, say, Perl_parse to parse. It must be called as Perl_parse. This function should not have a compatibility macro to define, say, Perl_parse to parse. It must be called as Perl_parse. (TBT) x This function isn't exported out of the Perl core. この関数は Perl コアの外側へエクスポートされません。 m This is implemented as a macro. これはマクロとして実装されています。 X This function is explicitly exported. この関数は明示的にエクスポートされます。 E This function is visible to extensions included in the Perl core. この関数は Perl コアに含まれるエクステンションから見えます。 b Binary backward compatibility; this function is a macro but also has a Perl_ implementation (which is exported). Binary backward compatibility; this function is a macro but also has a Perl_ implementation (which is exported). (TBT) others See the comments at the top of embed.fnc for others. See the comments at the top of embed.fnc for others. (TBT) If you edit embed.pl or embed.fnc, you will need to run make regen_headers to force a rebuild of embed.h and other auto-generated files. If you edit embed.pl or embed.fnc, you will need to run make regen_headers to force a rebuild of embed.h and other auto-generated files. (TBT) If you are printing IVs, UVs, or NVS instead of the stdio(3) style formatting codes like %d, %ld, %f, you should use the following macros for portability If you are printing IVs, UVs, or NVS instead of the stdio(3) style formatting codes like %d, %ld, %f, you should use the following macros for portability (TBT) These will take care of 64-bit integers and long doubles. For example: These will take care of 64-bit integers and long doubles. For example: (TBT) The IVdf will expand to whatever is the correct format for the IVs. The IVdf will expand to whatever is the correct format for the IVs. (TBT) If you are printing addresses of pointers, use UVxf combined with PTR2UV(), do not use %lx or %p. If you are printing addresses of pointers, use UVxf combined with PTR2UV(), do not use %lx or %p. (TBT) Because pointer size does not necessarily equal integer size, use the follow macros to do it right. Because pointer size does not necessarily equal integer size, use the follow macros to do it right. (TBT) For example: 例えば: and および There are a couple of macros to do very basic exception handling in XS modules. You have to define NO_XSLOCKS before including XSUB.h to be able to use these macros: There are a couple of macros to do very basic exception handling in XS modules. You have to define NO_XSLOCKS before including XSUB.h to be able to use these macros: (TBT) You can use these macros if you call code that may croak, but you need to do some cleanup before giving control back to Perl. For example: You can use these macros if you call code that may croak, but you need to do some cleanup before giving control back to Perl. For example: (TBT) Note that you always have to rethrow an exception that has been caught. Using these macros, it is not possible to just catch the exception and ignore it. If you have to ignore the exception, you have to use the call_* function. Note that you always have to rethrow an exception that has been caught. Using these macros, it is not possible to just catch the exception and ignore it. If you have to ignore the exception, you have to use the call_* function. (TBT) The advantage of using the above macros is that you don't have to setup an extra function for call_*, and that using these macros is faster than using call_*. The advantage of using the above macros is that you don't have to setup an extra function for call_*, and that using these macros is faster than using call_*. (TBT) There's an effort going on to document the internal functions and automatically produce reference manuals from them - perlapi is one such manual which details all the functions which are available to XS writers. perlintern is the autogenerated manual for the functions which are not part of the API and are supposedly for internal use only. There's an effort going on to document the internal functions and automatically produce reference manuals from them - perlapi is one such manual which details all the functions which are available to XS writers. perlintern is the autogenerated manual for the functions which are not part of the API and are supposedly for internal use only. (TBT) Source documentation is created by putting POD comments into the C source, like this: Source documentation is created by putting POD comments into the C source, like this: (TBT) . ]]> Please try and supply some documentation if you add functions to the Perl core. Please try and supply some documentation if you add functions to the Perl core. (TBT) (後方互換性) The Perl API changes over time. New functions are added or the interfaces of existing functions are changed. The Devel::PPPort module tries to provide compatibility code for some of these changes, so XS writers don't have to code it themselves when supporting multiple versions of Perl. The Perl API changes over time. New functions are added or the interfaces of existing functions are changed. The Devel::PPPort module tries to provide compatibility code for some of these changes, so XS writers don't have to code it themselves when supporting multiple versions of Perl. (TBT) Devel::PPPort generates a C header file ppport.h that can also be run as a Perl script. To generate ppport.h, run: Devel::PPPort generates a C header file ppport.h that can also be run as a Perl script. To generate ppport.h, run: (TBT) Besides checking existing XS code, the script can also be used to retrieve compatibility information for various API calls using the --api-info command line switch. For example: Besides checking existing XS code, the script can also be used to retrieve compatibility information for various API calls using the --api-info command line switch. For example: (TBT) For details, see perldoc ppport.h. 詳細については、perldoc ppport.h を参照してください。 (Unicode 対応) Perl 5.6.0 introduced Unicode support. It's important for porters and XS writers to understand this support and make sure that the code they write does not corrupt Unicode data. Perl 5.6.0 introduced Unicode support. It's important for porters and XS writers to understand this support and make sure that the code they write does not corrupt Unicode data. (TBT) (ところで、Unicode って 何 ?) In the olden, less enlightened times, we all used to use ASCII. Most of us did, anyway. The big problem with ASCII is that it's American. Well, no, that's not actually the problem; the problem is that it's not particularly useful for people who don't use the Roman alphabet. What used to happen was that particular languages would stick their own alphabet in the upper range of the sequence, between 128 and 255. Of course, we then ended up with plenty of variants that weren't quite ASCII, and the whole point of it being a standard was lost. In the olden, less enlightened times, we all used to use ASCII. Most of us did, anyway. The big problem with ASCII is that it's American. Well, no, that's not actually the problem; the problem is that it's not particularly useful for people who don't use the Roman alphabet. What used to happen was that particular languages would stick their own alphabet in the upper range of the sequence, between 128 and 255. Of course, we then ended up with plenty of variants that weren't quite ASCII, and the whole point of it being a standard was lost. (TBT) Worse still, if you've got a language like Chinese or Japanese that has hundreds or thousands of characters, then you really can't fit them into a mere 256, so they had to forget about ASCII altogether, and build their own systems using pairs of numbers to refer to one character. Worse still, if you've got a language like Chinese or Japanese that has hundreds or thousands of characters, then you really can't fit them into a mere 256, so they had to forget about ASCII altogether, and build their own systems using pairs of numbers to refer to one character. (TBT) To fix this, some people formed Unicode, Inc. and produced a new character set containing all the characters you can possibly think of and more. There are several ways of representing these characters, and the one Perl uses is called UTF-8. UTF-8 uses a variable number of bytes to represent a character. You can learn more about Unicode and Perl's Unicode model in perlunicode. To fix this, some people formed Unicode, Inc. and produced a new character set containing all the characters you can possibly think of and more. There are several ways of representing these characters, and the one Perl uses is called UTF-8. UTF-8 uses a variable number of bytes to represent a character. You can learn more about Unicode and Perl's Unicode model in perlunicode. (TBT) (UTF-8 文字列を認識するには?) You can't. This is because UTF-8 data is stored in bytes just like non-UTF-8 data. The Unicode character 200, (0xC8 for you hex types) capital E with a grave accent, is represented by the two bytes v196.172. Unfortunately, the non-Unicode string chr(196).chr(172) has that byte sequence as well. So you can't tell just by looking - this is what makes Unicode input an interesting problem. You can't. This is because UTF-8 data is stored in bytes just like non-UTF-8 data. The Unicode character 200, (0xC8 for you hex types) capital E with a grave accent, is represented by the two bytes v196.172. Unfortunately, the non-Unicode string chr(196).chr(172) has that byte sequence as well. So you can't tell just by looking - this is what makes Unicode input an interesting problem. (TBT) In general, you either have to know what you're dealing with, or you have to guess. The API function is_utf8_string can help; it'll tell you if a string contains only valid UTF-8 characters. However, it can't do the work for you. On a character-by-character basis, is_utf8_char will tell you whether the current character in a string is valid UTF-8. In general, you either have to know what you're dealing with, or you have to guess. The API function is_utf8_string can help; it'll tell you if a string contains only valid UTF-8 characters. However, it can't do the work for you. On a character-by-character basis, is_utf8_char will tell you whether the current character in a string is valid UTF-8. (TBT) As mentioned above, UTF-8 uses a variable number of bytes to store a character. Characters with values 0...127 are stored in one byte, just like good ol' ASCII. Character 128 is stored as v194.128; this continues up to character 191, which is v194.191. Now we've run out of bits (191 is binary 10111111) so we move on; 192 is v195.128. And so it goes on, moving to three bytes at character 2048. As mentioned above, UTF-8 uses a variable number of bytes to store a character. Characters with values 0...127 are stored in one byte, just like good ol' ASCII. Character 128 is stored as v194.128; this continues up to character 191, which is v194.191. Now we've run out of bits (191 is binary 10111111) so we move on; 192 is v195.128. And so it goes on, moving to three bytes at character 2048. (TBT) Assuming you know you're dealing with a UTF-8 string, you can find out how long the first character in it is with the UTF8SKIP macro: Assuming you know you're dealing with a UTF-8 string, you can find out how long the first character in it is with the UTF8SKIP macro: (TBT) Another way to skip over characters in a UTF-8 string is to use utf8_hop, which takes a string and a number of characters to skip over. You're on your own about bounds checking, though, so don't use it lightly. Another way to skip over characters in a UTF-8 string is to use utf8_hop, which takes a string and a number of characters to skip over. You're on your own about bounds checking, though, so don't use it lightly. (TBT) All bytes in a multi-byte UTF-8 character will have the high bit set, so you can test if you need to do something special with this character like this (the UTF8_IS_INVARIANT() is a macro that tests whether the byte can be encoded as a single byte even in UTF-8): All bytes in a multi-byte UTF-8 character will have the high bit set, so you can test if you need to do something special with this character like this (the UTF8_IS_INVARIANT() is a macro that tests whether the byte can be encoded as a single byte even in UTF-8): (TBT) You can also see in that example that we use utf8_to_uv to get the value of the character; the inverse function uv_to_utf8 is available for putting a UV into UTF-8: You can also see in that example that we use utf8_to_uv to get the value of the character; the inverse function uv_to_utf8 is available for putting a UV into UTF-8: (TBT) You must convert characters to UVs using the above functions if you're ever in a situation where you have to match UTF-8 and non-UTF-8 characters. You may not skip over UTF-8 characters in this case. If you do this, you'll lose the ability to match hi-bit non-UTF-8 characters; for instance, if your UTF-8 string contains v196.172, and you skip that character, you can never match a chr(200) in a non-UTF-8 string. So don't do that! You must convert characters to UVs using the above functions if you're ever in a situation where you have to match UTF-8 and non-UTF-8 characters. You may not skip over UTF-8 characters in this case. If you do this, you'll lose the ability to match hi-bit non-UTF-8 characters; for instance, if your UTF-8 string contains v196.172, and you skip that character, you can never match a chr(200) in a non-UTF-8 string. So don't do that! (TBT) Currently, Perl deals with Unicode strings and non-Unicode strings slightly differently. A flag in the SV, SVf_UTF8, indicates that the string is internally encoded as UTF-8. Without it, the byte value is the codepoint number and vice versa (in other words, the string is encoded as iso-8859-1). You can check and manipulate this flag with the following macros: Currently, Perl deals with Unicode strings and non-Unicode strings slightly differently. A flag in the SV, SVf_UTF8, indicates that the string is internally encoded as UTF-8. Without it, the byte value is the codepoint number and vice versa (in other words, the string is encoded as iso-8859-1). You can check and manipulate this flag with the following macros: (TBT) This flag has an important effect on Perl's treatment of the string: if Unicode data is not properly distinguished, regular expressions, length, substr and other string handling operations will have undesirable results. This flag has an important effect on Perl's treatment of the string: if Unicode data is not properly distinguished, regular expressions, length, substr and other string handling operations will have undesirable results. (TBT) The problem comes when you have, for instance, a string that isn't flagged as UTF-8, and contains a byte sequence that could be UTF-8 - especially when combining non-UTF-8 and UTF-8 strings. The problem comes when you have, for instance, a string that isn't flagged as UTF-8, and contains a byte sequence that could be UTF-8 - especially when combining non-UTF-8 and UTF-8 strings. (TBT) Never forget that the SVf_UTF8 flag is separate to the PV value; you need be sure you don't accidentally knock it off while you're manipulating SVs. More specifically, you cannot expect to do this: Never forget that the SVf_UTF8 flag is separate to the PV value; you need be sure you don't accidentally knock it off while you're manipulating SVs. More specifically, you cannot expect to do this: (TBT) The char* string does not tell you the whole story, and you can't copy or reconstruct an SV just by copying the string value. Check if the old SV has the UTF8 flag set, and act accordingly: The char* string does not tell you the whole story, and you can't copy or reconstruct an SV just by copying the string value. Check if the old SV has the UTF8 flag set, and act accordingly: (TBT) In fact, your frobnicate function should be made aware of whether or not it's dealing with UTF-8 data, so that it can handle the string appropriately. In fact, your frobnicate function should be made aware of whether or not it's dealing with UTF-8 data, so that it can handle the string appropriately. (TBT) Since just passing an SV to an XS function and copying the data of the SV is not enough to copy the UTF8 flags, even less right is just passing a char * to an XS function. Since just passing an SV to an XS function and copying the data of the SV is not enough to copy the UTF8 flags, even less right is just passing a char * to an XS function. (TBT) If you're mixing UTF-8 and non-UTF-8 strings, it is necessary to upgrade one of the strings to UTF-8. If you've got an SV, the easiest way to do this is: If you're mixing UTF-8 and non-UTF-8 strings, it is necessary to upgrade one of the strings to UTF-8. If you've got an SV, the easiest way to do this is: (TBT) However, you must not do this, for example: However, you must not do this, for example: (TBT) If you do this in a binary operator, you will actually change one of the strings that came into the operator, and, while it shouldn't be noticeable by the end user, it can cause problems in deficient code. If you do this in a binary operator, you will actually change one of the strings that came into the operator, and, while it shouldn't be noticeable by the end user, it can cause problems in deficient code. (TBT) Instead, bytes_to_utf8 will give you a UTF-8-encoded copy of its string argument. This is useful for having the data available for comparisons and so on, without harming the original SV. There's also utf8_to_bytes to go the other way, but naturally, this will fail if the string contains any characters above 255 that can't be represented in a single byte. Instead, bytes_to_utf8 will give you a UTF-8-encoded copy of its string argument. This is useful for having the data available for comparisons and so on, without harming the original SV. There's also utf8_to_bytes to go the other way, but naturally, this will fail if the string contains any characters above 255 that can't be represented in a single byte. (TBT) (他に知っておくべきことは?) Not really. Just remember these things: 実際にはありません。 単に以下のことを覚えておいてください: There's no way to tell if a string is UTF-8 or not. You can tell if an SV is UTF-8 by looking at is SvUTF8 flag. Don't forget to set the flag if something should be UTF-8. Treat the flag as part of the PV, even though it's not - if you pass on the PV to somewhere, pass on the flag too. There's no way to tell if a string is UTF-8 or not. You can tell if an SV is UTF-8 by looking at is SvUTF8 flag. Don't forget to set the flag if something should be UTF-8. Treat the flag as part of the PV, even though it's not - if you pass on the PV to somewhere, pass on the flag too. (TBT) If a string is UTF-8, always use utf8_to_uv to get at the value, unless UTF8_IS_INVARIANT(*s) in which case you can use *s. If a string is UTF-8, always use utf8_to_uv to get at the value, unless UTF8_IS_INVARIANT(*s) in which case you can use *s. (TBT) When writing a character uv to a UTF-8 string, always use uv_to_utf8, unless UTF8_IS_INVARIANT(uv)) in which case you can use *s = uv. When writing a character uv to a UTF-8 string, always use uv_to_utf8, unless UTF8_IS_INVARIANT(uv)) in which case you can use *s = uv. (TBT) Mixing UTF-8 and non-UTF-8 strings is tricky. Use bytes_to_utf8 to get a new string which is UTF-8 encoded. There are tricks you can use to delay deciding whether you need to use a UTF-8 string until you get to a high character - HALF_UPGRADE is one of those. Mixing UTF-8 and non-UTF-8 strings is tricky. Use bytes_to_utf8 to get a new string which is UTF-8 encoded. There are tricks you can use to delay deciding whether you need to use a UTF-8 string until you get to a high character - HALF_UPGRADE is one of those. (TBT) Custom operator support is a new experimental feature that allows you to define your own ops. This is primarily to allow the building of interpreters for other languages in the Perl core, but it also allows optimizations through the creation of "macro-ops" (ops which perform the functions of multiple ops which are usually executed together, such as gvsv, gvsv, add.) Custom operator support is a new experimental feature that allows you to define your own ops. This is primarily to allow the building of interpreters for other languages in the Perl core, but it also allows optimizations through the creation of "macro-ops" (ops which perform the functions of multiple ops which are usually executed together, such as gvsv, gvsv, add.) (TBT) This feature is implemented as a new op type, OP_CUSTOM. The Perl core does not "know" anything special about this op type, and so it will not be involved in any optimizations. This also means that you can define your custom ops to be any op structure - unary, binary, list and so on - you like. This feature is implemented as a new op type, OP_CUSTOM. The Perl core does not "know" anything special about this op type, and so it will not be involved in any optimizations. This also means that you can define your custom ops to be any op structure - unary, binary, list and so on - you like. (TBT) It's important to know what custom operators won't do for you. They won't let you add new syntax to Perl, directly. They won't even let you add new keywords, directly. In fact, they won't change the way Perl compiles a program at all. You have to do those changes yourself, after Perl has compiled the program. You do this either by manipulating the op tree using a CHECK block and the B::Generate module, or by adding a custom peephole optimizer with the optimize module. It's important to know what custom operators won't do for you. They won't let you add new syntax to Perl, directly. They won't even let you add new keywords, directly. In fact, they won't change the way Perl compiles a program at all. You have to do those changes yourself, after Perl has compiled the program. You do this either by manipulating the op tree using a CHECK block and the B::Generate module, or by adding a custom peephole optimizer with the optimize module. (TBT) When you do this, you replace ordinary Perl ops with custom ops by creating ops with the type OP_CUSTOM and the pp_addr of your own PP function. This should be defined in XS code, and should look like the PP ops in pp_*.c. You are responsible for ensuring that your op takes the appropriate number of values from the stack, and you are responsible for adding stack marks if necessary. When you do this, you replace ordinary Perl ops with custom ops by creating ops with the type OP_CUSTOM and the pp_addr of your own PP function. This should be defined in XS code, and should look like the PP ops in pp_*.c. You are responsible for ensuring that your op takes the appropriate number of values from the stack, and you are responsible for adding stack marks if necessary. (TBT) You should also "register" your op with the Perl interpreter so that it can produce sensible error and warning messages. Since it is possible to have multiple custom ops within the one "logical" op type OP_CUSTOM, Perl uses the value of o->op_ppaddr as a key into the PL_custom_op_descs and PL_custom_op_names hashes. This means you need to enter a name and description for your op at the appropriate place in the PL_custom_op_names and PL_custom_op_descs hashes. You should also "register" your op with the Perl interpreter so that it can produce sensible error and warning messages. Since it is possible to have multiple custom ops within the one "logical" op type OP_CUSTOM, Perl uses the value of o->op_ppaddr as a key into the PL_custom_op_descs and PL_custom_op_names hashes. This means you need to enter a name and description for your op at the appropriate place in the PL_custom_op_names and PL_custom_op_descs hashes. (TBT) Forthcoming versions of B::Generate (version 1.0 and above) should directly support the creation of custom ops by name. Forthcoming versions of B::Generate (version 1.0 and above) should directly support the creation of custom ops by name. (TBT) Until May 1997, this document was maintained by Jeff Okamoto <okamoto@corp.hp.com>. It is now maintained as part of Perl itself by the Perl 5 Porters <perl5-porters@perl.org>. Until May 1997, this document was maintained by Jeff Okamoto <okamoto@corp.hp.com>. It is now maintained as part of Perl itself by the Perl 5 Porters <perl5-porters@perl.org>. (TBT) With lots of help and suggestions from Dean Roehrich, Malcolm Beattie, Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil Bowers, Matthew Green, Tim Bunce, Spider Boardman, Ulrich Pfeifer, Stephen McCamant, and Gurusamy Sarathy. With lots of help and suggestions from Dean Roehrich, Malcolm Beattie, Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil Bowers, Matthew Green, Tim Bunce, Spider Boardman, Ulrich Pfeifer, Stephen McCamant, and Gurusamy Sarathy. (TBT) perlapi(1), perlintern(1), perlxs(1), perlembed(1) Created: KIMURA Koichi Updated: Kentaro Shirakata <argrath@ub32.org> (5.10.0-)