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__halt_compiler コンパイラの実行を中止する


__halt_compiler(): void

コンパイラの実行を中止します。 これは、インストール用ファイルのようなデータを PHP スクリプトに埋め込んでいる場合に便利です。

データの開始位置(バイト値)は、定数 __COMPILER_HALT_OFFSET__ で定義されています。 これはファイル内で __halt_compiler() が使用されている場合にのみ存在します。





例1 __halt_compiler() の例


// このファイルをオープンします
$fp = fopen(__FILE__, 'r');

// データのある位置までファイルポインタを移動します
fseek($fp, __COMPILER_HALT_OFFSET__);

// それを出力します

// ここでスクリプトの実行を終了します
__halt_compiler(); インストールデータ(例: tar, gz, PHP など..



__halt_compiler() は、いちばん外側のスコープでのみ使用可能です。

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User Contributed Notes 7 notes

9 years ago
This function can be used in eval() -- it will halt the eval, but not the script eval"() was called in.
ravenswd at gmail dot com
7 years ago
If "__halt_compiler();" appears in a file which is "include"d or "require"d, then the called-in file will be treated as if it physically cuts off at the "__halt_compiler();". In other words, "__halt_compiler();" only affects the physical file it's in, an outer file that pulls it in will continue to execute.
ravenswd at gmail dot com
13 years ago
__halt_compiler is also useful for debugging. If you need to temporarily make a change that will introduce an error later on, use __halt_compiler to prevent syntax errors. For example:

if ( $something ):
// endif placed here for debugging purposes
// original location of endif -- would produce syntax error if __halt_compiler was not there
joey at gimo dot co dot uk
9 years ago
I don't exactly know what PHP is doing internally but I don't understand the sanity behind how in token_get_all __halt_compiler is handled.

This is actually valid there:
__halt_compiler/**/ /**/ /**/ /**/ /** */();raw

Normally it pops off just any three tokens so you can have even __halt_compiler***, __halt_compiler))), etc in token _get all.

The weird thing is that is also skips T_OPEN_TAG but in the context __halt_compiler runs in this tag should not be posible. Instead it will pick up < and ? as operators and php as a T_STRING.

It ignores the token at any point so this is also valid:
__halt_compiler()/**/ /**/ /**/ /**/ /** */;raw

When I test this with a php file rather than the tokeniser it works the same.

I can only conclude that PHP/__halt_compiler is pretty weird.

I think this is from attempting to weakly imitate the same syntax handling as in functions (I guess you can put comments/whitespace anywhere). I find it annoying and counter productive though.

Even this is valid:
__halt_compiler// comment\n();raw

A general problem that compound matters is that tokenise wont check whether or not syntax is valid (tokens against each other). When running as PHP you must have ();.
9 years ago
Joey, you're wrong saying that __halt_compiler have strange behavior. This structure works exactly the same as any other build in structure like empty or isset (even similarly to functions; at least in tokenizer level).

About T_OPEN_TAG - after one open tag is present you didn't expect other one in current php code section, so tokenizer try to handle this "thing" in other way and it's perfectly normal...
alex at 1stleg dot com
3 years ago
Please note that __HALT_COMPILER() must be uppercase if used from a pharstub:
cwk32 at mail dot ustc dot edu dot cn
8 years ago
if you find the value of __COMPILER_HALT_OFFSET__ is highly strange. Maybe...

there are some complier optimization tools, like eAccelator(very old). When the program is pre-complied and cached, the __COMPILER_HALT_OFFSET__ will be 0 = =
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