从php核心代码分析require和include的区别

深入理解PHP之require/include顺序
http:///article/25867.htm

普及
在php手册中：

require() is identical to include() except upon failure it will also produce a fatal E_ERROR level error. In other words, it will halt the script whereas include() only emits a warning (E_WARNING) which allows the script to continue.

就是说在失败的时候，require是会中止php运行的，而include是可以继续运行的。倒底有什么样的区别呢？我们带着这个疑问来一起进入PHP的核心代码。下面是一个PHP运行过程的图（这个图是出自哪里的？鸟哥画的？）

补习一下：lex是代码扫描器，扫描代码用的，yacc是Yet Another Compiler Compiler，作用是把任何一种代码的语法转成yacc语法，yacc就是解析器（真TMD绕）。lex在c下的后缀是*.l yacc是*.y

正题下面看操作记录：

cc@cc-laptop:/opt/workspace$ svn checkout http://svn.php.net/repository/php/php-src/branches/PHP_5_3 php-src-5.3从svn取最新的php源代码。

开始深入：

cc@cc-laptop:/opt/workspace/php-src-5.3$ find . -type f -name “*.l” -exec grep -Hn “require_once” {} ;./Zend/zend_language_scanner.l:1093:”require_once” {寻找lex代码扫描器文件中出现require_once的地方，zend_language_scanner.l的1093行。1093 “require_once” {1094 return T_REQUIRE_ONCE;1095 }

然后再搜一下T_REQUIRE_ONCE,

cc@cc-laptop:/opt/workspace/php-src-5.3$ find . -type f -name “*.y” -exec grep -Hn “T_INCLUDE” {} ;./Zend/zend_language_parser.y:52:%left T_INCLUDE T_INCLUDE_ONCE T_EVAL T_REQUIRE T_REQUIRE_ONCE./Zend/zend_language_parser.y:985: | T_INCLUDE expr { zend_do_include_or_eval(ZEND_INCLUDE, &$$, &$2 TSRMLS_CC); }./Zend/zend_language_parser.y:986: | T_INCLUDE_ONCE expr { zend_do_include_or_eval(ZEND_INCLUDE_ONCE, &$$, &$2 TSRMLS_CC); }

在985行附近，有这样一群代码：

internal_functions_in_yacc:T_ISSET ‘(‘ isset_variables ‘)' { $$ = $3; }| T_EMPTY ‘(‘ variable ‘)' { zend_do_isset_or_isempty(ZEND_ISEMPTY, &$$, &$3 TSRMLS_CC); }| T_INCLUDE expr { zend_do_include_or_eval(ZEND_INCLUDE, &$$, &$2 TSRMLS_CC); }| T_INCLUDE_ONCE expr { zend_do_include_or_eval(ZEND_INCLUDE_ONCE, &$$, &$2 TSRMLS_CC); }| T_EVAL ‘(‘ expr ‘)' { zend_do_include_or_eval(ZEND_EVAL, &$$, &$3 TSRMLS_CC); }| T_REQUIRE expr { zend_do_include_or_eval(ZEND_REQUIRE, &$$, &$2 TSRMLS_CC); }| T_REQUIRE_ONCE expr { zend_do_include_or_eval(ZEND_REQUIRE_ONCE, &$$, &$2 TSRMLS_CC); };

于是乎，我们需要继续深入寻找zend_do_include_or_eval，

cc@cc-laptop:/opt/workspace/php-src-5.3$ find . -type f -name “*.c” -exec grep -Hn “zend_do_include_or_eval” {} ;./Zend/zend_compile.c:4317:void zend_do_include_or_eval(int type, znode *result, const znode *op1 TSRMLS_DC) /* {{{ */

zend_do_include_or_eval中组装了一个结构体，ZEND_INCLUDE_OR_EVAL。
再在zend_vm_def.h中找到ZEND_VM_HANDLER(73, ZEND_INCLUDE_OR_EVAL, CONST|TMP|VAR|CV, ANY)：switch (Z_LVAL(opline->op2.u.constant)) {代码略}
中间关键的一句是：new_op_array = compile_filename(Z_LVAL(opline->op2.u.constant), inc_filename TSRMLS_CC);
在zend_complie.h文件中:ZEND_API zend_op_array *compile_filename(int type, zval *filename TSRMLS_DC);
这个函数定义在zend_language_scaner.l文件中，找出最核心的代码：

if (open_file_for_scanning(file_handle TSRMLS_CC)==FAILURE) {// require与include的差别：错误信息的显示级别（有bailout和无bailout）if (type==ZEND_REQUIRE) { //require时zend_message_dispatcher(ZMSG_FAILED_REQUIRE_FOPEN, file_handle->filename TSRMLS_CC);zend_bailout();} else {zend_message_dispatcher(ZMSG_FAILED_INCLUDE_FOPEN, file_handle->filename TSRMLS_CC);}compilation_successful=0;} else {代码略}

继续追踪zend_message_dispatcher可以在main/main.c文件中找到php_message_handler_for_zend函数：

//include输出错误信息时的级别为：E_WARNINGcase ZMSG_FAILED_INCLUDE_FOPEN:php_error_docref(“function.include” TSRMLS_CC, E_WARNING, “Failed opening ‘%s' for inclusion (include_path='%s')”, php_strip_url_passwd((char *) data), STR_PRINT(PG(include_path)));break;//require输出错误信息时的级别为：E_COMPILE_ERROR代码略

总结和开头PHP手册所说完全一致，require和include的区别在于，出现错误时，一个是error一个是warning。


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