A brief discussion of PHP source code fifteen: About the array_walk function

This article mainly introduces the brief discussion on PHP source code 15: Regarding the array_walk function, it has a certain reference value. Now I share it with you. Friends in need can refer to it.

Brief discussion on PHP source code 10 Five: About the array_walk function

array_walk

(PHP 3 >= 3.0.3, PHP 4, PHP 5)
array_walk — Apply user function to each member of the array
Description

bool array_walk (array &array, callback funcname [, mixed userdata] )

Returns TRUE if successful and FALSE if failed.
Apply the user-defined function funcname to each cell in the array array. Typically funcname accepts two parameters. The value of the array parameter is used as the first one, and the key name is used as the second one. If the optional argument userdata is provided, it will be passed as the third argument to callback funcname.
If the funcname function requires more parameters than given, an E_WARNING level error will be generated each time array_walk() calls funcname. These warnings can be suppressed by preceding the array_walk() call with PHP's error operator @, or by using error_reporting().
Note: If funcname needs to act directly on the values ​​in the array, specify the first parameter to funcname as a reference. Thus any changes to these cells will also change the original array itself.
Note: Passing key name and userdata into funcname is new in PHP 4.0.

array_walk() is not affected by array's internal array pointer. array_walk() will walk through the entire array regardless of the position of the pointer. (This is because the program resets the pointer of the hash table where the array is located at the beginning of the array traversal)
The user should not change the array itself in the callback function. For example, add/delete units, unset units, etc. If the array that array_walk() acts on changes, the behavior of this function is undefined and unpredictable.
Program implementation description:
The last call of the extension is the function php_array_walk:

   static int php_array_walk(HashTable *target_hash, zval **userdata, int recursive TSRMLS_DC)

When recursive == 0, this function is the array_walk function implementation

When recursive == 1 , this function is the implementation of the array_walk_recursive function

In the source code, the program will traverse the entire array, and for each array element, make relevant function calls based on the passed in function
The function call is as follows:

fci.size = sizeof(fci);
            fci.function_table = EG(function_table);
            fci.function_name = *BG(array_walk_func_name);
            fci.symbol_table = NULL;
            fci.object_pp = NULL;
            fci.retval_ptr_ptr = &retval_ptr;
            fci.param_count = userdata ? 3 : 2;
            fci.params = args;
            fci.no_separation = 0;             /* Call the userland function */
            if (zend_call_function(&fci, &array_walk_fci_cache TSRMLS_CC) == SUCCESS) {

A structure is used in this function call. The comments added by me are as follows:

 typedef struct _zend_fcall_info {
 size_t size;    //    整个结构体的长度，等于sizeof(此函数体的变量)
 HashTable *function_table;    //    executor_globals.function_table
 zval *function_name;    //    函数名 
 HashTable *symbol_table;
 zval **retval_ptr_ptr;        //    函数的返回值
 zend_uint param_count;    //    参数个数
 zval ***params;            //    所调用函数的参数
 zval **object_pp;        //    用于对象的方法调用时，存储对象
 zend_bool no_separation;    //    是否清空参数所在的栈} zend_fcall_info;

The above are personal notes. If there are any mistakes, please correct me!

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