A brief discussion of PHP source code 18: About array_diff_key, array_diff_assoc, array_udiff_assoc functions

This article mainly introduces the eighteenth chapter of PHP source code: About array_diff_key, array_diff_assoc, array_udiff_assoc functions, which have certain reference value. Now I share them with you. Friends in need can refer to them

Talking about PHP source code 18: About array_diff_key, array_diff_assoc, array_udiff_assoc function

[array_diff_key]

(PHP 5 >= 5.1.0RC1)
array_diff_key — Use key name comparison to calculate the array Difference set
Description

array array_diff_key (array array1, array array2 [, array ...])

array_diff_key() returns an array that includes all occurrences in array1 But the value of the key does not appear in any other parameter array. Note that the relationship remains unchanged.

【array_diff_assoc】

(PHP 4 >= 4.3.0, PHP 5)
array_diff_assoc — Calculates the difference of an array with index checking
Description

array array_diff_assoc ( array array1, array array2 [, array ...] )

array_diff_assoc() Returns an array that includes all values ​​in array1 but not in any other parameter array. Note that unlike array_diff(), key names are also used for comparison.

The reason why these three functions are put together is because the last function they call is one function: php_array_diff_key
[array_diff_uassoc]

(PHP 5)
array_diff_uassoc — Use user The provided callback function does index checking to calculate the difference set of the array
Description

array array_diff_uassoc (array array1, array array2 [, array ..., callback key_compare_func] )

array_diff_uassoc( ) returns an array containing all values ​​in array1 that are not in any other parameter array.

The way these three functions call php-array_diff_key is as follows:

  array_diff_key:         php_array_diff_key(INTERNAL_FUNCTION_PARAM_PASSTHRU, DIFF_COMP_DATA_NONE);array_diff_assoc:      php_array_diff_key(INTERNAL_FUNCTION_PARAM_PASSTHRU, DIFF_COMP_DATA_INTERNAL);array_udiff_assoc:    php_array_diff_key(INTERNAL_FUNCTION_PARAM_PASSTHRU, DIFF_COMP_DATA_USER);

The macro definition of the parameters is as follows:

  #define INTERNAL_FUNCTION_PARAM_PASSTHRU ht, return_value, return_value_ptr, this_ptr, return_value_used TSRMLS_CC #define DIFF_COMP_DATA_NONE    -1#define DIFF_COMP_DATA_INTERNAL 0#define DIFF_COMP_DATA_USER     1

The php_array_diff_key function first needs to be based on the incoming data_compare_type (i.e. The three macros defined above), determine the comparison function to be used, then traverse the first array, compare each element with other arrays to see if other numbers exist

If they exist, delete them
For An explanatory note on the source code of this function:

 for (i = 0; i < argc; i++) {
        if (Z_TYPE_PP(args[i]) != IS_ARRAY) {
            php_error_docref(NULL TSRMLS_CC, E_WARNING, "Argument #%d is not an array", i + 1);
            RETVAL_NULL();
            goto out;    //    goto语句，这个貌似一般是高手用的，嘿嘿
        }
    } 
    array_init(return_value);    //    返回数组初始化，初始化存储此数组的Hash Table     for (p = Z_ARRVAL_PP(args[0])->pListHead; p != NULL; p = p->pListNext) {    //    遍历第一个参数包含的双向链表
        if (p->nKeyLength == 0) {    //    数组索引为数字
            ok = 1;
            for (i = 1; i < argc; i++) {    //    对其它的数组进行判断
                if (zend_hash_index_find(Z_ARRVAL_PP(args[i]), p->h, (void**)&data) == SUCCESS &&
                    (!diff_data_compare_func ||
                     diff_data_compare_func((zval**)p->pData, data TSRMLS_CC) == 0)) {
                    ok = 0;
                    break;
                }
            }
            if (ok) {    在第一个数组中，不在其它数组中                (*((zval**)p->pData))->refcount++;
                zend_hash_index_update(Z_ARRVAL_P(return_value), p->h, p->pData, sizeof(zval*), NULL);
            }
        } else {    //    索引为字符串
            ok = 1;
            for (i = 1; i < argc; i++) {
                if (zend_hash_quick_find(Z_ARRVAL_PP(args[i]), p->arKey, p->nKeyLength, p->h, (void**)&data) == SUCCESS &&
                    (!diff_data_compare_func ||
                     diff_data_compare_func((zval**)p->pData, data TSRMLS_CC) == 0)) {
                    ok = 0;
                    break;
                }
            }
            if (ok) {
                (*((zval**)p->pData))->refcount++;
                zend_hash_quick_update(Z_ARRVAL_P(return_value), p->arKey, p->nKeyLength, p->h, p->pData, sizeof(zval*), NULL);
            }
        }
    }

About the comparison function:

DIFF_COMP_DATA_NONE parameter corresponds to NULL, that is, there is no comparison, just use the index search
DIFF_COMP_DATA_INTERNAL The parameter corresponds to zval_compare, that is, both the index and the value will be compared.
DIFF_COMP_DATA_USER The parameter corresponds to zval_user_compare, which is a user-defined function.

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