php内置函数分析之array_diff_assoc()

static void php_array_diff_key(INTERNAL_FUNCTION_PARAMETERS, int data_compare_type) /* {{{ */
{
    uint idx;
    Bucket *p;
    int argc, i;
    zval *args;
    int (*diff_data_compare_func)(zval *, zval *) = NULL;
    zend_bool ok;
    zval *val, *data;

    /* Get the argument count */
    argc = ZEND_NUM_ARGS();
    if (data_compare_type == DIFF_COMP_DATA_USER) {  // array_diff_uassoc
        if (argc < 3) {
            php_error_docref(NULL, E_WARNING, "at least 3 parameters are required, %d given", ZEND_NUM_ARGS());
            return;
        }
        // 类型描述符：f  - function or array containing php method call info (returned as zend_fcall_info and zend_fcall_info_cache)
        if (zend_parse_parameters(ZEND_NUM_ARGS(), "+f", &args, &argc, &BG(user_compare_fci), &BG(user_compare_fci_cache)) == FAILURE) {
            return;
        }
        diff_data_compare_func = zval_user_compare; // 用户自定义的回调函数
    } else {  
        // 至少两个参数
        if (argc < 2) {
            php_error_docref(NULL, E_WARNING, "at least 2 parameters are required, %d given", ZEND_NUM_ARGS());
            return;
        }
        if (zend_parse_parameters(ZEND_NUM_ARGS(), "+", &args, &argc) == FAILURE) {
            return;
        }
        // array_diff_assoc
        if (data_compare_type == DIFF_COMP_DATA_INTERNAL) {
            diff_data_compare_func = zval_compare; //字符串比较函数
        }
    }
    
    // 参数（array_diff_uassoc时回调函数除外）必须是数组
    for (i = 0; i < argc; i++) {
        if (Z_TYPE(args[i]) != IS_ARRAY) {
            php_error_docref(NULL, E_WARNING, "Argument #%d is not an array", i + 1);
            RETURN_NULL();
        }
    }

    array_init(return_value);
    
    // 循环第一个数组
    for (idx = 0; idx < Z_ARRVAL(args[0])->nNumUsed; idx++) {
        p = Z_ARRVAL(args[0])->arData + idx;
        val = &p->val;
        if (Z_TYPE_P(val) == IS_UNDEF) continue; // 跳过已销毁的元素。
        if (UNEXPECTED(Z_TYPE_P(val) == IS_INDIRECT)) { // ???
            val = Z_INDIRECT_P(val);
            if (Z_TYPE_P(val) == IS_UNDEF) continue;
        }
        if (Z_ISREF_P(val) && Z_REFCOUNT_P(val) == 1) {
            ZVAL_UNREF(val);
        }
        if (p->key == NULL) { // 键为整数
            ok = 1;
            // 遍历其他数组，查找
            for (i = 1; i < argc; i++) {
                // 键和值都要一致
                if ((data = zend_hash_index_find(Z_ARRVAL(args[i]), p->h)) != NULL &&
                    (!diff_data_compare_func ||
                    diff_data_compare_func(val, data) == 0)
                ) {
                    // 找到之后，ok置为0                    
                    ok = 0;
                    break;
                }
            }
            // 没有再其他数组中找到，则将该元素（键和值）保存到return_value中
            if (ok) {
                if (Z_REFCOUNTED_P(val)) {
                    Z_ADDREF_P(val);
                }
                zend_hash_index_update(Z_ARRVAL_P(return_value), p->h, val);
            }
        } else {  // 键为字符串
            ok = 1;
            for (i = 1; i < argc; i++) {
                // 键和值都要一致
                if ((data = zend_hash_find_ind(Z_ARRVAL(args[i]), p->key)) != NULL &&
                    (!diff_data_compare_func ||
                    diff_data_compare_func(val, data) == 0)
                ) {
                    // 找到之后，ok置为0
                    ok = 0;
                    break;
                }
            }
            // 没有再其他数组中找到，则将该元素（键和值）保存到return_value中
            if (ok) {
                if (Z_REFCOUNTED_P(val)) {
                    Z_ADDREF_P(val);
                }
                zend_hash_update(Z_ARRVAL_P(return_value), p->key, val);
            }
        }
    }
}