深入PHP内核之array_multisort

这个函数是我第一次看手册的时候，没看明白是怎么回事，所以有必要记录一下

用法

bool array_multisort ( array &$arr [, mixed $arg = SORT_ASC [, mixed $arg = SORT_REGULAR [, mixed $... ]]] )

array_multisort() 可以用来一次对多个数组进行排序，或者根据某一维或多维对多维数组进行排序。

关联（string）键名保持不变，但数字键名会被重新索引。

排序顺序标志：

• SORT_ASC - 按照上升顺序排序
• SORT_DESC - 按照下降顺序排序

排序类型标志：

• SORT_REGULAR - 将项目按照通常方法比较
• SORT_NUMERIC - 将项目按照数值比较
• SORT_STRING - 将项目按照字符串比较

每个数组之后不能指定两个同类的排序标志。每个数组后指定的排序标志仅对该数组有效 - 在此之前为默认值 SORT_ASC 和 SORT_REGULAR。

输入数组被当成一个表的列并以行来排序——这类似于 SQL 的 ORDER BY 子句的功能。第一个数组是要排序的主要数组。数组中的行（值）比较为相同的话就按照下一个输入数组中相应值的大小来排序，依此类推。

本函数的参数结构有些不同寻常，但是非常灵活。第一个参数必须是一个数组。接下来的每个参数可以是数组或者是下面列出的排序标志。

示例一：

<?php
function my_sort($arrays, $sort_key, $sort_order = SORT_ASC, $sort_type = SORT_NUMERIC)
{
    if (is_array($arrays)) {
        foreach ($arrays as $array) {
            if (is_array($array)) {
                $key_arrays[] = $array[$sort_key];
            } else {
                return false;
            }
        }
    } else {
        return false;
    }
    array_multisort($key_arrays, $sort_order, $sort_type, $arrays);
    return $arrays;
}

$person = array(
    array('id' => 1, 'name' => 'fj', 'weight' => 100, 'height' => 180),
    array('id' => 2, 'name' => 'tom', 'weight' => 53, 'height' => 150),
    array('id' => 3, 'name' => 'jerry', 'weight' => 120, 'height' => 156),
    array('id' => 4, 'name' => 'bill', 'weight' => 110, 'height' => 190),
    array('id' => 5, 'name' => 'linken', 'weight' => 80, 'height' => 200),
    array('id' => 6, 'name' => 'madana', 'weight' => 95, 'height' => 110),
    array('id' => 7, 'name' => 'jordan', 'weight' => 70, 'height' => 170)
);

$person = my_sort($person, 'name', SORT_ASC, SORT_STRING);

var_dump($person);

?>

结果

array (size=7)
  0 =>
    array (size=4)
      'id' => int 4
      'name' => string 'bill' (length=4)
      'weight' => int 110
      'height' => int 190
  1 =>
    array (size=4)
      'id' => int 1
      'name' => string 'fj' (length=2)
      'weight' => int 100
      'height' => int 180
  2 =>
    array (size=4)
      'id' => int 3
      'name' => string 'jerry' (length=5)
      'weight' => int 120
      'height' => int 156
  3 =>
    array (size=4)
      'id' => int 7
      'name' => string 'jordan' (length=6)
      'weight' => int 70
      'height' => int 170
  4 =>
    array (size=4)
      'id' => int 5
      'name' => string 'linken' (length=6)
      'weight' => int 80
      'height' => int 200
  5 =>
    array (size=4)
      'id' => int 6
      'name' => string 'madana' (length=6)
      'weight' => int 95
      'height' => int 110
  6 =>
    array (size=4)
      'id' => int 2
      'name' => string 'tom' (length=3)
      'weight' => int 53
      'height' => int 150

示例二：

<?php
$grade = array(
    "score" => array(70, 95, 70.0, 60, "70"),
    "name" => array("Zhang San", "Li Si", "Wang Wu", "Zhao Liu", "Liu Qi")
);
array_multisort($grade["score"], SORT_NUMERIC, SORT_DESC,
// 将分数作为数值，由高到低排序
    $grade["name"], SORT_STRING, SORT_ASC);
// 将名字作为字符串，由小到大排序
var_dump($grade);

结果

array (size=2)
  'score' =>
    array (size=5)
      0 => int 95
      1 => string '70' (length=2)
      2 => float 70
      3 => int 70
      4 => int 60
  'name' =>
    array (size=5)
      0 => string 'Li Si' (length=5)
      1 => string 'Liu Qi' (length=6)
      2 => string 'Wang Wu' (length=7)
      3 => string 'Zhang San' (length=9)
      4 => string 'Zhao Liu' (length=8)

我看来，这算一个比较神奇的函数了

/* {{{ proto bool array_multisort(array ar1 [, SORT_ASC|SORT_DESC [, SORT_REGULAR|SORT_NUMERIC|SORT_STRING|SORT_NATURAL|SORT_FLAG_CASE]] [, array ar2 [, SORT_ASC|SORT_DESC [, SORT_REGULAR|SORT_NUMERIC|SORT_STRING|SORT_NATURAL|SORT_FLAG_CASE]], ...])
   Sort multiple arrays at once similar to how ORDER BY clause works in SQL */
PHP_FUNCTION(array_multisort)
{
	zval***			args;
	zval***			arrays;
	Bucket***		indirect;
	Bucket*			p;
	HashTable*		hash;
	int				argc;
	int				array_size;
	int				num_arrays = 0;
	int				parse_state[MULTISORT_LAST];   /* 0 - flag not allowed 1 - flag allowed */
	int				sort_order = PHP_SORT_ASC;
	int				sort_type  = PHP_SORT_REGULAR;
	int				i, k;

	if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "+", &args, &argc) == FAILURE) {
		return;
	}

	/* Allocate space for storing pointers to input arrays and sort flags. */
	arrays = (zval ***)ecalloc(argc, sizeof(zval **));
	for (i = 0; i < MULTISORT_LAST; i++) {
		parse_state[i] = 0;
		ARRAYG(multisort_flags)[i] = (int *)ecalloc(argc, sizeof(int));
	}

	/* Here we go through the input arguments and parse them. Each one can
	 * be either an array or a sort flag which follows an array. If not
	 * specified, the sort flags defaults to PHP_SORT_ASC and PHP_SORT_REGULAR
	 * accordingly. There can't be two sort flags of the same type after an
	 * array, and the very first argument has to be an array. */
	for (i = 0; i < argc; i++) {
		if (Z_TYPE_PP(args[i]) == IS_ARRAY) {
			/* We see the next array, so we update the sort flags of
			 * the previous array and reset the sort flags. */
			if (i > 0) {
				ARRAYG(multisort_flags)[MULTISORT_ORDER][num_arrays - 1] = sort_order;
				ARRAYG(multisort_flags)[MULTISORT_TYPE][num_arrays - 1] = sort_type;
				sort_order = PHP_SORT_ASC;
				sort_type = PHP_SORT_REGULAR;
			}
			arrays[num_arrays++] = args[i];

			/* Next one may be an array or a list of sort flags. */
			for (k = 0; k < MULTISORT_LAST; k++) {
				parse_state[k] = 1;
			}
		} else if (Z_TYPE_PP(args[i]) == IS_LONG) {
			switch (Z_LVAL_PP(args[i]) & ~PHP_SORT_FLAG_CASE) {
				case PHP_SORT_ASC:
				case PHP_SORT_DESC:
					/* flag allowed here */
					if (parse_state[MULTISORT_ORDER] == 1) {
						/* Save the flag and make sure then next arg is not the current flag. */
						sort_order = Z_LVAL_PP(args[i]) == PHP_SORT_DESC ? -1 : 1;
						parse_state[MULTISORT_ORDER] = 0;
					} else {
						php_error_docref(NULL TSRMLS_CC, E_WARNING, "Argument #%d is expected to be an array or sorting flag that has not already been specified", i + 1);
						MULTISORT_ABORT;
					}
					break;

				case PHP_SORT_REGULAR:
				case PHP_SORT_NUMERIC:
				case PHP_SORT_STRING:
				case PHP_SORT_NATURAL:
#if HAVE_STRCOLL
				case PHP_SORT_LOCALE_STRING:
#endif
					/* flag allowed here */
					if (parse_state[MULTISORT_TYPE] == 1) {
						/* Save the flag and make sure then next arg is not the current flag. */
						sort_type = Z_LVAL_PP(args[i]);
						parse_state[MULTISORT_TYPE] = 0;
					} else {
						php_error_docref(NULL TSRMLS_CC, E_WARNING, "Argument #%d is expected to be an array or sorting flag that has not already been specified", i + 1);
						MULTISORT_ABORT;
					}
					break;

				default:
					php_error_docref(NULL TSRMLS_CC, E_WARNING, "Argument #%d is an unknown sort flag", i + 1);
					MULTISORT_ABORT;
					break;

			}
		} else {
			php_error_docref(NULL TSRMLS_CC, E_WARNING, "Argument #%d is expected to be an array or a sort flag", i + 1);
			MULTISORT_ABORT;
		}
	}
	/* Take care of the last array sort flags. */
	ARRAYG(multisort_flags)[MULTISORT_ORDER][num_arrays - 1] = sort_order;
	ARRAYG(multisort_flags)[MULTISORT_TYPE][num_arrays - 1] = sort_type;

	/* Make sure the arrays are of the same size. */
	array_size = zend_hash_num_elements(Z_ARRVAL_PP(arrays[0]));
	for (i = 0; i < num_arrays; i++) {
		if (zend_hash_num_elements(Z_ARRVAL_PP(arrays[i])) != array_size) {
			php_error_docref(NULL TSRMLS_CC, E_WARNING, "Array sizes are inconsistent");
			MULTISORT_ABORT;
		}
	}

	/* If all arrays are empty we don't need to do anything. */
	if (array_size < 1) {
		for (k = 0; k < MULTISORT_LAST; k++) {
			efree(ARRAYG(multisort_flags)[k]);
		}
		efree(arrays);
		efree(args);
		RETURN_TRUE;
	}

	/* Create the indirection array. This array is of size MxN, where
	 * M is the number of entries in each input array and N is the number
	 * of the input arrays + 1. The last column is NULL to indicate the end
	 * of the row. */
	indirect = (Bucket ***)safe_emalloc(array_size, sizeof(Bucket **), 0);
	for (i = 0; i < array_size; i++) {
		indirect[i] = (Bucket **)safe_emalloc((num_arrays + 1), sizeof(Bucket *), 0);
	}
	for (i = 0; i < num_arrays; i++) {
		k = 0;
		for (p = Z_ARRVAL_PP(arrays[i])->pListHead; p; p = p->pListNext, k++) {
			indirect[k][i] = p;
		}
	}
	for (k = 0; k < array_size; k++) {
		indirect[k][num_arrays] = NULL;
	}

	/* Do the actual sort magic - bada-bim, bada-boom. */
	zend_qsort(indirect, array_size, sizeof(Bucket **), php_multisort_compare TSRMLS_CC);

	/* Restructure the arrays based on sorted indirect - this is mostly taken from zend_hash_sort() function. */
	HANDLE_BLOCK_INTERRUPTIONS();
	for (i = 0; i < num_arrays; i++) {
		hash = Z_ARRVAL_PP(arrays[i]);
		hash->pListHead = indirect[0][i];;
		hash->pListTail = NULL;
		hash->pInternalPointer = hash->pListHead;

		for (k = 0; k < array_size; k++) {
			if (hash->pListTail) {
				hash->pListTail->pListNext = indirect[k][i];
			}
			indirect[k][i]->pListLast = hash->pListTail;
			indirect[k][i]->pListNext = NULL;
			hash->pListTail = indirect[k][i];
		}

		p = hash->pListHead;
		k = 0;
		while (p != NULL) {
			if (p->nKeyLength == 0)
				p->h = k++;
			p = p->pListNext;
		}
		hash->nNextFreeElement = array_size;
		zend_hash_rehash(hash);
	}
	HANDLE_UNBLOCK_INTERRUPTIONS();

	/* Clean up. */
	for (i = 0; i < array_size; i++) {
		efree(indirect[i]);
	}
	efree(indirect);
	for (k = 0; k < MULTISORT_LAST; k++) {
		efree(ARRAYG(multisort_flags)[k]);
	}
	efree(arrays);
	efree(args);
	RETURN_TRUE;
}

待续

参考：http://php.net/manual/zh/function.array-multisort.php