usort 多个key匹配.

遇到这么个问题,好烦,不过官方手册还是很强大的,谢谢啦.

 

<?php 
$testAry = array( 
  array('a' => 1, 'b' => 2, 'c' => 3), 
  array('a' => 2, 'b' => 1, 'c' => 3), 
  array('a' => 3, 'b' => 2, 'c' => 1), 
  array('a' => 1, 'b' => 3, 'c' => 2), 
  array('a' => 2, 'b' => 3, 'c' => 1), 
  array('a' => 3, 'b' => 1, 'c' => 2) 
); 

Utility::orderBy($testAry, 'a ASC, b DESC'); 

//Result: 
$testAry = array( 
  array('a' => 1, 'b' => 3, 'c' => 2), 
  array('a' => 1, 'b' => 2, 'c' => 3), 
  array('a' => 2, 'b' => 3, 'c' => 1), 
  array('a' => 2, 'b' => 1, 'c' => 3), 
  array('a' => 3, 'b' => 2, 'c' => 1), 
  array('a' => 3, 'b' => 1, 'c' => 2) 
); 
?> 

 

To sort an array of objects you would do something like: 
Utility::orderBy($objectAry, 'getCreationDate() DESC, getSubOrder() ASC'); 

This would sort an array of objects that have methods getCreationDate() and getSubOrder(). 

Here is the function: 

<?php 
class Utility { 
    /* 
    * @param array $ary the array we want to sort 
    * @param string $clause a string specifying how to sort the array similar to SQL ORDER BY clause 
    * @param bool $ascending that default sorts fall back to when no direction is specified 
    * @return null 
    */ 
    public static function orderBy(&$ary, $clause, $ascending = true) { 
        $clause = str_ireplace('order by', '', $clause); 
        $clause = preg_replace('/\s+/', ' ', $clause); 
        $keys = explode(',', $clause); 
        $dirMap = array('desc' => 1, 'asc' => -1); 
        $def = $ascending ? -1 : 1; 

        $keyAry = array(); 
        $dirAry = array(); 
        foreach($keys as $key) { 
            $key = explode(' ', trim($key)); 
            $keyAry[] = trim($key[0]); 
            if(isset($key[1])) { 
                $dir = strtolower(trim($key[1])); 
                $dirAry[] = $dirMap[$dir] ? $dirMap[$dir] : $def; 
            } else { 
                $dirAry[] = $def; 
            } 
        } 

        $fnBody = ''; 
        for($i = count($keyAry) - 1; $i >= 0; $i--) { 
            $k = $keyAry[$i]; 
            $t = $dirAry[$i]; 
            $f = -1 * $t; 
            $aStr = '$a[\''.$k.'\']'; 
            $bStr = '$b[\''.$k.'\']'; 
            if(strpos($k, '(') !== false) { 
                $aStr = '$a->'.$k; 
                $bStr = '$b->'.$k; 
            } 

            if($fnBody == '') { 
                $fnBody .= "if({$aStr} == {$bStr}) { return 0; }\n"; 
                $fnBody .= "return ({$aStr} < {$bStr}) ? {$t} : {$f};\n";                
            } else { 
                $fnBody = "if({$aStr} == {$bStr}) {\n" . $fnBody; 
                $fnBody .= "}\n"; 
                $fnBody .= "return ({$aStr} < {$bStr}) ? {$t} : {$f};\n"; 
            } 
        } 

        if($fnBody) { 
            $sortFn = create_function('$a,$b', $fnBody); 
            usort($ary, $sortFn);        
        } 
    } 
} 
?>