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ArrayUtils.php
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ArrayUtils.php
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<?php
/**
* Methods to play with arrays.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
*/
/**
* A collection of static methods to play with arrays.
*
* @since 1.21
*/
class ArrayUtils {
/**
* Sort the given array in a pseudo-random order which depends only on the
* given key and each element value in $array. This is typically used for load
* balancing between servers each with a local cache.
*
* Keys are preserved. The input array is modified in place.
*
* Note: Benchmarking on PHP 5.3 and 5.4 indicates that for small
* strings, md5() is only 10% slower than hash('joaat',...) etc.,
* since the function call overhead dominates. So there's not much
* justification for breaking compatibility with installations
* compiled with ./configure --disable-hash.
*
* @param array &$array Array to sort
* @param string $key
* @param string $separator A separator used to delimit the array elements and the
* key. This can be chosen to provide backwards compatibility with
* various consistent hash implementations that existed before this
* function was introduced.
*/
public static function consistentHashSort( &$array, $key, $separator = "\000" ) {
$hashes = [];
foreach ( $array as $elt ) {
$hashes[$elt] = md5( $elt . $separator . $key );
}
uasort( $array, static function ( $a, $b ) use ( $hashes ) {
return strcmp( $hashes[$a], $hashes[$b] );
} );
}
/**
* Given an array of non-normalised probabilities, this function will select
* an element and return the appropriate key
*
* @param array $weights
* @return int|string|false
*/
public static function pickRandom( $weights ) {
if ( !is_array( $weights ) || count( $weights ) == 0 ) {
return false;
}
$sum = array_sum( $weights );
if ( $sum == 0 ) {
# No loads on any of them
# In previous versions, this triggered an unweighted random selection,
# but this feature has been removed as of April 2006 to allow for strict
# separation of query groups.
return false;
}
$max = mt_getrandmax();
$rand = mt_rand( 0, $max ) / $max * $sum;
$sum = 0;
foreach ( $weights as $i => $w ) {
$sum += $w;
# Do not return keys if they have 0 weight.
# Note that the "all 0 weight" case is handed above
if ( $w > 0 && $sum >= $rand ) {
break;
}
}
return $i;
}
/**
* Do a binary search, and return the index of the largest item that sorts
* less than or equal to the target value.
*
* @since 1.23
*
* @param callable $valueCallback A function to call to get the value with
* a given array index.
* @param int $valueCount The number of items accessible via $valueCallback,
* indexed from 0 to $valueCount - 1
* @param callable $comparisonCallback A callback to compare two values, returning
* -1, 0 or 1 in the style of strcmp().
* @param mixed $target The target value to find.
*
* @return int|bool The item index of the lower bound, or false if the target value
* sorts before all items.
*/
public static function findLowerBound( $valueCallback, $valueCount,
$comparisonCallback, $target
) {
if ( $valueCount === 0 ) {
return false;
}
$min = 0;
$max = $valueCount;
do {
$mid = $min + ( ( $max - $min ) >> 1 );
$item = $valueCallback( $mid );
$comparison = $comparisonCallback( $target, $item );
if ( $comparison > 0 ) {
$min = $mid;
} elseif ( $comparison == 0 ) {
$min = $mid;
break;
} else {
$max = $mid;
}
} while ( $min < $max - 1 );
if ( $min == 0 ) {
$item = $valueCallback( $min );
$comparison = $comparisonCallback( $target, $item );
if ( $comparison < 0 ) {
// Before the first item
return false;
}
}
return $min;
}
/**
* Do array_diff_assoc() on multi-dimensional arrays.
*
* Note: empty arrays are removed.
*
* @since 1.23
*
* @param array $array1 The array to compare from
* @param array ...$arrays More arrays to compare against
* @return array An array containing all the values from array1
* that are not present in any of the other arrays.
*/
public static function arrayDiffAssocRecursive( $array1, ...$arrays ) {
$ret = [];
foreach ( $array1 as $key => $value ) {
if ( is_array( $value ) ) {
$args = [ $value ];
foreach ( $arrays as $array ) {
if ( isset( $array[$key] ) ) {
$args[] = $array[$key];
}
}
$valueret = self::arrayDiffAssocRecursive( ...$args );
if ( count( $valueret ) ) {
$ret[$key] = $valueret;
}
} else {
foreach ( $arrays as $array ) {
if ( isset( $array[$key] ) && $array[$key] === $value ) {
continue 2;
}
}
$ret[$key] = $value;
}
}
return $ret;
}
/**
* Make an array consisting of every combination of the elements of the
* input arrays. Each element of the output array is an array with a number
* of elements equal to the number of input parameters.
*
* In mathematical terms, this is an n-ary Cartesian product.
*
* For example, ArrayUtils::cartesianProduct( [ 1, 2 ], [ 'a', 'b' ] )
* produces [ [ 1, 'a' ], [ 1, 'b' ], [ 2, 'a' ], [ 2, 'b' ] ]
*
* If any of the input arrays is empty, the result is the empty array [].
* This is in keeping with the mathematical definition.
*
* If no parameters are given, the result is also the empty array.
*
* The array keys are ignored. This implementation uses the internal
* pointers of the input arrays to keep track of the current position
* without referring to the keys.
*
* @since 1.35
*
* @param array ...$inputArrays
* @return array
*/
public static function cartesianProduct( ...$inputArrays ) {
$numInputs = count( $inputArrays );
if ( $numInputs === 0 ) {
return [];
}
// Reset the internal pointers
foreach ( $inputArrays as &$inputArray ) {
if ( !count( $inputArray ) ) {
return [];
}
reset( $inputArray );
}
unset( $inputArray );
$outputArrays = [];
$done = false;
while ( !$done ) {
// Construct the output array element
$element = [];
foreach ( $inputArrays as $inputArray ) {
$element[] = current( $inputArray );
}
$outputArrays[] = $element;
// Increment the pointers starting from the least significant.
// If the least significant rolls over back to the start of the
// array, continue with the next most significant, and so on until
// that stops happening. If all pointers roll over, we are done.
$done = true;
for ( $paramIndex = $numInputs - 1; $paramIndex >= 0; $paramIndex-- ) {
next( $inputArrays[$paramIndex] );
if ( key( $inputArrays[$paramIndex] ) === null ) {
reset( $inputArrays[$paramIndex] );
// continue
} else {
$done = false;
break;
}
}
}
return $outputArrays;
}
}

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