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wp-content/plugins/wp-smushit/core/class-array-utils.php

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+<?php
+
+namespace Smush\Core;
+
+class Array_Utils {
+	public function array_hash( $array, $keys = array() ) {
+		$hash = 0;
+		if ( is_array( $array ) ) {
+			foreach ( $array as $key => $value ) {
+				if ( is_array( $value ) ) {
+					$value_hash = $this->array_hash(
+						$value,
+						array_merge( $keys, array( $key ) )
+					);
+				} else {
+					$prefix     = join( '~', $keys );
+					$value_hash = crc32( $prefix . $value );
+				}
+
+				$hash += $value_hash;
+			}
+		}
+
+		return $hash;
+	}
+
+	public function get_array_value( $array, $key ) {
+		return isset( $array[ $key ] ) ? $array[ $key ] : null;
+	}
+
+	public function ensure_array( $array ) {
+		return empty( $array ) || ! is_array( $array )
+			? array()
+			: $array;
+	}
+
+	/**
+	 * WARNING: This trick works only for arrays in which all the values are valid keys.
+	 * @see https://stackoverflow.com/a/8321701
+	 *
+	 * @param $array scalar[]
+	 *
+	 * @return array Unique array
+	 */
+	public function fast_array_unique( $array ) {
+		if ( ! is_array( $array ) ) {
+			return array();
+		}
+
+		return array_keys( array_flip( $array ) );
+	}
+}