6e9b4f0e9c
Per wikitech-l consensus: https://lists.wikimedia.org/pipermail/wikitech-l/2016-February/084821.html Notes: * Disabled CallTimePassByReference due to false positives (T127163) Change-Id: I2c8ce713ce6600a0bb7bf67537c87044c7a45c4b
199 lines
6.5 KiB
PHP
199 lines
6.5 KiB
PHP
<?php
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/**
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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*/
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/**
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* Construct objects from configuration instructions.
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*
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* @author Bryan Davis <bd808@wikimedia.org>
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* @copyright © 2014 Bryan Davis and Wikimedia Foundation.
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*/
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class ObjectFactory {
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/**
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* Instantiate an object based on a specification array.
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*
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* The specification array must contain a 'class' key with string value
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* that specifies the class name to instantiate or a 'factory' key with
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* a callable (is_callable() === true). It can optionally contain
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* an 'args' key that provides arguments to pass to the
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* constructor/callable.
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*
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* Values in the arguments collection which are Closure instances will be
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* expanded by invoking them with no arguments before passing the
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* resulting value on to the constructor/callable. This can be used to
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* pass IDatabase instances or other live objects to the
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* constructor/callable. This behavior can be suppressed by adding
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* closure_expansion => false to the specification.
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*
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* The specification may also contain a 'calls' key that describes method
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* calls to make on the newly created object before returning it. This
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* pattern is often known as "setter injection". The value of this key is
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* expected to be an associative array with method names as keys and
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* argument lists as values. The argument list will be expanded (or not)
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* in the same way as the 'args' key for the main object.
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*
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* @param array $spec Object specification
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* @return object
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* @throws InvalidArgumentException when object specification does not
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* contain 'class' or 'factory' keys
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* @throws ReflectionException when 'args' are supplied and 'class'
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* constructor is non-public or non-existent
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*/
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public static function getObjectFromSpec( $spec ) {
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$args = isset( $spec['args'] ) ? $spec['args'] : [];
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$expandArgs = !isset( $spec['closure_expansion'] ) ||
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$spec['closure_expansion'] === true;
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if ( $expandArgs ) {
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$args = static::expandClosures( $args );
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}
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if ( isset( $spec['class'] ) ) {
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$clazz = $spec['class'];
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if ( !$args ) {
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$obj = new $clazz();
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} else {
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$obj = static::constructClassInstance( $clazz, $args );
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}
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} elseif ( isset( $spec['factory'] ) ) {
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$obj = call_user_func_array( $spec['factory'], $args );
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} else {
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throw new InvalidArgumentException(
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'Provided specification lacks both factory and class parameters.'
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);
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}
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if ( isset( $spec['calls'] ) && is_array( $spec['calls'] ) ) {
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// Call additional methods on the newly created object
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foreach ( $spec['calls'] as $method => $margs ) {
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if ( $expandArgs ) {
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$margs = static::expandClosures( $margs );
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}
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call_user_func_array( [ $obj, $method ], $margs );
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}
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}
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return $obj;
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}
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/**
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* Iterate a list and call any closures it contains.
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*
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* @param array $list List of things
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* @return array List with any Closures replaced with their output
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*/
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protected static function expandClosures( $list ) {
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return array_map( function ( $value ) {
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if ( is_object( $value ) && $value instanceof Closure ) {
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// If $value is a Closure, call it.
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return $value();
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} else {
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return $value;
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}
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}, $list );
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}
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/**
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* Construct an instance of the given class using the given arguments.
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*
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* PHP's `call_user_func_array()` doesn't work with object construction so
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* we have to use other measures. Starting with PHP 5.6.0 we could use the
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* "splat" operator (`...`) to unpack the array into an argument list.
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* Sadly there is no way to conditionally include a syntax construct like
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* a new operator in a way that allows older versions of PHP to still
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* parse the file. Instead, we will try a loop unrolling technique that
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* works for 0-10 arguments. If we are passed 11 or more arguments we will
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* take the performance penalty of using
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* `ReflectionClass::newInstanceArgs()` to construct the desired object.
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*
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* @param string $clazz Class name
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* @param array $args Constructor arguments
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* @return mixed Constructed instance
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*/
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public static function constructClassInstance( $clazz, $args ) {
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// $args should be a non-associative array; show nice error if that's not the case
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if ( $args && array_keys( $args ) !== range( 0, count( $args ) - 1 ) ) {
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throw new InvalidArgumentException( __METHOD__ . ': $args cannot be an associative array' );
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}
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// TODO: when PHP min version supported is >=5.6.0 replace this
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// with `return new $clazz( ... $args );`.
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$obj = null;
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switch ( count( $args ) ) {
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case 0:
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$obj = new $clazz();
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break;
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case 1:
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$obj = new $clazz( $args[0] );
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break;
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case 2:
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$obj = new $clazz( $args[0], $args[1] );
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break;
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case 3:
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$obj = new $clazz( $args[0], $args[1], $args[2] );
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break;
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case 4:
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$obj = new $clazz( $args[0], $args[1], $args[2], $args[3] );
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break;
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case 5:
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$obj = new $clazz(
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$args[0], $args[1], $args[2], $args[3], $args[4]
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);
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break;
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case 6:
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$obj = new $clazz(
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$args[0], $args[1], $args[2], $args[3], $args[4],
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$args[5]
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);
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break;
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case 7:
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$obj = new $clazz(
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$args[0], $args[1], $args[2], $args[3], $args[4],
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$args[5], $args[6]
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);
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break;
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case 8:
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$obj = new $clazz(
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$args[0], $args[1], $args[2], $args[3], $args[4],
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$args[5], $args[6], $args[7]
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);
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break;
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case 9:
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$obj = new $clazz(
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$args[0], $args[1], $args[2], $args[3], $args[4],
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$args[5], $args[6], $args[7], $args[8]
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);
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break;
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case 10:
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$obj = new $clazz(
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$args[0], $args[1], $args[2], $args[3], $args[4],
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$args[5], $args[6], $args[7], $args[8], $args[9]
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);
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break;
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default:
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// Fall back to using ReflectionClass and curse the developer
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// who decided that 11+ args was a reasonable method
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// signature.
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$ref = new ReflectionClass( $clazz );
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$obj = $ref->newInstanceArgs( $args );
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}
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return $obj;
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}
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}
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