8000 feature #46142 [ExpressionLanguage] Add support for null coalescing s… · symfony/symfony@39191b4 · GitHub
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feature #46142 [ExpressionLanguage] Add support for null coalescing syntax (mytuny)
This PR was merged into the 6.2 branch. Discussion ---------- [ExpressionLanguage] Add support for null coalescing syntax | Q | A | ------------- | --- | Branch? | 6.1 | Bug fix? | no | New feature? | yes | Deprecations? | no | Tickets | Fix #45411, #21691 | License | MIT | Doc PR | symfony/symfony-docs#16743 This is another waited feature for the syntax of the expression-language component. The [null-coalescing](https://wiki.php.net/rfc/isset_ternary) operator ``??`` becomes a need for variant programming needs these days. Following my previous PR introducing the null-safe operator (#45795). I'm hereby introducing yet another essential operator to make the syntax even more complete. The null-coalescing operator is a syntactic sugar for a common use of ternary in conjunction with ``isset()`` (in PHP) or equivalent in other languages. This is such a common use-case to the point that almost all majors programming syntax nowadays support a sort of a short-hand for that operation namely coalescing operator. Now it's time for the syntax of Expression-Language to do so! Expressions like: * ``foo.bar ?? 'default'`` * ``foo[3] ?? 'default'`` * ``foo.bar ?? foo['bar'] ?? 'default'`` will default to the expression in the right-hand-side of the ``??`` operator whenever the expression in the left-hand-side of it does not exist or it's ``null``. Note that this coalescing behavior can be chained and the validation logic takes decreasing priority from left to right. Commits ------- 8e3c505 [ExpressionLanguage] Add support for null coalescing syntax
2 parents aee7c31 + 8e3c505 commit 39191b4

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‎src/Symfony/Component/ExpressionLanguage/CHANGELOG.md

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@@ -4,6 +4,7 @@ CHANGELOG
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6.1
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---
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* Add support for null-coalescing syntax
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* Add support for null-safe syntax when parsing object's methods and properties
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* Add new operators: `contains`, `starts with` and `ends with`
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* Support lexing numbers with the numeric literal separator `_`

‎src/Symfony/Component/ExpressionLanguage/Lexer.php

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@@ -77,6 +77,10 @@ public function tokenize(string $expression): TokenStream
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// null-safe
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$tokens[] = new Token(Token::PUNCTUATION_TYPE, '?.', ++$cursor);
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++$cursor;
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} elseif ('?' === $expression[$cursor] && '?' === ($expression[$cursor + 1] ?? '')) {
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// null-coalescing
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$tokens[] = new Token(Token::PUNCTUATION_TYPE, '??', ++$cursor);
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++$cursor;
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} elseif (str_contains('.,?:', $expression[$cursor])) {
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// punctuation
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$tokens[] = new Token(Token::PUNCTUATION_TYPE, $expression[$cursor], $cursor + 1);

‎src/Symfony/Component/ExpressionLanguage/Node/GetAttrNode.php

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@@ -25,6 +25,7 @@ class GetAttrNode extends Node
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public const ARRAY_CALL = 3;
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private bool $isShortCircuited = false;
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public bool $isNullCoalesce = false;
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public function __construct(Node $node, Node $attribute, ArrayNode $arguments, int $type)
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{
@@ -72,8 +73,7 @@ public function evaluate(array $functions, array $values)
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switch ($this->attributes['type']) {
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case self::PROPERTY_CALL:
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$obj = $this->nodes['node']->evaluate($functions, $values);
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if (null === $obj && $this->nodes['attribute']->isNullSafe) {
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if (null === $obj && ($this->nodes['attribute']->isNullSafe || $this->isNullCoalesce)) {
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$this->isShortCircuited = true;
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return null;
@@ -88,6 +88,10 @@ public function evaluate(array $functions, array $values)
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$property = $this->nodes['attribute']->attributes['value'];
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if ($this->isNullCoalesce) {
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return $obj->$property ?? null;
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}
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return $obj->$property;
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case self::METHOD_CALL:
@@ -118,10 +122,14 @@ public function evaluate(array $functions, array $values)
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return null;
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}
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if (!\is_array($array) && !$array instanceof \ArrayAccess) {
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if (!\is_array($array) && !$array instanceof \ArrayAccess && !(null === $array && $this->isNullCoalesce)) {
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throw new \RuntimeException(sprintf('Unable to get an item of non-array "%s".', $this->nodes['node']->dump()));
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}
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if ($this->isNullCoalesce) {
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return $array[$this->nodes['attribute']->evaluate($functions, $values)] ?? null;
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}
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return $array[$this->nodes['attribute']->evaluate($functions, $values)];
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}
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}

‎src/Symfony/Component/ExpressionLanguage/Node/NullCoalesceNode.php

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@@ -0,0 +1,52 @@
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<?php
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/*
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* This file is part of the Symfony package.
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*
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* (c) Fabien Potencier <fabien@symfony.com>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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namespace Symfony\Component\ExpressionLanguage\Node;
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use Symfony\Component\ExpressionLanguage\Compiler;
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/**
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* @author Fabien Potencier <fabien@symfony.com>
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*
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* @internal
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*/
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class NullCoalesceNode extends Node
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{
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public function __construct(Node $expr1, Node $expr2)
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{
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parent::__construct(['expr1' => $expr1, 'expr2' => $expr2]);
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}
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public function compile(Compiler $compiler)
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{
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$compiler
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->raw('((')
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->compile($this->nodes['expr1'])
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->raw(') ?? (')
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->compile($this->nodes['expr2'])
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->raw('))')
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;
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}
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public function evaluate(array $functions, array $values)
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{
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if ($this->nodes['expr1'] instanceof GetAttrNode) {
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$this->nodes['expr1']->isNullCoalesce = true;
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}
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return $this->nodes['expr1']->evaluate($functions, $values) ?? $this->nodes['expr2']->evaluate($functions, $values);
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}
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public function toArray()
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{
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return ['(', $this->nodes['expr1'], ') ?? (', $this->nodes['expr2'], ')'];
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}
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}

‎src/Symfony/Component/ExpressionLanguage/Parser.php

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@@ -176,6 +176,13 @@ protected function getPrimary()
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protected function parseConditionalExpression(Node\Node $expr)
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{
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while ($this->stream->current->test(Token::PUNCTUATION_TYPE, '??')) {
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$this->stream->next();
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$expr2 = $this->parseExpression();
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$expr = new Node\NullCoalesceNode($expr, $expr2);
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}
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while ($this->stream->current->test(Token::PUNCTUATION_TYPE, '?')) {
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$this->stream->next();
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if (!$this->stream->current->test(Token::PUNCTUATION_TYPE, ':')) {

‎src/Symfony/Component/ExpressionLanguage/Tests/ExpressionLanguageTest.php

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@@ -315,6 +315,44 @@ public function provideInvalidNullSafe()
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yield ['foo?.bar["baz"].qux.quux', (object) ['bar' => ['baz' => null]], 'Unable to get property "qux" of non-object "foo.bar["baz"]".'];
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}
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/**
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* @dataProvider provideNullCoalescing
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*/
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public function testNullCoalescingEvaluate($expression, $foo)
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{
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$expressionLanguage = new ExpressionLanguage();
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$this->assertSame($expressionLanguage->evaluate($expression, ['foo' => $foo]), 'default');
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}
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/**
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* @dataProvider provideNullCoalescing
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*/
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public function testNullCoalescingCompile($expression, $foo)
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{
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$expressionLanguage = new ExpressionLanguage();
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$this->assertSame(eval(sprintf('return %s;', $expressionLanguage->compile($expression, ['foo' => 'foo']))), 'default');
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}
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public function provideNullCoalescing()
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{
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$foo = new class() extends \stdClass {
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public function bar()
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{
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return null;
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}
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};
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yield ['foo.bar ?? "default"', null];
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yield ['foo.bar.baz ?? "default"', (object) ['bar' => null]];
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yield ['foo.bar ?? foo.baz ?? "default"', null];
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yield ['foo[0] ?? "default"', []];
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yield ['foo["bar"] ?? "default"', ['bar' => null]];
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yield ['foo["baz"] ?? "default"', ['bar' => null]];
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yield ['foo["bar"]["baz"] ?? "default"', ['bar' => null]];
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yield ['foo["bar"].baz ?? "default"', ['bar' => null]];
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yield ['foo.bar().baz ?? "default"', $foo];
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}
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/**
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* @dataProvider getRegisterCallbacks
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*/

‎src/Symfony/Component/ExpressionLanguage/Tests/ParserTest.php

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@@ -163,6 +163,16 @@ public function getParseData()
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'foo?.not()',
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['foo'],
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],
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[
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new Node\NullCoalesceNode(new Node\GetAttrNode(new Node\NameNode('foo'), new Node\ConstantNode('bar', true), new Node\ArgumentsNode(), Node\GetAttrNode::PROPERTY_CALL), new Node\ConstantNode('default')),
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'foo.bar ?? "default"',
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['foo'],
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],
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[
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new Node\NullCoalesceNode(new Node\GetAttrNode(new Node\NameNode('foo'), new Node\ConstantNode('bar'), new Node\ArgumentsNode(), Node\GetAttrNode::ARRAY_CALL), new Node\ConstantNode('default')),
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'foo["bar"] ?? "default"',
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['foo'],
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],
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// chained calls
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[

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