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feature #4735 Add the = assignment operator (fabpot)
This PR was merged into the 3.x branch. Discussion ---------- Add the = assignment operator Commits ------- bfbbef0 Add the = assignment operator
2 parents 820eed3 + bfbbef0 commit be1797d

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‎CHANGELOG‎

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# 3.23.0 (2026-XX-XX)
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* Add `=` assignment operator (allows to set variables in expression or to replace the short-form of the set tag)
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* Add `?.` null-safe operator
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* Add `===` and `!==` operators (equivalent to the `same as` and `not same as` tests)
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‎doc/operators_precedence.rst‎

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+------------+------------------+---------+---------------+-------------------------------------------------------------------+
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| | ``?`` | infix | Left | Conditional operator (a ? b : c) |
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+------------+------------------+---------+---------------+-------------------------------------------------------------------+
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| | ``=`` | | Right | Assignment operator |
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+------------+------------------+---------+---------------+-------------------------------------------------------------------+
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When a precedence will change in 4.0, the new precedence is indicated by the arrow ``=>``.
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@@ -198,3 +200,5 @@ Here is the same table for Twig 4.0 with adjusted precedences:
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+------------+------------------+---------+---------------+-------------------------------------------------------------------+
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| | ``?`` | infix | Left | Conditional operator (a ? b : c) |
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+------------+------------------+---------+---------------+-------------------------------------------------------------------+
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| | ``=`` | | Right | Assignment operator |
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+------------+------------------+---------+---------------+-------------------------------------------------------------------+

‎doc/tags/set.rst‎

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@@ -27,6 +27,16 @@ The assigned value can be any valid :ref:`Twig expression
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{% set user = {'name': 'Fabien'} %}
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{% set name = 'Fabien' ~ ' ' ~ 'Potencier' %}
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.. tip::
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To assign a value within an expression, use the :ref:`= operator
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<assignment-operator>`:
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.. code-block:: twig
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{# use assignment within a larger expression #}
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{{ (result = fetch_data()) ? result : 'default' }}
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Several variables can be assigned in one block:
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.. code-block:: twig

‎doc/templates.rst‎

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@@ -131,15 +131,40 @@ The following variables are always available in templates:
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Setting Variables
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~~~~~~~~~~~~~~~~~
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You can assign values to variables inside code blocks. Assignments use the
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:doc:`set<tags/set>` tag:
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You can assign values to variables inside code blocks using either the
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:doc:`set<tags/set>` tag or the :ref:`= operator <assignment-operator>`:
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.. code-block:: twig
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{% set name = 'Fabien' %}
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{% set numbers = [1, 2] %}
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{% set map = {'city': 'Paris'} %}
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{# or #}
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{% do name = 'Fabien' %}
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{% do numbers = [1, 2] %}
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{% do map = {'city': 'Paris'} %}
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For simple assignments, both are equivalent. However, the ``set`` tag provides
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additional features:
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* **Multi-target assignment**: Assign multiple variables at once:
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.. code-block:: twig
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{% set first, last = 'Fabien', 'Potencier' %}
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* **Block capture**: Capture chunks of template content into a variable:
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.. code-block:: html+twig
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{% set content %}
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<div id="pagination">...</div>
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{% endset %}
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See the :doc:`set<tags/set>` tag documentation for more details.
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Filters
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-------
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Support for expanding the arguments of a function call was introduced in
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Twig 3.15.
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.. _assignment-operator:
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* ``=``: The assignment operator assigns a value to a variable within an
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expression:
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.. code-block:: twig
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{# assign #}
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{% do b = 1 + 3 %}
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{# assign and output the result #}
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{{ b = 1 + 3 }}
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{# assignments can be chained #}
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{% do a = b = 'foo' %}
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{# assignment can be used inside other expressions #}
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{% do a = (b = 4) + 5 %}
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.. versionadded:: 3.23
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The ``=`` assignment operator was added in Twig 3.23.
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* ``=>``: The arrow operator allows the creation of functions. A function is
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made of arguments (use parentheses for multiple arguments) and an arrow
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(``=>``) followed by an expression to execute. The expression has access to

‎src/ExpressionParser/Infix/ArgumentsTrait.php‎

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use Twig\Error\SyntaxError;
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use Twig\Node\Expression\ArrayExpression;
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use Twig\Node\Expression\Binary\SetBinary;
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use Twig\Node\Expression\Unary\SpreadUnary;
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use Twig\Node\Expression\Variable\ContextVariable;
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use Twig\Node\Expression\Variable\LocalVariable;
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}
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$name = null;
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if (($token = $stream->nextIf(Token::OPERATOR_TYPE, '=')) || ($token = $stream->nextIf(Token::PUNCTUATION_TYPE, ':'))) {
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if ($value instanceof SetBinary) {
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$name = $value->getNode('left')->getAttribute('name');
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$value = $value->getNode('right');
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} elseif (($token = $stream->nextIf(Token::OPERATOR_TYPE, '=')) || ($token = $stream->nextIf(Token::PUNCTUATION_TYPE, ':'))) {
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if (!$value instanceof ContextVariable) {
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throw new SyntaxError(\sprintf('A parameter name must be a string, "%s" given.', $value::class), $token->getLine(), $stream->getSourceContext());
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}

‎src/ExpressionParser/Infix/AssignmentExpressionParser.php‎

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<?php
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/*
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* This file is part of Twig.
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*
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* (c) Fabien Potencier
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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 Twig\ExpressionParser\Infix;
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use Twig\Error\SyntaxError;
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use Twig\ExpressionParser\InfixAssociativity;
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use Twig\Node\Expression\AbstractExpression;
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use Twig\Node\Expression\Binary\AbstractBinary;
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use Twig\Node\Expression\Binary\SetBinary;
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use Twig\Node\Expression\Variable\ContextVariable;
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use Twig\Parser;
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use Twig\Token;
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/**
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* @internal
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*/
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class AssignmentExpressionParser extends BinaryOperatorExpressionParser
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{
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public function __construct(
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string $name,
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) {
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parent::__construct(SetBinary::class, $name, 0, InfixAssociativity::Right);
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}
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/**
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* @return AbstractBinary
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*/
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public function parse(Parser $parser, AbstractExpression $left, Token $token): AbstractExpression
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{
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if (!$left instanceof ContextVariable) {
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throw new SyntaxError(\sprintf('Cannot assign to "%s", only variables can be assigned.', $left::class), $token->getLine(), $parser->getStream()->getSourceContext());
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}
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$right = $parser->parseExpression(InfixAssociativity::Left === $this->getAssociativity() ? $this->getPrecedence() + 1 : $this->getPrecedence());
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$right = match ($this->getName()) {
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'=' => $right,
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default => throw new \LogicException(\sprintf('Unknown operator: %s.', $this->getName())),
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};
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return new SetBinary($left, $right, $token->getLine());
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}
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public function getDescription(): string
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{
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return 'Assignment operator';
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}
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}

‎src/Extension/CoreExtension.php‎

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use Twig\Error\RuntimeError;
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use Twig\Error\SyntaxError;
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use Twig\ExpressionParser\Infix\ArrowExpressionParser;
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use Twig\ExpressionParser\Infix\AssignmentExpressionParser;
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use Twig\ExpressionParser\Infix\BinaryOperatorExpressionParser;
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use Twig\ExpressionParser\Infix\ConditionalTernaryExpressionParser;
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use Twig\ExpressionParser\Infix\DotExpressionParser;
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// ternary operator
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new ConditionalTernaryExpressionParser(),
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// assignment operator
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new AssignmentExpressionParser('='),
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// Twig callables
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new IsExpressionParser(),
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new IsNotExpressionParser(),

‎src/Lexer.php‎

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private function getOperatorRegex(): string
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{
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$expressionParsers = ['='];
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$expressionParsers = [];
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foreach ($this->env->getExpressionParsers() as $expressionParser) {
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$expressionParsers = array_merge($expressionParsers, [$expressionParser->getName()], $expressionParser->getAliases());
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}

‎src/Node/Expression/Binary/SetBinary.php‎

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<?php
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/*
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* This file is part of Twig.
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*
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* (c) Fabien Potencier
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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 Twig\Node\Expression\Binary;
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use Twig\Compiler;
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use Twig\Node\Expression\AbstractExpression;
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use Twig\Node\Expression\Variable\AssignContextVariable;
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use Twig\Node\Expression\Variable\ContextVariable;
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use Twig\Node\Node;
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/**
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* @author Fabien Potencier <fabien@symfony.com>
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*/
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class SetBinary extends AbstractBinary
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{
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/**
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* @param ContextVariable $left
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* @param AbstractExpression $right
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*/
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public function __construct(Node $left, Node $right, int $lineno)
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{
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$name = $left->getAttribute('name');
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if (!\is_string($name)) {
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throw new \LogicException('The "name" attribute must be a string.');
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}
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$left = new AssignContextVariable($name, $left->getTemplateLine());
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parent::__construct($left, $right, $lineno);
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}
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public function operator(Compiler $compiler): Compiler
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{
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return $compiler->raw('=');
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}
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}

‎tests/ExpressionParserTest.php‎

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// ?? stronger than ()
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// yield '?? vs ()' => ['{{ (1 ?? "a") }}', '{{ ((1 ?? "a")) }}', eval("return 1;")];
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// = stronger than anything else
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yield '= same as literal' => ['{% do c = "a" %}{{ c }}', '{% do c = ("a") %}{{ c }}', eval("return 'a';")];
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yield '= stronger than .' => ['{% do c = a.b %}{{ c }}', '{% do c = (a.b) %}{{ c }}', eval("\$a = ['b' => 1]; return \$a['b'];"), $context];
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yield '= stronger than math' => ['{% do a = 1 + 3 %}{{ a }}', '{% do a = (1 + 3) %}{{ a }}', eval('$a = 1 + 3; return $a;')];
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yield '= stronger than logical' => ['{% do a = false or true %}{{ a }}', '{% do a = (false or true) %}{{ a }}', eval('$a = false || true; return $a;')];
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yield '= stronger than ternary' => ['{% do c = 4 ? 0 : -1 %}{{ c }}', '{% do c = (4 ? 0 : -1) %}{{ c }}', eval('return 4 ? 0 : -1;')];
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}
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}
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