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410 lines
16 KiB
410 lines
16 KiB
2 years ago
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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;
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/**
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* Parsers a token stream.
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*
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* This parser implements a "Precedence climbing" algorithm.
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*
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* @see http://www.engr.mun.ca/~theo/Misc/exp_parsing.htm
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* @see http://en.wikipedia.org/wiki/Operator-precedence_parser
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*
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* @author Fabien Potencier <fabien@symfony.com>
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*/
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class Parser
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{
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public const OPERATOR_LEFT = 1;
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public const OPERATOR_RIGHT = 2;
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private $stream;
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private $unaryOperators;
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private $binaryOperators;
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private $functions;
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private $names;
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private $lint;
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public function __construct(array $functions)
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{
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$this->functions = $functions;
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$this->unaryOperators = [
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'not' => ['precedence' => 50],
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'!' => ['precedence' => 50],
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'-' => ['precedence' => 500],
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'+' => ['precedence' => 500],
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];
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$this->binaryOperators = [
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'or' => ['precedence' => 10, 'associativity' => self::OPERATOR_LEFT],
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'||' => ['precedence' => 10, 'associativity' => self::OPERATOR_LEFT],
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'and' => ['precedence' => 15, 'associativity' => self::OPERATOR_LEFT],
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'&&' => ['precedence' => 15, 'associativity' => self::OPERATOR_LEFT],
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'|' => ['precedence' => 16, 'associativity' => self::OPERATOR_LEFT],
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'^' => ['precedence' => 17, 'associativity' => self::OPERATOR_LEFT],
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'&' => ['precedence' => 18, 'associativity' => self::OPERATOR_LEFT],
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'==' => ['precedence' => 20, 'associativity' => self::OPERATOR_LEFT],
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'===' => ['precedence' => 20, 'associativity' => self::OPERATOR_LEFT],
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'!=' => ['precedence' => 20, 'associativity' => self::OPERATOR_LEFT],
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'!==' => ['precedence' => 20, 'associativity' => self::OPERATOR_LEFT],
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'<' => ['precedence' => 20, 'associativity' => self::OPERATOR_LEFT],
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'>' => ['precedence' => 20, 'associativity' => self::OPERATOR_LEFT],
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'>=' => ['precedence' => 20, 'associativity' => self::OPERATOR_LEFT],
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'<=' => ['precedence' => 20, 'associativity' => self::OPERATOR_LEFT],
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'not in' => ['precedence' => 20, 'associativity' => self::OPERATOR_LEFT],
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'in' => ['precedence' => 20, 'associativity' => self::OPERATOR_LEFT],
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'matches' => ['precedence' => 20, 'associativity' => self::OPERATOR_LEFT],
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'..' => ['precedence' => 25, 'associativity' => self::OPERATOR_LEFT],
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'+' => ['precedence' => 30, 'associativity' => self::OPERATOR_LEFT],
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'-' => ['precedence' => 30, 'associativity' => self::OPERATOR_LEFT],
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'~' => ['precedence' => 40, 'associativity' => self::OPERATOR_LEFT],
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'*' => ['precedence' => 60, 'associativity' => self::OPERATOR_LEFT],
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'/' => ['precedence' => 60, 'associativity' => self::OPERATOR_LEFT],
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'%' => ['precedence' => 60, 'associativity' => self::OPERATOR_LEFT],
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'**' => ['precedence' => 200, 'associativity' => self::OPERATOR_RIGHT],
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];
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}
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/**
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* Converts a token stream to a node tree.
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*
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* The valid names is an array where the values
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* are the names that the user can use in an expression.
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*
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* If the variable name in the compiled PHP code must be
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* different, define it as the key.
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*
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* For instance, ['this' => 'container'] means that the
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* variable 'container' can be used in the expression
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* but the compiled code will use 'this'.
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*
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* @return Node\Node
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*
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* @throws SyntaxError
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*/
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public function parse(TokenStream $stream, array $names = [])
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{
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$this->lint = false;
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return $this->doParse($stream, $names);
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}
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/**
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* Validates the syntax of an expression.
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*
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* The syntax of the passed expression will be checked, but not parsed.
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* If you want to skip checking dynamic variable names, pass `null` instead of the array.
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*
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* @throws SyntaxError When the passed expression is invalid
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*/
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public function lint(TokenStream $stream, ?array $names = []): void
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{
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$this->lint = true;
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$this->doParse($stream, $names);
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}
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/**
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* @throws SyntaxError
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*/
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private function doParse(TokenStream $stream, ?array $names = []): Node\Node
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{
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$this->stream = $stream;
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$this->names = $names;
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$node = $this->parseExpression();
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if (!$stream->isEOF()) {
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throw new SyntaxError(sprintf('Unexpected token "%s" of value "%s".', $stream->current->type, $stream->current->value), $stream->current->cursor, $stream->getExpression());
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}
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$this->stream = null;
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$this->names = null;
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return $node;
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}
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public function parseExpression(int $precedence = 0)
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{
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$expr = $this->getPrimary();
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$token = $this->stream->current;
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while ($token->test(Token::OPERATOR_TYPE) && isset($this->binaryOperators[$token->value]) && $this->binaryOperators[$token->value]['precedence'] >= $precedence) {
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$op = $this->binaryOperators[$token->value];
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$this->stream->next();
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$expr1 = $this->parseExpression(self::OPERATOR_LEFT === $op['associativity'] ? $op['precedence'] + 1 : $op['precedence']);
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$expr = new Node\BinaryNode($token->value, $expr, $expr1);
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$token = $this->stream->current;
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}
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if (0 === $precedence) {
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return $this->parseConditionalExpression($expr);
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}
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return $expr;
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}
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protected function getPrimary()
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{
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$token = $this->stream->current;
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if ($token->test(Token::OPERATOR_TYPE) && isset($this->unaryOperators[$token->value])) {
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$operator = $this->unaryOperators[$token->value];
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$this->stream->next();
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$expr = $this->parseExpression($operator['precedence']);
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return $this->parsePostfixExpression(new Node\UnaryNode($token->value, $expr));
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}
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if ($token->test(Token::PUNCTUATION_TYPE, '(')) {
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$this->stream->next();
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$expr = $this->parseExpression();
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$this->stream->expect(Token::PUNCTUATION_TYPE, ')', 'An opened parenthesis is not properly closed');
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return $this->parsePostfixExpression($expr);
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}
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return $this->parsePrimaryExpression();
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}
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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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$this->stream->next();
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if (!$this->stream->current->test(Token::PUNCTUATION_TYPE, ':')) {
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$expr2 = $this->parseExpression();
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if ($this->stream->current->test(Token::PUNCTUATION_TYPE, ':')) {
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$this->stream->next();
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$expr3 = $this->parseExpression();
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} else {
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$expr3 = new Node\ConstantNode(null);
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}
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} else {
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$this->stream->next();
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$expr2 = $expr;
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$expr3 = $this->parseExpression();
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}
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$expr = new Node\ConditionalNode($expr, $expr2, $expr3);
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}
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return $expr;
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}
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public function parsePrimaryExpression()
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{
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$token = $this->stream->current;
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switch ($token->type) {
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case Token::NAME_TYPE:
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$this->stream->next();
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switch ($token->value) {
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case 'true':
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case 'TRUE':
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return new Node\ConstantNode(true);
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case 'false':
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case 'FALSE':
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return new Node\ConstantNode(false);
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case 'null':
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case 'NULL':
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return new Node\ConstantNode(null);
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default:
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if ('(' === $this->stream->current->value) {
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if (false === isset($this->functions[$token->value])) {
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throw new SyntaxError(sprintf('The function "%s" does not exist.', $token->value), $token->cursor, $this->stream->getExpression(), $token->value, array_keys($this->functions));
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}
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$node = new Node\FunctionNode($token->value, $this->parseArguments());
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} else {
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if (!$this->lint || \is_array($this->names)) {
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if (!\in_array($token->value, $this->names, true)) {
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throw new SyntaxError(sprintf('Variable "%s" is not valid.', $token->value), $token->cursor, $this->stream->getExpression(), $token->value, $this->names);
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}
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// is the name used in the compiled code different
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// from the name used in the expression?
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if (\is_int($name = array_search($token->value, $this->names))) {
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$name = $token->value;
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}
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} else {
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$name = $token->value;
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}
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$node = new Node\NameNode($name);
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}
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}
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break;
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case Token::NUMBER_TYPE:
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case Token::STRING_TYPE:
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$this->stream->next();
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return new Node\ConstantNode($token->value);
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default:
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if ($token->test(Token::PUNCTUATION_TYPE, '[')) {
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$node = $this->parseArrayExpression();
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} elseif ($token->test(Token::PUNCTUATION_TYPE, '{')) {
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$node = $this->parseHashExpression();
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} else {
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throw new SyntaxError(sprintf('Unexpected token "%s" of value "%s".', $token->type, $token->value), $token->cursor, $this->stream->getExpression());
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}
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}
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return $this->parsePostfixExpression($node);
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}
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public function parseArrayExpression()
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{
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$this->stream->expect(Token::PUNCTUATION_TYPE, '[', 'An array element was expected');
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$node = new Node\ArrayNode();
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$first = true;
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while (!$this->stream->current->test(Token::PUNCTUATION_TYPE, ']')) {
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if (!$first) {
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$this->stream->expect(Token::PUNCTUATION_TYPE, ',', 'An array element must be followed by a comma');
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// trailing ,?
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if ($this->stream->current->test(Token::PUNCTUATION_TYPE, ']')) {
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break;
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}
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}
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$first = false;
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$node->addElement($this->parseExpression());
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}
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$this->stream->expect(Token::PUNCTUATION_TYPE, ']', 'An opened array is not properly closed');
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return $node;
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}
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public function parseHashExpression()
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{
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$this->stream->expect(Token::PUNCTUATION_TYPE, '{', 'A hash element was expected');
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$node = new Node\ArrayNode();
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$first = true;
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while (!$this->stream->current->test(Token::PUNCTUATION_TYPE, '}')) {
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if (!$first) {
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$this->stream->expect(Token::PUNCTUATION_TYPE, ',', 'A hash value must be followed by a comma');
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// trailing ,?
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if ($this->stream->current->test(Token::PUNCTUATION_TYPE, '}')) {
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break;
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}
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}
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$first = false;
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// a hash key can be:
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//
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// * a number -- 12
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// * a string -- 'a'
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// * a name, which is equivalent to a string -- a
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// * an expression, which must be enclosed in parentheses -- (1 + 2)
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if ($this->stream->current->test(Token::STRING_TYPE) || $this->stream->current->test(Token::NAME_TYPE) || $this->stream->current->test(Token::NUMBER_TYPE)) {
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$key = new Node\ConstantNode($this->stream->current->value);
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$this->stream->next();
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} elseif ($this->stream->current->test(Token::PUNCTUATION_TYPE, '(')) {
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$key = $this->parseExpression();
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} else {
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$current = $this->stream->current;
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throw new SyntaxError(sprintf('A hash key must be a quoted string, a number, a name, or an expression enclosed in parentheses (unexpected token "%s" of value "%s".', $current->type, $current->value), $current->cursor, $this->stream->getExpression());
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}
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$this->stream->expect(Token::PUNCTUATION_TYPE, ':', 'A hash key must be followed by a colon (:)');
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$value = $this->parseExpression();
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$node->addElement($value, $key);
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}
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$this->stream->expect(Token::PUNCTUATION_TYPE, '}', 'An opened hash is not properly closed');
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return $node;
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}
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public function parsePostfixExpression(Node\Node $node)
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{
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$token = $this->stream->current;
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while (Token::PUNCTUATION_TYPE == $token->type) {
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if ('.' === $token->value) {
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$this->stream->next();
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$token = $this->stream->current;
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$this->stream->next();
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if (
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Token::NAME_TYPE !== $token->type
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&&
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// Operators like "not" and "matches" are valid method or property names,
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||
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//
|
||
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// In other words, besides NAME_TYPE, OPERATOR_TYPE could also be parsed as a property or method.
|
||
|
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// This is because operators are processed by the lexer prior to names. So "not" in "foo.not()" or "matches" in "foo.matches" will be recognized as an operator first.
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||
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// But in fact, "not" and "matches" in such expressions shall be parsed as method or property names.
|
||
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//
|
||
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// And this ONLY works if the operator consists of valid characters for a property or method name.
|
||
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//
|
||
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// Other types, such as STRING_TYPE and NUMBER_TYPE, can't be parsed as property nor method names.
|
||
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//
|
||
|
|
// As a result, if $token is NOT an operator OR $token->value is NOT a valid property or method name, an exception shall be thrown.
|
||
|
|
(Token::OPERATOR_TYPE !== $token->type || !preg_match('/[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*/A', $token->value))
|
||
|
|
) {
|
||
|
|
throw new SyntaxError('Expected name.', $token->cursor, $this->stream->getExpression());
|
||
|
|
}
|
||
|
|
|
||
|
|
$arg = new Node\ConstantNode($token->value, true);
|
||
|
|
|
||
|
|
$arguments = new Node\ArgumentsNode();
|
||
|
|
if ($this->stream->current->test(Token::PUNCTUATION_TYPE, '(')) {
|
||
|
|
$type = Node\GetAttrNode::METHOD_CALL;
|
||
|
|
foreach ($this->parseArguments()->nodes as $n) {
|
||
|
|
$arguments->addElement($n);
|
||
|
|
}
|
||
|
|
} else {
|
||
|
|
$type = Node\GetAttrNode::PROPERTY_CALL;
|
||
|
|
}
|
||
|
|
|
||
|
|
$node = new Node\GetAttrNode($node, $arg, $arguments, $type);
|
||
|
|
} elseif ('[' === $token->value) {
|
||
|
|
$this->stream->next();
|
||
|
|
$arg = $this->parseExpression();
|
||
|
|
$this->stream->expect(Token::PUNCTUATION_TYPE, ']');
|
||
|
|
|
||
|
|
$node = new Node\GetAttrNode($node, $arg, new Node\ArgumentsNode(), Node\GetAttrNode::ARRAY_CALL);
|
||
|
|
} else {
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
|
||
|
|
$token = $this->stream->current;
|
||
|
|
}
|
||
|
|
|
||
|
|
return $node;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Parses arguments.
|
||
|
|
*/
|
||
|
|
public function parseArguments()
|
||
|
|
{
|
||
|
|
$args = [];
|
||
|
|
$this->stream->expect(Token::PUNCTUATION_TYPE, '(', 'A list of arguments must begin with an opening parenthesis');
|
||
|
|
while (!$this->stream->current->test(Token::PUNCTUATION_TYPE, ')')) {
|
||
|
|
if (!empty($args)) {
|
||
|
|
$this->stream->expect(Token::PUNCTUATION_TYPE, ',', 'Arguments must be separated by a comma');
|
||
|
|
}
|
||
|
|
|
||
|
|
$args[] = $this->parseExpression();
|
||
|
|
}
|
||
|
|
$this->stream->expect(Token::PUNCTUATION_TYPE, ')', 'A list of arguments must be closed by a parenthesis');
|
||
|
|
|
||
|
|
return new Node\Node($args);
|
||
|
|
}
|
||
|
|
}
|