<?php
/*
* This file is part of Twig.
*
* (c) 2009 Fabien Potencier
* (c) 2009 Armin Ronacher
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
/**
* Parses expressions.
*
* This parser implements a "Precedence climbing" algorithm.
*
* @see http://www.engr.mun.ca/~theo/Misc/exp_parsing.htm
* @see http://en.wikipedia.org/wiki/Operator-precedence_parser
*
* @package twig
* @author Fabien Potencier <fabien@symfony.com>
*/
class Twig_ExpressionParser
{
const OPERATOR_LEFT = 1;
const OPERATOR_RIGHT = 2;
protected $parser;
protected $unaryOperators;
protected $binaryOperators;
public function __construct(Twig_Parser $parser, array $unaryOperators, array $binaryOperators)
{
$this->parser = $parser;
$this->unaryOperators = $unaryOperators;
$this->binaryOperators = $binaryOperators;
}
public function parseExpression($precedence = 0)
{
$expr = $this->getPrimary();
$token = $this->parser->getCurrentToken();
while ($this->isBinary($token) && $this->binaryOperators[$token->getValue()]['precedence'] >= $precedence) {
$op = $this->binaryOperators[$token->getValue()];
$this->parser->getStream()->next();
if (isset($op['callable'])) {
$expr = call_user_func($op['callable'], $this->parser, $expr);
} else {
$expr1 = $this->parseExpression(self::OPERATOR_LEFT === $op['associativity'] ? $op['precedence'] + 1 : $op['precedence']);
$class = $op['class'];
$expr = new $class($expr, $expr1, $token->getLine());
}
$token = $this->parser->getCurrentToken();
}
if (0 === $precedence) {
return $this->parseConditionalExpression($expr);
}
return $expr;
}
protected function getPrimary()
{
$token = $this->parser->getCurrentToken();
if ($this->isUnary($token)) {
$operator = $this->unaryOperators[$token->getValue()];
$this->parser->getStream()->next();
$expr = $this->parseExpression($operator['precedence']);
$class = $operator['class'];
return $this->parsePostfixExpression(new $class($expr, $token->getLine()));
} elseif ($token->test(Twig_Token::PUNCTUATION_TYPE, '(')) {
$this->parser->getStream()->next();
$expr = $this->parseExpression();
$this->parser->getStream()->expect(Twig_Token::PUNCTUATION_TYPE, ')', 'An opened parenthesis is not properly closed');
return $this->parsePostfixExpression($expr);
}
return $this->parsePrimaryExpression();
}
protected function parseConditionalExpression($expr)
{
while ($this->parser->getStream()->test(Twig_Token::PUNCTUATION_TYPE, '?')) {
$this->parser->getStream()->next();
$expr2 = $this->parseExpression();
$this->parser->getStream()->expect(Twig_Token::PUNCTUATION_TYPE, ':', 'The ternary operator must have a default value');
$expr3 = $this->parseExpression();
$expr = new Twig_Node_Expression_Conditional($expr, $expr2, $expr3, $this->parser->getCurrentToken()->getLine());
}
return $expr;
}
protected function isUnary(Twig_Token $token)
{
return $token->test(Twig_Token::OPERATOR_TYPE) && isset($this->unaryOperators[$token->getValue()]);
}
protected function isBinary(Twig_Token $token)
{
return $token->test(Twig_Token::OPERATOR_TYPE) && isset($this->binaryOperators[$token->getValue()]);
}
public function parsePrimaryExpression()
{
$token = $this->parser->getCurrentToken();
switch ($token->getType()) {
case Twig_Token::NAME_TYPE:
$this->parser->getStream()->next();
switch ($token->getValue()) {
case 'true':
case 'TRUE':
$node = new Twig_Node_Expression_Constant(true, $token->getLine());
break;
case 'false':
case 'FALSE':
$node = new Twig_Node_Expression_Constant(false, $token->getLine());
break;
case 'none':
case 'NONE':
case 'null':
case 'NULL':
$node = new Twig_Node_Expression_Constant(null, $token->getLine());
break;
default:
if ('(' === $this->parser->getCurrentToken()->getValue()) {
$node = $this->getFunctionNode($token->getValue(), $token->getLine());
} else {
$node = new Twig_Node_Expression_Name($token->getValue(), $token->getLine());
}
}
break;
case Twig_Token::NUMBER_TYPE:
$this->parser->getStream()->next();
$node = new Twig_Node_Expression_Constant($token->getValue(), $token->getLine());
break;
case Twig_Token::STRING_TYPE:
case Twig_Token::INTERPOLATION_START_TYPE:
$node = $this->parseStringExpression();
break;
default:
if ($token->test(Twig_Token::PUNCTUATION_TYPE, '[')) {
$node = $this->parseArrayExpression();
} elseif ($token->test(Twig_Token::PUNCTUATION_TYPE, '{')) {
$node = $this->parseHashExpression();
} else {
throw new Twig_Error_Syntax(sprintf('Unexpected token "%s" of value "%s"', Twig_Token::typeToEnglish($token->getType(), $token->getLine()), $token->getValue()), $token->getLine());
}
}
return $this->parsePostfixExpression($node);
}
public function parseStringExpression()
{
$stream = $this->parser->getStream();
$nodes = array();
// a string cannot be followed by another string in a single expression
$nextCanBeString = true;
while (true) {
if ($stream->test(Twig_Token::STRING_TYPE) && $nextCanBeString) {
$token = $stream->next();
$nodes[] = new Twig_Node_Expression_Constant($token->getValue(), $token->getLine());
$nextCanBeString = false;
} elseif ($stream->test(Twig_Token::INTERPOLATION_START_TYPE)) {
$stream->next();
$nodes[] = $this->parseExpression();
$stream->expect(Twig_Token::INTERPOLATION_END_TYPE);
$nextCanBeString = true;
} else {
break;
}
}
$expr = array_shift($nodes);
foreach ($nodes as $node) {
$expr = new Twig_Node_Expression_Binary_Concat($expr, $node, $node->getLine());
}
return $expr;
}
public function parseArrayExpression()
{
$stream = $this->parser->getStream();
$stream->expect(Twig_Token::PUNCTUATION_TYPE, '[', 'An array element was expected');
$node = new Twig_Node_Expression_Array(array(), $stream->getCurrent()->getLine());
$first = true;
while (!$stream->test(Twig_Token::PUNCTUATION_TYPE, ']')) {
if (!$first) {
$stream->expect(Twig_Token::PUNCTUATION_TYPE, ',', 'An array element must be followed by a comma');
// trailing ,?
if ($stream->test(Twig_Token::PUNCTUATION_TYPE, ']')) {
break;
}
}
$first = false;
$node->addElement($this->parseExpression());
}
$stream->expect(Twig_Token::PUNCTUATION_TYPE, ']', 'An opened array is not properly closed');
return $node;
}
public function parseHashExpression()
{
$stream = $this->parser->getStream();
$stream->expect(Twig_Token::PUNCTUATION_TYPE, '{', 'A hash element was expected');
$node = new Twig_Node_Expression_Array(array(), $stream->getCurrent()->getLine());
$first = true;
while (!$stream->test(Twig_Token::PUNCTUATION_TYPE, '}')) {
if (!$first) {
$stream->expect(Twig_Token::PUNCTUATION_TYPE, ',', 'A hash value must be followed by a comma');
// trailing ,?
if ($stream->test(Twig_Token::PUNCTUATION_TYPE, '}')) {
break;
}
}
$first = false;
// a hash key can be:
//
// * a number -- 12
// * a string -- 'a'
// * a name, which is equivalent to a string -- a
// * an expression, which must be enclosed in parentheses -- (1 + 2)
if ($stream->test(Twig_Token::STRING_TYPE) || $stream->test(Twig_Token::NAME_TYPE) || $stream->test(Twig_Token::NUMBER_TYPE)) {
$token = $stream->next();
$key = new Twig_Node_Expression_Constant($token->getValue(), $token->getLine());
} elseif ($stream->test(Twig_Token::PUNCTUATION_TYPE, '(')) {
$key = $this->parseExpression();
} else {
$current = $stream->getCurrent();
throw new Twig_Error_Syntax(sprintf('A hash key must be a quoted string, a number, a name, or an expression enclosed in parentheses (unexpected token "%s" of value "%s"', Twig_Token::typeToEnglish($current->getType(), $current->getLine()), $current->getValue()), $current->getLine());
}
$stream->expect(Twig_Token::PUNCTUATION_TYPE, ':', 'A hash key must be followed by a colon (:)');
$value = $this->parseExpression();
$node->addElement($value, $key);
}
$stream->expect(Twig_Token::PUNCTUATION_TYPE, '}', 'An opened hash is not properly closed');
return $node;
}
public function parsePostfixExpression($node)
{
while (true) {
$token = $this->parser->getCurrentToken();
if ($token->getType() == Twig_Token::PUNCTUATION_TYPE) {
if ('.' == $token->getValue() || '[' == $token->getValue()) {
$node = $this->parseSubscriptExpression($node);
} elseif ('|' == $token->getValue()) {
$node = $this->parseFilterExpression($node);
} else {
break;
}
} else {
break;
}
}
return $node;
}
public function getFunctionNode($name, $line)
{
$args = $this->parseArguments();
switch ($name) {
case 'parent':
if (!count($this->parser->getBlockStack())) {
throw new Twig_Error_Syntax('Calling "parent" outside a block is forbidden', $line);
}
if (!$this->parser->getParent() && !$this->parser->hasTraits()) {
throw new Twig_Error_Syntax('Calling "parent" on a template that does not extend nor "use" another template is forbidden', $line);
}
return new Twig_Node_Expression_Parent($this->parser->peekBlockStack(), $line);
case 'block':
return new Twig_Node_Expression_BlockReference($args->getNode(0), false, $line);
case 'attribute':
if (count($args) < 2) {
throw new Twig_Error_Syntax('The "attribute" function takes at least two arguments (the variable and the attributes)', $line);
}
return new Twig_Node_Expression_GetAttr($args->getNode(0), $args->getNode(1), count($args) > 2 ? $args->getNode(2) : new Twig_Node_Expression_Array(array(), $line), Twig_TemplateInterface::ANY_CALL, $line);
default:
if (null !== $alias = $this->parser->getImportedFunction($name)) {
$arguments = new Twig_Node_Expression_Array(array(), $line);
foreach ($args as $n) {
$arguments->addElement($n);
}
$node = new Twig_Node_Expression_MethodCall($alias['node'], $alias['name'], $arguments, $line);
$node->setAttribute('safe', true);
return $node;
}
$class = $this->getFunctionNodeClass($name);
return new $class($name, $args, $line);
}
}
public function parseSubscriptExpression($node)
{
$stream = $this->parser->getStream();
$token = $stream->next();
$lineno = $token->getLine();
$arguments = new Twig_Node_Expression_Array(array(), $lineno);
$type = Twig_TemplateInterface::ANY_CALL;
if ($token->getValue() == '.') {
$token = $stream->next();
if (
$token->getType() == Twig_Token::NAME_TYPE
||
$token->getType() == Twig_Token::NUMBER_TYPE
||
($token->getType() == Twig_Token::OPERATOR_TYPE && preg_match(Twig_Lexer::REGEX_NAME, $token->getValue()))
) {
$arg = new Twig_Node_Expression_Constant($token->getValue(), $lineno);
if ($stream->test(Twig_Token::PUNCTUATION_TYPE, '(')) {
$type = Twig_TemplateInterface::METHOD_CALL;
foreach ($this->parseArguments() as $n) {
$arguments->addElement($n);
}
}
} else {
throw new Twig_Error_Syntax('Expected name or number', $lineno);
}
} else {
$type = Twig_TemplateInterface::ARRAY_CALL;
$arg = $this->parseExpression();
// slice?
if ($stream->test(Twig_Token::PUNCTUATION_TYPE, ':')) {
$stream->next();
if ($stream->test(Twig_Token::PUNCTUATION_TYPE, ']')) {
$length = new Twig_Node_Expression_Constant(null, $token->getLine());
} else {
$length = $this->parseExpression();
}
$class = $this->getFilterNodeClass('slice');
$arguments = new Twig_Node(array($arg, $length));
$filter = new $class($node, new Twig_Node_Expression_Constant('slice', $token->getLine()), $arguments, $token->getLine());
$stream->expect(Twig_Token::PUNCTUATION_TYPE, ']');
return $filter;
}
$stream->expect(Twig_Token::PUNCTUATION_TYPE, ']');
}
return new Twig_Node_Expression_GetAttr($node, $arg, $arguments, $type, $lineno);
}
public function parseFilterExpression($node)
{
$this->parser->getStream()->next();
return $this->parseFilterExpressionRaw($node);
}
public function parseFilterExpressionRaw($node, $tag = null)
{
while (true) {
$token = $this->parser->getStream()->expect(Twig_Token::NAME_TYPE);
$name = new Twig_Node_Expression_Constant($token->getValue(), $token->getLine());
if (!$this->parser->getStream()->test(Twig_Token::PUNCTUATION_TYPE, '(')) {
$arguments = new Twig_Node();
} else {
$arguments = $this->parseArguments();
}
$class = $this->getFilterNodeClass($name->getAttribute('value'));
$node = new $class($node, $name, $arguments, $token->getLine(), $tag);
if (!$this->parser->getStream()->test(Twig_Token::PUNCTUATION_TYPE, '|')) {
break;
}
$this->parser->getStream()->next();
}
return $node;
}
public function parseArguments()
{
$args = array();
$stream = $this->parser->getStream();
$stream->expect(Twig_Token::PUNCTUATION_TYPE, '(', 'A list of arguments must be opened by a parenthesis');
while (!$stream->test(Twig_Token::PUNCTUATION_TYPE, ')')) {
if (!empty($args)) {
$stream->expect(Twig_Token::PUNCTUATION_TYPE, ',', 'Arguments must be separated by a comma');
}
$args[] = $this->parseExpression();
}
$stream->expect(Twig_Token::PUNCTUATION_TYPE, ')', 'A list of arguments must be closed by a parenthesis');
return new Twig_Node($args);
}
public function parseAssignmentExpression()
{
$targets = array();
while (true) {
$token = $this->parser->getStream()->expect(Twig_Token::NAME_TYPE, null, 'Only variables can be assigned to');
if (in_array($token->getValue(), array('true', 'false', 'none'))) {
throw new Twig_Error_Syntax(sprintf('You cannot assign a value to "%s"', $token->getValue()), $token->getLine());
}
$targets[] = new Twig_Node_Expression_AssignName($token->getValue(), $token->getLine());
if (!$this->parser->getStream()->test(Twig_Token::PUNCTUATION_TYPE, ',')) {
break;
}
$this->parser->getStream()->next();
}
return new Twig_Node($targets);
}
public function parseMultitargetExpression()
{
$targets = array();
while (true) {
$targets[] = $this->parseExpression();
if (!$this->parser->getStream()->test(Twig_Token::PUNCTUATION_TYPE, ',')) {
break;
}
$this->parser->getStream()->next();
}
return new Twig_Node($targets);
}
protected function getFunctionNodeClass($name)
{
$functionMap = $this->parser->getEnvironment()->getFunctions();
if (isset($functionMap[$name]) && $functionMap[$name] instanceof Twig_Function_Node) {
return $functionMap[$name]->getClass();
}
return 'Twig_Node_Expression_Function';
}
protected function getFilterNodeClass($name)
{
$filterMap = $this->parser->getEnvironment()->getFilters();
if (isset($filterMap[$name]) && $filterMap[$name] instanceof Twig_Filter_Node) {
return $filterMap[$name]->getClass();
}
return 'Twig_Node_Expression_Filter';
}
}
