inc/Twig/ExpressionParser.php

   1 <?php
   2
   3 /*
   4  * This file is part of Twig.
   5  *
   6  * (c) 2009 Fabien Potencier
   7  * (c) 2009 Armin Ronacher
   8  *
   9  * For the full copyright and license information, please view the LICENSE
  10  * file that was distributed with this source code.
  11  */
  12
  13 /**
  14  * Parses expressions.
  15  *
  16  * This parser implements a "Precedence climbing" algorithm.
  17  *
  18  * @see http://www.engr.mun.ca/~theo/Misc/exp_parsing.htm
  19  * @see http://en.wikipedia.org/wiki/Operator-precedence_parser
  20  *
  21  * @author Fabien Potencier <fabien@symfony.com>
  22  */
  23 class Twig_ExpressionParser
  24 {
  25     const OPERATOR_LEFT = 1;
  26     const OPERATOR_RIGHT = 2;
  27
  28     protected $parser;
  29     protected $unaryOperators;
  30     protected $binaryOperators;
  31
  32     public function __construct(Twig_Parser $parser, array $unaryOperators, array $binaryOperators)
  33     {
  34         $this->parser = $parser;
  35         $this->unaryOperators = $unaryOperators;
  36         $this->binaryOperators = $binaryOperators;
  37     }
  38
  39     public function parseExpression($precedence = 0)
  40     {
  41         $expr = $this->getPrimary();
  42         $token = $this->parser->getCurrentToken();
  43         while ($this->isBinary($token) && $this->binaryOperators[$token->getValue()]['precedence'] >= $precedence) {
  44             $op = $this->binaryOperators[$token->getValue()];
  45             $this->parser->getStream()->next();
  46
  47             if (isset($op['callable'])) {
  48                 $expr = call_user_func($op['callable'], $this->parser, $expr);
  49             } else {
  50                 $expr1 = $this->parseExpression(self::OPERATOR_LEFT === $op['associativity'] ? $op['precedence'] + 1 : $op['precedence']);
  51                 $class = $op['class'];
  52                 $expr = new $class($expr, $expr1, $token->getLine());
  53             }
  54
  55             $token = $this->parser->getCurrentToken();
  56         }
  57
  58         if (0 === $precedence) {
  59             return $this->parseConditionalExpression($expr);
  60         }
  61
  62         return $expr;
  63     }
  64
  65     protected function getPrimary()
  66     {
  67         $token = $this->parser->getCurrentToken();
  68
  69         if ($this->isUnary($token)) {
  70             $operator = $this->unaryOperators[$token->getValue()];
  71             $this->parser->getStream()->next();
  72             $expr = $this->parseExpression($operator['precedence']);
  73             $class = $operator['class'];
  74
  75             return $this->parsePostfixExpression(new $class($expr, $token->getLine()));
  76         } elseif ($token->test(Twig_Token::PUNCTUATION_TYPE, '(')) {
  77             $this->parser->getStream()->next();
  78             $expr = $this->parseExpression();
  79             $this->parser->getStream()->expect(Twig_Token::PUNCTUATION_TYPE, ')', 'An opened parenthesis is not properly closed');
  80
  81             return $this->parsePostfixExpression($expr);
  82         }
  83
  84         return $this->parsePrimaryExpression();
  85     }
  86
  87     protected function parseConditionalExpression($expr)
  88     {
  89         while ($this->parser->getStream()->test(Twig_Token::PUNCTUATION_TYPE, '?')) {
  90             $this->parser->getStream()->next();
  91             if (!$this->parser->getStream()->test(Twig_Token::PUNCTUATION_TYPE, ':')) {
  92                 $expr2 = $this->parseExpression();
  93                 if ($this->parser->getStream()->test(Twig_Token::PUNCTUATION_TYPE, ':')) {
  94                     $this->parser->getStream()->next();
  95                     $expr3 = $this->parseExpression();
  96                 } else {
  97                     $expr3 = new Twig_Node_Expression_Constant('', $this->parser->getCurrentToken()->getLine());
  98                 }
  99             } else {
 100                 $this->parser->getStream()->next();
 101                 $expr2 = $expr;
 102                 $expr3 = $this->parseExpression();
 103             }
 104
 105             $expr = new Twig_Node_Expression_Conditional($expr, $expr2, $expr3, $this->parser->getCurrentToken()->getLine());
 106         }
 107
 108         return $expr;
 109     }
 110
 111     protected function isUnary(Twig_Token $token)
 112     {
 113         return $token->test(Twig_Token::OPERATOR_TYPE) && isset($this->unaryOperators[$token->getValue()]);
 114     }
 115
 116     protected function isBinary(Twig_Token $token)
 117     {
 118         return $token->test(Twig_Token::OPERATOR_TYPE) && isset($this->binaryOperators[$token->getValue()]);
 119     }
 120
 121     public function parsePrimaryExpression()
 122     {
 123         $token = $this->parser->getCurrentToken();
 124         switch ($token->getType()) {
 125             case Twig_Token::NAME_TYPE:
 126                 $this->parser->getStream()->next();
 127                 switch ($token->getValue()) {
 128                     case 'true':
 129                     case 'TRUE':
 130                         $node = new Twig_Node_Expression_Constant(true, $token->getLine());
 131                         break;
 132
 133                     case 'false':
 134                     case 'FALSE':
 135                         $node = new Twig_Node_Expression_Constant(false, $token->getLine());
 136                         break;
 137
 138                     case 'none':
 139                     case 'NONE':
 140                     case 'null':
 141                     case 'NULL':
 142                         $node = new Twig_Node_Expression_Constant(null, $token->getLine());
 143                         break;
 144
 145                     default:
 146                         if ('(' === $this->parser->getCurrentToken()->getValue()) {
 147                             $node = $this->getFunctionNode($token->getValue(), $token->getLine());
 148                         } else {
 149                             $node = new Twig_Node_Expression_Name($token->getValue(), $token->getLine());
 150                         }
 151                 }
 152                 break;
 153
 154             case Twig_Token::NUMBER_TYPE:
 155                 $this->parser->getStream()->next();
 156                 $node = new Twig_Node_Expression_Constant($token->getValue(), $token->getLine());
 157                 break;
 158
 159             case Twig_Token::STRING_TYPE:
 160             case Twig_Token::INTERPOLATION_START_TYPE:
 161                 $node = $this->parseStringExpression();
 162                 break;
 163
 164             default:
 165                 if ($token->test(Twig_Token::PUNCTUATION_TYPE, '[')) {
 166                     $node = $this->parseArrayExpression();
 167                 } elseif ($token->test(Twig_Token::PUNCTUATION_TYPE, '{')) {
 168                     $node = $this->parseHashExpression();
 169                 } else {
 170                     throw new Twig_Error_Syntax(sprintf('Unexpected token "%s" of value "%s"', Twig_Token::typeToEnglish($token->getType(), $token->getLine()), $token->getValue()), $token->getLine(), $this->parser->getFilename());
 171                 }
 172         }
 173
 174         return $this->parsePostfixExpression($node);
 175     }
 176
 177     public function parseStringExpression()
 178     {
 179         $stream = $this->parser->getStream();
 180
 181         $nodes = array();
 182         // a string cannot be followed by another string in a single expression
 183         $nextCanBeString = true;
 184         while (true) {
 185             if ($stream->test(Twig_Token::STRING_TYPE) && $nextCanBeString) {
 186                 $token = $stream->next();
 187                 $nodes[] = new Twig_Node_Expression_Constant($token->getValue(), $token->getLine());
 188                 $nextCanBeString = false;
 189             } elseif ($stream->test(Twig_Token::INTERPOLATION_START_TYPE)) {
 190                 $stream->next();
 191                 $nodes[] = $this->parseExpression();
 192                 $stream->expect(Twig_Token::INTERPOLATION_END_TYPE);
 193                 $nextCanBeString = true;
 194             } else {
 195                 break;
 196             }
 197         }
 198
 199         $expr = array_shift($nodes);
 200         foreach ($nodes as $node) {
 201             $expr = new Twig_Node_Expression_Binary_Concat($expr, $node, $node->getLine());
 202         }
 203
 204         return $expr;
 205     }
 206
 207     public function parseArrayExpression()
 208     {
 209         $stream = $this->parser->getStream();
 210         $stream->expect(Twig_Token::PUNCTUATION_TYPE, '[', 'An array element was expected');
 211
 212         $node = new Twig_Node_Expression_Array(array(), $stream->getCurrent()->getLine());
 213         $first = true;
 214         while (!$stream->test(Twig_Token::PUNCTUATION_TYPE, ']')) {
 215             if (!$first) {
 216                 $stream->expect(Twig_Token::PUNCTUATION_TYPE, ',', 'An array element must be followed by a comma');
 217
 218                 // trailing ,?
 219                 if ($stream->test(Twig_Token::PUNCTUATION_TYPE, ']')) {
 220                     break;
 221                 }
 222             }
 223             $first = false;
 224
 225             $node->addElement($this->parseExpression());
 226         }
 227         $stream->expect(Twig_Token::PUNCTUATION_TYPE, ']', 'An opened array is not properly closed');
 228
 229         return $node;
 230     }
 231
 232     public function parseHashExpression()
 233     {
 234         $stream = $this->parser->getStream();
 235         $stream->expect(Twig_Token::PUNCTUATION_TYPE, '{', 'A hash element was expected');
 236
 237         $node = new Twig_Node_Expression_Array(array(), $stream->getCurrent()->getLine());
 238         $first = true;
 239         while (!$stream->test(Twig_Token::PUNCTUATION_TYPE, '}')) {
 240             if (!$first) {
 241                 $stream->expect(Twig_Token::PUNCTUATION_TYPE, ',', 'A hash value must be followed by a comma');
 242
 243                 // trailing ,?
 244                 if ($stream->test(Twig_Token::PUNCTUATION_TYPE, '}')) {
 245                     break;
 246                 }
 247             }
 248             $first = false;
 249
 250             // a hash key can be:
 251             //
 252             //  * a number -- 12
 253             //  * a string -- 'a'
 254             //  * a name, which is equivalent to a string -- a
 255             //  * an expression, which must be enclosed in parentheses -- (1 + 2)
 256             if ($stream->test(Twig_Token::STRING_TYPE) || $stream->test(Twig_Token::NAME_TYPE) || $stream->test(Twig_Token::NUMBER_TYPE)) {
 257                 $token = $stream->next();
 258                 $key = new Twig_Node_Expression_Constant($token->getValue(), $token->getLine());
 259             } elseif ($stream->test(Twig_Token::PUNCTUATION_TYPE, '(')) {
 260                 $key = $this->parseExpression();
 261             } else {
 262                 $current = $stream->getCurrent();
 263
 264                 throw new Twig_Error_Syntax(sprintf('A hash key must be a quoted string, a number, a name, or an expression enclosed in parentheses (unexpected token "%s" of value "%s"', Twig_Token::typeToEnglish($current->getType(), $current->getLine()), $current->getValue()), $current->getLine(), $this->parser->getFilename());
 265             }
 266
 267             $stream->expect(Twig_Token::PUNCTUATION_TYPE, ':', 'A hash key must be followed by a colon (:)');
 268             $value = $this->parseExpression();
 269
 270             $node->addElement($value, $key);
 271         }
 272         $stream->expect(Twig_Token::PUNCTUATION_TYPE, '}', 'An opened hash is not properly closed');
 273
 274         return $node;
 275     }
 276
 277     public function parsePostfixExpression($node)
 278     {
 279         while (true) {
 280             $token = $this->parser->getCurrentToken();
 281             if ($token->getType() == Twig_Token::PUNCTUATION_TYPE) {
 282                 if ('.' == $token->getValue() || '[' == $token->getValue()) {
 283                     $node = $this->parseSubscriptExpression($node);
 284                 } elseif ('|' == $token->getValue()) {
 285                     $node = $this->parseFilterExpression($node);
 286                 } else {
 287                     break;
 288                 }
 289             } else {
 290                 break;
 291             }
 292         }
 293
 294         return $node;
 295     }
 296
 297     public function getFunctionNode($name, $line)
 298     {
 299         switch ($name) {
 300             case 'parent':
 301                 $args = $this->parseArguments();
 302                 if (!count($this->parser->getBlockStack())) {
 303                     throw new Twig_Error_Syntax('Calling "parent" outside a block is forbidden', $line, $this->parser->getFilename());
 304                 }
 305
 306                 if (!$this->parser->getParent() && !$this->parser->hasTraits()) {
 307                     throw new Twig_Error_Syntax('Calling "parent" on a template that does not extend nor "use" another template is forbidden', $line, $this->parser->getFilename());
 308                 }
 309
 310                 return new Twig_Node_Expression_Parent($this->parser->peekBlockStack(), $line);
 311             case 'block':
 312                 return new Twig_Node_Expression_BlockReference($this->parseArguments()->getNode(0), false, $line);
 313             case 'attribute':
 314                 $args = $this->parseArguments();
 315                 if (count($args) < 2) {
 316                     throw new Twig_Error_Syntax('The "attribute" function takes at least two arguments (the variable and the attributes)', $line, $this->parser->getFilename());
 317                 }
 318
 319                 return new Twig_Node_Expression_GetAttr($args->getNode(0), $args->getNode(1), count($args) > 2 ? $args->getNode(2) : new Twig_Node_Expression_Array(array(), $line), Twig_TemplateInterface::ANY_CALL, $line);
 320             default:
 321                 if (null !== $alias = $this->parser->getImportedSymbol('function', $name)) {
 322                     $arguments = new Twig_Node_Expression_Array(array(), $line);
 323                     foreach ($this->parseArguments() as $n) {
 324                         $arguments->addElement($n);
 325                     }
 326
 327                     $node = new Twig_Node_Expression_MethodCall($alias['node'], $alias['name'], $arguments, $line);
 328                     $node->setAttribute('safe', true);
 329
 330                     return $node;
 331                 }
 332
 333                 $args = $this->parseArguments(true);
 334                 $class = $this->getFunctionNodeClass($name, $line);
 335
 336                 return new $class($name, $args, $line);
 337         }
 338     }
 339
 340     public function parseSubscriptExpression($node)
 341     {
 342         $stream = $this->parser->getStream();
 343         $token = $stream->next();
 344         $lineno = $token->getLine();
 345         $arguments = new Twig_Node_Expression_Array(array(), $lineno);
 346         $type = Twig_TemplateInterface::ANY_CALL;
 347         if ($token->getValue() == '.') {
 348             $token = $stream->next();
 349             if (
 350                 $token->getType() == Twig_Token::NAME_TYPE
 351                 ||
 352                 $token->getType() == Twig_Token::NUMBER_TYPE
 353                 ||
 354                 ($token->getType() == Twig_Token::OPERATOR_TYPE && preg_match(Twig_Lexer::REGEX_NAME, $token->getValue()))
 355             ) {
 356                 $arg = new Twig_Node_Expression_Constant($token->getValue(), $lineno);
 357
 358                 if ($stream->test(Twig_Token::PUNCTUATION_TYPE, '(')) {
 359                     $type = Twig_TemplateInterface::METHOD_CALL;
 360                     foreach ($this->parseArguments() as $n) {
 361                         $arguments->addElement($n);
 362                     }
 363                 }
 364             } else {
 365                 throw new Twig_Error_Syntax('Expected name or number', $lineno, $this->parser->getFilename());
 366             }
 367
 368             if ($node instanceof Twig_Node_Expression_Name && null !== $this->parser->getImportedSymbol('template', $node->getAttribute('name'))) {
 369                 if (!$arg instanceof Twig_Node_Expression_Constant) {
 370                     throw new Twig_Error_Syntax(sprintf('Dynamic macro names are not supported (called on "%s")', $node->getAttribute('name')), $token->getLine(), $this->parser->getFilename());
 371                 }
 372
 373                 $node = new Twig_Node_Expression_MethodCall($node, 'get'.$arg->getAttribute('value'), $arguments, $lineno);
 374                 $node->setAttribute('safe', true);
 375
 376                 return $node;
 377             }
 378         } else {
 379             $type = Twig_TemplateInterface::ARRAY_CALL;
 380
 381             // slice?
 382             $slice = false;
 383             if ($stream->test(Twig_Token::PUNCTUATION_TYPE, ':')) {
 384                 $slice = true;
 385                 $arg = new Twig_Node_Expression_Constant(0, $token->getLine());
 386             } else {
 387                 $arg = $this->parseExpression();
 388             }
 389
 390             if ($stream->test(Twig_Token::PUNCTUATION_TYPE, ':')) {
 391                 $slice = true;
 392                 $stream->next();
 393             }
 394
 395             if ($slice) {
 396                 if ($stream->test(Twig_Token::PUNCTUATION_TYPE, ']')) {
 397                     $length = new Twig_Node_Expression_Constant(null, $token->getLine());
 398                 } else {
 399                     $length = $this->parseExpression();
 400                 }
 401
 402                 $class = $this->getFilterNodeClass('slice', $token->getLine());
 403                 $arguments = new Twig_Node(array($arg, $length));
 404                 $filter = new $class($node, new Twig_Node_Expression_Constant('slice', $token->getLine()), $arguments, $token->getLine());
 405
 406                 $stream->expect(Twig_Token::PUNCTUATION_TYPE, ']');
 407
 408                 return $filter;
 409             }
 410
 411             $stream->expect(Twig_Token::PUNCTUATION_TYPE, ']');
 412         }
 413
 414         return new Twig_Node_Expression_GetAttr($node, $arg, $arguments, $type, $lineno);
 415     }
 416
 417     public function parseFilterExpression($node)
 418     {
 419         $this->parser->getStream()->next();
 420
 421         return $this->parseFilterExpressionRaw($node);
 422     }
 423
 424     public function parseFilterExpressionRaw($node, $tag = null)
 425     {
 426         while (true) {
 427             $token = $this->parser->getStream()->expect(Twig_Token::NAME_TYPE);
 428
 429             $name = new Twig_Node_Expression_Constant($token->getValue(), $token->getLine());
 430             if (!$this->parser->getStream()->test(Twig_Token::PUNCTUATION_TYPE, '(')) {
 431                 $arguments = new Twig_Node();
 432             } else {
 433                 $arguments = $this->parseArguments(true);
 434             }
 435
 436             $class = $this->getFilterNodeClass($name->getAttribute('value'), $token->getLine());
 437
 438             $node = new $class($node, $name, $arguments, $token->getLine(), $tag);
 439
 440             if (!$this->parser->getStream()->test(Twig_Token::PUNCTUATION_TYPE, '|')) {
 441                 break;
 442             }
 443
 444             $this->parser->getStream()->next();
 445         }
 446
 447         return $node;
 448     }
 449
 450     /**
 451      * Parses arguments.
 452      *
 453      * @param Boolean $namedArguments Whether to allow named arguments or not
 454      * @param Boolean $definition     Whether we are parsing arguments for a function definition
 455      */
 456     public function parseArguments($namedArguments = false, $definition = false)
 457     {
 458         $args = array();
 459         $stream = $this->parser->getStream();
 460
 461         $stream->expect(Twig_Token::PUNCTUATION_TYPE, '(', 'A list of arguments must begin with an opening parenthesis');
 462         while (!$stream->test(Twig_Token::PUNCTUATION_TYPE, ')')) {
 463             if (!empty($args)) {
 464                 $stream->expect(Twig_Token::PUNCTUATION_TYPE, ',', 'Arguments must be separated by a comma');
 465             }
 466
 467             if ($definition) {
 468                 $token = $stream->expect(Twig_Token::NAME_TYPE, null, 'An argument must be a name');
 469                 $value = new Twig_Node_Expression_Name($token->getValue(), $this->parser->getCurrentToken()->getLine());
 470             } else {
 471                 $value = $this->parseExpression();
 472             }
 473
 474             $name = null;
 475             if ($namedArguments && $stream->test(Twig_Token::OPERATOR_TYPE, '=')) {
 476                 $token = $stream->next();
 477                 if (!$value instanceof Twig_Node_Expression_Name) {
 478                     throw new Twig_Error_Syntax(sprintf('A parameter name must be a string, "%s" given', get_class($value)), $token->getLine(), $this->parser->getFilename());
 479                 }
 480                 $name = $value->getAttribute('name');
 481
 482                 if ($definition) {
 483                     $value = $this->parsePrimaryExpression();
 484
 485                     if (!$this->checkConstantExpression($value)) {
 486                         throw new Twig_Error_Syntax(sprintf('A default value for an argument must be a constant (a boolean, a string, a number, or an array).'), $token->getLine(), $this->parser->getFilename());
 487                     }
 488                 } else {
 489                     $value = $this->parseExpression();
 490                 }
 491             }
 492
 493             if ($definition) {
 494                 if (null === $name) {
 495                     $name = $value->getAttribute('name');
 496                     $value = new Twig_Node_Expression_Constant(null, $this->parser->getCurrentToken()->getLine());
 497                 }
 498                 $args[$name] = $value;
 499             } else {
 500                 if (null === $name) {
 501                     $args[] = $value;
 502                 } else {
 503                     $args[$name] = $value;
 504                 }
 505             }
 506         }
 507         $stream->expect(Twig_Token::PUNCTUATION_TYPE, ')', 'A list of arguments must be closed by a parenthesis');
 508
 509         return new Twig_Node($args);
 510     }
 511
 512     public function parseAssignmentExpression()
 513     {
 514         $targets = array();
 515         while (true) {
 516             $token = $this->parser->getStream()->expect(Twig_Token::NAME_TYPE, null, 'Only variables can be assigned to');
 517             if (in_array($token->getValue(), array('true', 'false', 'none'))) {
 518                 throw new Twig_Error_Syntax(sprintf('You cannot assign a value to "%s"', $token->getValue()), $token->getLine(), $this->parser->getFilename());
 519             }
 520             $targets[] = new Twig_Node_Expression_AssignName($token->getValue(), $token->getLine());
 521
 522             if (!$this->parser->getStream()->test(Twig_Token::PUNCTUATION_TYPE, ',')) {
 523                 break;
 524             }
 525             $this->parser->getStream()->next();
 526         }
 527
 528         return new Twig_Node($targets);
 529     }
 530
 531     public function parseMultitargetExpression()
 532     {
 533         $targets = array();
 534         while (true) {
 535             $targets[] = $this->parseExpression();
 536             if (!$this->parser->getStream()->test(Twig_Token::PUNCTUATION_TYPE, ',')) {
 537                 break;
 538             }
 539             $this->parser->getStream()->next();
 540         }
 541
 542         return new Twig_Node($targets);
 543     }
 544
 545     protected function getFunctionNodeClass($name, $line)
 546     {
 547         $env = $this->parser->getEnvironment();
 548
 549         if (false === $function = $env->getFunction($name)) {
 550             $message = sprintf('The function "%s" does not exist', $name);
 551             if ($alternatives = $env->computeAlternatives($name, array_keys($env->getFunctions()))) {
 552                 $message = sprintf('%s. Did you mean "%s"', $message, implode('", "', $alternatives));
 553             }
 554
 555             throw new Twig_Error_Syntax($message, $line, $this->parser->getFilename());
 556         }
 557
 558         if ($function instanceof Twig_SimpleFunction) {
 559             return $function->getNodeClass();
 560         }
 561
 562         return $function instanceof Twig_Function_Node ? $function->getClass() : 'Twig_Node_Expression_Function';
 563     }
 564
 565     protected function getFilterNodeClass($name, $line)
 566     {
 567         $env = $this->parser->getEnvironment();
 568
 569         if (false === $filter = $env->getFilter($name)) {
 570             $message = sprintf('The filter "%s" does not exist', $name);
 571             if ($alternatives = $env->computeAlternatives($name, array_keys($env->getFilters()))) {
 572                 $message = sprintf('%s. Did you mean "%s"', $message, implode('", "', $alternatives));
 573             }
 574
 575             throw new Twig_Error_Syntax($message, $line, $this->parser->getFilename());
 576         }
 577
 578         if ($filter instanceof Twig_SimpleFilter) {
 579             return $filter->getNodeClass();
 580         }
 581
 582         return $filter instanceof Twig_Filter_Node ? $filter->getClass() : 'Twig_Node_Expression_Filter';
 583     }
 584
 585     // checks that the node only contains "constant" elements
 586     protected function checkConstantExpression(Twig_NodeInterface $node)
 587     {
 588         if (!($node instanceof Twig_Node_Expression_Constant || $node instanceof Twig_Node_Expression_Array)) {
 589             return false;
 590         }
 591
 592         foreach ($node as $n) {
 593             if (!$this->checkConstantExpression($n)) {
 594                 return false;
 595             }
 596         }
 597
 598         return true;
 599     }
 600 }