File Source for Symbol.php

<?php
/**
* PHP_ParserGenerator, a php 5 parser generator.
*
* This is a direct port of the Lemon parser generator, found at
* {@link http://www.hwaci.com/sw/lemon/}
*
* PHP version 5
*
* LICENSE:
*
* Copyright (c) 2006, Gregory Beaver <cellog@php.net>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the distribution.
* * Neither the name of the PHP_ParserGenerator nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* @category php
* @package PHP_ParserGenerator
* @author Gregory Beaver <cellog@php.net>
* @copyright 2006 Gregory Beaver
* @license http://www.opensource.org/licenses/bsd-license.php New BSD License
* @version CVS: $Id$
* @since File available since Release 0.1.0
*/
/**
* Symbols (terminals and nonterminals) of the grammar are stored in this class
*
* @package PHP_ParserGenerator
* @author Gregory Beaver <cellog@php.net>
* @copyright 2006 Gregory Beaver
* @license http://www.opensource.org/licenses/bsd-license.php New BSD License
* @version @package_version@
* @since Class available since Release 0.1.0
*/
class PHP_ParserGenerator_Symbol
{
/**
* Symbols that start with a capital letter like FOO.
*
* These are tokens directly from the lexer
*/
const TERMINAL = 1;
/**
* Symbols that start with a lower-case letter like foo.
*
* These are grammar rules like "foo ::= BLAH."
*/
const NONTERMINAL = 2;
/**
* Multiple terminal symbols.
*
* These are a grammar rule that consists of several terminals like
* FOO|BAR|BAZ. Note that non-terminals cannot be in a multi-terminal,
* and a multi-terminal acts like a single terminal.
*
* "FOO|BAR FOO|BAZ" is actually two multi-terminals, FOO|BAR and FOO|BAZ.
*/
const MULTITERMINAL = 3;
const LEFT = 1;
const RIGHT = 2;
const NONE = 3;
const UNK = 4;
/**
* Name of the symbol
*
* @var string
*/
public $name;
/**
* Index of this symbol.
*
* This will ultimately end up representing the symbol in the generated
* parser
* @var int
*/
public $index;
/**
* Symbol type
*
* One of PHP_ParserGenerator_Symbol::TERMINAL,
* PHP_ParserGenerator_Symbol::NONTERMINAL or
* PHP_ParserGenerator_Symbol::MULTITERMINAL
* @var int
*/
public $type;
/**
* Linked list of rules that use this symbol, if it is a non-terminal.
* @var PHP_ParserGenerator_Rule
*/
public $rule;
/**
* Fallback token in case this token doesn't parse
* @var PHP_ParserGenerator_Symbol
*/
public $fallback;
/**
* Precendence, if defined.
*
* -1 if no unusual precedence
* @var int
*/
public $prec = -1;
/**
* Associativity if precedence is defined.
*
* One of PHP_ParserGenerator_Symbol::LEFT,
* PHP_ParserGenerator_Symbol::RIGHT, PHP_ParserGenerator_Symbol::NONE
* or PHP_ParserGenerator_Symbol::UNK
* @var unknown_type
*/
public $assoc;
/**
* First-set for all rules of this symbol
*
* @var array
*/
public $firstset;
/**
* True if this symbol is a non-terminal and can generate an empty
* result.
*
* For instance "foo ::= ."
* @var boolean
*/
public $lambda;
/**
* Code that executes whenever this symbol is popped from the stack during
* error processing.
*
* @var string|0
*/
public $destructor = 0;
/**
* Line number of destructor code
* @var int
*/
public $destructorln;
/**
* Unused relic of the C version of Lemon.
*
* The data type of information held by this object. Only used
* if this is a non-terminal
* @var string
*/
public $datatype;
/**
* Unused relic of the C version of Lemon.
*
* The data type number. In the parser, the value
* stack is a union. The .yy%d element of this
* union is the correct data type for this object
* @var string
*/
public $dtnum;
/**#@+
* The following fields are used by MULTITERMINALs only
*/
/**
* Number of terminal symbols in the MULTITERMINAL
*
* This is of course the same as count($this->subsym)
* @var int
*/
public $nsubsym;
/**
* Array of terminal symbols in the MULTITERMINAL
* @var array an array of {@link PHP_ParserGenerator_Symbol} objects
*/
public $subsym = array();
/**#@-*/
/**
* Singleton storage of symbols
*
* @var array an array of PHP_ParserGenerator_Symbol objects
*/
private static $symbol_table = array();
/**
* Return a pointer to the (terminal or nonterminal) symbol "x".
* Create a new symbol if this is the first time "x" has been seen.
* (this is a singleton)
* @param string
* @return PHP_ParserGenerator_Symbol
*/
public static function Symbol_new($x)
{
if (isset(self::$symbol_table[$x])) {
return self::$symbol_table[$x];
}
$sp = new PHP_ParserGenerator_Symbol;
$sp->name = $x;
$sp->type = preg_match('/[A-Z]/', $x[0]) ? self::TERMINAL : self::NONTERMINAL;
$sp->rule = 0;
$sp->fallback = 0;
$sp->prec = -1;
$sp->assoc = self::UNK;
$sp->firstset = array();
$sp->lambda = false;
$sp->destructor = 0;
$sp->datatype = 0;
self::$symbol_table[$sp->name] = $sp;
return $sp;
}
/**
* Return the number of unique symbols
* @return int
*/
public static function Symbol_count()
{
return count(self::$symbol_table);
}
public static function Symbol_arrayof()
{
return array_values(self::$symbol_table);
}
public static function Symbol_find($x)
{
if (isset(self::$symbol_table[$x])) {
return self::$symbol_table[$x];
}
return 0;
}
/**
* Sort function helper for symbols
*
* Symbols that begin with upper case letters (terminals or tokens)
* must sort before symbols that begin with lower case letters
* (non-terminals). Other than that, the order does not matter.
*
* We find experimentally that leaving the symbols in their original
* order (the order they appeared in the grammar file) gives the
* smallest parser tables in SQLite.
* @param PHP_ParserGenerator_Symbol
* @param PHP_ParserGenerator_Symbol
*/
public static function sortSymbols($a, $b)
{
$i1 = $a->index + 10000000*(ord($a->name[0]) > ord('Z'));
$i2 = $b->index + 10000000*(ord($b->name[0]) > ord('Z'));
return $i1 - $i2;
}
/**
* Return true if two symbols are the same.
*/
public static function same_symbol(PHP_ParserGenerator_Symbol $a, PHP_ParserGenerator_Symbol $b)
{
if ($a === $b) return 1;
if ($a->type != self::MULTITERMINAL) return 0;
if ($b->type != self::MULTITERMINAL) return 0;
if ($a->nsubsym != $b->nsubsym) return 0;
for ($i = 0; $i < $a->nsubsym; $i++) {
if ($a->subsym[$i] != $b->subsym[$i]) return 0;
}
return 1;
}
}

	PHP_ParserGenerator

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Source for file Symbol.php