288 lines
8.5 KiB
PHP
288 lines
8.5 KiB
PHP
<?php
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/**
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* PHP_ParserGenerator, a php 5 parser generator.
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*
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* This is a direct port of the Lemon parser generator, found at
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* {@link http://www.hwaci.com/sw/lemon/}
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*
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* PHP version 5
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*
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* LICENSE:
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*
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* Copyright (c) 2006, Gregory Beaver <cellog@php.net>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the distribution.
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* * Neither the name of the PHP_ParserGenerator nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* @category php
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* @package PHP_ParserGenerator
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* @author Gregory Beaver <cellog@php.net>
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* @copyright 2006 Gregory Beaver
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* @license http://www.opensource.org/licenses/bsd-license.php New BSD License
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* @version CVS: $Id: Symbol.php,v 1.1 2006/07/18 00:53:10 cellog Exp $
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* @since File available since Release 0.1.0
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*/
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/**
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* Symbols (terminals and nonterminals) of the grammar are stored in this class
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*
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* @package PHP_ParserGenerator
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* @author Gregory Beaver <cellog@php.net>
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* @copyright 2006 Gregory Beaver
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* @license http://www.opensource.org/licenses/bsd-license.php New BSD License
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* @version 0.1.5
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* @since Class available since Release 0.1.0
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*/
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class PHP_ParserGenerator_Symbol
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{
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/**
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* Symbols that start with a capital letter like FOO.
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*
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* These are tokens directly from the lexer
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*/
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const TERMINAL = 1;
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/**
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* Symbols that start with a lower-case letter like foo.
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*
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* These are grammar rules like "foo ::= BLAH."
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*/
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const NONTERMINAL = 2;
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/**
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* Multiple terminal symbols.
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*
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* These are a grammar rule that consists of several terminals like
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* FOO|BAR|BAZ. Note that non-terminals cannot be in a multi-terminal,
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* and a multi-terminal acts like a single terminal.
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*
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* "FOO|BAR FOO|BAZ" is actually two multi-terminals, FOO|BAR and FOO|BAZ.
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*/
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const MULTITERMINAL = 3;
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const LEFT = 1;
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const RIGHT = 2;
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const NONE = 3;
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const UNK = 4;
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/**
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* Name of the symbol
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*
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* @var string
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*/
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public $name;
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/**
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* Index of this symbol.
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*
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* This will ultimately end up representing the symbol in the generated
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* parser
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* @var int
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*/
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public $index;
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/**
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* Symbol type
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*
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* One of PHP_ParserGenerator_Symbol::TERMINAL,
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* PHP_ParserGenerator_Symbol::NONTERMINAL or
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* PHP_ParserGenerator_Symbol::MULTITERMINAL
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* @var int
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*/
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public $type;
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/**
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* Linked list of rules that use this symbol, if it is a non-terminal.
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* @var PHP_ParserGenerator_Rule
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*/
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public $rule;
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/**
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* Fallback token in case this token doesn't parse
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* @var PHP_ParserGenerator_Symbol
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*/
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public $fallback;
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/**
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* Precendence, if defined.
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*
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* -1 if no unusual precedence
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* @var int
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*/
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public $prec = -1;
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/**
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* Associativity if precedence is defined.
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*
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* One of PHP_ParserGenerator_Symbol::LEFT,
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* PHP_ParserGenerator_Symbol::RIGHT, PHP_ParserGenerator_Symbol::NONE
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* or PHP_ParserGenerator_Symbol::UNK
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* @var unknown_type
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*/
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public $assoc;
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/**
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* First-set for all rules of this symbol
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*
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* @var array
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*/
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public $firstset;
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/**
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* True if this symbol is a non-terminal and can generate an empty
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* result.
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*
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* For instance "foo ::= ."
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* @var boolean
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*/
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public $lambda;
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/**
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* Code that executes whenever this symbol is popped from the stack during
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* error processing.
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*
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* @var string|0
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*/
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public $destructor = 0;
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/**
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* Line number of destructor code
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* @var int
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*/
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public $destructorln;
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/**
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* Unused relic of the C version of Lemon.
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*
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* The data type of information held by this object. Only used
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* if this is a non-terminal
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* @var string
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*/
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public $datatype;
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/**
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* Unused relic of the C version of Lemon.
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*
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* The data type number. In the parser, the value
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* stack is a union. The .yy%d element of this
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* union is the correct data type for this object
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* @var string
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*/
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public $dtnum;
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/**#@+
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* The following fields are used by MULTITERMINALs only
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*/
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/**
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* Number of terminal symbols in the MULTITERMINAL
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*
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* This is of course the same as count($this->subsym)
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* @var int
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*/
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public $nsubsym;
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/**
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* Array of terminal symbols in the MULTITERMINAL
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* @var array an array of {@link PHP_ParserGenerator_Symbol} objects
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*/
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public $subsym = array();
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/**#@-*/
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/**
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* Singleton storage of symbols
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*
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* @var array an array of PHP_ParserGenerator_Symbol objects
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*/
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private static $symbol_table = array();
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/**
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* Return a pointer to the (terminal or nonterminal) symbol "x".
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* Create a new symbol if this is the first time "x" has been seen.
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* (this is a singleton)
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* @param string
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* @return PHP_ParserGenerator_Symbol
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*/
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public static function Symbol_new($x)
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{
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if (isset(self::$symbol_table[$x])) {
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return self::$symbol_table[$x];
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}
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$sp = new PHP_ParserGenerator_Symbol;
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$sp->name = $x;
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$sp->type = preg_match('/[A-Z]/', $x[0]) ? self::TERMINAL : self::NONTERMINAL;
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$sp->rule = 0;
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$sp->fallback = 0;
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$sp->prec = -1;
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$sp->assoc = self::UNK;
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$sp->firstset = array();
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$sp->lambda = false;
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$sp->destructor = 0;
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$sp->datatype = 0;
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self::$symbol_table[$sp->name] = $sp;
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return $sp;
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}
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/**
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* Return the number of unique symbols
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* @return int
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*/
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public static function Symbol_count()
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{
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return count(self::$symbol_table);
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}
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public static function Symbol_arrayof()
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{
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return array_values(self::$symbol_table);
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}
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public static function Symbol_find($x)
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{
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if (isset(self::$symbol_table[$x])) {
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return self::$symbol_table[$x];
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}
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return 0;
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}
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/**
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* Sort function helper for symbols
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*
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* Symbols that begin with upper case letters (terminals or tokens)
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* must sort before symbols that begin with lower case letters
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* (non-terminals). Other than that, the order does not matter.
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*
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* We find experimentally that leaving the symbols in their original
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* order (the order they appeared in the grammar file) gives the
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* smallest parser tables in SQLite.
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* @param PHP_ParserGenerator_Symbol
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* @param PHP_ParserGenerator_Symbol
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*/
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public static function sortSymbols($a, $b)
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{
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$i1 = $a->index + 10000000*(ord($a->name[0]) > ord('Z'));
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$i2 = $b->index + 10000000*(ord($b->name[0]) > ord('Z'));
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return $i1 - $i2;
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}
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/**
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* Return true if two symbols are the same.
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*/
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public static function same_symbol(PHP_ParserGenerator_Symbol $a, PHP_ParserGenerator_Symbol $b)
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{
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if ($a === $b) return 1;
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if ($a->type != self::MULTITERMINAL) return 0;
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if ($b->type != self::MULTITERMINAL) return 0;
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if ($a->nsubsym != $b->nsubsym) return 0;
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for ($i = 0; $i < $a->nsubsym; $i++) {
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if ($a->subsym[$i] != $b->subsym[$i]) return 0;
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}
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return 1;
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}
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}
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