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97 lines
1.6 KiB
97 lines
1.6 KiB
3 years ago
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// SimpleQueryParser.cc
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//
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// SimpleQueryParser: (abstract) a family of parsers that generate queries
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// for strings with the syntax (word|phrase){(word|phrase)}
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// combining them in a single operator.
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// The operator to apply is tbd by concrete classes.
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//
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// Part of the ht://Dig package <http://www.htdig.org/>
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// Copyright (c) 1995-2004 The ht://Dig Group
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// For copyright details, see the file COPYING in your distribution
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// or the GNU Library General Public License (LGPL) version 2 or later
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// <http://www.gnu.org/copyleft/lgpl.html>
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//
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// $Id: SimpleQueryParser.cc,v 1.4 2004/05/28 13:15:24 lha Exp $
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//
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#include "SimpleQueryParser.h"
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#include "OperatorQuery.h"
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//
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// expr == term { term }
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//
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Query *
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SimpleQueryParser::ParseExpression()
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{
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Query *result = 0;
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Query *term = ParseTerm();
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if(term)
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{
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if(token.IsEnd())
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{
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result = term;
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}
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else
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{
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result = MakeQuery();
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result->Add(term);
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while(!token.IsEnd())
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{
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term = ParseTerm();
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if(term)
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{
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result->Add(term);
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}
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}
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}
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}
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if(!term)
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{
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delete result;
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result = 0;
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}
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return result;
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}
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//
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// term == word | '"' phrase '"'
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//
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Query *
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SimpleQueryParser::ParseTerm()
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{
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Query *result = 0;
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if(token.IsQuote())
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{
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token.Next();
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result = ParsePhrase();
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if(result)
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{
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if(token.IsQuote())
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{
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token.Next();
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}
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else
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{
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Expected("closing \"");
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delete result;
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result = 0;
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}
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}
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}
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else if(token.IsWord())
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{
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// don't advance token here!
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result = ParseWord();
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}
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else
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{
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Expected("a word or a quoted phrase");
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}
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return result;
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}
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