parser.cpp

C Preprocessor,antlr的grammar语言描述,用于学习词法分析,语法分析

/* ANTLR Translator Generator
 * Project led by Terence Parr at http://www.jGuru.com
 * Software rights: http://www.antlr.org/RIGHTS.html
 *
 * $Id: //depot/code/org.antlr/main/main/lib/cpp/src/Parser.cpp#4 $
 */
/* 1999-2007 Version 3.2 November 2007
 *
 * Optional version
 *
 * Modified by David Wigg at London South Bank University for CPP_parser.g
 * to provide extra output in stderr in reportError for recognitionExceptions
 * to guarantee display in DOS window
 *
 * See MyReadMe.txt for further information
 *
 * This file is best viewed in courier font with tabs set to 4 spaces
 */

#include "antlr/Parser.hpp"

#include "antlr/BitSet.hpp"
#include "antlr/TokenBuffer.hpp"
#include "antlr/MismatchedTokenException.hpp"
//#include "antlr/ASTFactory.hpp"
#include <iostream>

#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
namespace antlr {
#endif
ANTLR_C_USING(exit)

/**A generic ANTLR parser (LL(k) for k>=1) containing a bunch of
 * utility routines useful at any lookahead depth.  We distinguish between
 * the LL(1) and LL(k) parsers because of efficiency.  This may not be
 * necessary in the near future.
 *
 * Each parser object contains the state of the parse including a lookahead
 * cache (the form of which is determined by the subclass), whether or
 * not the parser is in guess mode, where tokens come from, etc...
 *
 * <p>
 * During <b>guess</b> mode, the current lookahead token(s) and token type(s)
 * cache must be saved because the token stream may not have been informed
 * to save the token (via <tt>mark</tt>) before the <tt>try</tt> block.
 * Guessing is started by:
 * <ol>
 * <li>saving the lookahead cache.
 * <li>marking the current position in the TokenBuffer.
 * <li>increasing the guessing level.
 * </ol>
 *
 * After guessing, the parser state is restored by:
 * <ol>
 * <li>restoring the lookahead cache.
 * <li>rewinding the TokenBuffer.
 * <li>decreasing the guessing level.
 * </ol>
 *
 * @see antlr.Token
 * @see antlr.TokenBuffer
 * @see antlr.TokenStream
 * @see antlr.LL1Parser
 * @see antlr.LLkParser
 */

bool DEBUG_PARSER=false;

Parser::Parser(TokenBuffer& input)
: inputState(new ParserInputState(input)), astFactory(0), traceDepth(0)
{
}

Parser::Parser(TokenBuffer* input)
: inputState(new ParserInputState(input)), astFactory(0), traceDepth(0)
{
}

Parser::Parser(const ParserSharedInputState& state)
: inputState(state), astFactory(0), traceDepth(0)
{
}

Parser::~Parser()
{
}

/** Consume tokens until one matches the given token */
void Parser::consumeUntil(int tokenType)
{
	while (LA(1) != Token::EOF_TYPE && LA(1) != tokenType)
		consume();
}

/** Consume tokens until one matches the given token set */
void Parser::consumeUntil(const BitSet& set)
{
	while (LA(1) != Token::EOF_TYPE && !set.member(LA(1)))
		consume();
}

/**Make sure current lookahead symbol matches token type <tt>t</tt>.
 * Throw an exception upon mismatch, which is catch by either the
 * error handler or by the syntactic predicate.
 */
void Parser::match(int t)
{	
	if ( DEBUG_PARSER )
	{
		traceIndent();
		ANTLR_USE_NAMESPACE(std)cout << "enter match(" << t << ") with LA(1)=" << LA(1) << ANTLR_USE_NAMESPACE(std)endl;
	}
	if ( LA(1)!=t ) {
		if ( DEBUG_PARSER )
		{
			traceIndent();
			ANTLR_USE_NAMESPACE(std)cout << "token mismatch: " << LA(1) << "!=" << t << ANTLR_USE_NAMESPACE(std)endl;
		}
		throw MismatchedTokenException(getTokenNames(), getNumTokens(), LT(1), t, false, getFilename());
	} else {
		// mark token as consumed -- fetch next token deferred until LA/LT
		consume();
	}
}

/**Make sure current lookahead symbol matches the given set
 * Throw an exception upon mismatch, which is catch by either the
 * error handler or by the syntactic predicate.
 */
void Parser::match(const BitSet& b)
{
	if ( DEBUG_PARSER )
	{
		traceIndent();
		ANTLR_USE_NAMESPACE(std)cout << "enter match(" << "bitset" /*b.toString()*/
			  << ") with LA(1)=" << LA(1) << ANTLR_USE_NAMESPACE(std)endl;
	}
	if ( !b.member(LA(1)) ) {
		if ( DEBUG_PARSER )
		{
			traceIndent();
			ANTLR_USE_NAMESPACE(std)cout << "token mismatch: " << LA(1) << " not member of "
				  << "bitset" /*b.toString()*/ << ANTLR_USE_NAMESPACE(std)endl;
		}
		throw MismatchedTokenException(getTokenNames(), getNumTokens(), LT(1), b, false, getFilename());
	} else {
		// mark token as consumed -- fetch next token deferred until LA/LT
		consume();
	}
}

void Parser::matchNot(int t)
{
	if ( LA(1)==t ) {
		// Throws inverted-sense exception
		throw MismatchedTokenException(getTokenNames(), getNumTokens(), LT(1), t, true, getFilename());
	} else {
		// mark token as consumed -- fetch next token deferred until LA/LT
		consume();
	}
}

void Parser::panic()
{
	ANTLR_USE_NAMESPACE(std)cerr << "Parser: panic" << ANTLR_USE_NAMESPACE(std)endl;
	exit(1);
}

/** Parser error-reporting function can be overridden in subclass */
void Parser::reportError(const RecognitionException& ex)
{
	// DW 060204 Amended to indicate error in DOS window
	ANTLR_USE_NAMESPACE(std)cerr << "cerr " << ex.toString().c_str() << ANTLR_USE_NAMESPACE(std)endl;
	// DW 060204 Inserted to show position of condition in trace output
	ANTLR_USE_NAMESPACE(std)cout << "cout " << ex.toString().c_str() << ANTLR_USE_NAMESPACE(std)endl;
}

/** Parser error-reporting function can be overridden in subclass */
void Parser::reportError(const ANTLR_USE_NAMESPACE(std)string& s)
{
	if ( getFilename()=="" )
		ANTLR_USE_NAMESPACE(std)cerr << "error: " << s.c_str() << ANTLR_USE_NAMESPACE(std)endl;
	else
		ANTLR_USE_NAMESPACE(std)cerr << getFilename().c_str() << ": error: " << s.c_str() << ANTLR_USE_NAMESPACE(std)endl;
}

/** Parser warning-reporting function can be overridden in subclass */
void Parser::reportWarning(const ANTLR_USE_NAMESPACE(std)string& s)
{
	if ( getFilename()=="" )
		ANTLR_USE_NAMESPACE(std)cerr << "warning: " << s.c_str() << ANTLR_USE_NAMESPACE(std)endl;
	else
		ANTLR_USE_NAMESPACE(std)cerr << getFilename().c_str() << ": warning: " << s.c_str() << ANTLR_USE_NAMESPACE(std)endl;
}

/** Set or change the input token buffer */
//	void setTokenBuffer(TokenBuffer<Token>* t);

void Parser::traceIndent()
{
	for( int i = 0; i < traceDepth; i++ )
		ANTLR_USE_NAMESPACE(std)cout << " ";
}

void Parser::traceIn(const char* rname)
{
	traceDepth++;

	for( int i = 0; i < traceDepth; i++ )
		ANTLR_USE_NAMESPACE(std)cout << " ";

	ANTLR_USE_NAMESPACE(std)cout << "> " << rname
		<< "; LA(1)==" << LT(1)->getText().c_str()
		<<	((inputState->guessing>0)?" [guessing]":"")
		<< ANTLR_USE_NAMESPACE(std)endl;
}

void Parser::traceOut(const char* rname)
{
	for( int i = 0; i < traceDepth; i++ )
		ANTLR_USE_NAMESPACE(std)cout << " ";

	ANTLR_USE_NAMESPACE(std)cout << "< " << rname
		<< "; LA(1)==" << LT(1)->getText().c_str()
		<<	((inputState->guessing>0)?" [guessing]":"")
		<< ANTLR_USE_NAMESPACE(std)endl;

	traceDepth--;
}

#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
}
#endif