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/*
* Copyright (C) 2007-2023 Xagasoft, All rights reserved.
*
* This file is part of the libbu++ library and is released under the
* terms of the license contained in the file LICENSE.
*/
#ifndef BU_PARSER_H
#define BU_PARSER_H
#include "bu/string.h"
#include "bu/list.h"
#include "bu/array.h"
#include "bu/hash.h"
#include "bu/signals.h"
#include "bu/lexer.h"
namespace Bu
{
/**
* The base framework for a LR(1) grammar parser. Provided a proper set of
* ParserStates this will prase any input the lexer can provide.
*/
class Parser
{
public:
Parser();
virtual ~Parser();
/**
* When a Lexer is pushed onto the stack it becomes the source for
* future tokens read by the parser until it is popped off the stack.
* The Parser takes ownership of every Lexer pushed onto the stack,
* and will delete it when it is popped off the stack.
*/
void pushLexer( Lexer *pLex );
/**
* Pop a lexer off the stack, and delete it.
*/
void popLexer();
Lexer::Token *popToken();
void pushToken( Lexer::Token *pTok );
/**
* Execute a parse.
*/
void parse();
void setRootNonTerminal( int iRoot );
void setRootNonTerminal( const Bu::String &sRoot );
typedef Bu::Signal1<void, Parser &> Reduction;
/**
* Represents a possible state, either a terminal or non-terminal symbol
* in a Production.
*/
class State
{
public:
enum Type
{
typeTerminal,
typeTerminalPush,
typeNonTerminal,
typeReduction
};
State( Type eType, int iIndex );
virtual ~State();
//private:
Type eType;
int iIndex;
};
typedef Bu::List<State> Production;
class NonTerminal
{
public:
NonTerminal();
virtual ~NonTerminal();
void addProduction( Production p );
void setCanSkip();
// private:
typedef Bu::List<Production> ProductionList;
ProductionList lProduction;
bool bCanSkip;
};
int addNonTerminal( const Bu::String &sName, NonTerminal &nt );
int addNonTerminal( const Bu::String &sName );
void setNonTerminal( const Bu::String &sName, NonTerminal &nt );
int getNonTerminalId( const Bu::String &sName );
bool hasNonTerminal( const Bu::String &sName );
int addReduction( const Bu::String &sName, const Reduction &r );
int addReduction( const Bu::String &sName );
void setReduction( const Bu::String &sName, const Reduction &r );
int getReductionId( const Bu::String &sName );
bool hasReduction( const Bu::String &sName );
private:
bool selectProduction( int iNt, Lexer::Token *ptCur );
void advanceState();
private:
typedef Bu::List<Lexer *> LexerStack;
typedef Bu::List<Lexer::Token *> TokenStack;
typedef Bu::List<Production::const_iterator> StateStack;
typedef Bu::Array<Reduction> ReductionArray;
typedef Bu::Hash<Bu::String,int> NameIndexHash;
typedef Bu::Array<NonTerminal> NonTerminalArray;
LexerStack sLexer;
TokenStack sToken;
StateStack sState;
ReductionArray aReduction;
NameIndexHash hReductionName;
NonTerminalArray aNonTerminal;
NameIndexHash hNonTerminalName;
int iRootNonTerminal;
};
Bu::Formatter &operator<<( Bu::Formatter &f, Bu::Parser::State::Type t );
Bu::Formatter &operator<<( Bu::Formatter &f, const Bu::Parser::State &s );
};
#endif
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