From fc16fc104a038146c8ab6c2e9fad38e18663a09f Mon Sep 17 00:00:00 2001
From: Mike Buland <eichlan@xagasoft.com>
Date: Tue, 12 Oct 2010 18:10:47 +0000
Subject: It's getting close.  I'm not 100% sure abouth this method yet...

---
 src/parser.cpp | 160 +++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 149 insertions(+), 11 deletions(-)

(limited to 'src/parser.cpp')

diff --git a/src/parser.cpp b/src/parser.cpp
index e8e8ff2..b563691 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -24,21 +24,127 @@ void Bu::Parser::popLexer()
 
 void Bu::Parser::parse()
 {
-	for(;;)
+	int iCurNt = iRootNonTerminal;
+	Lexer::Token *ptCur = sLexer.peek()->nextToken();
+	//Lexer::Token *ptNext = sLexer.peek()->nextToken();
+	selectProduction( iCurNt, ptCur );
+	sio << "Token: " << *ptCur << sio.nl;
+	
+	while( !sState.isEmpty() )
 	{
-		Bu::Lexer::Token *pToken = sLexer.peek()->nextToken();
-		sio << sLexer.peek()->tokenToString( *pToken ) << sio.nl;
-		if( pToken->iToken < 0 )
+		sio << "Currently: " << *sState.peek() << sio.nl;
+		switch( (*sState.peek()).eType )
 		{
-			delete sLexer.peekPop();
-			if( sLexer.isEmpty() )
+			case State::typeTerminal:
+				sio << "terminal: " << ptCur->iToken << " == "
+					<< (*sState.peek()).iIndex << sio.nl;
+				if( ptCur->iToken == (*sState.peek()).iIndex )
+				{
+					advanceState();
+					delete ptCur;
+					ptCur = sLexer.peek()->nextToken();
+					sio << "Token: " << *ptCur << sio.nl;
+				}
+				else
+				{
+					throw Bu::ExceptionBase("Error parsing code.");
+				}
+				break;
+
+			case State::typeTerminalPush:
+				sio << "terminalpush: " << ptCur->iToken << " == "
+					<< (*sState.peek()).iIndex << sio.nl;
+				if( ptCur->iToken == (*sState.peek()).iIndex )
+				{
+					advanceState();
+					sToken.push( ptCur );
+
+					ptCur = sLexer.peek()->nextToken();
+					sio << "Token: " << *ptCur << sio.nl;
+				}
+				else
+				{
+					throw Bu::ExceptionBase("Error parsing code.");
+				}
+				break;
+
+			case State::typeNonTerminal:
+				sio << "nonterminal: " << ptCur->iToken << " --> "
+					<< (*sState.peek()).iIndex << sio.nl;
+				{
+					int iNt = (*sState.peek()).iIndex;
+					advanceState();
+					if( !selectProduction( iNt, ptCur ) )
+					{
+						throw Bu::ExceptionBase("Error parsing code.");
+					}
+				}
+				break;
+
+			case State::typeReduction:
+				sio << "reduction" << sio.nl;
+				aReduction[(*sState.peek()).iIndex]( *this );
+				advanceState();
+				break;
+		}
+	}	
+}
+
+bool Bu::Parser::selectProduction( int iNt, Lexer::Token *ptCur )
+{
+	NonTerminal &nt = aNonTerminal[iNt];
+	int j = 0;
+	for( NonTerminal::ProductionList::iterator i = nt.lProduction.begin();
+		 i; i++,j++ )
+	{
+		if( (*i).isEmpty() )
+			continue;
+		if( (*i).first().eType == State::typeTerminal ||
+			(*i).first().eType == State::typeTerminalPush )
+		{
+			if( (*i).first().iIndex == ptCur->iToken )
 			{
-				delete pToken;
-				return;
+				sState.push( (*i).begin() );
+				sio << "Pushing production " << j << " from nt " << iNt
+					<< sio.nl;
+				return true;
 			}
 		}
-		delete pToken;
-	}	
+		else if( (*i).first().eType == State::typeNonTerminal )
+		{
+			sState.push( (*i).begin() );
+			sio << "Pushing production " << j << " from nt " << iNt
+				<< " as test." << sio.nl;
+			if( !selectProduction( (*i).first().iIndex, ptCur ) )
+			{
+				sState.pop();
+				sio << "Production " << j << " from nt " << iNt
+					<< " didn't work out." << sio.nl;
+			}
+			else
+			{
+				return true;
+			}
+		}
+	}
+	if( nt.bCanSkip )
+		return true;
+	return false;
+}
+
+void Bu::Parser::advanceState()
+{
+	if( sState.isEmpty() )
+		return;
+
+	sState.peek()++;
+	if( !sState.peek() )
+	{
+		sState.pop();
+		sio << "State advanced, End of production." << sio.nl;
+		return;
+	}
+	sio << "State advanced, now: " << *(sState.peek()) << sio.nl;
 }
 
 void Bu::Parser::setRootNonTerminal( int iRoot )
@@ -56,6 +162,7 @@ int Bu::Parser::addNonTerminal( const Bu::FString &sName, NonTerminal &nt )
 	int iId = aNonTerminal.getSize();
 	aNonTerminal.append( nt );
 	hNonTerminalName.insert( sName, iId );
+	sio << "nt '" << sName << "' = " << iId << sio.nl;
 	return iId;
 }
 
@@ -64,6 +171,7 @@ int Bu::Parser::addNonTerminal( const Bu::FString &sName )
 	int iId = aNonTerminal.getSize();
 	aNonTerminal.append( NonTerminal() );
 	hNonTerminalName.insert( sName, iId );
+	sio << "nt '" << sName << "' = " << iId << sio.nl;
 	return iId;
 }
 
@@ -121,7 +229,8 @@ Bu::Parser::State::~State()
 // Bu::Parser::NonTerminal
 //
 
-Bu::Parser::NonTerminal::NonTerminal()
+Bu::Parser::NonTerminal::NonTerminal() :
+	bCanSkip( false )
 {
 }
 
@@ -134,3 +243,32 @@ void Bu::Parser::NonTerminal::addProduction( Production p )
 	lProduction.append( p );
 }
 
+void Bu::Parser::NonTerminal::setCanSkip()
+{
+	bCanSkip = true;
+}
+
+Bu::Formatter &Bu::operator<<( Bu::Formatter &f, Bu::Parser::State::Type t )
+{
+	switch( t )
+	{
+		case Bu::Parser::State::typeTerminal:
+			return f << "typeTerminal";
+
+		case Bu::Parser::State::typeTerminalPush:
+			return f << "typeTerminalPush";
+
+		case Bu::Parser::State::typeNonTerminal:
+			return f << "typeNonTerminal";
+
+		case Bu::Parser::State::typeReduction:
+			return f << "typeReduction";
+	}
+	return f << "***error***";
+}
+
+Bu::Formatter &Bu::operator<<( Bu::Formatter &f, const Bu::Parser::State &s )
+{
+	return f << "{" << s.eType << ": " << s.iIndex << "}";
+}
+
-- 
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