It's getting close. I'm not 100% sure abouth this method yet...

4 files changed, 211 insertions, 21 deletions

diff --git a/src/lexer.h b/src/lexer.h
index 5847269..e8a17b5 100644
--- a/src/lexer.h
+++ b/src/lexer.h
@@ -19,7 +19,7 @@ namespace Bu
                 Lexer();
                 virtual ~Lexer();
 
-                typedef int32_t TokenType;
+                typedef int TokenType;
 
                 class Token
                 {
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 << "}";
+}
+
diff --git a/src/parser.h b/src/parser.h
index e720e54..5b5d4a8 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -62,7 +62,7 @@ namespace Bu
                         State( Type eType, int iIndex );
                         virtual ~State();
 
-                private:
+                //private:
                         Type eType;
                         int iIndex;
                 };
@@ -76,10 +76,12 @@ namespace Bu
                         virtual ~NonTerminal();
 
                         void addProduction( Production p );
+                        void setCanSkip();
 
-                private:
+//              private:
                         typedef Bu::List<Production> ProductionList;
                         ProductionList lProduction;
+                        bool bCanSkip;
                 };
 
                 int addNonTerminal( const Bu::FString &sName, NonTerminal &nt );
@@ -93,6 +95,10 @@ namespace Bu
                 int getReductionId( const Bu::FString &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;
@@ -109,6 +115,9 @@ namespace Bu
                 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
diff --git a/src/tools/parser.cpp b/src/tools/parser.cpp
index e4fc95f..76d4a72 100644
--- a/src/tools/parser.cpp
+++ b/src/tools/parser.cpp
@@ -157,15 +157,44 @@ void redPrint( Bu::Parser &p )
 {
 }
 
+/* Basic grammer example:
+ *
+ * input: expr '='
+ *      ;
+ *
+ * expr: expr '+' expr
+ *     | '(' expr ')'
+ *     | NUMBER
+ *     ;
+ *
+ * The problem is, that we can't actually make something left hand recursive,
+ * so we break it into two exprs:
+ *
+ * expr': '(' expr ')'
+ *      | NUMBER
+ *      ;
+ *
+ * expr: expr' expr''
+ *     ;
+ *
+ * expr'': '+' expr
+ *       |
+ *       ;
+ *
+ * 5 + 5 + 5 =
+ */
+
 int main( int argc, char *argv[] )
 {
         File fIn( argv[1], File::Read );
 
         Parser p;
 
+        p.addNonTerminal("expr");
+        p.addNonTerminal("expr'");
+        p.addNonTerminal("expr''");
         {
                 Parser::NonTerminal nt;
-                int iSelf = p.addNonTerminal("expr");
                 nt.addProduction(
                         Parser::Production(
                                 Parser::State(
@@ -175,7 +204,7 @@ int main( int argc, char *argv[] )
                                 ).append(
                                 Parser::State(
                                         Parser::State::typeNonTerminal,
-                                        iSelf
+                                        p.getNonTerminalId("expr")
                                         )
                                 ).append(
                                 Parser::State(
@@ -185,9 +214,11 @@ int main( int argc, char *argv[] )
                                 )
                         );
                 nt.addProduction(
-                        Parser::Production()
+                        Parser::Production(
+                                )
                         );
-                p.addNonTerminal( "expr", nt );
+                nt.setCanSkip();
+                p.setNonTerminal("expr''", nt );
         }
         {
                 Parser::NonTerminal nt;
@@ -197,14 +228,26 @@ int main( int argc, char *argv[] )
                                         Parser::State::typeTerminalPush,
                                         tokNumber
                                         )
+                                )
+                        );
+                p.setNonTerminal("expr'", nt );
+        }
+        {
+                Parser::NonTerminal nt;
+                nt.addProduction(
+                        Parser::Production(
+                                Parser::State(
+                                        Parser::State::typeNonTerminal,
+                                        p.getNonTerminalId("expr'")
+                                        )
                                 ).append(
                                 Parser::State(
                                         Parser::State::typeNonTerminal,
-                                        p.getNonTerminalId("expr")
+                                        p.getNonTerminalId("expr''")
                                         )
                                 )
                         );
-                p.addNonTerminal( "expr'", nt );
+                p.setNonTerminal("expr", nt );
         }
         {
                 Parser::NonTerminal nt;
@@ -212,7 +255,7 @@ int main( int argc, char *argv[] )
                         Parser::Production(
                                 Parser::State(
                                         Parser::State::typeNonTerminal,
-                                        p.getNonTerminalId("expr'")
+                                        p.getNonTerminalId("expr")
                                         )
                                 ).append(
                                 Parser::State(