source: downloads/RenderSystems/GL/src/atifs/src/Compiler2Pass.cpp @ 5

/*
-----------------------------------------------------------------------------
This source file is part of OGRE
(Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2006 Torus Knot Software Ltd
Also see acknowledgements in Readme.html

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA, or go to
http://www.gnu.org/copyleft/lesser.txt.

You may alternatively use this source under the terms of a specific version of
the OGRE Unrestricted License provided you have obtained such a license from
Torus Knot Software Ltd.
-----------------------------------------------------------------------------
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "Compiler2Pass.h"

Compiler2Pass::Compiler2Pass()
{
        // reserve some memory space in the containers being used
        mTokenInstructions.reserve(100);
        mConstants.reserve(80);
        // default contexts allows all contexts
        // subclass should change it to fit the language being compiled
        mActiveContexts = 0xffffffff;

}



void Compiler2Pass::InitSymbolTypeLib()
{
        uint token_ID;
        // find a default text for all Symbol Types in library

        // scan through all the rules and initialize TypeLib with index to text and index to rules for non-terminal tokens
        for(int i = 0; i < mRulePathLibCnt; i++) {
                token_ID = mRootRulePath[i].mTokenID;
                // make sure SymbolTypeLib holds valid token
                assert(mSymbolTypeLib[token_ID].mID == token_ID);
                switch(mRootRulePath[i].mOperation) {
                        case otRULE:
                                // if operation is a rule then update typelib
                                mSymbolTypeLib[token_ID].mRuleID = i;

                        case otAND:
                        case otOR:
                        case otOPTIONAL:
                                // update text index in typelib
                                if (mRootRulePath[i].mSymbol != NULL) mSymbolTypeLib[token_ID].mDefTextID = i;
                                break;
                }
        }

}


bool Compiler2Pass::compile(const char* source)
{
        bool Passed = false;

        mSource = source;
        // start compiling if there is a rule base to work with
        if(mRootRulePath != NULL) {
                 Passed = doPass1();

                if(Passed) {
                        Passed = doPass2();
                }
        }
        return Passed;
}


bool Compiler2Pass::doPass1()
{
        // scan through Source string and build a token list using TokenInstructions
        // this is a simple brute force lexical scanner/analyzer that also parses the formed
        // token for proper semantics and context in one pass

        mCurrentLine = 1;
        mCharPos = 0;
        // reset position in Constants container
        mConstants.clear();
        mEndOfSource = strlen(mSource);

        // start with a clean slate
        mTokenInstructions.clear();
        // tokenize and check semantics untill an error occurs or end of source is reached
        // assume RootRulePath has pointer to rules so start at index + 1 for first rule path
        // first rule token would be a rule definition so skip over it
        bool passed = processRulePath(0);
        // if a symbol in source still exists then the end of source was not reached and there was a problem some where
        if (positionToNextSymbol()) passed = false;
        return passed;

}


bool Compiler2Pass::processRulePath( uint rulepathIDX)
{
        // rule path determines what tokens and therefore what symbols are acceptable from the source
        // it is assumed that the tokens with the longest similar symbols are arranged first so
        // if a match is found it is accepted and no further searching is done

        // record position of last token in container
        // to be used as the rollback position if a valid token is not found
        uint TokenContainerOldSize = mTokenInstructions.size();
        int OldCharPos = mCharPos;
        int OldLinePos = mCurrentLine;
        uint OldConstantsSize = mConstants.size();

        // keep track of what non-terminal token activated the rule
        uint ActiveNTTRule = mRootRulePath[rulepathIDX].mTokenID;
        // start rule path at next position for definition
        rulepathIDX++;

        // assume the rule will pass
        bool Passed = true;
        bool EndFound = false;

        // keep following rulepath until the end is reached
        while (EndFound == false) {
                switch (mRootRulePath[rulepathIDX].mOperation) {

                        case otAND:
                                // only validate if the previous rule passed
                                if(Passed) Passed = ValidateToken(rulepathIDX, ActiveNTTRule); 
                                break;

                        case otOR:
                                // only validate if the previous rule failed
                                if ( Passed == false ) {
                                        // clear previous tokens from entry and try again
                                        mTokenInstructions.resize(TokenContainerOldSize);
                                        Passed = ValidateToken(rulepathIDX, ActiveNTTRule);
                                }
                                else { // path passed up to this point therefore finished so pretend end marker found
                                        EndFound = true;
                                }
                                break;

                        case otOPTIONAL:
                                // if previous passed then try this rule but it does not effect succes of rule since its optional
                                if(Passed) ValidateToken(rulepathIDX, ActiveNTTRule); 
                                break;

                        case otREPEAT:
                                // repeat until no tokens of this type found 
                                // at least one must be found
                                if(Passed) {
                                        int TokensPassed = 0;
                                        // keep calling until failure
                                        while ( Passed = ValidateToken(rulepathIDX, ActiveNTTRule)) {
                                                // increment count for previous passed token
                                                TokensPassed++;
                                        }
                                        // defaults to Passed = fail
                                        // if at least one token found then return passed = true
                                        if (TokensPassed > 0) Passed = true;
                                }
                                break;

                        case otEND:
                                // end of rule found so time to return
                                EndFound = true;
                                if(Passed == false) {
                                        // the rule did not validate so get rid of tokens decoded
                                        // roll back the token container end position to what it was when rule started
                                        // this will get rid of all tokens that had been pushed on the container while
                                        // trying to validating this rule
                                        mTokenInstructions.resize(TokenContainerOldSize);
                                        mConstants.resize(OldConstantsSize);
                                        mCharPos = OldCharPos;
                                        mCurrentLine = OldLinePos;
                                }
                                break;

                        default:
                                // an exception should be raised since the code should never get here
                                Passed = false;
                                EndFound = true;
                                break;

                }


                // move on to the next rule in the path
                rulepathIDX++;
        }

        return Passed;

}


bool Compiler2Pass::ValidateToken(const uint rulepathIDX, const uint activeRuleID)
{
        int tokenlength = 0;
        // assume the test is going to fail
        bool Passed = false;
        uint TokenID = mRootRulePath[rulepathIDX].mTokenID;
        // only validate token if context is correct
        if (mSymbolTypeLib[TokenID].mContextKey & mActiveContexts) {
        
                // if terminal token then compare text of symbol with what is in source
                if ( mSymbolTypeLib[TokenID].mRuleID == 0){

                        if (positionToNextSymbol()) {
                                // if Token is supposed to be a number then check if its a numerical constant
                                if (TokenID == mValueID) {
                                        float constantvalue;
                                        if(Passed = isFloatValue(constantvalue, tokenlength)) {
                                                mConstants.push_back(constantvalue);
                                        }
                                        
                                }
                                // compare token symbol text with source text
                                else Passed = isSymbol(mRootRulePath[rulepathIDX].mSymbol, tokenlength);
                                        
                                if(Passed) {
                                        TokenInst newtoken;
                                        // push token onto end of container
                                        newtoken.mID = TokenID;
                                        newtoken.mNTTRuleID = activeRuleID;
                                        newtoken.mLine = mCurrentLine;
                                        newtoken.mPos = mCharPos;

                                        mTokenInstructions.push_back(newtoken);
                                        // update source position
                                        mCharPos += tokenlength;

                                        // allow token instruction to change the ActiveContexts
                                        // use token contexts pattern to clear ActiveContexts pattern bits
                                        mActiveContexts &= ~mSymbolTypeLib[TokenID].mContextPatternClear;
                                        // use token contexts pattern to set ActiveContexts pattern bits
                                        mActiveContexts |= mSymbolTypeLib[TokenID].mContextPatternSet;
                                }
                        }

                }
                // else a non terminal token was found
                else {

                        // execute rule for non-terminal
                        // get rule_ID for index into  rulepath to be called
                        Passed = processRulePath(mSymbolTypeLib[TokenID].mRuleID);
                }
        }


        return Passed;

}


char* Compiler2Pass::getTypeDefText(const uint sid)
{
        return mRootRulePath[mSymbolTypeLib[sid].mDefTextID].mSymbol;
}


bool Compiler2Pass::isFloatValue(float& fvalue, int& charsize)
{
        // check to see if it is a numeric float value
        bool valuefound = false;

        const char* startptr = mSource + mCharPos;
        char* endptr = NULL;

        fvalue = (float)strtod(startptr, &endptr);
        // if a valid float was found then endptr will have the pointer to the first invalid character
        if(endptr) {
                if(endptr>startptr) {
                        // a valid value was found so process it
                        charsize = endptr - startptr;
                        valuefound = true;
                }
        }

        return valuefound;
}


bool Compiler2Pass::isSymbol(const char* symbol, int& symbolsize)
{
        // compare text at source+charpos with the symbol : limit testing to symbolsize
        bool symbolfound = false;
        symbolsize = strlen(symbol);
        if(strncmp(mSource + mCharPos, symbol, symbolsize)==0) {
                symbolfound = true;
        }

        return symbolfound;
}


bool Compiler2Pass::positionToNextSymbol()
{
        bool validsymbolfound = false;
        bool endofsource = false;
        while(!validsymbolfound && !endofsource) {
                skipWhiteSpace();
                skipEOL();
                skipComments();
                // have we reached the end of the string?
                if (mCharPos == mEndOfSource) endofsource = true;
                else {
                        // if ASCII > space then assume valid character is found
                        if (mSource[mCharPos] > ' ') validsymbolfound = true;
                }
        }// end of while

        return validsymbolfound;
}



void Compiler2Pass::skipComments()
{
  // if current char and next are // then search for EOL
        if(mCharPos < mEndOfSource) {
                if( ((mSource[mCharPos] == '/') && (mSource[mCharPos + 1] == '/')) ||
                        (mSource[mCharPos] == ';') ||
                        (mSource[mCharPos] == '#') ) findEOL();
        }
}


void Compiler2Pass::findEOL()
{
        // find eol charter and move to this position
        const char* newpos = strchr(&mSource[mCharPos], '\n');
        if(newpos) {
                mCharPos += newpos - &mSource[mCharPos];
        }
        // couldn't find end of line so skip to the end
        else mCharPos = mEndOfSource - 1;

}


void Compiler2Pass::skipEOL()
{
        if ((mSource[mCharPos] == '\n') || (mSource[mCharPos] == '\r')) {
                mCurrentLine++;
                mCharPos++;
                if ((mSource[mCharPos] == '\n') || (mSource[mCharPos] == '\r')) {
                        mCharPos++;
                }
        }
}


void Compiler2Pass::skipWhiteSpace()
{
        // FIX - this method kinda slow
        while((mSource[mCharPos] == ' ') || (mSource[mCharPos] == '\t')) mCharPos++; // find first non white space character
}