GOP/GOP_Parser.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * Produced by:
 *      George ElKoura
 *      Side Effects
 *      477 Richmond Street West
 *      Toronto, Ontario
 *      Canada   M5V 3E7
 *      416-504-9876
 *
 *
 * COMMENTS:  This is a general purpose skeleton of a parser.
 *            It has facilities to provide failry straightforward parsing
 *            of a "language".  
 *
 *            To parse a string, just instantiate the derived parser and
 *            call the doIt() method.
 *
 */

#ifndef __GOP_Parser_h__
#define __GOP_Parser_h__

#include "GOP_API.h"
#include <UT/UT_String.h>


// These are the state constants that are common to all parsers.
// Most parsers will probably want to add their own, must be
// careful to number them uniquely.
#define         ST_START        0
#define         ST_ERROR        99


class GOP_API GOP_Parser
{
public:
    GOP_Parser(const UT_String &str); 
    virtual ~GOP_Parser() {}

    // This is the method that the user would call to start the
    // parsing.  The return value can be parser-depenedent.  
    // (e.g. the number of items parsed, an error value, etc...)
    // The return value should be placed in myReturnVal
    virtual int doIt();

protected:
    UT_String           myString;

    
    
    //////////// State Handlers
    virtual void        handleStart() = 0;
    virtual void        handleError() = 0;

    //////////// Utility Methods
    void                startToken();
    void                endToken();

    // Each parser should override this method and use it to 
    // manage state transitions.  Return false if you want the
    // dispatcher to stop (e.g. when an error occurs)
    virtual bool        dispatch(char c) = 0; 

    // Method that loops on the characters of the string and calls dispatch.
    // There should be no need to override this method.
    virtual void        parseDispatcher();

    // Called during the constructor to initialize the state machine
    // before any parsing is done.
    virtual void        init();

    // Called after the parsing is done.
    virtual void        finish();
    
    // Grabs the current token, goes to 'state' and returns true if
    // successful.  Otherwise goes to state ST_ERROR and returns false
    bool                getInt  (int   &retval, unsigned state);
    bool                getFloat(float &retval, unsigned state);

    // Checks if the current token is the character c, (stripping out
    // all leading and trailing spaces
    bool                isChar(char c);

    // We also need to count '\0' as a space
    bool                isSpace(char c) { return (isspace(c) || c == '\0'); }



    //////////// State Variables
    char                *myTokBegin;
    char                *myTokEnd;
    char                *myTokLastGood;
    unsigned             myCurrentState;
    int                  myReturnVal;

    //////////// Utility Variables
    char                myTempChar;
};


#endif

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