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/* $Id$ */
/*
* Copyright (C) 2006 Richard Braun
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU 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 General Public License for more details.
*
* You should have received a copy of the GNU 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
*/
#ifndef _MTXSYMBOL_H
#define _MTXSYMBOL_H
#include <string>
#include <vector>
#include "mtx.h"
#include "mtxvalue.h"
#include "mtxlanguage.h"
/**
* A structure representing a special name.
*
* Special names are e.g. "about" or "exit". They have a special meaning
* and are associated to a function. They should never be used as variable
* names or normal function names.
*/
struct mtx_special_name
{
/**
* The special name.
*/
const char *name;
/**
* Pointer to a function implementing the action associated to the special
* name.
*/
std::string (*function)(const MtxSymbol *);
};
/**
* A symbol.
*
* Symbols are named or temporary values in the language engine.
* E.g. in the expression "a + 2", both \a a and \a 2 are symbols.
*/
class MtxSymbol
{
private:
/**
* Name of the symbol. An unnamed symbol is considered temporary.
*/
std::string name;
/**
* The value associated to the symbol.
*/
MtxValue *value;
/**
* If true, the symbol is special. I.e. it is created from a special name.
* When a special symbol is returned by the engine, the engine user should
* not display the "name = " string that usually prefixes the string
* representation of the value, so that the output of the commands
* associated to special names is unaltered when displayed.
*
* @see setSpecial()
* @see isSpecial()
*/
bool special;
/**
* Set the special member according to the name of the symbol.
*
* @see special
* @see isSpecial()
*/
void setSpecial();
/**
* Return the index of the struct special_name entry which name matches
* the symbol name. The special member must be true, or this method will
* raise an MtxException exception.
*/
size_t getSpecial() const;
/**
* List of special names and function pointers associated to them.
*/
static struct mtx_special_name special_names[];
protected:
/**
* Address of the MtxLanguage object used to retreive global symbols.
*
* The copy constructor and operator = must not duplicate the content
* of this pointer.
*/
MtxLanguage *language;
public:
/**
* Default constructor.
*
* A symbol created with this constructor is unusable, as it doesn't
* have any link to an MtxLanguage object. The language object is needed
* to get and set named symbols from the global variable namespace of the
* language engine.
*/
MtxSymbol();
/**
* Create a named variable.
*
* The value doesn't always need to be stored in the object itself, as
* it will be retreived from the MtxLanguage object.
*/
MtxSymbol(MtxLanguage *language, const std::string &name);
/**
* Create a temporary object.
*/
MtxSymbol(MtxLanguage *language, const MtxValue &value);
/**
* Create a named symbol with a value.
*/
MtxSymbol(MtxLanguage *language, const std::string &name,
const MtxValue &value);
MtxSymbol(const MtxSymbol &symbol);
virtual ~MtxSymbol();
MtxSymbol & operator=(const MtxSymbol &symbol);
/**
* Return a copy of the symbol.
*
* This method is actually where execution takes place.
*
* @param create if the symbol is a nonexistent named variable, create it
* @param fail_if_special if the symbol is special, raise an exception
*/
virtual MtxSymbol getSymbol(bool create = false,
bool fail_if_special = true) const;
/**
* Return the name of the symbol.
*/
virtual std::string getName() const;
/**
* Set the name of the symbol. The symbol becomes a named variable if it
* was unnamed. It will be registered in the MtxLanguage object when
* getSymbol() is called.
*/
void setName(const std::string &name);
/**
* Return the address of the underlying value associated to the symbol.
*
* This address can be NULL if no value was associated.
*/
virtual MtxValue * getValue() const;
/**
* Return the string representation of the underlying value.
*/
virtual std::string toString() const;
/**
* This method should never be used on a MtxSymbol object.
*
* @see MtxExpression
*/
virtual bool isSilent() const;
/**
* Return the special member.
*
* @see special
* @see setSpecial()
*/
bool isSpecial() const;
/**
* Return the address of the associated MtxLanguage object.
*/
MtxLanguage * getLanguage() const;
};
/*
* Functions associated to special names.
*/
std::string about(const MtxSymbol *symbol);
std::string list(const MtxSymbol *symbol);
std::string quit(const MtxSymbol *symbol);
#endif /* _MTXSYMBOL_H */
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