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/***************************************************************************
expression.h - Expression parser
-------------------
copyright : (C) 2004 Michal Rudolf <[email protected]>
***************************************************************************/
/***************************************************************************
* *
* 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. *
* *
***************************************************************************/
#ifndef _HAVE_EXPRESSION_H_
#define _HAVE_EXPRESSION_H_
#include <tqstring.h>
#include <tqvaluelist.h>
#include <tqvariant.h>
class Expression
{
public:
Expression();
Expression(const TQString& expr);
/* set string to parse */
Expression& operator=(const TQString& s);
/* calculate value */
TQVariant value(bool* valid = 0);
/* equivalent of setString(s) and value(valid) */
TQVariant value(const TQString& s, bool* valid = 0);
/* equivalent of setString(s) and checking if value(valid) is true */
bool isTrue(const TQString& s, bool* valid = 0);
private:
enum Type {TypeInt, TypeDouble, TypeString};
/* parsing function - top-down approach */
/* parse terminal (number or string) */
TQVariant parseNumber();
/* parse -x expression */
TQVariant parseMinus();
/* parse (x) expression */
TQVariant parseBracket();
/* parse x*y, x/y and x%y expressions */
TQVariant parseMultiply();
/* parse x+y and x-y expressions */
TQVariant parseAdd();
/* parse !x and (equivalent) not x expressions */
TQVariant parseNot();
/* parse x==y, x<=y, x>=y, x<y and x>y expressions */
TQVariant parseComparison();
/* parse x && y, (equivalent) x and y expressions */
TQVariant parseAnd();
/* parse x || y and (equivalent) x or y expressions */
TQVariant parseOr();
/* starting point of parsing - just call first function above */
TQVariant parse();
/* check if we still have next argument */
bool validate();
/* return next argument to parse or null if there is none */
TQString next() const;
/* set error position for future error reporting */
void setError(int pos = -1);
/* compare various types of TQVariant (strings, floats, ints */
int compare(const TQVariant v1, const TQVariant v2) const;
/* return common type for binary operations */
Type commonType(const TQVariant v1, const TQVariant v2) const;
TQValueList<TQVariant> m_parts;
uint m_start;
bool m_error;
uint m_errorPosition;
};
#endif
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