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