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81 lines
2.8 KiB
81 lines
2.8 KiB
15 years ago
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/***************************************************************************
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expression.h - Expression parser
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-------------------
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copyright : (C) 2004 Michal Rudolf <mrudolf@kdewebdwev.org>
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***************************************************************************/
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/***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************/
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#ifndef _HAVE_EXPRESSION_H_
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#define _HAVE_EXPRESSION_H_
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#include <qstring.h>
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#include <qvaluelist.h>
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#include <qvariant.h>
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class Expression
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{
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public:
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Expression();
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Expression(const QString& expr);
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/* set string to parse */
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Expression& operator=(const QString& s);
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/* calculate value */
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QVariant value(bool* valid = 0);
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/* equivalent of setString(s) and value(valid) */
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QVariant value(const QString& s, bool* valid = 0);
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/* equivalent of setString(s) and checking if value(valid) is true */
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bool isTrue(const QString& s, bool* valid = 0);
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private:
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enum Type {TypeInt, TypeDouble, TypeString};
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/* parsing function - top-down approach */
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/* parse terminal (number or string) */
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QVariant parseNumber();
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/* parse -x expression */
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QVariant parseMinus();
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/* parse (x) expression */
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QVariant parseBracket();
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/* parse x*y, x/y and x%y expressions */
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QVariant parseMultiply();
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/* parse x+y and x-y expressions */
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QVariant parseAdd();
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/* parse !x and (equivalent) not x expressions */
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QVariant parseNot();
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/* parse x==y, x<=y, x>=y, x<y and x>y expressions */
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QVariant parseComparison();
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/* parse x && y, (equivalent) x and y expressions */
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QVariant parseAnd();
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/* parse x || y and (equivalent) x or y expressions */
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QVariant parseOr();
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/* starting point of parsing - just call first function above */
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QVariant parse();
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/* check if we still have next argument */
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bool validate();
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/* return next argument to parse or null if there is none */
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QString next() const;
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/* set error position for future error reporting */
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void setError(int pos = -1);
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/* compare various types of QVariant (strings, floats, ints */
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int compare(const QVariant v1, const QVariant v2) const;
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/* return common type for binary operations */
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Type commonType(const QVariant v1, const QVariant v2) const;
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QValueList<QVariant> m_parts;
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uint m_start;
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bool m_error;
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uint m_errorPosition;
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};
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#endif
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