54 lines
1.8 KiB
C
54 lines
1.8 KiB
C
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//------------------------------------------------------------------------------
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// ConstExpr - base class for rules expressions.
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//------------------------------------------------------------------------------
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// Copyright: See the COPYRIGHT file.
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//------------------------------------------------------------------------------
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// Notes: (1)This class basically defines an interface for expressions.
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//------------------------------------------------------------------------------
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// History:
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//
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// 15 Jan 1998 Matthew J. Rutherford, Riverside Technology, inc
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// Created initial version.
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// 20 Feb 1998 MJR Added the verify function.
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// 05 May 1998 MJR Added the copy() function.
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//------------------------------------------------------------------------------
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#ifndef ConstExpr_INCLUDED
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#define ConstExpr_INCLUDED
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#include "Expression.h"
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class ConstExpr : public Expression
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{
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public:
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ConstExpr( char* ); // Create a constant expression.
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~ConstExpr(); // Destroy a constant expression.
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Expression* copy(); // Copy the expression.
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virtual double evaluate( ); // This will evaluate the expression.
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// The integer will receive a flag that
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// tells what the returned string
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// contains (ie. BOOLEAN, VALUE,
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// VARIABLE) so that the calling
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// function can use this information
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// to make some decision.
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char* toString(); // Prints the constant as a string.
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virtual int verify(); // Verifies that the constants do
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// evalutate.
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private:
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void initialize(); // Initializes private data members.
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char _constant[MAXC]; // String to hold constant or
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// variable name.
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double *_value; // The actual value of the constant.
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int _is_local_value, // Flag to tell if the value in
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// _value is allocated locally.
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_is_verified; // Flag that gets set when an expression
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// evaluates successfully.
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};
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#endif
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