|
|
|
|
|
//===== Copyright <EFBFBD> 1996-2006, Valve Corporation, All rights reserved. ======//
|
|
|
|
|
|
//
|
|
|
|
|
|
// Purpose: ExprSimplifier builds a binary tree from an infix expression (in the
|
|
|
|
|
|
// form of a character array).
|
|
|
|
|
|
//
|
|
|
|
|
|
//===========================================================================//
|
|
|
|
|
|
|
|
|
|
|
|
#ifndef EXPREVALUATOR_H
|
|
|
|
|
|
#define EXPREVALUATOR_H
|
|
|
|
|
|
|
|
|
|
|
|
#if defined( _WIN32 )
|
|
|
|
|
|
#pragma once
|
|
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
|
|
static const char OR_OP = '|';
|
|
|
|
|
|
static const char AND_OP = '&';
|
|
|
|
|
|
static const char NOT_OP = '!';
|
|
|
|
|
|
|
|
|
|
|
|
#define MAX_IDENTIFIER_LEN 128
|
|
|
|
|
|
enum Kind {CONDITIONAL, NOT, LITERAL};
|
|
|
|
|
|
|
|
|
|
|
|
struct ExprNode
|
|
|
|
|
|
{
|
|
|
|
|
|
ExprNode *left; // left sub-expression
|
|
|
|
|
|
ExprNode *right; // right sub-expression
|
|
|
|
|
|
Kind kind; // kind of node this is
|
|
|
|
|
|
union
|
|
|
|
|
|
{
|
|
|
|
|
|
char cond; // the conditional
|
|
|
|
|
|
bool value; // the value
|
|
|
|
|
|
} data;
|
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
typedef ExprNode *ExprTree;
|
|
|
|
|
|
|
|
|
|
|
|
// callback to evaluate a $<symbol> during evaluation, return true or false
|
|
|
|
|
|
typedef bool (*GetSymbolProc_t)( const char *pKey );
|
|
|
|
|
|
typedef void (*SyntaxErrorProc_t)( const char *pReason );
|
|
|
|
|
|
|
|
|
|
|
|
class CExpressionEvaluator
|
|
|
|
|
|
{
|
|
|
|
|
|
public:
|
|
|
|
|
|
CExpressionEvaluator();
|
|
|
|
|
|
~CExpressionEvaluator();
|
|
|
|
|
|
bool Evaluate( bool &result, const char *pInfixExpression, GetSymbolProc_t pGetSymbolProc = 0, SyntaxErrorProc_t pSyntaxErrorProc = 0 );
|
|
|
|
|
|
|
|
|
|
|
|
private:
|
|
|
|
|
|
CExpressionEvaluator( CExpressionEvaluator& ); // prevent copy constructor being used
|
|
|
|
|
|
|
|
|
|
|
|
char GetNextToken( void );
|
|
|
|
|
|
void FreeNode( ExprNode *pNode );
|
|
|
|
|
|
ExprNode *AllocateNode( void );
|
|
|
|
|
|
void FreeTree( ExprTree &node );
|
|
|
|
|
|
bool IsConditional( bool &bCondition, const char token );
|
|
|
|
|
|
bool IsNotOp( const char token );
|
|
|
|
|
|
bool IsIdentifierOrConstant( const char token );
|
|
|
|
|
|
bool MakeExprNode( ExprTree &tree, char token, Kind kind, ExprTree left, ExprTree right );
|
|
|
|
|
|
bool MakeFactor( ExprTree &tree );
|
|
|
|
|
|
bool MakeTerm( ExprTree &tree );
|
|
|
|
|
|
bool MakeExpression( ExprTree &tree );
|
|
|
|
|
|
bool BuildExpression( void );
|
|
|
|
|
|
bool SimplifyNode( ExprTree &node );
|
|
|
|
|
|
|
|
|
|
|
|
ExprTree m_ExprTree; // Tree representation of the expression
|
|
|
|
|
|
char m_CurToken; // Current token read from the input expression
|
|
|
|
|
|
const char *m_pExpression; // Array of the expression characters
|
|
|
|
|
|
int m_CurPosition; // Current position in the input expression
|
|
|
|
|
|
char m_Identifier[MAX_IDENTIFIER_LEN]; // Stores the identifier string
|
|
|
|
|
|
GetSymbolProc_t m_pGetSymbolProc;
|
|
|
|
|
|
SyntaxErrorProc_t m_pSyntaxErrorProc;
|
|
|
|
|
|
bool m_bSetup;
|
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
#endif
|
