1 files changed, 74 insertions, 0 deletions
diff --git a/external/vpc/public/tier1/exprevaluator.h b/external/vpc/public/tier1/exprevaluator.h
new file mode 100644
index 0000000..89dffc6
--- /dev/null
+++ b/external/vpc/public/tier1/exprevaluator.h
@@ -0,0 +1,74 @@
+//===== Copyright � 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