//***************************************************************************
//
//   (c) 2000-2001 by Microsoft Corp. All Rights Reserved.
//
//   like.h
//
//   a-davcoo     28-Feb-00       Implements the SQL like operation.
//
//***************************************************************************

#ifndef _LIKE_H_
#define _LIKE_H_


#include <string.h>

//
// The CLike class implements the SQL "like" operation.  To compare test 
// strings to an expression, construct an instance of the CLike class using 
// the expression and an optional escape character.  Then use the Match() 
// method on that instance to test each string.  Note, this class makes it's
// own copy of the expression used to construct it.  This implementation 
// supports the '%' and '_' wildard characters as well as the [] and [^] 
// constructs for matching sets of characters and ranges of characters.
//
class POLARITY CLike
{
public:
    CLike() : m_expression(NULL) {} 
    CLike( LPCWSTR expression, WCHAR escape='\0' );
    CLike( const CLike& rOther ) : m_expression(NULL) { *this = rOther; }
    CLike& operator= ( const CLike& rOther );
    ~CLike();
    
    bool Match (LPCWSTR string);
    LPCWSTR GetExpression() { return m_expression; }
    void SetExpression( LPCWSTR string, WCHAR escape='\0' );

protected:
    LPWSTR m_expression;
    WCHAR m_escape;
    
    // Recursive function and helpers for performing like operation.
    bool DoLike (LPCWSTR pattern, LPCWSTR string, WCHAR escape);
    bool MatchSet (LPCWSTR pattern, LPCWSTR string, int &skip);
};


#endif // _LIKE_H_