Source code of Windows XP (NT5)
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/*++
Copyright (c) 1999-2001 Microsoft Corporation, All Rights Reserved
Module Name:
GENLEX.H
Abstract:
Generic lexer framework classes.
History:
--*/
#ifndef _GENLEX_H_
#define _GENLEX_H_
#include <Polarity.h>
class CGenLexSource
{
public:
virtual wchar_t NextChar() = 0;
// Return 0 on end-of-input
virtual void Pushback(wchar_t) = 0;
virtual void Reset() = 0;
};
class CTextLexSource : public CGenLexSource
{
const wchar_t *m_pSrcBuf;
const wchar_t *m_pStart;
public:
CTextLexSource(const wchar_t *pSrc) { SetString(pSrc); }
// Binds directly to <pSrc> buffer, but doesn't delete it.
wchar_t NextChar()
{
if (!m_pSrcBuf)
return 0;
else
return *m_pSrcBuf++ ? m_pSrcBuf[-1] : 0;
}
void Pushback(wchar_t)
{
if (m_pSrcBuf)
--m_pSrcBuf;
}
void Reset() { m_pSrcBuf = m_pStart; }
void SetString (const wchar_t *pSrc) { m_pSrcBuf = m_pStart = pSrc; }
};
#pragma pack(2)
struct LexEl
{
wchar_t cFirst, cLast;
WORD wGotoState;
WORD wReturnTok;
WORD wInstructions;
};
#pragma pack()
// Lexer driver instructions
#define GLEX_ACCEPT 0x1 // Add the char to the token
#define GLEX_CONSUME 0x2 // Consume the char without adding to token
#define GLEX_PUSHBACK 0x4 // Place the char back in the source buffer for next token
#define GLEX_NOT 0x8 // A match occurs if the char is NOT the one specified
#define GLEX_LINEFEED 0x10 // Increase the source linecount
#define GLEX_RETURN 0x20 // Return the indicated token to caller
#define GLEX_ANY wchar_t(0xFFFF) // Any character
#define GLEX_EMPTY wchar_t(0xFFFE) // When subrange is not specified
class CGenLexer
{
wchar_t *m_pTokenBuf;
int m_nCurrentLine;
int m_nCurBufSize;
CGenLexSource *m_pSrc;
LexEl *m_pTable;
public:
CGenLexer(LexEl *pTbl, CGenLexSource *pSrc);
~CGenLexer();
int NextToken();
// Returns 0 on end of input.
wchar_t* GetTokenText() { return m_pTokenBuf; }
int GetLineNum() { return m_nCurrentLine; }
void Reset();
};
#endif