Source code of Windows XP (NT5)
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/*++
Copyright (c) 1995 Microsoft Corporation
Module Name:
lexer.hxx
Abstract:
This module implements functions to recognize the tokens in the string
repressentation of the search filter. The format of the search filter
according to the RFC 1960.
Author:
Shankara Shastry [ShankSh] 08-Jul-1996
++*/
#include "nds.hxx"
#pragma hdrstop
DFA_STATE CQryLexer::_pStateTable[MAX_STATES][MAX_CHAR_CLASSES] = gStateTable;
DWORD CQryLexer::_pCharClassTable[] = gCharClassTable;
//+---------------------------------------------------------------------------
// Function: CQryLexer
//
// Synopsis: Constructor: Allocate memory for the pattern and initialize
//
// Arguments: szBuffer: pattern
//
// Returns:
//
// Modifies:
//
// History: 07-09-96 ShankSh Created.
//
//----------------------------------------------------------------------------
CQryLexer::CQryLexer(
LPWSTR szBuffer
):
_ptr(NULL),
_Buffer(NULL),
_dwEndofString(0),
_dwState(ATTRTYPE_START_STATE),
_lexeme()
{
_bInitialized = FALSE;
if (!szBuffer || !*szBuffer) {
return;
}
_Buffer = (LPWSTR) AllocADsMem(
(wcslen(szBuffer)+1) * sizeof(WCHAR)
);
if(_Buffer)
wcscpy(_Buffer,
szBuffer
);
_ptr = _Buffer;
}
//+---------------------------------------------------------------------------
// Function: GetNextToken
//
// Synopsis: Give the next valid token
//
// Arguments:
//
// Returns:
//
// Modifies:
//
// History: 07-09-96 ShankSh Created.
//
//----------------------------------------------------------------------------
HRESULT
CQryLexer::GetNextToken(
LPWSTR *ppszToken,
LPDWORD pdwToken
)
{
WCHAR wcNextChar;
DWORD dwActionId;
DFA_STATE dfaState;
DWORD dwStartState = _dwState;
// If there is no pattern
if(!_ptr) {
*pdwToken = TOKEN_ENDINPUT;
RRETURN (S_OK);
}
// Start forming the lexeme.
_lexeme.ResetLexeme();
*ppszToken = NULL;
*pdwToken = TOKEN_ERROR;
while (_dwState != ERROR_STATE && _dwState < FINAL_STATES_BEGIN) {
// Get the character class from the character and then index the
// state table
wcNextChar = NextChar();
DWORD now = GetCharClass(wcNextChar);
dwActionId = _pStateTable[_dwState][GetCharClass(wcNextChar)].
dwActionId;
_dwState = _pStateTable[_dwState][GetCharClass(wcNextChar)].
dwNextState;
if(_dwState == ERROR_STATE) {
BAIL_ON_FAILURE (E_FAIL);
}
PerformAction(_dwState,
wcNextChar,
dwActionId
);
}
_bInitialized = TRUE;
if(*pdwToken == TOKEN_ENDINPUT)
RRETURN (S_OK);
*ppszToken = _lexeme.GetLexeme();
*pdwToken = GetTokenFromState(_dwState);
_dwStateSave = _dwState;
// This is to set the start state for the next token to be recognized
if(*pdwToken == TOKEN_ATTRTYPE) {
_dwState = ATTRVAL_START_STATE;
}
else if (*pdwToken == TOKEN_ATTRVAL) {
_dwState = ATTRTYPE_START_STATE;
}
else if (*pdwToken == TOKEN_PRESENT) {
_dwState = ATTRTYPE_START_STATE;
} else {
_dwState = dwStartState;
}
RRETURN (S_OK);
error:
RRETURN (E_FAIL);
}
//+---------------------------------------------------------------------------
// Function: GetCurrentToken
//
// Synopsis: Give the current valid token, and do not advance unless
// it is the first token
//
// Arguments:
//
// Returns:
//
// Modifies:
//
// History: 07-09-96 ShankSh Created.
//
//----------------------------------------------------------------------------
HRESULT
CQryLexer::GetCurrentToken(
LPWSTR *ppszToken,
LPDWORD pdwToken
)
{
if (!_bInitialized) {
HRESULT hr;
hr = GetNextToken(
ppszToken,
pdwToken
);
return hr;
} else {
*ppszToken = _lexeme.GetLexeme();
*pdwToken = GetTokenFromState(_dwStateSave);
return (S_OK);
}
}
//+---------------------------------------------------------------------------
// Function: NextChar
//
// Synopsis: Returns the next chaarcter in the pattern
//
// Arguments:
//
// Returns:
//
// Modifies:
//
// History: 07-09-96 ShankSh Created.
//
//----------------------------------------------------------------------------
WCHAR
CQryLexer::NextChar()
{
if (_ptr == NULL || *_ptr == L'\0') {
_dwEndofString = TRUE;
return(L'\0');
}
return(*_ptr++);
}
//+---------------------------------------------------------------------------
// Function: PushbackChar
//
// Synopsis: Puts back a character to the unrecognised pattern
//
// Arguments:
//
// Returns:
//
// Modifies:
//
// History: 07-09-96 ShankSh Created.
//
//----------------------------------------------------------------------------
void
CQryLexer::PushbackChar()
{
if (_dwEndofString) {
return;
}
_ptr--;
}
HRESULT
CQryLexer::PerformAction(
DWORD dwCurrState,
WCHAR wcCurrChar,
DWORD dwActionId
)
{
switch(dwActionId) {
case ACTION_PUSHBACK_CHAR:
PushbackChar();
break;
case ACTION_PUSHBACK_2CHAR:
PushbackChar();
PushbackChar();
_lexeme.PushBackChar();
break;
case ACTION_IGNORE_ESCAPECHAR:
break;
case ACTION_DEFAULT:
_lexeme.PushNextChar(wcCurrChar);
break;
}
if(_dwState >= FINAL_STATES_BEGIN)
_lexeme.PushNextChar(L'\0');
RRETURN (S_OK);
}
//+---------------------------------------------------------------------------
// Function: CQryLexer::GetTokenFromState
//
// Synopsis:
//
// Arguments:
//
// Returns:
//
// Modifies:
//
// History: 07-09-96 ShankSh Created.
//
//----------------------------------------------------------------------------
inline DWORD
CQryLexer::GetTokenFromState(
DWORD dwCurrState
)
{
return (dwCurrState - FINAL_STATES_BEGIN);
}
//+---------------------------------------------------------------------------
// Function: ~CQryLexer
//
// Synopsis:
//
// Arguments:
//
// Returns:
//
// Modifies:
//
// History: 07-09-96 ShankSh Created.
//
//----------------------------------------------------------------------------
CQryLexer::~CQryLexer()
{
if( _Buffer )
FreeADsMem (_Buffer);
}
//+---------------------------------------------------------------------------
// Function: CLexeme
//
// Synopsis: Constructor: Allocate memory for the pattern and initialize
//
// Arguments:
//
// Returns:
//
// Modifies:
//
// History: 07-09-96 ShankSh Created.
//
//----------------------------------------------------------------------------
CLexeme::CLexeme(
):
_dwMaxLength(0),
_dwIndex(0)
{
_pszLexeme = (LPWSTR) AllocADsMem(LEXEME_UNIT_LENGTH * sizeof(WCHAR));
if(_pszLexeme)
_dwMaxLength = LEXEME_UNIT_LENGTH;
}
//+---------------------------------------------------------------------------
// Function: ~CLexeme
//
// Synopsis: Destructor
//
// Arguments:
//
// Returns:
//
// Modifies:
//
// History: 07-09-96 ShankSh Created.
//
//----------------------------------------------------------------------------
inline CLexeme::~CLexeme(
)
{
if(_pszLexeme)
FreeADsMem(_pszLexeme);
}
//+---------------------------------------------------------------------------
// Function: PushNextChar
//
// Synopsis: Add the next character after making sure there is enough memory
//
// Arguments:
//
// Returns:
//
// Modifies:
//
// History: 07-09-96 ShankSh Created.
//
//----------------------------------------------------------------------------
HRESULT
CLexeme::PushNextChar(
WCHAR wcNextChar
)
{
if(_dwIndex >= _dwMaxLength)
{
_pszLexeme = (LPWSTR) ReallocADsMem(
_pszLexeme,
_dwMaxLength * sizeof(WCHAR),
(_dwMaxLength + LEXEME_UNIT_LENGTH) * sizeof(WCHAR)
);
BAIL_ON_NULL(_pszLexeme);
_dwMaxLength += LEXEME_UNIT_LENGTH;
}
_pszLexeme[_dwIndex++] = wcNextChar;
RRETURN (S_OK);
error:
RRETURN (E_FAIL);
}
HRESULT
CLexeme::PushBackChar()
{
_pszLexeme[--_dwIndex] = '\0';
RRETURN (S_OK);
}
//+---------------------------------------------------------------------------
//
// Function: RemoveWhiteSpaces
//
// Synopsis: Removes the leading and trailing white spaces
//
// Arguments: pszText Text strings from which the leading
// and trailing white spaces are to be
// removed
//
// Returns: LPWSTR Pointer to the modified string
//
// Modifies:
//
// History: 08-15-96 ShankSh Created.
//
//----------------------------------------------------------------------------
LPWSTR
RemoveWhiteSpaces(
LPWSTR pszText)
{
LPWSTR pChar;
if(!pszText)
return (pszText);
while(*pszText && iswspace(*pszText))
pszText++;
for(pChar = pszText + wcslen(pszText) - 1; pChar >= pszText; pChar--) {
if(!iswspace(*pChar))
break;
else
*pChar = L'\0';
}
return pszText;
}