//This function implements the DFA for th parser's lexer.
//It generates a token which is used by the LALR state
//machine.
private Token LookAheadDFA(LookAheadBuffer lookAheadBuffer)
{
string ch = lookAheadBuffer.LookAhead(1);
if (String.IsNullOrEmpty(ch) || ch[0] == Char.MaxValue)
{
return new Token(egtDataManager.GetFirstSymbolOfType(SymbolType.End), String.Empty)
{
StartPosition = lookAheadBuffer.Position,
EndPosition = lookAheadBuffer.Position
};
}
int currentDFA = 0;
int lookAheadPosition = 1;
//Next byte in the input Stream
int lastAcceptState = -1;
//We have not yet accepted a character string
int lastAcceptPosition = -1;
while (true)
{
bool found = false;
ch = lookAheadBuffer.LookAhead(lookAheadPosition);
if (!String.IsNullOrEmpty(ch))
{
foreach (FAEdge edge in egtDataManager.GetFAState(currentDFA).Edges)
{
//Look for character in the Character Set Table
if (edge.Characters.Contains(ch[0]))
{
int target = edge.Target;
if (egtDataManager.GetFAState(target).Accept != null)
{
lastAcceptState = target;
lastAcceptPosition = lookAheadPosition;
}
currentDFA = target;
lookAheadPosition++;
found = true;
break;
}
}
}
if (!found)
{
Symbol symbol = null;
string data = String.Empty;
// Lexer cannot recognize symbol
if (lastAcceptState == -1)
{
symbol = egtDataManager.GetFirstSymbolOfType(SymbolType.Error);
data = lookAheadBuffer.GetTextFromBuffer(1);
}
else
{
symbol = egtDataManager.GetFAState(lastAcceptState).Accept;
data = lookAheadBuffer.GetTextFromBuffer(lastAcceptPosition);
}
return new Token(symbol, data)
{
StartPosition = lookAheadBuffer.Position
};
}
}
}
//This function implements the DFA for th parser's lexer.
//It generates a token which is used by the LALR state
//machine.
private Token LookAheadDFA(LookAheadBuffer lookAheadBuffer)
{
string ch = lookAheadBuffer.LookAhead(1);
if (String.IsNullOrEmpty(ch) || ch[0] == Char.MaxValue)
{
return(new Token(egtDataManager.GetFirstSymbolOfType(SymbolType.End), String.Empty)
{
StartPosition = lookAheadBuffer.Position,
EndPosition = lookAheadBuffer.Position
});
}
int currentDFA = 0;
int lookAheadPosition = 1;
//Next byte in the input Stream
int lastAcceptState = -1;
//We have not yet accepted a character string
int lastAcceptPosition = -1;
while (true)
{
bool found = false;
ch = lookAheadBuffer.LookAhead(lookAheadPosition);
if (!String.IsNullOrEmpty(ch))
{
foreach (FAEdge edge in egtDataManager.GetFAState(currentDFA).Edges)
{
//Look for character in the Character Set Table
if (edge.Characters.Contains(ch[0]))
{
int target = edge.Target;
if (egtDataManager.GetFAState(target).Accept != null)
{
lastAcceptState = target;
lastAcceptPosition = lookAheadPosition;
}
currentDFA = target;
lookAheadPosition++;
found = true;
break;
}
}
}
if (!found)
{
Symbol symbol = null;
string data = String.Empty;
// Lexer cannot recognize symbol
if (lastAcceptState == -1)
{
symbol = egtDataManager.GetFirstSymbolOfType(SymbolType.Error);
data = lookAheadBuffer.GetTextFromBuffer(1);
}
else
{
symbol = egtDataManager.GetFAState(lastAcceptState).Accept;
data = lookAheadBuffer.GetTextFromBuffer(lastAcceptPosition);
}
return(new Token(symbol, data)
{
StartPosition = lookAheadBuffer.Position
});
}
}
}
