private TerminalToken SkipAfterCommentEnd()
{
int commentDepth = 1;
TerminalToken token = null;
while (commentDepth > 0)
{
token = tokenizer.RetrieveToken();
if (token.Symbol is SymbolCommentEnd)
{
commentDepth--;
}
else if (token.Symbol is SymbolCommentStart)
{
commentDepth++;
}
else if (token.Symbol is SymbolEnd)
{
FireEOFError();
break;
}
}
if (commentDepth == 0)
{
return(token);
}
else
{
return(null);
}
}
private bool ProcessCommentStart(TerminalToken token)
{
if (OnCommentRead == null)
{
return(SkipAfterCommentEnd() != null);
}
else
{
Location start = this.tokenizer.GetCurrentLocation();
TerminalToken commentEnd = SkipAfterCommentEnd();
bool result = commentEnd != null;
if (result)
{
Location end = this.tokenizer.GetCurrentLocation();
string str = this.tokenizer.GetInput();
int len = end.Position - start.Position;
string comment = str.Substring(start.Position, len - commentEnd.Text.Length);
CommentReadEventArgs args = new CommentReadEventArgs(token.Text + comment,
comment,
false);
OnCommentRead(this, args);
}
return(result);
}
}
private TerminalToken GetLookahead()
{
if (lookahead != null)
{
return(lookahead);
}
do
{
TerminalToken token = tokenizer.RetrieveToken();
if (token.Symbol is SymbolCommentLine)
{
if (!ProcessCommentLine(token))
{
continueParsing = false;
}
}
else if (token.Symbol is SymbolCommentStart)
{
if (!ProcessCommentStart(token))
{
continueParsing = false;
}
}
else if (token.Symbol is SymbolWhiteSpace)
{
if (!ProcessWhiteSpace(token))
{
continueParsing = false;
}
}
else if (token.Symbol is SymbolError)
{
if (!ProcessError(token))
{
continueParsing = false;
}
}
else
{
lookahead = token;
}
if (!continueParsing)
{
break;
}
} while (lookahead == null);
if ((lookahead != null) && (OnTokenRead != null))
{
TokenReadEventArgs args = new TokenReadEventArgs(lookahead);
OnTokenRead(this, args);
if (args.Continue == false)
{
continueParsing = false;
lookahead = null;
}
}
return(lookahead);
}
public ParseErrorEventArgs(TerminalToken unexpectedToken,
SymbolCollection expectedTokens)
{
this.unexpectedToken = unexpectedToken;
this.expectedTokens = expectedTokens;
this.contin = ContinueMode.Stop;
this.nextToken = null;
}
private void FireEOFError()
{
TerminalToken eofToken = new TerminalToken(SymbolCollection.EOF,
SymbolCollection.EOF.Name,
tokenizer.GetCurrentLocation());
FireParseError(eofToken);
}
private void Reset()
{
stateStack = new StateStack();
stateStack.Push(startState);
tokenStack = new TokenStack();
lookahead = null;
continueParsing = true;
accepted = false;
}
private void DoShift(TerminalToken token, ShiftAction action)
{
stateStack.Push(action.State);
tokenStack.Push(token);
lookahead = null;
if (OnShift != null)
{
OnShift(this, new ShiftEventArgs(token, action.State));
}
}
private bool ProcessError(TerminalToken token)
{
if (OnTokenError != null)
{
TokenErrorEventArgs e = new TokenErrorEventArgs(token);
OnTokenError(this, e);
return(e.Continue);
}
else
{
return(false);
}
}
private void FireParseError(TerminalToken token)
{
if (OnParseError != null)
{
ParseErrorEventArgs e =
new ParseErrorEventArgs(token, FindExpectedTokens());
OnParseError(this, e);
continueParsing = e.Continue != ContinueMode.Stop;
lookahead = e.NextToken;
if ((e.NextToken != null) && (e.Continue == ContinueMode.Insert))
{
tokenizer.SetCurrentLocation(token.Location);
}
}
}
/// <summary>
/// Parse the input with tokens and rules.
/// </summary>
/// <param name="input">The source input</param>
/// <returns>The nonterminal token that the input has been reduced to.
/// Null if the parse has failed.</returns>
public NonterminalToken Parse(String input)
{
Reset();
tokenizer.SetInput(input);
while (continueParsing)
{
TerminalToken token = GetLookahead();
if (token != null)
{
ParseTerminal(token);
}
}
if (accepted)
{
return((NonterminalToken)tokenStack.Pop());
}
else
{
return(null);
}
}
private bool ProcessCommentLine(TerminalToken token)
{
if (OnCommentRead == null)
{
return(SkipToEndOfLine());
}
else
{
Location start = this.tokenizer.GetCurrentLocation();
bool result = SkipToEndOfLine();
if (result)
{
Location end = this.tokenizer.GetCurrentLocation();
string str = this.tokenizer.GetInput();
int len = end.Position - start.Position;
string comment = str.Substring(start.Position, len);
CommentReadEventArgs args = new CommentReadEventArgs(token.Text + comment,
comment,
true);
OnCommentRead(this, args);
}
return(result);
}
}
private void ParseTerminal(TerminalToken token)
{
State currentState = stateStack.Peek();
Action action = currentState.Actions.Get(token.Symbol);
if (action is ShiftAction)
{
DoShift(token, (ShiftAction)action);
}
else if (action is ReduceAction)
{
DoReduce(token, (ReduceAction)action);
}
else if (action is AcceptAction)
{
DoAccept(token, (AcceptAction)action);
}
else
{
continueParsing = false;
FireParseError(token);
}
}
public ShiftEventArgs(TerminalToken token, State newState)
{
this.token = token;
this.newState = newState;
}
public TokenErrorEventArgs(TerminalToken token)
{
this.token = token;
this.contin = false;
}
public TokenReadEventArgs(TerminalToken token)
{
this.token = token;
contin = true;
}
