|
public TryMatch ( |
||
| context | ||
| source | ISourceStream | |
| return | Token | |
private void MatchRegularToken()
{
if (_grammar.FlagIsSet(LanguageFlags.EmitLineStartToken))
{
if (Context.Source.Location.Line > Context.PreviousLineStart.Line)
{
Context.CurrentToken = Context.Source.CreateToken(_grammar.LineStartTerminal);
Context.PreviousLineStart = Context.Source.Location;
return;
}
}
//Find matching terminal
// First, try terminals with explicit "first-char" prefixes, selected by current char in source
ComputeCurrentTerminals();
//If we have more than one candidate; let grammar method select
if (Context.CurrentTerminals.Count > 1)
{
_grammar.OnScannerSelectTerminal(Context);
}
MatchTerminals();
//If we don't have a token from terminals, try Grammar's method
if (Context.CurrentToken == null)
{
Context.CurrentToken = _grammar.TryMatch(Context, Context.SourceStream);
}
if (Context.CurrentToken is MultiToken)
{
UnpackMultiToken();
}
}
private bool MatchRegularTerminals()
{
//We need to eject LineStart BEFORE we try to produce a real token; this LineStart token should reach
// the parser, make it change the state and with it to change the set of expected tokens. So when we
// finally move to scan the real token, the expected terminal set is correct.
if (NeedLineStartToken(Context.Source.Location))
{
Context.CurrentToken = Context.Source.CreateToken(_grammar.LineStartTerminal);
Context.PreviousLineStart = Context.Source.Location;
return(true);
}
//Find matching terminal
// First, try terminals with explicit "first-char" prefixes, selected by current char in source
ComputeCurrentTerminals();
//If we have more than one candidate; let grammar method select
if (Context.CurrentTerminals.Count > 1)
{
_grammar.OnScannerSelectTerminal(Context);
}
MatchTerminals();
//If we don't have a token from terminals, try Grammar's method
if (Context.CurrentToken == null)
{
Context.CurrentToken = _grammar.TryMatch(Context, Context.SourceStream);
}
if (Context.CurrentToken is MultiToken)
{
UnpackMultiToken();
}
return(Context.CurrentToken != null);
}//method
