public override Maybe <Token> NextToken()
{
do
{
Maybe <Token> t_ = Lexer.NextToken();
redo:
if (!t_.HasValue)
{
break;
}
var t = t_.Value;
if (t.IsWhitespace)
{
AddWSToken(t);
continue;
}
else if (t.Kind == TokenKind.Other)
{
switch (t.Type())
{
case TokenType.PPdefine:
case TokenType.PPundef:
ReadRest(_rest);
bool undef = t.Type() == TokenType.PPundef;
if (_rest.Count == 1 && _rest[0].Type() == TokenType.Id)
{
if (undef)
{
DefinedSymbols.Remove((Symbol)_rest[0].Value);
}
else
{
DefinedSymbols.Add((Symbol)_rest[0].Value);
}
}
else
{
ErrorSink.Error(t.ToSourceRange(SourceFile), "'{0}' should be followed by a single, simple identifier", undef ? "#undef" : "#define");
}
continue;
case TokenType.PPif:
var tree = ReadRestAsTokenTree();
LNode expr = ParseExpr(tree);
var cond = Evaluate(expr) ?? false;
_ifRegions.Push(Pair.Create(t, cond));
t_ = SaveDirectiveAndAutoSkip(t, cond);
goto redo;
case TokenType.PPelse:
case TokenType.PPelif:
var tree_ = ReadRestAsTokenTree();
if (_ifRegions.Count == 0)
{
ErrorSink.Error(t.ToSourceRange(SourceFile),
"Missing #if clause before '{0}'", t);
_ifRegions.Push(Pair.Create(t, false));
}
bool isElif = t.Type() == TokenType.PPelif, hasExpr = tree_.HasIndex(0);
if (hasExpr != isElif)
{
Error(t, isElif ? "Missing condition on #elif" : "Unexpected tokens after #else");
}
bool cond_ = true;
if (hasExpr)
{
LNode expr_ = ParseExpr(tree_);
cond_ = Evaluate(expr_) ?? false;
}
if (_ifRegions.Peek().B)
{
cond_ = false;
}
t_ = SaveDirectiveAndAutoSkip(t, cond_);
if (cond_)
{
_ifRegions.Push(Pair.Create(_ifRegions.Pop().A, cond_));
}
goto redo;
case TokenType.PPendif:
var tree__ = ReadRestAsTokenTree();
if (_ifRegions.Count == 0)
{
Error(t, "Missing #if before #endif");
}
else
{
_ifRegions.Pop();
if (tree__.Count > 0)
{
Error(t, "Unexpected tokens after #endif");
}
}
_triviaList.Add(t);
continue;
case TokenType.PPerror:
_triviaList.Add(t);
Error(t, t.Value.ToString());
continue;
case TokenType.PPwarning:
_triviaList.Add(t);
ErrorSink.Warning(t.ToSourceRange(SourceFile), t.Value.ToString());
continue;
case TokenType.PPregion:
_triviaList.Add(t);
_regions.Push(t);
continue;
case TokenType.PPendregion:
_triviaList.Add(t);
if (_regions.Count == 0)
{
ErrorSink.Warning(t.ToSourceRange(SourceFile), "#endregion without matching #region");
}
else
{
_regions.Pop();
}
continue;
case TokenType.PPline:
_triviaList.Add(new Token(t.TypeInt, t.StartIndex, Lexer.InputPosition));
var rest = ReadRestAsTokenTree();
// TODO: use LineRemapper
ErrorSink.Write(Severity.Note, t.ToSourceRange(SourceFile), "Support for #line is not implemented");
continue;
case TokenType.PPpragma:
_triviaList.Add(new Token(t.TypeInt, t.StartIndex, Lexer.InputPosition));
var rest_ = ReadRestAsTokenTree();
// TODO
ErrorSink.Write(Severity.Note, t.ToSourceRange(SourceFile), "Support for #pragma is not implemented");
continue;
}
}
return(t_);
} while (true);
// end of stream
if (_ifRegions.Count > 0)
{
ErrorSink.Error(_ifRegions.Peek().A.ToSourceRange(SourceFile), "#if without matching #endif");
}
if (_regions.Count > 0)
{
ErrorSink.Warning(_regions.Peek().ToSourceRange(SourceFile), "#region without matching #endregion");
}
return(Maybe <Token> .NoValue);
}