/// <summary>
/// Basic error recovery that adds a samicolon if it is possible.
/// </summary>
/// <param name="lexerState">Current parser state.</param>
/// <returns><c>True</c> is semicolon is expected, <c>False</c> otherwise.</returns>
public bool TryRecover(ILexerState lexerState)
{
if (lexerState.IsExpectedToken((int)Tokens.T_SEMI))
{
lexerState.SetToken(0, new CompleteToken(Tokens.T_SEMI, new SemanticValueType(), new Span(lexerState.PreviousToken.TokenPosition.End, 0), ";"));
return(true);
}
return(false);
}
public IEnumerable <IToken> Tokenize(string expression)
{
states_ = new Stack <ILexerState>();
currentState_ = new LiteralLexerState(new CommonState());
characters_ = expression.GetEnumerator();
while (characters_.MoveNext())
{
IToken token = currentState_.Handle(this);
if (token != null)
{
yield return(token);
}
}
}
private Token MakeToken(ILexerState state) =>
state.Token.With(v => v.TypeMatch()
.With(Case.Is <NumberLexerState>(), _ => (Token) new IntegerToken()
{
Value = int.Parse(v.TokenValue.Value)
})
.With(Case.Is <SymbolLexerState>(), _ => v.TokenValue.Match()
.With(_parsers.KeywordParser.Is, _parsers.KeywordParser.Make)
.Else(id => new IdentifierToken {
Identifier = id
})
.Do())
.Else(_ => v.TokenValue.Match()
.With(_parsers.SymbolParser.Is, _parsers.SymbolParser.Make)
.With(_parsers.OperatorParser.Is, _parsers.OperatorParser.Make)
.Do()
)
.Do()
);
public ILexerState CreateTailToken(IForwardReadSequence <char> sequence, ILexerState state, IParserSet parsers) => new InitialLexerState(sequence, (LexerStateBase)state, parsers);
/// <summary> /// Always fails to recover. /// </summary> /// <param name="lexerState">Current parser state.</param> /// <returns>Always <c>False</c>.</returns> public bool TryRecover(ILexerState lexerState) => false;
public void EndState()
{
currentState_ = states_.Pop();
}
public void ToState(ILexerState state)
{
states_.Push(currentState_);
currentState_ = state;
}