private bool Advance(TokenType type, out ParseException failure)
{
Validate.NonNull(type, nameof(type));
if (this.CurrentToken.Type != type)
{
failure = ParseException.UnexpectedCharactersError(this.CurrentToken.ToString());
return(false);
}
else
{
this.pos++;
failure = null;
return(true);
}
}
private bool Atom(out object success, out ParseException failure)
{
if (this.CurrentToken.Type == TokenType.Number)
{
NumberToken tok = this.CurrentToken as NumberToken;
if (!this.Advance(TokenType.Number, out failure))
{
success = null;
return(false);
}
else
{
success = new DoubleMeasurement(tok.Value);
failure = null;
return(true);
}
}
else if (this.CurrentToken.Type == TokenType.Id)
{
IdToken tok = this.CurrentToken as IdToken;
if (!this.Advance(TokenType.Id, out failure))
{
success = null;
return(false);
}
else
{
if (this.Units.ContainsKey(tok.StringValue))
{
success = this.Units[tok.StringValue];
return(true);
}
else
{
success = null;
failure = ParseException.UndefinedUnitDiscovered(tok.StringValue);
return(false);
}
}
}
else if (this.CurrentToken.Type == TokenType.OpenParen)
{
if (!this.Advance(TokenType.OpenParen, out failure))
{
success = null;
return(false);
}
else if (!this.AddExpression(out success, out failure))
{
return(false);
}
else if (!this.Advance(TokenType.CloseParen, out failure))
{
return(false);
}
else
{
return(true);
}
}
else if (this.CurrentToken.Type == TokenType.OpenBracket)
{
if (!this.Advance(TokenType.OpenBracket, out failure))
{
success = null;
return(false);
}
else if (!this.AddExpression(out success, out failure))
{
return(false);
}
else if (!this.Advance(TokenType.CloseBracket, out failure))
{
return(false);
}
else
{
return(true);
}
}
else if (this.CurrentToken.Type == TokenType.Plus || this.CurrentToken.Type == TokenType.Minus)
{
if (!this.Advance(this.CurrentToken.Type, out failure))
{
success = null;
return(false);
}
else if (!this.AddExpression(out success, out failure))
{
return(false);
}
else
{
return(Evaluation.ApplyUrnaryOperator(
this.AllOperators,
this.CurrentToken.Type == TokenType.Plus ? UrnaryOperatorType.Positation : UrnaryOperatorType.Negation,
success,
out success,
out failure
));
}
}
else
{
success = null;
failure = ParseException.UnexpectedCharactersError(this.CurrentToken.StringValue);
return(false);
}
}
