/// <summary>
/// Advance
/// returns true on successful advance
/// and false on an erroneous token
///
/// Doesn't return error until the bogus input is encountered.
/// Advance() returns true even after EndOfInput is encountered.
/// </summary>
internal bool Advance()
{
if (errorState)
{
return(false);
}
if (lookahead?.IsToken(Token.TokenType.EndOfInput) == true)
{
return(true);
}
SkipWhiteSpace();
// Update error position after skipping whitespace
errorPosition = parsePoint + 1;
if (parsePoint >= expression.Length)
{
lookahead = new Token(Token.TokenType.EndOfInput, null /* end of input */);
}
else
{
switch (expression[parsePoint])
{
case ',':
lookahead = new Token(Token.TokenType.Comma, comma);
parsePoint++;
break;
case '(':
lookahead = new Token(Token.TokenType.LeftParenthesis, leftParenthesis);
parsePoint++;
break;
case ')':
lookahead = new Token(Token.TokenType.RightParenthesis, rightParenthesis);
parsePoint++;
break;
case '$':
if (!ParseProperty())
{
return(false);
}
break;
case '%':
// If the caller specified that he DOESN'T want to allow item metadata ...
if ((this.options & ParserOptions.AllowItemMetadata) == 0)
{
errorPosition = this.parsePoint;
errorState = true;
errorResource = "UnexpectedCharacterInCondition";
unexpectedlyFound = "%";
return(false);
}
if (!ParseItemMetadata())
{
return(false);
}
break;
case '@':
int start = this.parsePoint;
// If the caller specified that he DOESN'T want to allow item lists ...
if ((this.options & ParserOptions.AllowItemLists) == 0)
{
if ((parsePoint + 1) < expression.Length && expression[parsePoint + 1] == '(')
{
errorPosition = start + 1;
errorState = true;
errorResource = "ItemListNotAllowedInThisConditional";
return(false);
}
}
if (!ParseItemList())
{
return(false);
}
break;
case '!':
// negation and not-equal
if ((parsePoint + 1) < expression.Length && expression[parsePoint + 1] == '=')
{
lookahead = new Token(Token.TokenType.NotEqualTo, notEqualTo);
parsePoint += 2;
}
else
{
lookahead = new Token(Token.TokenType.Not, not);
parsePoint++;
}
break;
case '>':
// gt and gte
if ((parsePoint + 1) < expression.Length && expression[parsePoint + 1] == '=')
{
lookahead = new Token(Token.TokenType.GreaterThanOrEqualTo, greaterThanOrEqualTo);
parsePoint += 2;
}
else
{
lookahead = new Token(Token.TokenType.GreaterThan, greaterThan);
parsePoint++;
}
break;
case '<':
// lt and lte
if ((parsePoint + 1) < expression.Length && expression[parsePoint + 1] == '=')
{
lookahead = new Token(Token.TokenType.LessThanOrEqualTo, lessThanOrEqualTo);
parsePoint += 2;
}
else
{
lookahead = new Token(Token.TokenType.LessThan, lessThan);
parsePoint++;
}
break;
case '=':
if ((parsePoint + 1) < expression.Length && expression[parsePoint + 1] == '=')
{
lookahead = new Token(Token.TokenType.EqualTo, equalTo);
parsePoint += 2;
}
else
{
errorPosition = parsePoint + 2; // expression[parsePoint + 1], counting from 1
errorResource = "IllFormedEqualsInCondition";
if ((parsePoint + 1) < expression.Length)
{
// store the char we found instead
unexpectedlyFound = Convert.ToString(expression[parsePoint + 1], CultureInfo.InvariantCulture);
}
else
{
unexpectedlyFound = EndOfInput;
}
parsePoint++;
errorState = true;
return(false);
}
break;
case '\'':
if (!ParseQuotedString())
{
return(false);
}
break;
default:
// Simple strings, function calls, decimal numbers, hex numbers
if (!ParseRemaining())
{
return(false);
}
break;
}
}
return(true);
}
internal bool IsNext(Token.TokenType type)
{
return(lookahead.IsToken(type));
}