private static IExpression ParseInFirstValueState(TokenConsumer tokenConsumer)
{
var valueToken = tokenConsumer.EatToken <ValueToken>();
if (!tokenConsumer.HasNextToken)
{
return(new ExistsExpression(valueToken.Value));
}
var secondToken = tokenConsumer.PeekToken();
switch (secondToken.TokenType)
{
case TokenType.Equal:
return(ParseEqualExpression(tokenConsumer, valueToken));
case TokenType.ExclamationEqual:
return(ParseNotEqualExpression(tokenConsumer, valueToken));
case TokenType.In:
return(ParseInExpression(tokenConsumer, valueToken));
case TokenType.NotIn:
return(ParseNotInExpression(tokenConsumer, valueToken));
case TokenType.Comma:
tokenConsumer.EatToken(TokenType.Comma);
return(new ExistsExpression(valueToken.Value));
default:
throw new ArgumentOutOfRangeException();
}
}
private static IExpression ParseNotExistsExpression(TokenConsumer tokenConsumer)
{
tokenConsumer.EatToken(TokenType.Exclamation);
var valueToken = tokenConsumer.EatToken <ValueToken>();
return(new NotExistsExpression(valueToken.Value));
}
private static IEnumerable <IExpression> Parse(TokenConsumer tokenConsumer)
{
while (tokenConsumer.HasToken)
{
var firstToken = tokenConsumer.PeekToken();
switch (firstToken.TokenType)
{
case TokenType.Value:
yield return(ParseInFirstValueState(tokenConsumer));
break;
case TokenType.Exclamation:
yield return(ParseNotExistsExpression(tokenConsumer));
break;
case TokenType.Comma:
tokenConsumer.EatToken(TokenType.Comma);
break;
default:
throw new Exception($"Not expected token {firstToken.TokenType}");
}
}
}
private static NotEqualExpression ParseNotEqualExpression(TokenConsumer tokenConsumer, ValueToken keyToken)
{
tokenConsumer.EatToken <ExclamationEqualToken>();
var valueToken = tokenConsumer.EatToken <ValueToken>();
return(new NotEqualExpression(
keyToken.Value,
valueToken.Value));
}
private static NotInExpression ParseNotInExpression(TokenConsumer tokenConsumer, ValueToken valueToken)
{
tokenConsumer.EatToken(TokenType.NotIn);
var arraySyntax = ParseArraySyntax(tokenConsumer);
return(new NotInExpression(
valueToken.Value,
arraySyntax.Values.Select(value => value.Value)));
}
private static ArraySyntax ParseArraySyntax(TokenConsumer tokenConsumer)
{
tokenConsumer.EatToken(TokenType.OpenParentheses);
var valueTokens = new List <ValueToken>();
while (true)
{
var valueToken = tokenConsumer.EatToken <ValueToken>();
valueTokens.Add(valueToken);
if (tokenConsumer.PeekToken().TokenType == TokenType.CloseParentheses)
{
break;
}
tokenConsumer.EatToken(TokenType.Comma);
}
tokenConsumer.EatToken(TokenType.CloseParentheses);
return(new ArraySyntax(valueTokens));
}
public static IEnumerable <IExpression> Parse(Token[] tokens)
{
var tokenConsumer = new TokenConsumer(tokens);
return(Parse(tokenConsumer));
}
