private static FormatException GenerateFilterParseException(MetricFilterExpressionToken encountered, MetricFilterExpressionToken.TokenType expected)
{
return(new FormatException(
string.Format(CultureInfo.InvariantCulture, "Failed to parse expression. Expected {0} token (encountered {1}).", expected, encountered)));
}
// Parse filter clause (or parenthesized expression) corresponds to F -> ID EQ VALUE | (E)
private static MetricFilterExpressionTree ParseFilterClause(MetricFilterExpressionTokenizer tokenizer)
{
if (tokenizer == null || tokenizer.IsEmpty)
{
throw GenerateFilterParseException(null, MetricFilterExpressionToken.TokenType.Identifier);
}
MetricFilterExpressionToken token = tokenizer.Current;
switch (token.Type)
{
case MetricFilterExpressionToken.TokenType.Identifier: // F -> ID EQ VALUE
// validate and store the parameter name
FilterParameter parameter = ParseParameter(token.Value);
// Consume name
tokenizer.Advance();
// Verify and comsume EQ
if (tokenizer.IsEmpty || tokenizer.Current.Type != MetricFilterExpressionToken.TokenType.EqOperator)
{
throw GenerateFilterParseException(tokenizer.Current, MetricFilterExpressionToken.TokenType.EqOperator);
}
tokenizer.Advance();
MetricFilterExpressionToken.TokenType expectedType = GetExpectedTokenTypeForParameter(parameter);
// Verify, store, and consume value
if (tokenizer.IsEmpty || tokenizer.Current.Type != expectedType)
{
throw GenerateFilterParseException(tokenizer.Current, expectedType);
}
string value = tokenizer.Current.Value;
tokenizer.Advance();
return(new MetricFilterExpressionTree()
{
Value = new KeyValuePair <FilterParameter, string>(ParseParameter(token.Value), value)
});
case MetricFilterExpressionToken.TokenType.OpenParen: // F -> (E)
// Consume (
tokenizer.Advance();
// Match Expression
MetricFilterExpressionTree node = ParseFilterExpression(tokenizer);
// Verify and consume )
if (tokenizer.IsEmpty || tokenizer.Current.Type != MetricFilterExpressionToken.TokenType.CloseParen)
{
throw GenerateFilterParseException(tokenizer.Current, MetricFilterExpressionToken.TokenType.CloseParen);
}
tokenizer.Advance();
return(node);
default:
throw GenerateFilterParseException(token, MetricFilterExpressionToken.TokenType.Identifier);
}
}
