// Parse Filter Term (conjunction) corresponds to T -> F AND T | F
private static MetricFilterExpressionTree ParseFilterTerm(MetricFilterExpressionTokenizer tokenizer)
{
// Match Clause
MetricFilterExpressionTree node = ParseFilterClause(tokenizer);
// T -> F
if (tokenizer.IsEmpty)
{
return(node);
}
if (tokenizer.Current.Type == MetricFilterExpressionToken.TokenType.AndOperator)
{
// Consume AND
tokenizer.Advance();
// T -> F AND T
return(new MetricFilterExpressionTree()
{
IsConjunction = true,
LeftExpression = node,
RightExpression = ParseFilterTerm(tokenizer)
});
}
return(node);
}
// Parse Filter Expression (disjunction) corresponds to E -> T OR E | T
private static MetricFilterExpressionTree ParseFilterExpression(MetricFilterExpressionTokenizer tokenizer)
{
MetricFilterExpressionTree node = ParseFilterTerm(tokenizer);
// E -> T
if (tokenizer.IsEmpty)
{
return(node);
}
if (tokenizer.Current.Type == MetricFilterExpressionToken.TokenType.OrOperator)
{
// Consume OR
tokenizer.Advance();
// E -> T OR E
return(new MetricFilterExpressionTree()
{
IsConjunction = false,
LeftExpression = node,
RightExpression = ParseFilterExpression(tokenizer)
});
}
return(node);
}
// 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);
}
}
// 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 =
parameter == FilterParameter.TimeGrain ? MetricFilterExpressionToken.TokenType.DurationValue :
parameter == FilterParameter.Name ? MetricFilterExpressionToken.TokenType.StringValue :
MetricFilterExpressionToken.TokenType.DateTimeOffsetValue;
// 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);
}
}
// Parse Filter Term (conjunction) corresponds to T -> F AND T | F
private static MetricFilterExpressionTree ParseFilterTerm(MetricFilterExpressionTokenizer tokenizer)
{
// Match Clause
MetricFilterExpressionTree node = ParseFilterClause(tokenizer);
// T -> F
if (tokenizer.IsEmpty)
{
return node;
}
if (tokenizer.Current.Type == MetricFilterExpressionToken.TokenType.AndOperator)
{
// Consume AND
tokenizer.Advance();
// T -> F AND T
return new MetricFilterExpressionTree()
{
IsConjunction = true,
LeftExpression = node,
RightExpression = ParseFilterTerm(tokenizer)
};
}
return node;
}
// Parse Filter Expression (disjunction) corresponds to E -> T OR E | T
private static MetricFilterExpressionTree ParseFilterExpression(MetricFilterExpressionTokenizer tokenizer)
{
MetricFilterExpressionTree node = ParseFilterTerm(tokenizer);
// E -> T
if (tokenizer.IsEmpty)
{
return node;
}
if (tokenizer.Current.Type == MetricFilterExpressionToken.TokenType.OrOperator)
{
// Consume OR
tokenizer.Advance();
// E -> T OR E
return new MetricFilterExpressionTree()
{
IsConjunction = false,
LeftExpression = node,
RightExpression = ParseFilterExpression(tokenizer)
};
}
return node;
}