public CallOperator(StandaloneMetric caller, MetricExpression callee)
: base(caller, callee)
{
if (caller == null || callee == null)
{
throw new ArgumentNullException();
}
_caller = caller;
_callee = callee;
}
public static MetricExpression ParseExpression(string expression)
{
var parser = new MetricExpressionParser();
MetricExpression metricExpression = parser.Parse(expression);
if (metricExpression == null)
{
throw new InvalidOperationException(
string.Format(
"Parse expression {0} failed. \nError message: {1}",
expression,
parser.LastErrorMessage));
}
return(metricExpression);
}
public SelectionOperator(MetricExpression host, int fieldIndex)
: base(host)
{
if (fieldIndex < 0)
{
throw new ArgumentException("fieldIndex must not be negative");
}
if (fieldIndex >= host.FieldNames.Length)
{
throw new ArgumentException("fieldIndex is greater than host's total fields");
}
_fieldIndex = fieldIndex;
_fieldNames = new string[1] {
host.FieldNames[fieldIndex]
};
}
public MetricExpression Parse(string expression)
{
// reset status and internal data structures.
Reset();
// parse all tokens out and put it in queue.
Tokenizer _tokenizer = new Tokenizer(expression);
Token token = null;
do
{
if (!_tokenizer.GetNextToken(out token))
{
LastErrorMessage = "Parse token failed: " + _tokenizer.LastErrorMessage;
return(null);
}
if (token != null)
{
_tokens.Enqueue(token);
}
} while (token != null);
// use recursive descending parsing
MetricExpression metric = Parse();
if (metric != null)
{
token = PeekNextToken();
if (token != null)
{
LastErrorMessage = string.Format("Unexpected token {0} left after parsing at {1}", token.Type, token.StartPosition);
return(null);
}
}
return(metric);
}
protected MetricBinaryOperator(MetricExpression operand1, MetricExpression operand2)
{
Operand1 = operand1;
Operand2 = operand2;
}
private MetricExpression Parse()
{
// parse the first part, such as MA[20]
var metric = ParseMetric();
if (metric == null)
{
return(null);
}
// parse the call operation part, such as (MA[20])
MetricExpression callee = null;
var token = PeekNextToken();
if (token != null && token.Type == TokenType.LeftParenthese)
{
GetNextToken();
callee = Parse();
if (callee == null || !Expect(TokenType.RightParenthese, out token))
{
return(null);
}
}
// parse the selection part, such as .DIF
var fieldIndex = -1;
token = PeekNextToken();
if (token != null && token.Type == TokenType.Dot)
{
GetNextToken();
if (!Expect(TokenType.Identifier, out token))
{
return(null);
}
var field = token.Value;
// verify if the selection name is part of metric definition
var metricType = metric.Metric.GetType();
var attribute = metricType.GetCustomAttribute <MetricAttribute>();
if (!attribute.NameToFieldIndexMap.ContainsKey(field))
{
LastErrorMessage = string.Format("{0} is not a valid subfield of metric {1}", field, metricType.Name);
return(null);
}
fieldIndex = attribute.NameToFieldIndexMap[field];
}
MetricExpression retValue = metric;
if (callee != null)
{
retValue = new CallOperator(metric, callee);
}
if (fieldIndex >= 0)
{
retValue = new SelectionOperator(retValue, fieldIndex);
}
return(retValue);
}
protected MetricUnaryOperator(MetricExpression operand)
{
Operand = operand;
}
