private bool MatchComplexSegment(TemplateSegment routeSegment,
string requestSegment,
IDictionary <string, object> defaults,
RouteValueDictionary values)
{
Contract.Assert(routeSegment != null);
Contract.Assert(routeSegment.Parts.Count > 1);
// Find last literal segment and get its last index in the string
var lastIndex = requestSegment.Length;
var indexOfLastSegmentUsed = routeSegment.Parts.Count - 1;
TemplatePart parameterNeedsValue = null; // Keeps track of a parameter segment that is pending a value
TemplatePart lastLiteral = null; // Keeps track of the left-most literal we've encountered
while (indexOfLastSegmentUsed >= 0)
{
var newLastIndex = lastIndex;
var part = routeSegment.Parts[indexOfLastSegmentUsed];
if (part.IsParameter)
{
// Hold on to the parameter so that we can fill it in when we locate the next literal
parameterNeedsValue = part;
}
else
{
Contract.Assert(part.IsLiteral);
lastLiteral = part;
var startIndex = lastIndex - 1;
// If we have a pending parameter subsegment, we must leave at least one character for that
if (parameterNeedsValue != null)
{
startIndex--;
}
if (startIndex < 0)
{
return(false);
}
var indexOfLiteral = requestSegment.LastIndexOf(part.Text,
startIndex,
StringComparison.OrdinalIgnoreCase);
if (indexOfLiteral == -1)
{
// If we couldn't find this literal index, this segment cannot match
return(false);
}
// If the first subsegment is a literal, it must match at the right-most extent of the request URI.
// Without this check if your route had "/Foo/" we'd match the request URI "/somethingFoo/".
// This check is related to the check we do at the very end of this function.
if (indexOfLastSegmentUsed == (routeSegment.Parts.Count - 1))
{
if ((indexOfLiteral + part.Text.Length) != requestSegment.Length)
{
return(false);
}
}
newLastIndex = indexOfLiteral;
}
if ((parameterNeedsValue != null) &&
(((lastLiteral != null) && (part.IsLiteral)) || (indexOfLastSegmentUsed == 0)))
{
// If we have a pending parameter that needs a value, grab that value
int parameterStartIndex;
int parameterTextLength;
if (lastLiteral == null)
{
if (indexOfLastSegmentUsed == 0)
{
parameterStartIndex = 0;
}
else
{
parameterStartIndex = newLastIndex;
Contract.Assert(false, "indexOfLastSegementUsed should always be 0 from the check above");
}
parameterTextLength = lastIndex;
}
else
{
// If we're getting a value for a parameter that is somewhere in the middle of the segment
if ((indexOfLastSegmentUsed == 0) && (part.IsParameter))
{
parameterStartIndex = 0;
parameterTextLength = lastIndex;
}
else
{
parameterStartIndex = newLastIndex + lastLiteral.Text.Length;
parameterTextLength = lastIndex - parameterStartIndex;
}
}
var parameterValueString = requestSegment.Substring(parameterStartIndex, parameterTextLength);
if (string.IsNullOrEmpty(parameterValueString))
{
// If we're here that means we have a segment that contains multiple sub-segments.
// For these segments all parameters must have non-empty values. If the parameter
// has an empty value it's not a match.
return(false);
}
else
{
// If there's a value in the segment for this parameter, use the subsegment value
values.Add(parameterNeedsValue.Name, parameterValueString);
}
parameterNeedsValue = null;
lastLiteral = null;
}
lastIndex = newLastIndex;
indexOfLastSegmentUsed--;
}
// If the last subsegment is a parameter, it's OK that we didn't parse all the way to the left extent of
// the string since the parameter will have consumed all the remaining text anyway. If the last subsegment
// is a literal then we *must* have consumed the entire text in that literal. Otherwise we end up matching
// the route "Foo" to the request URI "somethingFoo". Thus we have to check that we parsed the *entire*
// request URI in order for it to be a match.
// This check is related to the check we do earlier in this function for LiteralSubsegments.
return((lastIndex == 0) || routeSegment.Parts[0].IsParameter);
}
private static bool ParseLiteral(TemplateParserContext context, TemplateSegment segment)
{
context.Mark();
string encoded;
while (true)
{
if (context.Current == Separator)
{
encoded = context.Capture();
context.Back();
break;
}
else if (context.Current == OpenBrace)
{
if (!context.Next())
{
// This is a dangling open-brace, which is not allowed
context.Error = Resources.TemplateRoute_MismatchedParameter;
return(false);
}
if (context.Current == OpenBrace)
{
// This is an 'escaped' brace in a literal, like "{{foo" - keep going.
}
else
{
// We've just seen the start of a parameter, so back up and return
context.Back();
encoded = context.Capture();
context.Back();
break;
}
}
else if (context.Current == CloseBrace)
{
if (!context.Next())
{
// This is a dangling close-brace, which is not allowed
context.Error = Resources.TemplateRoute_MismatchedParameter;
return(false);
}
if (context.Current == CloseBrace)
{
// This is an 'escaped' brace in a literal, like "{{foo" - keep going.
}
else
{
// This is an unbalanced close-brace, which is not allowed
context.Error = Resources.TemplateRoute_MismatchedParameter;
return(false);
}
}
if (!context.Next())
{
encoded = context.Capture();
break;
}
}
var decoded = encoded.Replace("}}", "}").Replace("{{", "}");
if (IsValidLiteral(context, decoded))
{
segment.Parts.Add(TemplatePart.CreateLiteral(decoded));
return(true);
}
else
{
return(false);
}
}