private bool MatchComplexSegment(
TemplateSegment routeSegment,
string requestSegment,
IReadOnlyDictionary <string, object> defaults,
RouteValueDictionary values)
{
var indexOfLastSegment = routeSegment.Parts.Count - 1;
// We match the request to the template starting at the rightmost parameter
// If the last segment of template is optional, then request can match the
// template with or without the last parameter. So we start with regular matching,
// but if it doesn't match, we start with next to last parameter. Example:
// Template: {p1}/{p2}.{p3?}. If the request is one/two.three it will match right away
// giving p3 value of three. But if the request is one/two, we start matching from the
// rightmost giving p3 the value of two, then we end up not matching the segment.
// In this case we start again from p2 to match the request and we succeed giving
// the value two to p2
if (routeSegment.Parts[indexOfLastSegment].IsOptional &&
routeSegment.Parts[indexOfLastSegment - 1].IsOptionalSeperator)
{
if (MatchComplexSegmentCore(routeSegment, requestSegment, Defaults, values, indexOfLastSegment))
{
return(true);
}
else
{
if (requestSegment.EndsWith(
routeSegment.Parts[indexOfLastSegment - 1].Text,
StringComparison.OrdinalIgnoreCase))
{
return(false);
}
return(MatchComplexSegmentCore(
routeSegment,
requestSegment,
Defaults,
values,
indexOfLastSegment - 2));
}
}
else
{
return(MatchComplexSegmentCore(routeSegment, requestSegment, Defaults, values, indexOfLastSegment));
}
}
private static bool ParseSegment(TemplateParserContext context, List <TemplateSegment> segments)
{
Debug.Assert(context != null);
Debug.Assert(segments != null);
var segment = new TemplateSegment();
while (true)
{
if (context.Current == OpenBrace)
{
if (!context.Next())
{
// This is a dangling open-brace, which is not allowed
context.Error = "context does not have next";
return(false);
}
if (context.Current == OpenBrace)
{
// This is an 'escaped' brace in a literal, like "{{foo"
context.Back();
if (!ParseLiteral(context, segment))
{
return(false);
}
}
else
{
// This is the inside of a parameter
if (!ParseParameter(context, segment))
{
return(false);
}
}
}
else if (context.Current == Separator)
{
// We've reached the end of the segment
break;
}
else
{
if (!ParseLiteral(context, segment))
{
return(false);
}
}
if (!context.Next())
{
// We've reached the end of the string
break;
}
}
if (IsSegmentValid(context, segment))
{
segments.Add(segment);
return(true);
}
else
{
return(false);
}
}
private static bool IsSegmentValid(TemplateParserContext context, TemplateSegment segment)
{
// If a segment has multiple parts, then it can't contain a catch all.
for (var i = 0; i < segment.Parts.Count; i++)
{
var part = segment.Parts[i];
if (part.IsParameter && part.IsCatchAll && segment.Parts.Count > 1)
{
context.Error = Resources.TemplateRoute_CannotHaveCatchAllInMultiSegment;
return(false);
}
}
// if a segment has multiple parts, then only the last one parameter can be optional
// if it is following a optional seperator.
for (var i = 0; i < segment.Parts.Count; i++)
{
var part = segment.Parts[i];
if (part.IsParameter && part.IsOptional && segment.Parts.Count > 1)
{
// This optional parameter is the last part in the segment
if (i == segment.Parts.Count - 1)
{
if (!segment.Parts[i - 1].IsLiteral)
{
// The optional parameter is preceded by something that is not a literal.
// Example of error message:
// "In the segment '{RouteValue}{param?}', the optional parameter 'param' is preceded
// by an invalid segment '{RouteValue}'. Only a period (.) can precede an optional parameter.
context.Error = string.Format(
Resources.TemplateRoute_OptionalParameterCanbBePrecededByPeriod,
segment.DebuggerToString(),
part.Name,
segment.Parts[i - 1].DebuggerToString());
return(false);
}
else if (segment.Parts[i - 1].Text != PeriodString)
{
// The optional parameter is preceded by a literal other than period.
// Example of error message:
// "In the segment '{RouteValue}-{param?}', the optional parameter 'param' is preceded
// by an invalid segment '-'. Only a period (.) can precede an optional parameter.
context.Error = string.Format(
Resources.TemplateRoute_OptionalParameterCanbBePrecededByPeriod,
segment.DebuggerToString(),
part.Name,
segment.Parts[i - 1].Text);
return(false);
}
segment.Parts[i - 1].IsOptionalSeperator = true;
}
else
{
// This optional parameter is not the last one in the segment
// Example:
// An optional parameter must be at the end of the segment.In the segment '{RouteValue?})',
// optional parameter 'RouteValue' is followed by ')'
var nextPart = segment.Parts[i + 1];
var invalidPartText = nextPart.IsParameter ? nextPart.Name : nextPart.Text;
context.Error = string.Format(
Resources.TemplateRoute_OptionalParameterHasTobeTheLast,
segment.DebuggerToString(),
segment.Parts[i].Name,
invalidPartText);
return(false);
}
}
}
// A segment cannot contain two consecutive parameters
var isLastSegmentParameter = false;
for (var i = 0; i < segment.Parts.Count; i++)
{
var part = segment.Parts[i];
if (part.IsParameter && isLastSegmentParameter)
{
context.Error = Resources.TemplateRoute_CannotHaveConsecutiveParameters;
return(false);
}
isLastSegmentParameter = part.IsParameter;
}
return(true);
}
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);
}
}
private static bool ParseParameter(TemplateParserContext context, TemplateSegment segment)
{
context.Mark();
while (true)
{
if (context.Current == OpenBrace)
{
// This is an open brace inside of a parameter, it has to be escaped
if (context.Next())
{
if (context.Current != OpenBrace)
{
// If we see something like "{p1:regex(^\d{3", we will come here.
context.Error = Resources.TemplateRoute_UnescapedBrace;
return(false);
}
}
else
{
// This is a dangling open-brace, which is not allowed
// Example: "{p1:regex(^\d{"
context.Error = Resources.TemplateRoute_MismatchedParameter;
return(false);
}
}
else if (context.Current == CloseBrace)
{
// When we encounter Closed brace here, it either means end of the parameter or it is a closed
// brace in the parameter, in that case it needs to be escaped.
// Example: {p1:regex(([}}])\w+}. First pair is escaped one and last marks end of the parameter
if (!context.Next())
{
// This is the end of the string -and we have a valid parameter
context.Back();
break;
}
if (context.Current == CloseBrace)
{
// This is an 'escaped' brace in a parameter name
}
else
{
// This is the end of the parameter
context.Back();
break;
}
}
if (!context.Next())
{
// This is a dangling open-brace, which is not allowed
context.Error = Resources.TemplateRoute_MismatchedParameter;
return(false);
}
}
var rawParameter = context.Capture();
var decoded = rawParameter.Replace("}}", "}").Replace("{{", "{");
// At this point, we need to parse the raw name for inline constraint,
// default values and optional parameters.
var templatePart = InlineRouteParameterParser.ParseRouteParameter(decoded);
if (templatePart.IsCatchAll && templatePart.IsOptional)
{
context.Error = Resources.TemplateRoute_CatchAllCannotBeOptional;
return(false);
}
if (templatePart.IsOptional && templatePart.DefaultValue != null)
{
// Cannot be optional and have a default value.
// The only way to declare an optional parameter is to have a ? at the end,
// hence we cannot have both default value and optional parameter within the template.
// A workaround is to add it as a separate entry in the defaults argument.
context.Error = Resources.TemplateRoute_OptionalCannotHaveDefaultValue;
return(false);
}
var parameterName = templatePart.Name;
if (IsValidParameterName(context, parameterName))
{
segment.Parts.Add(templatePart);
return(true);
}
else
{
return(false);
}
}
private bool MatchComplexSegmentCore(
TemplateSegment routeSegment,
string requestSegment,
IReadOnlyDictionary <string, object> defaults,
RouteValueDictionary values,
int indexOfLastSegmentUsed)
{
Debug.Assert(routeSegment != null);
Debug.Assert(routeSegment.Parts.Count > 1);
// Find last literal segment and get its last index in the string
var lastIndex = requestSegment.Length;
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
var outValues = new RouteValueDictionary();
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
{
Debug.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;
Debug.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
outValues.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.
if (lastIndex == 0 || routeSegment.Parts[0].IsParameter)
{
foreach (var item in outValues)
{
values.Add(item.Key, item.Value);
}
return(true);
}
return(false);
}