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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
#nullable disable
using System.Diagnostics;
#if !COMPONENTS
using Microsoft.AspNetCore.Http;
#else
using Microsoft.AspNetCore.Components.Routing;
#endif
using Microsoft.AspNetCore.Routing.Patterns;
using Microsoft.Extensions.Primitives;
namespace Microsoft.AspNetCore.Routing;
internal sealed class RoutePatternMatcher
{
// Perf: This is a cache to avoid looking things up in 'Defaults' each request.
private readonly bool[] _hasDefaultValue;
private readonly object[] _defaultValues;
public RoutePatternMatcher(
RoutePattern pattern,
RouteValueDictionary defaults)
{
ArgumentNullException.ThrowIfNull(pattern);
RoutePattern = pattern;
Defaults = defaults ?? new RouteValueDictionary();
// Perf: cache the default value for each parameter (other than complex segments).
_hasDefaultValue = new bool[RoutePattern.PathSegments.Count];
_defaultValues = new object[RoutePattern.PathSegments.Count];
for (var i = 0; i < RoutePattern.PathSegments.Count; i++)
{
var segment = RoutePattern.PathSegments[i];
if (!segment.IsSimple)
{
continue;
}
var part = segment.Parts[0];
if (!part.IsParameter)
{
continue;
}
var parameter = (RoutePatternParameterPart)part;
if (Defaults.TryGetValue(parameter.Name, out var value))
{
_hasDefaultValue[i] = true;
_defaultValues[i] = value;
}
}
}
public RouteValueDictionary Defaults { get; }
public RoutePattern RoutePattern { get; }
public bool TryMatch(PathString path, RouteValueDictionary values)
{
ArgumentNullException.ThrowIfNull(values);
var i = 0;
var pathTokenizer = new PathTokenizer(path);
// Perf: We do a traversal of the request-segments + route-segments twice.
//
// For most segment-types, we only really need to any work on one of the two passes.
//
// On the first pass, we're just looking to see if there's anything that would disqualify us from matching.
// The most common case would be a literal segment that doesn't match.
//
// On the second pass, we're almost certainly going to match the URL, so go ahead and allocate the 'values'
// and start capturing strings.
foreach (var stringSegment in pathTokenizer)
{
if (stringSegment.Length == 0)
{
return false;
}
var pathSegment = i >= RoutePattern.PathSegments.Count ? null : RoutePattern.PathSegments[i];
if (pathSegment == null && stringSegment.Length > 0)
{
// If pathSegment is null, then we're out of route segments. All we can match is the empty
// string.
return false;
}
else if (pathSegment.IsSimple && pathSegment.Parts[0] is RoutePatternParameterPart parameter && parameter.IsCatchAll)
{
// Nothing to validate for a catch-all - it can match any string, including the empty string.
//
// Also, a catch-all has to be the last part, so we're done.
break;
}
if (!TryMatchLiterals(i++, stringSegment, pathSegment))
{
return false;
}
}
for (; i < RoutePattern.PathSegments.Count; i++)
{
// We've matched the request path so far, but still have remaining route segments. These need
// to be all single-part parameter segments with default values or else they won't match.
var pathSegment = RoutePattern.PathSegments[i];
Debug.Assert(pathSegment != null);
if (!pathSegment.IsSimple)
{
// If the segment is a complex segment, it MUST contain literals, and we've parsed the full
// path so far, so it can't match.
return false;
}
var part = pathSegment.Parts[0];
if (part.IsLiteral || part.IsSeparator)
{
// If the segment is a simple literal - which need the URL to provide a value, so we don't match.
return false;
}
var parameter = (RoutePatternParameterPart)part;
if (parameter.IsCatchAll)
{
// Nothing to validate for a catch-all - it can match any string, including the empty string.
//
// Also, a catch-all has to be the last part, so we're done.
break;
}
// If we get here, this is a simple segment with a parameter. We need it to be optional, or for the
// defaults to have a value.
if (!_hasDefaultValue[i] && !parameter.IsOptional)
{
// There's no default for this (non-optional) parameter so it can't match.
return false;
}
}
// At this point we've very likely got a match, so start capturing values for real.
i = 0;
foreach (var requestSegment in pathTokenizer)
{
var pathSegment = RoutePattern.PathSegments[i++];
if (SavePathSegmentsAsValues(i, values, requestSegment, pathSegment))
{
break;
}
if (!pathSegment.IsSimple)
{
if (!MatchComplexSegment(pathSegment, requestSegment.AsSpan(), values))
{
return false;
}
}
}
for (; i < RoutePattern.PathSegments.Count; i++)
{
// We've matched the request path so far, but still have remaining route segments. We already know these
// are simple parameters that either have a default, or don't need to produce a value.
var pathSegment = RoutePattern.PathSegments[i];
Debug.Assert(pathSegment != null);
Debug.Assert(pathSegment.IsSimple);
var part = pathSegment.Parts[0];
Debug.Assert(part.IsParameter);
// It's ok for a catch-all to produce a null value
if (part is RoutePatternParameterPart parameter && (parameter.IsCatchAll || _hasDefaultValue[i]))
{
// Don't replace an existing value with a null.
var defaultValue = _defaultValues[i];
if (defaultValue != null || !values.ContainsKey(parameter.Name))
{
values[parameter.Name] = defaultValue;
}
}
}
// Copy all remaining default values to the route data
foreach (var kvp in Defaults)
{
#if RVD_TryAdd
values.TryAdd(kvp.Key, kvp.Value);
#else
if (!values.ContainsKey(kvp.Key))
{
values.Add(kvp.Key, kvp.Value);
}
#endif
}
return true;
}
private bool TryMatchLiterals(int index, StringSegment stringSegment, RoutePatternPathSegment pathSegment)
{
if (pathSegment.IsSimple && !pathSegment.Parts[0].IsParameter)
{
// This is a literal segment, so we need to match the text, or the route isn't a match.
if (pathSegment.Parts[0].IsLiteral)
{
var part = (RoutePatternLiteralPart)pathSegment.Parts[0];
if (!stringSegment.Equals(part.Content, StringComparison.OrdinalIgnoreCase))
{
return false;
}
}
else
{
var part = (RoutePatternSeparatorPart)pathSegment.Parts[0];
if (!stringSegment.Equals(part.Content, StringComparison.OrdinalIgnoreCase))
{
return false;
}
}
}
else if (pathSegment.IsSimple && pathSegment.Parts[0].IsParameter)
{
// For a parameter, validate that it's a has some length, or we have a default, or it's optional.
var part = (RoutePatternParameterPart)pathSegment.Parts[0];
if (stringSegment.Length == 0 &&
!_hasDefaultValue[index] &&
!part.IsOptional)
{
// There's no value for this parameter, the route can't match.
return false;
}
}
else
{
Debug.Assert(!pathSegment.IsSimple);
// Don't attempt to validate a complex segment at this point other than being non-empty,
// do it in the second pass.
}
return true;
}
private bool SavePathSegmentsAsValues(int index, RouteValueDictionary values, StringSegment requestSegment, RoutePatternPathSegment pathSegment)
{
if (pathSegment.IsSimple && pathSegment.Parts[0] is RoutePatternParameterPart parameter && parameter.IsCatchAll)
{
// A catch-all captures til the end of the string.
var captured = requestSegment.Buffer.Substring(requestSegment.Offset);
if (captured.Length > 0)
{
values[parameter.Name] = captured;
}
else
{
// It's ok for a catch-all to produce a null value, so we don't check _hasDefaultValue.
values[parameter.Name] = _defaultValues[index];
}
// A catch-all has to be the last part, so we're done.
return true;
}
else if (pathSegment.IsSimple && pathSegment.Parts[0].IsParameter)
{
// A simple parameter captures the whole segment, or a default value if nothing was
// provided.
parameter = (RoutePatternParameterPart)pathSegment.Parts[0];
if (requestSegment.Length > 0)
{
values[parameter.Name] = requestSegment.ToString();
}
else
{
if (_hasDefaultValue[index])
{
values[parameter.Name] = _defaultValues[index];
}
}
}
return false;
}
internal static bool MatchComplexSegment(
RoutePatternPathSegment routeSegment,
ReadOnlySpan<char> requestSegment,
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] is RoutePatternParameterPart parameter && parameter.IsOptional &&
routeSegment.Parts[indexOfLastSegment - 1].IsSeparator)
{
if (MatchComplexSegmentCore(routeSegment, requestSegment, values, indexOfLastSegment))
{
return true;
}
else
{
var separator = (RoutePatternSeparatorPart)routeSegment.Parts[indexOfLastSegment - 1];
if (requestSegment.EndsWith(
separator.Content,
StringComparison.OrdinalIgnoreCase))
{
return false;
}
return MatchComplexSegmentCore(
routeSegment,
requestSegment,
values,
indexOfLastSegment - 2);
}
}
else
{
return MatchComplexSegmentCore(routeSegment, requestSegment, values, indexOfLastSegment);
}
}
private static bool MatchComplexSegmentCore(
RoutePatternPathSegment routeSegment,
ReadOnlySpan<char> requestSegment,
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;
RoutePatternParameterPart parameterNeedsValue = null; // Keeps track of a parameter segment that is pending a value
RoutePatternPart 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 = (RoutePatternParameterPart)part;
}
else
{
Debug.Assert(part.IsLiteral || part.IsSeparator);
lastLiteral = part;
var startIndex = lastIndex;
// We are at the beginning of the segment and we still need to match a literal
if (startIndex == 0)
{
return false;
}
// If we have a pending parameter subsegment, we must leave at least one character for that
if (parameterNeedsValue != null)
{
startIndex--;
}
int indexOfLiteral;
if (part.IsLiteral)
{
var literal = (RoutePatternLiteralPart)part;
indexOfLiteral = requestSegment.Slice(0, startIndex).LastIndexOf(
literal.Content,
StringComparison.OrdinalIgnoreCase);
}
else
{
var literal = (RoutePatternSeparatorPart)part;
indexOfLiteral = requestSegment.Slice(0, startIndex).LastIndexOf(
literal.Content,
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 (part is RoutePatternLiteralPart literal && ((indexOfLiteral + literal.Content.Length) != requestSegment.Length))
{
return false;
}
else if (part is RoutePatternSeparatorPart separator && ((indexOfLiteral + separator.Content.Length) != requestSegment.Length))
{
return false;
}
}
newLastIndex = indexOfLiteral;
}
if ((parameterNeedsValue != null) &&
(((lastLiteral != null) && !part.IsParameter) || (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
{
if (lastLiteral.IsLiteral)
{
var literal = (RoutePatternLiteralPart)lastLiteral;
parameterStartIndex = newLastIndex + literal.Content.Length;
}
else
{
var separator = (RoutePatternSeparatorPart)lastLiteral;
parameterStartIndex = newLastIndex + separator.Content.Length;
}
parameterTextLength = lastIndex - parameterStartIndex;
}
}
var parameterValueSpan = requestSegment.Slice(parameterStartIndex, parameterTextLength);
if (parameterValueSpan.Length == 0)
{
// 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, new string(parameterValueSpan));
}
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[item.Key] = item.Value;
}
return true;
}
return false;
}
}
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