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TreeRouter.cs
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TreeRouter.cs
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// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Text.Encodings.Web;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Routing.Internal;
using Microsoft.AspNetCore.Routing.Logging;
using Microsoft.AspNetCore.Routing.Template;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.ObjectPool;
namespace Microsoft.AspNetCore.Routing.Tree
{
/// <summary>
/// An <see cref="IRouter"/> implementation for attribute routing.
/// </summary>
public class TreeRouter : IRouter
{
// Key used by routing and action selection to match an attribute route entry to a
// group of action descriptors.
public static readonly string RouteGroupKey = "!__route_group";
private readonly LinkGenerationDecisionTree _linkGenerationTree;
private readonly UrlMatchingTree[] _trees;
private readonly IDictionary<string, OutboundMatch> _namedEntries;
private readonly ILogger _logger;
private readonly ILogger _constraintLogger;
/// <summary>
/// Creates a new <see cref="TreeRouter"/>.
/// </summary>
/// <param name="trees">The list of <see cref="UrlMatchingTree"/> that contains the route entries.</param>
/// <param name="linkGenerationEntries">The set of <see cref="OutboundRouteEntry"/>.</param>
/// <param name="urlEncoder">The <see cref="UrlEncoder"/>.</param>
/// <param name="objectPool">The <see cref="ObjectPool{T}"/>.</param>
/// <param name="routeLogger">The <see cref="ILogger"/> instance.</param>
/// <param name="constraintLogger">The <see cref="ILogger"/> instance used
/// in <see cref="RouteConstraintMatcher"/>.</param>
/// <param name="version">The version of this route.</param>
public TreeRouter(
UrlMatchingTree[] trees,
IEnumerable<OutboundRouteEntry> linkGenerationEntries,
UrlEncoder urlEncoder,
ObjectPool<UriBuildingContext> objectPool,
ILogger routeLogger,
ILogger constraintLogger,
int version)
{
if (trees == null)
{
throw new ArgumentNullException(nameof(trees));
}
if (linkGenerationEntries == null)
{
throw new ArgumentNullException(nameof(linkGenerationEntries));
}
if (urlEncoder == null)
{
throw new ArgumentNullException(nameof(urlEncoder));
}
if (objectPool == null)
{
throw new ArgumentNullException(nameof(objectPool));
}
if (routeLogger == null)
{
throw new ArgumentNullException(nameof(routeLogger));
}
if (constraintLogger == null)
{
throw new ArgumentNullException(nameof(constraintLogger));
}
_trees = trees;
_logger = routeLogger;
_constraintLogger = constraintLogger;
_namedEntries = new Dictionary<string, OutboundMatch>(StringComparer.OrdinalIgnoreCase);
var outboundMatches = new List<OutboundMatch>();
foreach (var entry in linkGenerationEntries)
{
var binder = new TemplateBinder(urlEncoder, objectPool, entry.RouteTemplate, entry.Defaults);
var outboundMatch = new OutboundMatch() { Entry = entry, TemplateBinder = binder };
outboundMatches.Add(outboundMatch);
// Skip unnamed entries
if (entry.RouteName == null)
{
continue;
}
// We only need to keep one OutboundMatch per route template
// so in case two entries have the same name and the same template we only keep
// the first entry.
OutboundMatch namedMatch;
if (_namedEntries.TryGetValue(entry.RouteName, out namedMatch) &&
!string.Equals(
namedMatch.Entry.RouteTemplate.TemplateText,
entry.RouteTemplate.TemplateText,
StringComparison.OrdinalIgnoreCase))
{
throw new ArgumentException(
Resources.FormatAttributeRoute_DifferentLinkGenerationEntries_SameName(entry.RouteName),
nameof(linkGenerationEntries));
}
else if (namedMatch == null)
{
_namedEntries.Add(entry.RouteName, outboundMatch);
}
}
// The decision tree will take care of ordering for these entries.
_linkGenerationTree = new LinkGenerationDecisionTree(outboundMatches.ToArray());
Version = version;
}
/// <summary>
/// Gets the version of this route.
/// </summary>
public int Version { get; }
internal IEnumerable<UrlMatchingTree> MatchingTrees => _trees;
/// <inheritdoc />
public VirtualPathData GetVirtualPath(VirtualPathContext context)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
// If it's a named route we will try to generate a link directly and
// if we can't, we will not try to generate it using an unnamed route.
if (context.RouteName != null)
{
return GetVirtualPathForNamedRoute(context);
}
// The decision tree will give us back all entries that match the provided route data in the correct
// order. We just need to iterate them and use the first one that can generate a link.
var matches = _linkGenerationTree.GetMatches(context);
if (matches == null)
{
return null;
}
for (var i = 0; i < matches.Count; i++)
{
var path = GenerateVirtualPath(context, matches[i].Match.Entry, matches[i].Match.TemplateBinder);
if (path != null)
{
return path;
}
}
return null;
}
/// <inheritdoc />
public async Task RouteAsync(RouteContext context)
{
foreach (var tree in _trees)
{
var tokenizer = new PathTokenizer(context.HttpContext.Request.Path);
var root = tree.Root;
var treeEnumerator = new TreeEnumerator(root, tokenizer);
// Create a snapshot before processing the route. We'll restore this snapshot before running each
// to restore the state. This is likely an "empty" snapshot, which doesn't allocate.
var snapshot = context.RouteData.PushState(router: null, values: null, dataTokens: null);
while (treeEnumerator.MoveNext())
{
var node = treeEnumerator.Current;
foreach (var item in node.Matches)
{
var entry = item.Entry;
var matcher = item.TemplateMatcher;
try
{
if (!matcher.TryMatch(context.HttpContext.Request.Path, context.RouteData.Values))
{
continue;
}
if (!RouteConstraintMatcher.Match(
entry.Constraints,
context.RouteData.Values,
context.HttpContext,
this,
RouteDirection.IncomingRequest,
_constraintLogger))
{
continue;
}
_logger.MatchedRoute(entry.RouteName, entry.RouteTemplate.TemplateText);
context.RouteData.Routers.Add(entry.Handler);
await entry.Handler.RouteAsync(context);
if (context.Handler != null)
{
return;
}
}
finally
{
if (context.Handler == null)
{
// Restore the original values to prevent polluting the route data.
snapshot.Restore();
}
}
}
}
}
}
private struct TreeEnumerator : IEnumerator<UrlMatchingNode>
{
private readonly Stack<UrlMatchingNode> _stack;
private readonly PathTokenizer _tokenizer;
public TreeEnumerator(UrlMatchingNode root, PathTokenizer tokenizer)
{
_stack = new Stack<UrlMatchingNode>();
_tokenizer = tokenizer;
Current = null;
_stack.Push(root);
}
public UrlMatchingNode Current { get; private set; }
object IEnumerator.Current => Current;
public void Dispose()
{
}
public bool MoveNext()
{
if (_stack == null)
{
return false;
}
while (_stack.Count > 0)
{
var next = _stack.Pop();
// In case of wild card segment, the request path segment length can be greater
// Example:
// Template: a/{*path}
// Request Url: a/b/c/d
if (next.IsCatchAll && next.Matches.Count > 0)
{
Current = next;
return true;
}
// Next template has the same length as the url we are trying to match
// The only possible matching segments are either our current matches or
// any catch-all segment after this segment in which the catch all is empty.
else if (next.Depth == _tokenizer.Count)
{
if (next.Matches.Count > 0)
{
Current = next;
return true;
}
else
{
// We can stop looking as any other child node from this node will be
// either a literal, a constrained parameter or a parameter.
// (Catch alls and constrained catch alls will show up as candidate matches).
continue;
}
}
if (next.CatchAlls != null)
{
_stack.Push(next.CatchAlls);
}
if (next.ConstrainedCatchAlls != null)
{
_stack.Push(next.ConstrainedCatchAlls);
}
if (next.Parameters != null)
{
_stack.Push(next.Parameters);
}
if (next.ConstrainedParameters != null)
{
_stack.Push(next.ConstrainedParameters);
}
if (next.Literals.Count > 0)
{
UrlMatchingNode node;
Debug.Assert(next.Depth < _tokenizer.Count);
if (next.Literals.TryGetValue(_tokenizer[next.Depth].Value, out node))
{
_stack.Push(node);
}
}
}
return false;
}
public void Reset()
{
_stack.Clear();
Current = null;
}
}
private VirtualPathData GetVirtualPathForNamedRoute(VirtualPathContext context)
{
OutboundMatch match;
if (_namedEntries.TryGetValue(context.RouteName, out match))
{
var path = GenerateVirtualPath(context, match.Entry, match.TemplateBinder);
if (path != null)
{
return path;
}
}
return null;
}
private VirtualPathData GenerateVirtualPath(
VirtualPathContext context,
OutboundRouteEntry entry,
TemplateBinder binder)
{
// In attribute the context includes the values that are used to select this entry - typically
// these will be the standard 'action', 'controller' and maybe 'area' tokens. However, we don't
// want to pass these to the link generation code, or else they will end up as query parameters.
//
// So, we need to exclude from here any values that are 'required link values', but aren't
// parameters in the template.
//
// Ex:
// template: api/Products/{action}
// required values: { id = "5", action = "Buy", Controller = "CoolProducts" }
//
// result: { id = "5", action = "Buy" }
var inputValues = new RouteValueDictionary();
foreach (var kvp in context.Values)
{
if (entry.RequiredLinkValues.ContainsKey(kvp.Key))
{
var parameter = entry.RouteTemplate.GetParameter(kvp.Key);
if (parameter == null)
{
continue;
}
}
inputValues.Add(kvp.Key, kvp.Value);
}
var bindingResult = binder.GetValues(context.AmbientValues, inputValues);
if (bindingResult == null)
{
// A required parameter in the template didn't get a value.
return null;
}
var matched = RouteConstraintMatcher.Match(
entry.Constraints,
bindingResult.CombinedValues,
context.HttpContext,
this,
RouteDirection.UrlGeneration,
_constraintLogger);
if (!matched)
{
// A constraint rejected this link.
return null;
}
var pathData = entry.Handler.GetVirtualPath(context);
if (pathData != null)
{
// If path is non-null then the target router short-circuited, we don't expect this
// in typical MVC scenarios.
return pathData;
}
var path = binder.BindValues(bindingResult.AcceptedValues);
if (path == null)
{
return null;
}
return new VirtualPathData(this, path);
}
}
}