private IReadOnlyList <ActionDescriptor> EvaluateActionConstraints(
RouteContext context,
IReadOnlyList <ActionDescriptor> actions)
{
var candidates = new List <ActionSelectorCandidate>();
// Perf: Avoid allocations
for (var i = 0; i < actions.Count; i++)
{
var action = actions[i];
var constraints = _actionConstraintCache.GetActionConstraints(context.HttpContext, action);
candidates.Add(new ActionSelectorCandidate(action, constraints));
}
var matches = EvaluateActionConstraintsCore(context, candidates, startingOrder: null);
List <ActionDescriptor> results = null;
if (matches != null)
{
results = new List <ActionDescriptor>(matches.Count);
// Perf: Avoid allocations
for (var i = 0; i < matches.Count; i++)
{
var candidate = matches[i];
results.Add(candidate.Action);
}
}
return(results);
}
/// <inheritdoc />
public ActionDescriptor Select(RouteContext context)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
var tree = _decisionTreeProvider.DecisionTree;
var matchingRouteConstraints = tree.Select(context.RouteData.Values);
var candidates = new List <ActionSelectorCandidate>();
// Perf: Avoid allocations
for (var i = 0; i < matchingRouteConstraints.Count; i++)
{
var action = matchingRouteConstraints[i];
var constraints = _actionConstraintCache.GetActionConstraints(context.HttpContext, action);
candidates.Add(new ActionSelectorCandidate(action, constraints));
}
var matchingActionConstraints =
EvaluateActionConstraints(context, candidates, startingOrder: null);
List <ActionDescriptor> matchingActions = null;
if (matchingActionConstraints != null)
{
matchingActions = new List <ActionDescriptor>(matchingActionConstraints.Count);
// Perf: Avoid allocations
for (var i = 0; i < matchingActionConstraints.Count; i++)
{
var candidate = matchingActionConstraints[i];
matchingActions.Add(candidate.Action);
}
}
var finalMatches = SelectBestActions(matchingActions);
if (finalMatches == null || finalMatches.Count == 0)
{
return(null);
}
else if (finalMatches.Count == 1)
{
var selectedAction = finalMatches[0];
return(selectedAction);
}
else
{
var actionNames = string.Join(
Environment.NewLine,
finalMatches.Select(a => a.DisplayName));
_logger.AmbiguousActions(actionNames);
var message = Resources.FormatDefaultActionSelector_AmbiguousActions(
Environment.NewLine,
actionNames);
throw new AmbiguousActionException(message);
}
}