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/*
* Copyright 2013 eXo Platform SAS
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package juzu.impl.plugin.controller;
import juzu.request.Phase;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
/**
* Controller method resolution algorithm.
*
* Resolves a controller method for a specified set of parameter names. The algorithm attempts to resolve a single value
* with the following algorithm:
*
*
Filter the list of controllers, this is specific to the resolve method.
When no method is retained,
* the null value is returned.
When several methods are retained the resulting list is sorted according
* resolution order. If a first value is greater than all the others, this result is returned, otherwise a {@link
* AmbiguousResolutionException} is thrown.
*
* The resolution order uses three criteria for comparing two methods in the context of the specified parameter
* names.
*
*
The greater number of matched specified parameters.
The lesser number of unmatched method
* arguments.
The lesser number of unmatched method parameters.
The default controller class.
*
*
* @author Julien Viet
*/
public abstract class ControllerResolver {
// todo : take in account multi valued parameters
// todo : what happens with type conversion, somehow we should forbid m(String a) and m(int a)
public abstract M[] getHandlers();
public abstract String getId(M method);
public abstract Phase getPhase(M method);
public abstract String getName(M method);
public abstract boolean isDefault(M method);
public final boolean isIndex(M method) {
return isDefault(method) && "index".equals(getName(method));
}
public abstract Collection getParameterNames(M method);
private class Match implements Comparable {
/** . */
final M method;
/** . */
final int score1;
/** . */
final int score2;
/** . */
final int score3;
/** . */
final int score4;
Match(Set parameterNames, M method) {
this.method = method;
// The number of matched parameters
HashSet a = new HashSet(parameterNames);
a.retainAll(getParameterNames(method));
this.score1 = a.size();
// The number of unmatched arguments
a = new HashSet(getParameterNames(method));
a.removeAll(parameterNames);
this.score2 = a.size();
// The number of unmatched parameters
a = new HashSet(parameterNames);
a.removeAll(getParameterNames(method));
this.score3 = a.size();
// The default method
this.score4 = isDefault(method) ? 0 : 1;
}
public int compareTo(Match o) {
int delta = o.score1 - score1;
if (delta == 0) {
delta = score2 - o.score2;
if (delta == 0) {
delta = score3 - o.score3;
if (delta == 0) {
delta = score4 - o.score4;
}
}
}
return delta;
}
@Override
public String toString() {
return "Match[score1=" + score1 + ",score2=" + score2 + ",score3=" + score3 + ",score4=" + score4 + ",method=" + method + "]";
}
}
/**
* A method matches the filter when it has the render phase and the name index.
*
* @param phase the phare to match
* @param parameterNames the parameter names
* @return the resolved controller method
* @throws NullPointerException if the parameter names set is nul
* @throws AmbiguousResolutionException
* if more than a single result is found
*/
public final M resolve(Phase phase, Set parameterNames) throws NullPointerException, AmbiguousResolutionException {
if (parameterNames == null) {
throw new NullPointerException("No null parameter names accepted");
}
//
List matches = new ArrayList();
for (M method : getHandlers()) {
if (getPhase(method) == phase) {
if (phase == Phase.VIEW) {
if (getName(method).equals("index")) {
matches.add(new Match(parameterNames, method));
}
} else {
matches.add(new Match(parameterNames, method));
}
}
}
//
return select(matches);
}
/**
* A method matches the filter when it matches the phase and the method id.
*
* @param phase the phrase
* @param methodId the method id
* @param parameterNames the parameter names
* @return the resolved controller method
* @throws NullPointerException if any parameter is nul
* @throws AmbiguousResolutionException
* if more than a single result is found
*/
public final M resolveMethod(Phase phase, String methodId, final Set parameterNames) throws NullPointerException, AmbiguousResolutionException {
if (parameterNames == null) {
throw new NullPointerException("No null parameter names accepted");
}
if (phase == null) {
throw new NullPointerException("Phase parameter cannot be null");
}
//
List matches = new ArrayList();
for (M method : getHandlers()) {
if (getPhase(method) == phase && (methodId == null || methodId.equals(getId(method)))) {
matches.add(new Match(parameterNames, method));
}
}
//
return select(matches);
}
/**
* A method matches the filter when it matches the phase and the method id.
*
* @param phase the phrase
* @param methodId the method id
* @param parameterNames the parameter names
* @return the resolved controller method
* @throws NullPointerException if any parameter is nul
* @throws AmbiguousResolutionException
* if more than a single result is found
*/
public final List resolveMethods(Phase phase, String methodId, final Set parameterNames) throws NullPointerException, AmbiguousResolutionException {
if (parameterNames == null) {
throw new NullPointerException("No null parameter names accepted");
}
if (phase == null) {
throw new NullPointerException("Phase parameter cannot be null");
}
//
List matches = new ArrayList();
for (M method : getHandlers()) {
if (getPhase(method) == phase && (methodId == null || methodId.equals(getId(method)))) {
matches.add(new Match(parameterNames, method));
}
}
//
Collections.sort(matches);
ArrayList methods = new ArrayList(matches.size());
for (Match match : matches) {
methods.add(match.method);
}
//
return methods;
}
/**
* A method matches the filter when it matches the type name, the method name and contains all the parameters.
*
* @param typeName the optional type name
* @param methodName the method name
* @param parameterNames the parameter names
* @return the resolved controller method
* @throws NullPointerException if the methodName or parameterNames argument is null
* @throws AmbiguousResolutionException
* if more than a single result is found
*/
public M resolve(String typeName, String methodName, Set parameterNames) throws NullPointerException, AmbiguousResolutionException {
if (parameterNames == null) {
throw new NullPointerException("No null parameter names accepted");
}
if (methodName == null) {
throw new NullPointerException("Phase parameter cannot be null");
}
//
List matches = new ArrayList();
for (M method : getHandlers()) {
if (getParameterNames(method).containsAll(parameterNames)) {
if (typeName == null) {
if (getName(method).equals(methodName)) {
matches.add(new Match(parameterNames, method));
}
}
else {
String id = typeName + "." + methodName;
if (getId(method).equals(id)) {
matches.add(new Match(parameterNames, method));
}
}
}
}
//
return select(matches);
}
private M select(List matches) throws AmbiguousResolutionException {
M found = null;
if (matches.size() > 0) {
Collections.sort(matches);
Match first = matches.get(0);
if (matches.size() > 1) {
Match second = matches.get(1);
if (first.compareTo(second) == 0) {
throw new AmbiguousResolutionException("Two methods satisfies the index criteria: " +
first.method + " and " + second.method);
}
}
found = first.method;
}
return found;
}
}
