ratpack.groovy.internal.ClosureInvoker.java Source code

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Here is the source code for ratpack.groovy.internal.ClosureInvoker.java

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/*
 * Copyright 2013 the original author or authors.
 *
 * 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 ratpack.groovy.internal;

import com.google.common.base.Function;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.reflect.TypeToken;
import groovy.lang.Closure;
import ratpack.func.Action;
import ratpack.handling.internal.Extractions;
import ratpack.registry.Registry;

import java.util.Collections;
import java.util.List;

public class ClosureInvoker<T, D> {

    private final Closure<T> closure;
    private final List<TypeToken<?>> parameterTypes;
    private final boolean hasDefaultParam;

    @SuppressWarnings("unchecked")
    public ClosureInvoker(Closure<? extends T> closure) {
        this.closure = (Closure<T>) closure.clone();
        this.hasDefaultParam = closure.getMaximumNumberOfParameters() > 0;
        closure.setDelegate(null);

        this.parameterTypes = retrieveParameterTypes(this.closure);
    }

    public Closure<T> getClosure() {
        return closure;
    }

    public T invoke(Registry registry, D delegate, int resolveStrategy) {
        @SuppressWarnings("unchecked")
        Closure<T> clone = (Closure<T>) closure.clone();
        clone.setDelegate(delegate);
        clone.setResolveStrategy(resolveStrategy);

        if (parameterTypes.isEmpty()) {
            if (hasDefaultParam) {
                return clone.call(delegate);
            } else {
                return clone.call();
            }
        } else {
            Object[] services = Extractions.extract(parameterTypes, registry);
            return clone.call(services);
        }
    }

    public Action<D> toAction(final Registry registry, final int resolveStrategy) {
        return new Action<D>() {
            public void execute(D delegate) throws Exception {
                invoke(registry, delegate, resolveStrategy);
            }
        };
    }

    private static List<TypeToken<?>> retrieveParameterTypes(Closure<?> closure) {
        Class<?>[] parameterTypes = closure.getParameterTypes();
        if (parameterTypes.length == 1 && parameterTypes[0].equals(Object.class)) {
            return Collections.emptyList();
        } else {
            for (Class<?> clazz : parameterTypes) {
                if (clazz.isArray()) {
                    throw new IllegalStateException("Closure parameters cannot be array types (type: "
                            + clazz.getName() + ", closure: " + closure.getClass().getName() + ")");
                }
            }

            return Lists.transform(ImmutableList.copyOf(parameterTypes), new Function<Class<?>, TypeToken<?>>() {
                @Override
                public TypeToken<?> apply(Class<?> input) {
                    return TypeToken.of(input);
                }
            });
        }
    }
}