see.evaluation.evaluators.SimpleContext.java Source code

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Here is the source code for see.evaluation.evaluators.SimpleContext.java

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/*
 * Copyright 2011 Vasily Shiyan
 *
 * 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 see.evaluation.evaluators;

import com.google.common.base.Predicates;
import com.google.common.collect.ClassToInstanceMap;
import com.google.common.collect.ImmutableClassToInstanceMap;
import see.evaluation.Context;
import see.evaluation.Scope;

import static com.google.common.base.Predicates.not;
import static com.google.common.collect.Maps.filterKeys;

public class SimpleContext implements Context {

    private final Scope scope;
    private final ClassToInstanceMap<Object> services;

    private SimpleContext(Scope scope, ClassToInstanceMap<Object> services) {
        this.scope = scope;
        this.services = ImmutableClassToInstanceMap.copyOf(services);
    }

    public static SimpleContext create(Scope scope, ClassToInstanceMap<Object> services) {
        return new SimpleContext(scope, services);
    }

    public static SimpleContext withServices(Context context, ClassToInstanceMap<Object> services) {
        return create(context.getScope(), services);
    }

    public static SimpleContext withVariables(Context context, Scope variables) {
        return create(variables, context.getServices());
    }

    public static <T> Context addService(Context context, Class<T> serviceClass, T service) {
        if (service == context.getServices().getInstance(serviceClass))
            return context; // Return context, if it contains same instance

        return withServices(context,
                ImmutableClassToInstanceMap.builder()
                        .putAll(filterKeys(context.getServices(), not(Predicates.<Object>equalTo(serviceClass))))
                        .put(serviceClass, service).build());
    }

    @Override
    public Scope getScope() {
        return scope;
    }

    @Override
    public ClassToInstanceMap<Object> getServices() {
        return services;
    }
}