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Core components supporting the Micronaut Framework
There is a newer version: 4.6.5
/*
 * Copyright 2017-2020 original 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
 *
 * https://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 io.micronaut.aop;

import io.micronaut.core.annotation.AnnotationMetadataDelegate;
import io.micronaut.core.annotation.NonNull;
import io.micronaut.core.annotation.Nullable;
import io.micronaut.core.attr.MutableAttributeHolder;
import io.micronaut.core.type.Argument;
import io.micronaut.core.type.ArgumentValue;
import io.micronaut.core.type.Executable;
import io.micronaut.core.type.MutableArgumentValue;
import io.micronaut.core.util.CollectionUtils;

import java.util.Map;

/**
 * An InvocationContext passed to one or many {@link Interceptor} instances. Attributes can be stored within the
 * context and shared between multiple {@link Interceptor} implementations. The {@link #proceed()} method should be
 * called to proceed to the next {@link Interceptor} with the last interceptor in the chain being the original
 * decorated method implementation.
 *
 * The parameters to pass to the next {@link Interceptor} can be mutated using {@link MutableArgumentValue}
 * interface returned by the {@link #getParameters()} method
 *
 * @param  The declaring type
 * @param  The result of the method call
 * @author Graeme Rocher
 * @since 1.0
 */
public interface InvocationContext extends Executable, AnnotationMetadataDelegate, MutableAttributeHolder {

    /**
     * Returns the current parameters as a map of mutable argument values. This method allows mutation of the argument values
     * and is generally more expensive than using {@link #getParameterValues()} and {@link #getArguments()} directly, hence
     * should be used with care.
     *
     * @return The bound {@link ArgumentValue} instances
     */
    @NonNull Map> getParameters();

    /**
     * @return The target object
     */
    @NonNull T getTarget();

    /**
     * Proceeds with the invocation. If this is the last interceptor in the chain then the final implementation method is invoked
     *
     * @return The return value of the method
     * @throws RuntimeException chain may throw RTE
     */
    @Nullable R proceed() throws RuntimeException;

    /**
     * Proceeds with the invocation using the given interceptor as a position to start from. Mainly useful for {@link Introduction} advise where you want to
     * invoke the target multiple times or where you want to repeat the entire chain.
     *
     * @param from The interceptor to start from (note: will not be included in the execution)
     * @return The return value of the method
     * @throws RuntimeException chain may throw RTE
     */
    @Nullable R proceed(Interceptor from) throws RuntimeException;

    /**
     * @return An enum representing the kind of interception that is occurring.
     * @since 3.0.0
     */
    default @NonNull InterceptorKind getKind() {
        return InterceptorKind.AROUND;
    }

    @SuppressWarnings("unchecked")
    @Override
    default Class getDeclaringType() {
        return (Class) getTarget().getClass();
    }

    @SuppressWarnings("unchecked")
    @Override
    default InvocationContext setAttribute(@NonNull CharSequence name, Object value) {
        return (InvocationContext) MutableAttributeHolder.super.setAttribute(name, value);
    }

    /**
     * Returns the current state of the parameters as an array by parameter index. Note that mutations to the array have no effect.
     * If you wish to mutate the parameters use {@link #getParameters()} and the {@link MutableArgumentValue} interface instead
     *
     * @return The bound {@link ArgumentValue} instances
     */
    default @NonNull Object[] getParameterValues() {
        return getParameters()
            .values()
            .stream()
            .map(ArgumentValue::getValue)
            .toArray();
    }

    /**
     * Returns the current state of the parameters as a map keyed by parameter name.
     *
     * @return A map of parameter names to values
     */
    default @NonNull Map getParameterValueMap() {
        Argument[] arguments = getArguments();
        Object[] parameterValues = getParameterValues();
        Map valueMap = CollectionUtils.newLinkedHashMap(arguments.length);
        for (int i = 0; i < parameterValues.length; i++) {
            Object parameterValue = parameterValues[i];
            Argument arg = arguments[i];
            valueMap.put(arg.getName(), parameterValue);
        }
        return valueMap;
    }
}