com.eucalyptus.auth.PolicyEvaluationContext.java Source code

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Here is the source code for com.eucalyptus.auth.PolicyEvaluationContext.java

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/*************************************************************************
 * (c) Copyright 2016 Hewlett Packard Enterprise Development Company LP
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 3 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see http://www.gnu.org/licenses/.
 ************************************************************************/
package com.eucalyptus.auth;

import java.util.Collections;
import java.util.Map;
import java.util.concurrent.Callable;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import com.eucalyptus.util.TypedContext;
import com.eucalyptus.util.TypedKey;
import com.google.common.base.MoreObjects;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Maps;

/**
 *
 */
public class PolicyEvaluationContext {

    private final TypedContext attributes;
    private static final PolicyEvaluationContext empty = new PolicyEvaluationContext(Collections.emptyMap());
    private static final ThreadLocal<PolicyEvaluationContext> threadContext = new ThreadLocal<>();

    private PolicyEvaluationContext(final Map<TypedKey<?>, Object> attrMap) {
        attributes = TypedContext.newTypedContext(ImmutableMap.copyOf(attrMap));
    }

    public <T> T getAttribute(final TypedKey<T> key) {
        return attributes.get(key);
    }

    public boolean hasAttribute(final TypedKey<?> key) {
        return attributes.containsKey(key);
    }

    public <R> R doWithContext(final Callable<R> callable) throws Exception {
        final PolicyEvaluationContext previous = threadContext.get();
        threadContext.set(this);
        try {
            return callable.call();
        } finally {
            threadContext.set(previous);
        }
    }

    @Nonnull
    public static PolicyEvaluationContext get() {
        return MoreObjects.firstNonNull(threadContext.get(), empty);
    }

    public static Builder builder() {
        return new Builder();
    }

    public static final class Builder {
        private final Map<TypedKey<?>, Object> attributes = Maps.newHashMap();

        public <T> Builder attr(final PolicyEvaluationWriteContextKey<T> key, @Nonnull final T value) {
            //noinspection ConstantConditions
            if (value == null)
                throw new NullPointerException();
            attributes.put(key.getKey(), value);
            return this;
        }

        public <T> Builder attrIfNotNull(final PolicyEvaluationWriteContextKey<T> key, @Nullable final T value) {
            if (value != null) {
                attributes.put(key.getKey(), value);
            }
            return this;
        }

        public <T extends CharSequence> Builder attrIfNotNullOrEmpty(final PolicyEvaluationWriteContextKey<T> key,
                @Nullable final T value) {
            if (value != null && value.length() > 0) {
                attributes.put(key.getKey(), value);
            }
            return this;
        }

        public PolicyEvaluationContext build() {
            return new PolicyEvaluationContext(attributes);
        }
    }
}