org.prebake.service.plan.PlanGraph.java Source code

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Here is the source code for org.prebake.service.plan.PlanGraph.java

Source

// Copyright 2010, Mike Samuel
//
// 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 org.prebake.service.plan;

import org.prebake.core.BoundName;

import java.util.Set;

import javax.annotation.ParametersAreNonnullByDefault;

import com.google.common.base.Function;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMultimap;
import com.google.common.collect.Sets;

/**
 * A directed graph where nodes are {@link Product}s and an edge exists between
 * to nodes where the source produces outputs that might be inputs to the
 * target.
 *
 * @author Mike Samuel <mikesamuel@gmail.com>
 */
@ParametersAreNonnullByDefault
public final class PlanGraph {
    public final ImmutableMap<BoundName, Product> nodes;
    /**
     * Contains the name of each product that the key product depends upon
     * non-transitively.
     */
    public final ImmutableMultimap<BoundName, BoundName> edges;

    private PlanGraph(ImmutableMap<BoundName, Product> nodes, ImmutableMultimap<BoundName, BoundName> edges) {
        this.nodes = nodes;
        this.edges = edges;
    }

    public static class Builder {
        private final ImmutableMap<BoundName, Product> nodes;
        private final ImmutableMultimap.Builder<BoundName, BoundName> edges = ImmutableMultimap.builder();

        private Builder(ImmutableMap<BoundName, Product> nodes) {
            this.nodes = nodes;
        }

        public Builder edge(BoundName prerequisite, BoundName postrequisite) {
            assert nodes.containsKey(postrequisite) && nodes.containsKey(prerequisite);
            edges.put(postrequisite, prerequisite);
            return this;
        }

        public PlanGraph build() {
            return new PlanGraph(nodes, edges.build());
        }
    }

    public static Builder builder(Product... nodes) {
        ImmutableMap.Builder<BoundName, Product> products = ImmutableMap.builder();
        for (Product p : nodes) {
            products.put(p.name, p);
        }
        return new Builder(products.build());
    }

    public Walker walker(Function<BoundName, ?> action) {
        return new Walker(this, action);
    }

    public static final class Walker {
        final PlanGraph g;
        final Function<BoundName, ?> action;
        final Set<BoundName> visited = Sets.newHashSet();

        private Walker(PlanGraph g, Function<BoundName, ?> action) {
            this.g = g;
            this.action = action;
        }

        public void walk(BoundName node) {
            if (!visited.add(node)) {
                return;
            }
            action.apply(node);
            for (BoundName desc : g.edges.get(node)) {
                walk(desc);
            }
        }
    }

    /**
     * @param prods the required products.
     */
    public Recipe makeRecipe(final Set<BoundName> prods) throws DependencyCycleException, MissingProductException {
        return new RecipeMaker(this).makeRecipe(prods);
    }
}