com.google.common.graph.ValueGraphBuilder Maven / Gradle / Ivy
/*
* Copyright (C) 2016 The Guava 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 com.google.common.graph;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.graph.Graphs.checkNonNegative;
import com.google.common.annotations.Beta;
import com.google.common.base.Optional;
/**
* A builder for constructing instances of {@link MutableValueGraph} or {@link ImmutableValueGraph}
* with user-defined properties.
*
* A graph built by this class will have the following properties by default:
*
*
* - does not allow self-loops
*
- orders {@link Graph#nodes()} in the order in which the elements were added
*
*
* Examples of use:
*
*
{@code
* // Building a mutable value graph
* MutableValueGraph graph =
* ValueGraphBuilder.undirected().allowsSelfLoops(true).build();
* graph.putEdgeValue("San Francisco", "San Francisco", 0.0);
* graph.putEdgeValue("San Jose", "San Jose", 0.0);
* graph.putEdgeValue("San Francisco", "San Jose", 48.4);
*
* // Building an immutable value graph
* ImmutableValueGraph immutableGraph =
* ValueGraphBuilder.undirected()
* .allowsSelfLoops(true)
* .immutable()
* .putEdgeValue("San Francisco", "San Francisco", 0.0)
* .putEdgeValue("San Jose", "San Jose", 0.0)
* .putEdgeValue("San Francisco", "San Jose", 48.4)
* .build();
* }
*
* @author James Sexton
* @author Joshua O'Madadhain
* @param The most general node type this builder will support. This is normally {@code Object}
* unless it is constrained by using a method like {@link #nodeOrder}, or the builder is
* constructed based on an existing {@code ValueGraph} using {@link #from(ValueGraph)}.
* @param The most general value type this builder will support. This is normally {@code Object}
* unless the builder is constructed based on an existing {@code Graph} using {@link
* #from(ValueGraph)}.
* @since 20.0
*/
@Beta
public final class ValueGraphBuilder extends AbstractGraphBuilder {
/** Creates a new instance with the specified edge directionality. */
private ValueGraphBuilder(boolean directed) {
super(directed);
}
/** Returns a {@link ValueGraphBuilder} for building directed graphs. */
public static ValueGraphBuilder directed() {
return new ValueGraphBuilder<>(true);
}
/** Returns a {@link ValueGraphBuilder} for building undirected graphs. */
public static ValueGraphBuilder undirected() {
return new ValueGraphBuilder<>(false);
}
/**
* Returns a {@link ValueGraphBuilder} initialized with all properties queryable from {@code
* graph}.
*
* The "queryable" properties are those that are exposed through the {@link ValueGraph}
* interface, such as {@link ValueGraph#isDirected()}. Other properties, such as {@link
* #expectedNodeCount(int)}, are not set in the new builder.
*/
public static ValueGraphBuilder from(ValueGraph graph) {
return new ValueGraphBuilder(graph.isDirected())
.allowsSelfLoops(graph.allowsSelfLoops())
.nodeOrder(graph.nodeOrder());
}
/**
* Returns an {@link ImmutableValueGraph.Builder} with the properties of this {@link
* ValueGraphBuilder}.
*
* The returned builder can be used for populating an {@link ImmutableValueGraph}.
*
* @since 28.0
*/
public ImmutableValueGraph.Builder immutable() {
ValueGraphBuilder castBuilder = cast();
return new ImmutableValueGraph.Builder<>(castBuilder);
}
/**
* Specifies whether the graph will allow self-loops (edges that connect a node to itself).
* Attempting to add a self-loop to a graph that does not allow them will throw an {@link
* UnsupportedOperationException}.
*
* The default value is {@code false}.
*/
public ValueGraphBuilder allowsSelfLoops(boolean allowsSelfLoops) {
this.allowsSelfLoops = allowsSelfLoops;
return this;
}
/**
* Specifies the expected number of nodes in the graph.
*
* @throws IllegalArgumentException if {@code expectedNodeCount} is negative
*/
public ValueGraphBuilder expectedNodeCount(int expectedNodeCount) {
this.expectedNodeCount = Optional.of(checkNonNegative(expectedNodeCount));
return this;
}
/**
* Specifies the order of iteration for the elements of {@link Graph#nodes()}.
*
* The default value is {@link ElementOrder#insertion() insertion order}.
*/
public ValueGraphBuilder nodeOrder(ElementOrder nodeOrder) {
ValueGraphBuilder newBuilder = cast();
newBuilder.nodeOrder = checkNotNull(nodeOrder);
return newBuilder;
}
/**
* Returns an empty {@link MutableValueGraph} with the properties of this {@link
* ValueGraphBuilder}.
*/
public MutableValueGraph build() {
return new ConfigurableMutableValueGraph<>(this);
}
@SuppressWarnings("unchecked")
private ValueGraphBuilder cast() {
return (ValueGraphBuilder) this;
}
}