Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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.apache.tinkerpop.gremlin.process.traversal.step.util; import org.apache.commons.lang.ArrayUtils; import org.apache.tinkerpop.gremlin.process.traversal.Traversal; import org.apache.tinkerpop.gremlin.process.traversal.Traverser; import org.apache.tinkerpop.gremlin.process.traversal.step.TraversalParent; import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalUtil; import java.io.Serializable; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.function.Supplier; /** * The parameters held by a {@link Traversal}. * * @author Marko A. Rodriguez (http://markorodriguez.com) * @author Stephen Mallette (http://stephen.genoprime.com) */ public final class Parameters implements Cloneable, Serializable { private static final Object[] EMPTY_ARRAY = new Object[0]; private Map<Object, List<Object>> parameters = new HashMap<>(); /** * Checks for existence of key in parameter set. * * @param key the key to check * @return {@code true} if the key is present and {@code false} otherwise */ public boolean contains(final Object key) { return this.parameters.containsKey(key); } /** * Renames a key in the parameter set. * * @param oldKey the key to rename * @param newKey the new name of the key */ public void rename(final Object oldKey, final Object newKey) { this.parameters.put(newKey, this.parameters.remove(oldKey)); } public <S, E> List<E> get(final Traverser.Admin<S> traverser, final Object key, final Supplier<E> defaultValue) { final List<E> values = (List<E>) this.parameters.get(key); if (null == values) return Collections.singletonList(defaultValue.get()); final List<E> result = new ArrayList<>(); for (final Object value : values) { result.add( value instanceof Traversal.Admin ? TraversalUtil.apply(traverser, (Traversal.Admin<S, E>) value) : (E) value); } return result; } /** * Gets the value of a key and if that key isn't present returns the default value from the {@link Supplier}. * * @param key the key to retrieve * @param defaultValue the default value generator */ public <E> List<E> get(final Object key, final Supplier<E> defaultValue) { final List<E> list = (List<E>) this.parameters.get(key); return (null == list) ? Collections.singletonList(defaultValue.get()) : list; } /** * Remove a key from the parameter set. * * @param key the key to remove * @return the value of the removed key */ public Object remove(final Object key) { return parameters.remove(key); } public <S> Object[] getKeyValues(final Traverser.Admin<S> traverser, final Object... exceptKeys) { if (this.parameters.size() == 0) return EMPTY_ARRAY; final List<Object> keyValues = new ArrayList<>(); for (final Map.Entry<Object, List<Object>> entry : this.parameters.entrySet()) { if (!ArrayUtils.contains(exceptKeys, entry.getKey())) { for (final Object value : entry.getValue()) { keyValues.add(entry.getKey() instanceof Traversal.Admin ? TraversalUtil.apply(traverser, (Traversal.Admin<S, ?>) entry.getKey()) : entry.getKey()); keyValues.add(value instanceof Traversal.Admin ? TraversalUtil.apply(traverser, (Traversal.Admin<S, ?>) value) : value); } } } return keyValues.toArray(new Object[keyValues.size()]); } /** * Gets an immutable set of the parameters without evaluating them in the context of a {@link Traverser} as * is done in {@link #getKeyValues(Traverser.Admin, Object...)}. * * @param exceptKeys keys to not include in the returned {@link Map} */ public Map<Object, List<Object>> getRaw(final Object... exceptKeys) { if (parameters.isEmpty()) return Collections.emptyMap(); final List<Object> exceptions = Arrays.asList(exceptKeys); final Map<Object, List<Object>> raw = new HashMap<>(); for (Map.Entry<Object, List<Object>> entry : parameters.entrySet()) { if (!exceptions.contains(entry.getKey())) raw.put(entry.getKey(), entry.getValue()); } return Collections.unmodifiableMap(raw); } /** * Set parameters given key/value pairs. */ public void set(final Object... keyValues) { for (int i = 0; i < keyValues.length; i = i + 2) { if (keyValues[i + 1] != null) { List<Object> values = this.parameters.get(keyValues[i]); if (null == values) { values = new ArrayList<>(); values.add(keyValues[i + 1]); this.parameters.put(keyValues[i], values); } else { values.add(keyValues[i + 1]); } } } } public void integrateTraversals(final TraversalParent step) { for (final List<Object> values : this.parameters.values()) { for (final Object object : values) { if (object instanceof Traversal.Admin) { step.integrateChild((Traversal.Admin) object); } } } } public <S, E> List<Traversal.Admin<S, E>> getTraversals() { List<Traversal.Admin<S, E>> result = new ArrayList<>(); for (final List<Object> list : this.parameters.values()) { for (final Object object : list) { if (object instanceof Traversal.Admin) { result.add((Traversal.Admin) object); } } } return result; } public Parameters clone() { try { final Parameters clone = (Parameters) super.clone(); clone.parameters = new HashMap<>(); for (final Map.Entry<Object, List<Object>> entry : this.parameters.entrySet()) { final List<Object> values = new ArrayList<>(); for (final Object value : entry.getValue()) { values.add(value instanceof Traversal.Admin ? ((Traversal.Admin) value).clone() : value); } clone.parameters .put(entry.getKey() instanceof Traversal.Admin ? ((Traversal.Admin) entry.getKey()).clone() : entry.getKey(), values); } return clone; } catch (final CloneNotSupportedException e) { throw new IllegalStateException(e.getMessage(), e); } } public int hashCode() { int result = 1; for (final Map.Entry<Object, List<Object>> entry : this.parameters.entrySet()) { result ^= entry.getKey().hashCode(); for (final Object value : entry.getValue()) { result ^= Integer.rotateLeft(value.hashCode(), entry.getKey().hashCode()); } } return result; } public String toString() { return this.parameters.toString(); } }