001/*
002 * Copyright (C) 2011 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005 * in compliance with the License. You may obtain a copy of the License at
006 *
007 * http://www.apache.org/licenses/LICENSE-2.0
008 *
009 * Unless required by applicable law or agreed to in writing, software distributed under the License
010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
011 * or implied. See the License for the specific language governing permissions and limitations under
012 * the License.
013 */
014
015package com.google.common.hash;
016
017import com.google.common.annotations.Beta;
018import com.google.common.base.Preconditions;
019import java.io.InvalidObjectException;
020import java.io.ObjectInputStream;
021import java.io.OutputStream;
022import java.io.Serializable;
023import java.nio.charset.Charset;
024import javax.annotation.CheckForNull;
025import org.checkerframework.checker.nullness.qual.Nullable;
026
027/**
028 * Funnels for common types. All implementations are serializable.
029 *
030 * @author Dimitris Andreou
031 * @since 11.0
032 */
033@Beta
034@ElementTypesAreNonnullByDefault
035public final class Funnels {
036  private Funnels() {}
037
038  /** Returns a funnel that extracts the bytes from a {@code byte} array. */
039  public static Funnel<byte[]> byteArrayFunnel() {
040    return ByteArrayFunnel.INSTANCE;
041  }
042
043  private enum ByteArrayFunnel implements Funnel<byte[]> {
044    INSTANCE;
045
046    @Override
047    public void funnel(byte[] from, PrimitiveSink into) {
048      into.putBytes(from);
049    }
050
051    @Override
052    public String toString() {
053      return "Funnels.byteArrayFunnel()";
054    }
055  }
056
057  /**
058   * Returns a funnel that extracts the characters from a {@code CharSequence}, a character at a
059   * time, without performing any encoding. If you need to use a specific encoding, use {@link
060   * Funnels#stringFunnel(Charset)} instead.
061   *
062   * @since 15.0 (since 11.0 as {@code Funnels.stringFunnel()}.
063   */
064  public static Funnel<CharSequence> unencodedCharsFunnel() {
065    return UnencodedCharsFunnel.INSTANCE;
066  }
067
068  private enum UnencodedCharsFunnel implements Funnel<CharSequence> {
069    INSTANCE;
070
071    @Override
072    public void funnel(CharSequence from, PrimitiveSink into) {
073      into.putUnencodedChars(from);
074    }
075
076    @Override
077    public String toString() {
078      return "Funnels.unencodedCharsFunnel()";
079    }
080  }
081
082  /**
083   * Returns a funnel that encodes the characters of a {@code CharSequence} with the specified
084   * {@code Charset}.
085   *
086   * @since 15.0
087   */
088  public static Funnel<CharSequence> stringFunnel(Charset charset) {
089    return new StringCharsetFunnel(charset);
090  }
091
092  private static class StringCharsetFunnel implements Funnel<CharSequence>, Serializable {
093    private final Charset charset;
094
095    StringCharsetFunnel(Charset charset) {
096      this.charset = Preconditions.checkNotNull(charset);
097    }
098
099    @Override
100    public void funnel(CharSequence from, PrimitiveSink into) {
101      into.putString(from, charset);
102    }
103
104    @Override
105    public String toString() {
106      return "Funnels.stringFunnel(" + charset.name() + ")";
107    }
108
109    @Override
110    public boolean equals(@CheckForNull Object o) {
111      if (o instanceof StringCharsetFunnel) {
112        StringCharsetFunnel funnel = (StringCharsetFunnel) o;
113        return this.charset.equals(funnel.charset);
114      }
115      return false;
116    }
117
118    @Override
119    public int hashCode() {
120      return StringCharsetFunnel.class.hashCode() ^ charset.hashCode();
121    }
122
123    Object writeReplace() {
124      return new SerializedForm(charset);
125    }
126
127    private void readObject(ObjectInputStream stream) throws InvalidObjectException {
128      throw new InvalidObjectException("Use SerializedForm");
129    }
130
131    private static class SerializedForm implements Serializable {
132      private final String charsetCanonicalName;
133
134      SerializedForm(Charset charset) {
135        this.charsetCanonicalName = charset.name();
136      }
137
138      private Object readResolve() {
139        return stringFunnel(Charset.forName(charsetCanonicalName));
140      }
141
142      private static final long serialVersionUID = 0;
143    }
144  }
145
146  /**
147   * Returns a funnel for integers.
148   *
149   * @since 13.0
150   */
151  public static Funnel<Integer> integerFunnel() {
152    return IntegerFunnel.INSTANCE;
153  }
154
155  private enum IntegerFunnel implements Funnel<Integer> {
156    INSTANCE;
157
158    @Override
159    public void funnel(Integer from, PrimitiveSink into) {
160      into.putInt(from);
161    }
162
163    @Override
164    public String toString() {
165      return "Funnels.integerFunnel()";
166    }
167  }
168
169  /**
170   * Returns a funnel that processes an {@code Iterable} by funneling its elements in iteration
171   * order with the specified funnel. No separators are added between the elements.
172   *
173   * @since 15.0
174   */
175  public static <E extends @Nullable Object> Funnel<Iterable<? extends E>> sequentialFunnel(
176      Funnel<E> elementFunnel) {
177    return new SequentialFunnel<>(elementFunnel);
178  }
179
180  private static class SequentialFunnel<E extends @Nullable Object>
181      implements Funnel<Iterable<? extends E>>, Serializable {
182    private final Funnel<E> elementFunnel;
183
184    SequentialFunnel(Funnel<E> elementFunnel) {
185      this.elementFunnel = Preconditions.checkNotNull(elementFunnel);
186    }
187
188    @Override
189    public void funnel(Iterable<? extends E> from, PrimitiveSink into) {
190      for (E e : from) {
191        elementFunnel.funnel(e, into);
192      }
193    }
194
195    @Override
196    public String toString() {
197      return "Funnels.sequentialFunnel(" + elementFunnel + ")";
198    }
199
200    @Override
201    public boolean equals(@CheckForNull Object o) {
202      if (o instanceof SequentialFunnel) {
203        SequentialFunnel<?> funnel = (SequentialFunnel<?>) o;
204        return elementFunnel.equals(funnel.elementFunnel);
205      }
206      return false;
207    }
208
209    @Override
210    public int hashCode() {
211      return SequentialFunnel.class.hashCode() ^ elementFunnel.hashCode();
212    }
213  }
214
215  /**
216   * Returns a funnel for longs.
217   *
218   * @since 13.0
219   */
220  public static Funnel<Long> longFunnel() {
221    return LongFunnel.INSTANCE;
222  }
223
224  private enum LongFunnel implements Funnel<Long> {
225    INSTANCE;
226
227    @Override
228    public void funnel(Long from, PrimitiveSink into) {
229      into.putLong(from);
230    }
231
232    @Override
233    public String toString() {
234      return "Funnels.longFunnel()";
235    }
236  }
237
238  /**
239   * Wraps a {@code PrimitiveSink} as an {@link OutputStream}, so it is easy to {@link Funnel#funnel
240   * funnel} an object to a {@code PrimitiveSink} if there is already a way to write the contents of
241   * the object to an {@code OutputStream}.
242   *
243   * <p>The {@code close} and {@code flush} methods of the returned {@code OutputStream} do nothing,
244   * and no method throws {@code IOException}.
245   *
246   * @since 13.0
247   */
248  public static OutputStream asOutputStream(PrimitiveSink sink) {
249    return new SinkAsStream(sink);
250  }
251
252  private static class SinkAsStream extends OutputStream {
253    final PrimitiveSink sink;
254
255    SinkAsStream(PrimitiveSink sink) {
256      this.sink = Preconditions.checkNotNull(sink);
257    }
258
259    @Override
260    public void write(int b) {
261      sink.putByte((byte) b);
262    }
263
264    @Override
265    public void write(byte[] bytes) {
266      sink.putBytes(bytes);
267    }
268
269    @Override
270    public void write(byte[] bytes, int off, int len) {
271      sink.putBytes(bytes, off, len);
272    }
273
274    @Override
275    public String toString() {
276      return "Funnels.asOutputStream(" + sink + ")";
277    }
278  }
279}