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
034public final class Funnels {
035  private Funnels() {}
036
037  /** Returns a funnel that extracts the bytes from a {@code byte} array. */
038  public static Funnel<byte[]> byteArrayFunnel() {
039    return ByteArrayFunnel.INSTANCE;
040  }
041
042  private enum ByteArrayFunnel implements Funnel<byte[]> {
043    INSTANCE;
044
045    @Override
046    public void funnel(byte[] from, PrimitiveSink into) {
047      into.putBytes(from);
048    }
049
050    @Override
051    public String toString() {
052      return "Funnels.byteArrayFunnel()";
053    }
054  }
055
056  /**
057   * Returns a funnel that extracts the characters from a {@code CharSequence}, a character at a
058   * time, without performing any encoding. If you need to use a specific encoding, use {@link
059   * Funnels#stringFunnel(Charset)} instead.
060   *
061   * @since 15.0 (since 11.0 as {@code Funnels.stringFunnel()}.
062   */
063  public static Funnel<CharSequence> unencodedCharsFunnel() {
064    return UnencodedCharsFunnel.INSTANCE;
065  }
066
067  private enum UnencodedCharsFunnel implements Funnel<CharSequence> {
068    INSTANCE;
069
070    @Override
071    public void funnel(CharSequence from, PrimitiveSink into) {
072      into.putUnencodedChars(from);
073    }
074
075    @Override
076    public String toString() {
077      return "Funnels.unencodedCharsFunnel()";
078    }
079  }
080
081  /**
082   * Returns a funnel that encodes the characters of a {@code CharSequence} with the specified
083   * {@code Charset}.
084   *
085   * @since 15.0
086   */
087  public static Funnel<CharSequence> stringFunnel(Charset charset) {
088    return new StringCharsetFunnel(charset);
089  }
090
091  private static class StringCharsetFunnel implements Funnel<CharSequence>, Serializable {
092    private final Charset charset;
093
094    StringCharsetFunnel(Charset charset) {
095      this.charset = Preconditions.checkNotNull(charset);
096    }
097
098    @Override
099    public void funnel(CharSequence from, PrimitiveSink into) {
100      into.putString(from, charset);
101    }
102
103    @Override
104    public String toString() {
105      return "Funnels.stringFunnel(" + charset.name() + ")";
106    }
107
108    @Override
109    public boolean equals(@CheckForNull Object o) {
110      if (o instanceof StringCharsetFunnel) {
111        StringCharsetFunnel funnel = (StringCharsetFunnel) o;
112        return this.charset.equals(funnel.charset);
113      }
114      return false;
115    }
116
117    @Override
118    public int hashCode() {
119      return StringCharsetFunnel.class.hashCode() ^ charset.hashCode();
120    }
121
122    Object writeReplace() {
123      return new SerializedForm(charset);
124    }
125
126    private void readObject(ObjectInputStream stream) throws InvalidObjectException {
127      throw new InvalidObjectException("Use SerializedForm");
128    }
129
130    private static class SerializedForm implements Serializable {
131      private final String charsetCanonicalName;
132
133      SerializedForm(Charset charset) {
134        this.charsetCanonicalName = charset.name();
135      }
136
137      private Object readResolve() {
138        return stringFunnel(Charset.forName(charsetCanonicalName));
139      }
140
141      private static final long serialVersionUID = 0;
142    }
143  }
144
145  /**
146   * Returns a funnel for integers.
147   *
148   * @since 13.0
149   */
150  public static Funnel<Integer> integerFunnel() {
151    return IntegerFunnel.INSTANCE;
152  }
153
154  private enum IntegerFunnel implements Funnel<Integer> {
155    INSTANCE;
156
157    @Override
158    public void funnel(Integer from, PrimitiveSink into) {
159      into.putInt(from);
160    }
161
162    @Override
163    public String toString() {
164      return "Funnels.integerFunnel()";
165    }
166  }
167
168  /**
169   * Returns a funnel that processes an {@code Iterable} by funneling its elements in iteration
170   * order with the specified funnel. No separators are added between the elements.
171   *
172   * @since 15.0
173   */
174  public static <E extends @Nullable Object> Funnel<Iterable<? extends E>> sequentialFunnel(
175      Funnel<E> elementFunnel) {
176    return new SequentialFunnel<>(elementFunnel);
177  }
178
179  private static class SequentialFunnel<E extends @Nullable Object>
180      implements Funnel<Iterable<? extends E>>, Serializable {
181    private final Funnel<E> elementFunnel;
182
183    SequentialFunnel(Funnel<E> elementFunnel) {
184      this.elementFunnel = Preconditions.checkNotNull(elementFunnel);
185    }
186
187    @Override
188    public void funnel(Iterable<? extends E> from, PrimitiveSink into) {
189      for (E e : from) {
190        elementFunnel.funnel(e, into);
191      }
192    }
193
194    @Override
195    public String toString() {
196      return "Funnels.sequentialFunnel(" + elementFunnel + ")";
197    }
198
199    @Override
200    public boolean equals(@CheckForNull Object o) {
201      if (o instanceof SequentialFunnel) {
202        SequentialFunnel<?> funnel = (SequentialFunnel<?>) o;
203        return elementFunnel.equals(funnel.elementFunnel);
204      }
205      return false;
206    }
207
208    @Override
209    public int hashCode() {
210      return SequentialFunnel.class.hashCode() ^ elementFunnel.hashCode();
211    }
212  }
213
214  /**
215   * Returns a funnel for longs.
216   *
217   * @since 13.0
218   */
219  public static Funnel<Long> longFunnel() {
220    return LongFunnel.INSTANCE;
221  }
222
223  private enum LongFunnel implements Funnel<Long> {
224    INSTANCE;
225
226    @Override
227    public void funnel(Long from, PrimitiveSink into) {
228      into.putLong(from);
229    }
230
231    @Override
232    public String toString() {
233      return "Funnels.longFunnel()";
234    }
235  }
236
237  /**
238   * Wraps a {@code PrimitiveSink} as an {@link OutputStream}, so it is easy to {@link Funnel#funnel
239   * funnel} an object to a {@code PrimitiveSink} if there is already a way to write the contents of
240   * the object to an {@code OutputStream}.
241   *
242   * <p>The {@code close} and {@code flush} methods of the returned {@code OutputStream} do nothing,
243   * and no method throws {@code IOException}.
244   *
245   * @since 13.0
246   */
247  public static OutputStream asOutputStream(PrimitiveSink sink) {
248    return new SinkAsStream(sink);
249  }
250
251  private static class SinkAsStream extends OutputStream {
252    final PrimitiveSink sink;
253
254    SinkAsStream(PrimitiveSink sink) {
255      this.sink = Preconditions.checkNotNull(sink);
256    }
257
258    @Override
259    public void write(int b) {
260      sink.putByte((byte) b);
261    }
262
263    @Override
264    public void write(byte[] bytes) {
265      sink.putBytes(bytes);
266    }
267
268    @Override
269    public void write(byte[] bytes, int off, int len) {
270      sink.putBytes(bytes, off, len);
271    }
272
273    @Override
274    public String toString() {
275      return "Funnels.asOutputStream(" + sink + ")";
276    }
277  }
278}