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.OutputStream;
020import java.io.Serializable;
021import java.nio.charset.Charset;
022import org.checkerframework.checker.nullness.qual.Nullable;
023
024/**
025 * Funnels for common types. All implementations are serializable.
026 *
027 * @author Dimitris Andreou
028 * @since 11.0
029 */
030@Beta
031public final class Funnels {
032  private Funnels() {}
033
034  /** Returns a funnel that extracts the bytes from a {@code byte} array. */
035  public static Funnel<byte[]> byteArrayFunnel() {
036    return ByteArrayFunnel.INSTANCE;
037  }
038
039  private enum ByteArrayFunnel implements Funnel<byte[]> {
040    INSTANCE;
041
042    public void funnel(byte[] from, PrimitiveSink into) {
043      into.putBytes(from);
044    }
045
046    @Override
047    public String toString() {
048      return "Funnels.byteArrayFunnel()";
049    }
050  }
051
052  /**
053   * Returns a funnel that extracts the characters from a {@code CharSequence}, a character at a
054   * time, without performing any encoding. If you need to use a specific encoding, use {@link
055   * Funnels#stringFunnel(Charset)} instead.
056   *
057   * @since 15.0 (since 11.0 as {@code Funnels.stringFunnel()}.
058   */
059  public static Funnel<CharSequence> unencodedCharsFunnel() {
060    return UnencodedCharsFunnel.INSTANCE;
061  }
062
063  private enum UnencodedCharsFunnel implements Funnel<CharSequence> {
064    INSTANCE;
065
066    public void funnel(CharSequence from, PrimitiveSink into) {
067      into.putUnencodedChars(from);
068    }
069
070    @Override
071    public String toString() {
072      return "Funnels.unencodedCharsFunnel()";
073    }
074  }
075
076  /**
077   * Returns a funnel that encodes the characters of a {@code CharSequence} with the specified
078   * {@code Charset}.
079   *
080   * @since 15.0
081   */
082  public static Funnel<CharSequence> stringFunnel(Charset charset) {
083    return new StringCharsetFunnel(charset);
084  }
085
086  private static class StringCharsetFunnel implements Funnel<CharSequence>, Serializable {
087    private final Charset charset;
088
089    StringCharsetFunnel(Charset charset) {
090      this.charset = Preconditions.checkNotNull(charset);
091    }
092
093    public void funnel(CharSequence from, PrimitiveSink into) {
094      into.putString(from, charset);
095    }
096
097    @Override
098    public String toString() {
099      return "Funnels.stringFunnel(" + charset.name() + ")";
100    }
101
102    @Override
103    public boolean equals(@Nullable Object o) {
104      if (o instanceof StringCharsetFunnel) {
105        StringCharsetFunnel funnel = (StringCharsetFunnel) o;
106        return this.charset.equals(funnel.charset);
107      }
108      return false;
109    }
110
111    @Override
112    public int hashCode() {
113      return StringCharsetFunnel.class.hashCode() ^ charset.hashCode();
114    }
115
116    Object writeReplace() {
117      return new SerializedForm(charset);
118    }
119
120    private static class SerializedForm implements Serializable {
121      private final String charsetCanonicalName;
122
123      SerializedForm(Charset charset) {
124        this.charsetCanonicalName = charset.name();
125      }
126
127      private Object readResolve() {
128        return stringFunnel(Charset.forName(charsetCanonicalName));
129      }
130
131      private static final long serialVersionUID = 0;
132    }
133  }
134
135  /**
136   * Returns a funnel for integers.
137   *
138   * @since 13.0
139   */
140  public static Funnel<Integer> integerFunnel() {
141    return IntegerFunnel.INSTANCE;
142  }
143
144  private enum IntegerFunnel implements Funnel<Integer> {
145    INSTANCE;
146
147    public void funnel(Integer from, PrimitiveSink into) {
148      into.putInt(from);
149    }
150
151    @Override
152    public String toString() {
153      return "Funnels.integerFunnel()";
154    }
155  }
156
157  /**
158   * Returns a funnel that processes an {@code Iterable} by funneling its elements in iteration
159   * order with the specified funnel. No separators are added between the elements.
160   *
161   * @since 15.0
162   */
163  public static <E> Funnel<Iterable<? extends E>> sequentialFunnel(Funnel<E> elementFunnel) {
164    return new SequentialFunnel<E>(elementFunnel);
165  }
166
167  private static class SequentialFunnel<E> implements Funnel<Iterable<? extends E>>, Serializable {
168    private final Funnel<E> elementFunnel;
169
170    SequentialFunnel(Funnel<E> elementFunnel) {
171      this.elementFunnel = Preconditions.checkNotNull(elementFunnel);
172    }
173
174    public void funnel(Iterable<? extends E> from, PrimitiveSink into) {
175      for (E e : from) {
176        elementFunnel.funnel(e, into);
177      }
178    }
179
180    @Override
181    public String toString() {
182      return "Funnels.sequentialFunnel(" + elementFunnel + ")";
183    }
184
185    @Override
186    public boolean equals(@Nullable Object o) {
187      if (o instanceof SequentialFunnel) {
188        SequentialFunnel<?> funnel = (SequentialFunnel<?>) o;
189        return elementFunnel.equals(funnel.elementFunnel);
190      }
191      return false;
192    }
193
194    @Override
195    public int hashCode() {
196      return SequentialFunnel.class.hashCode() ^ elementFunnel.hashCode();
197    }
198  }
199
200  /**
201   * Returns a funnel for longs.
202   *
203   * @since 13.0
204   */
205  public static Funnel<Long> longFunnel() {
206    return LongFunnel.INSTANCE;
207  }
208
209  private enum LongFunnel implements Funnel<Long> {
210    INSTANCE;
211
212    public void funnel(Long from, PrimitiveSink into) {
213      into.putLong(from);
214    }
215
216    @Override
217    public String toString() {
218      return "Funnels.longFunnel()";
219    }
220  }
221
222  /**
223   * Wraps a {@code PrimitiveSink} as an {@link OutputStream}, so it is easy to {@link Funnel#funnel
224   * funnel} an object to a {@code PrimitiveSink} if there is already a way to write the contents of
225   * the object to an {@code OutputStream}.
226   *
227   * <p>The {@code close} and {@code flush} methods of the returned {@code OutputStream} do nothing,
228   * and no method throws {@code IOException}.
229   *
230   * @since 13.0
231   */
232  public static OutputStream asOutputStream(PrimitiveSink sink) {
233    return new SinkAsStream(sink);
234  }
235
236  private static class SinkAsStream extends OutputStream {
237    final PrimitiveSink sink;
238
239    SinkAsStream(PrimitiveSink sink) {
240      this.sink = Preconditions.checkNotNull(sink);
241    }
242
243    @Override
244    public void write(int b) {
245      sink.putByte((byte) b);
246    }
247
248    @Override
249    public void write(byte[] bytes) {
250      sink.putBytes(bytes);
251    }
252
253    @Override
254    public void write(byte[] bytes, int off, int len) {
255      sink.putBytes(bytes, off, len);
256    }
257
258    @Override
259    public String toString() {
260      return "Funnels.asOutputStream(" + sink + ")";
261    }
262  }
263}