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