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