/*
 * Copyright (C) 2011 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.hash;

import com.google.common.annotations.Beta;

import java.nio.charset.Charset;

/**
 * A {@link PrimitiveSink} that can compute a hash code after reading the input. Each hasher should
 * translate all multibyte values ({@link #putInt(int)}, {@link #putLong(long)}, etc) to bytes
 * in little-endian order.
 *
 * <p>The result of calling any methods after calling {@link #hash} is undefined.
 *
 * <p><b>Warning:</b> Chunks of data that are put into the {@link Hasher} are not delimited.
 * The resulting {@link HashCode} is dependent only on the bytes inserted, and the order in which
 * they were inserted, not how those bytes were chunked into discrete put() operations. For example,
 * the following three expressions all generate colliding hash codes: <pre>   {@code
 *
 *   newHasher().putString("ab").putString("c").hash()
 *   newHasher().putString("a").putString("bc").hash()
 *   newHasher().putChar('a').putChar('b').putChar('c').hash()}</pre>
 *
 * If you wish to avoid this, you must explicitly delimit your data chunks. For example:
 * <pre>   {@code
 *
 *   newHasher().putString("ab").putByte(DELIM).putString("c").hash()}</pre>
 *
 * @author Kevin Bourrillion
 * @since 11.0
 */
@Beta
public interface Hasher extends PrimitiveSink {
  @Override Hasher putByte(byte b);
  @Override Hasher putBytes(byte[] bytes);
  @Override Hasher putBytes(byte[] bytes, int off, int len);
  @Override Hasher putShort(short s);
  @Override Hasher putInt(int i);
  @Override Hasher putLong(long l);

  /**
   * Equivalent to {@code putInt(Float.floatToRawIntBits(f))}.
   */
  @Override Hasher putFloat(float f);

  /**
   * Equivalent to {@code putLong(Double.doubleToRawLongBits(d))}.
   */
  @Override Hasher putDouble(double d);

  /**
   * Equivalent to {@code putByte(b ? (byte) 1 : (byte) 0)}.
   */
  @Override Hasher putBoolean(boolean b);
  @Override Hasher putChar(char c);

  /**
   * Equivalent to processing each {@code char} value in the {@code CharSequence}, in order.
   * The input must not be updated while this method is in progress.
   */
  @Override Hasher putString(CharSequence charSequence);

  /**
   * Equivalent to {@code putBytes(charSequence.toString().getBytes(charset))}.
   */
  @Override Hasher putString(CharSequence charSequence, Charset charset);

  /**
   * A simple convenience for {@code funnel.funnel(object, this)}.
   */
  <T> Hasher putObject(T instance, Funnel<? super T> funnel);

  /**
   * Computes a hash code based on the data that have been provided to this hasher. The result is
   * unspecified if this method is called more than once on the same instance.
   */
  HashCode hash();
}

@@ -1615,49 +1615,66 @@
 you 
-must explicitly delimit your data
+should either prepend or append the size of each
  chunk
-s
 .
+%0A *
  For
@@ -1693,35 +1693,32 @@
  %3Cpre%3E   %7B@code%0A
- *%0A
  *   newHasher()
@@ -1710,32 +1710,52 @@
 *   newHasher().
+putInt(s1.length()).
 putString(%22ab%22).
@@ -1752,27 +1752,30 @@
 ing(
-%22ab%22
+s1
 ).put
-Byte(DELIM
+Int(s2.length()
 ).pu
@@ -1774,35 +1774,34 @@
 th()).putString(
-%22c%22
+s2
 ).hash()%7D%3C/pre%3E%0A

Stop recommending the use of delimiters when hashing strings. ------------- Created by MOE: http://code.google.com/p/moe-java MOE_MIGRATED_REVID=38631621