| /* |
| * 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 com.google.errorprone.annotations.CanIgnoreReturnValue; |
| import java.nio.ByteBuffer; |
| 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><b>Warning:</b> The result of calling any methods after calling {@link #hash} is undefined. |
| * |
| * <p><b>Warning:</b> Using a specific character encoding when hashing a {@link CharSequence} with |
| * {@link #putString(CharSequence, Charset)} is generally only useful for cross-language |
| * compatibility (otherwise prefer {@link #putUnencodedChars}). However, the character encodings |
| * must be identical across languages. Also beware that {@link Charset} definitions may occasionally |
| * change between Java releases. |
| * |
| * <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().putByte(b1).putByte(b2).putByte(b3).hash() |
| * newHasher().putByte(b1).putBytes(new byte[] { b2, b3 }).hash() |
| * newHasher().putBytes(new byte[] { b1, b2, b3 }).hash() |
| * }</pre> |
| * |
| * <p>If you wish to avoid this, you should either prepend or append the size of each chunk. Keep in |
| * mind that when dealing with char sequences, the encoded form of two concatenated char sequences |
| * is not equivalent to the concatenation of their encoded form. Therefore, {@link |
| * #putString(CharSequence, Charset)} should only be used consistently with <i>complete</i> |
| * sequences and not broken into chunks. |
| * |
| * @author Kevin Bourrillion |
| * @since 11.0 |
| */ |
| @Beta |
| @CanIgnoreReturnValue |
| 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 putBytes(ByteBuffer bytes); |
| |
| @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. In |
| * other words, no character encoding is performed; the low byte and high byte of each {@code |
| * char} are hashed directly (in that order). The input must not be updated while this method is |
| * in progress. |
| * |
| * <p><b>Warning:</b> This method will produce different output than most other languages do when |
| * running the same hash function on the equivalent input. For cross-language compatibility, use |
| * {@link #putString}, usually with a charset of UTF-8. For other use cases, use {@code |
| * putUnencodedChars}. |
| * |
| * @since 15.0 (since 11.0 as putString(CharSequence)). |
| */ |
| @Override |
| Hasher putUnencodedChars(CharSequence charSequence); |
| |
| /** |
| * Equivalent to {@code putBytes(charSequence.toString().getBytes(charset))}. |
| * |
| * <p><b>Warning:</b> This method, which reencodes the input before hashing it, is useful only for |
| * cross-language compatibility. For other use cases, prefer {@link #putUnencodedChars}, which is |
| * faster, produces the same output across Java releases, and hashes every {@code char} in the |
| * input, even if some are invalid. |
| */ |
| @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(); |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @deprecated This returns {@link Object#hashCode()}; you almost certainly mean to call {@code |
| * hash().asInt()}. |
| */ |
| @Override |
| @Deprecated |
| int hashCode(); |
| } |