eaglercraft-1.8/sources/main/java/com/google/common/hash/Hasher.java
2022-12-25 01:12:28 -08:00

132 lines
3.9 KiB
Java

/*
* 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 java.nio.charset.Charset;
import com.google.common.annotations.Beta;
/**
* 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
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.
*
* @since 15.0 (since 11.0 as putString(CharSequence)).
*/
@Override
Hasher putUnencodedChars(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();
}