81 lines
2.4 KiB
Java
81 lines
2.4 KiB
Java
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.os;
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import java.util.HashMap;
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/**
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* Helper class for writing pooled strings into a Parcel. It must be used
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* in conjunction with {@link android.os.PooledStringReader}. This really needs
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* to be pushed in to Parcel itself, but doing that is... complicated.
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* @hide
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*/
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public class PooledStringWriter {
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private final Parcel mOut;
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/**
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* Book-keeping for writing pooled string objects, mapping strings we have
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* written so far to their index in the pool. We deliberately use HashMap
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* here since performance is critical, we expect to be doing lots of adds to
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* it, and it is only a temporary object so its overall memory footprint is
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* not a signifciant issue.
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*/
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private final HashMap<String, Integer> mPool;
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/**
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* Book-keeping for writing pooling string objects, indicating where we
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* started writing the pool, which is where we need to ultimately store
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* how many strings are in the pool.
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*/
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private int mStart;
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/**
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* Next available index in the pool.
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*/
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private int mNext;
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public PooledStringWriter(Parcel out) {
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mOut = out;
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mPool = new HashMap<>();
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mStart = out.dataPosition();
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out.writeInt(0); // reserve space for final pool size.
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}
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public void writeString(String str) {
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final Integer cur = mPool.get(str);
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if (cur != null) {
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mOut.writeInt(cur);
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} else {
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mPool.put(str, mNext);
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mOut.writeInt(-(mNext+1));
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mOut.writeString(str);
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mNext++;
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}
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}
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public int getStringCount() {
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return mPool.size();
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}
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public void finish() {
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final int pos = mOut.dataPosition();
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mOut.setDataPosition(mStart);
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mOut.writeInt(mNext);
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mOut.setDataPosition(pos);
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}
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}
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