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/*
* Copyright (C) 2014 The CyanogenMod Project
*
* 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 org.lineageos.eleven.loaders;
import android.database.AbstractCursor;
import android.database.Cursor;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
/**
* This cursor basically wraps a song cursor and is given a list of the order of the ids of the
* contents of the cursor. It wraps the Cursor and simulates the internal cursor being sorted
* by moving the point to the appropriate spot
*/
public class SortedCursor extends AbstractCursor {
// cursor to wrap
private final Cursor mCursor;
// the map of external indices to internal indices
private ArrayList<Integer> mOrderedPositions;
// this contains the ids that weren't found in the underlying cursor
private ArrayList<Long> mMissingIds;
// this contains the mapped cursor positions and afterwards the extra ids that weren't found
private HashMap<Long, Integer> mMapCursorPositions;
// extra we want to store with the cursor
private ArrayList<Object> mExtraData;
/**
* @param cursor to wrap
* @param order the list of unique ids in sorted order to display
* @param columnName the column name of the id to look up in the internal cursor
*/
public SortedCursor(final Cursor cursor, final long[] order, final String columnName,
final List<? extends Object> extraData) {
if (cursor == null) {
throw new IllegalArgumentException("Non-null cursor is needed");
}
mCursor = cursor;
mMissingIds = buildCursorPositionMapping(order, columnName, extraData);
}
/**
* This function populates mOrderedPositions with the cursor positions in the order based
* on the order passed in
* @param order the target order of the internal cursor
* @param extraData Extra data we want to add to the cursor
* @return returns the ids that aren't found in the underlying cursor
*/
private ArrayList<Long> buildCursorPositionMapping(final long[] order,
final String columnName, final List<? extends Object> extraData) {
ArrayList<Long> missingIds = new ArrayList<Long>();
mOrderedPositions = new ArrayList<Integer>(mCursor.getCount());
mExtraData = new ArrayList<Object>();
mMapCursorPositions = new HashMap<Long, Integer>(mCursor.getCount());
final int idPosition = mCursor.getColumnIndex(columnName);
if (mCursor.moveToFirst()) {
// first figure out where each of the ids are in the cursor
do {
mMapCursorPositions.put(mCursor.getLong(idPosition), mCursor.getPosition());
} while (mCursor.moveToNext());
// now create the ordered positions to map to the internal cursor given the
// external sort order
for (int i = 0; order != null && i < order.length; i++) {
final long id = order[i];
if (mMapCursorPositions.containsKey(id)) {
mOrderedPositions.add(mMapCursorPositions.get(id));
mMapCursorPositions.remove(id);
if (extraData != null) {
mExtraData.add(extraData.get(i));
}
} else {
missingIds.add(id);
}
}
mCursor.moveToFirst();
}
return missingIds;
}
/**
* @return the list of ids that weren't found in the underlying cursor
*/
public ArrayList<Long> getMissingIds() {
return mMissingIds;
}
/**
* @return the list of ids that were in the underlying cursor but not part of the ordered list
*/
public Collection<Long> getExtraIds() {
return mMapCursorPositions.keySet();
}
/**
* @return the extra object data that was passed in to be attached to the current row
*/
public Object getExtraData() {
int position = getPosition();
return position < mExtraData.size() ? mExtraData.get(position) : null;
}
@Override
public void close() {
mCursor.close();
super.close();
}
@Override
public int getCount() {
return mOrderedPositions.size();
}
@Override
public String[] getColumnNames() {
return mCursor.getColumnNames();
}
@Override
public String getString(int column) {
return mCursor.getString(column);
}
@Override
public short getShort(int column) {
return mCursor.getShort(column);
}
@Override
public int getInt(int column) {
return mCursor.getInt(column);
}
@Override
public long getLong(int column) {
return mCursor.getLong(column);
}
@Override
public float getFloat(int column) {
return mCursor.getFloat(column);
}
@Override
public double getDouble(int column) {
return mCursor.getDouble(column);
}
@Override
public boolean isNull(int column) {
return mCursor.isNull(column);
}
@Override
public boolean onMove(int oldPosition, int newPosition) {
if (newPosition >= 0 && newPosition < getCount()) {
mCursor.moveToPosition(mOrderedPositions.get(newPosition));
return true;
}
return false;
}
}
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