168 lines
5.2 KiB
Java
168 lines
5.2 KiB
Java
/*
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* Copyright (c) 2019 Hemanth Savarala.
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*
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* Licensed under the GNU General Public License v3
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*
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* This is free software: you can redistribute it and/or modify it under
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* the terms of the GNU General Public License as published by
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* the Free Software Foundation either version 3 of the License, or (at your option) any later version.
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*
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* This software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*/
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package code.name.monkey.retromusic.loaders;
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import android.database.AbstractCursor;
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import android.database.Cursor;
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import androidx.annotation.NonNull;
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import androidx.annotation.Nullable;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.HashMap;
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/**
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* This cursor basically wraps a song cursor and is given a list of the order of the ids of the
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* contents of the cursor. It wraps the Cursor and simulates the internal cursor being sorted
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* by moving the point to the appropriate spot
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*/
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public class SortedCursor extends AbstractCursor {
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// cursor to wrap
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private final Cursor mCursor;
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// the map of external indices to internal indices
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private ArrayList<Integer> mOrderedPositions;
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// this contains the ids that weren't found in the underlying cursor
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private ArrayList<String> mMissingValues;
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// this contains the mapped cursor positions and afterwards the extra ids that weren't found
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private HashMap<String, Integer> mMapCursorPositions;
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/**
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* @param cursor to wrap
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* @param order the list of unique ids in sorted order to display
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* @param columnName the column name of the id to look up in the internal cursor
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*/
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public SortedCursor(@NonNull final Cursor cursor, @Nullable final String[] order, final String columnName) {
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mCursor = cursor;
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mMissingValues = buildCursorPositionMapping(order, columnName);
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}
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/**
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* This function populates mOrderedPositions with the cursor positions in the order based
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* on the order passed in
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*
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* @param order the target order of the internal cursor
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* @return returns the ids that aren't found in the underlying cursor
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*/
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@NonNull
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private ArrayList<String> buildCursorPositionMapping(@Nullable final String[] order, final String columnName) {
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ArrayList<String> missingValues = new ArrayList<>();
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mOrderedPositions = new ArrayList<>(mCursor.getCount());
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mMapCursorPositions = new HashMap<>(mCursor.getCount());
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final int valueColumnIndex = mCursor.getColumnIndex(columnName);
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if (mCursor.moveToFirst()) {
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// first figure out where each of the ids are in the cursor
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do {
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mMapCursorPositions.put(mCursor.getString(valueColumnIndex), mCursor.getPosition());
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} while (mCursor.moveToNext());
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if (order != null) {
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// now create the ordered positions to map to the internal cursor given the
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// external sort order
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for (final String value : order) {
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if (mMapCursorPositions.containsKey(value)) {
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mOrderedPositions.add(mMapCursorPositions.get(value));
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mMapCursorPositions.remove(value);
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} else {
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missingValues.add(value);
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}
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}
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}
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mCursor.moveToFirst();
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}
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return missingValues;
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}
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/**
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* @return the list of ids that weren't found in the underlying cursor
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*/
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public ArrayList<String> getMissingValues() {
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return mMissingValues;
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}
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/**
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* @return the list of ids that were in the underlying cursor but not part of the ordered list
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*/
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@NonNull
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public Collection<String> getExtraValues() {
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return mMapCursorPositions.keySet();
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}
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@Override
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public void close() {
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mCursor.close();
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super.close();
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}
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@Override
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public int getCount() {
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return mOrderedPositions.size();
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}
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@Override
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public String[] getColumnNames() {
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return mCursor.getColumnNames();
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}
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@Override
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public String getString(int column) {
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return mCursor.getString(column);
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}
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@Override
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public short getShort(int column) {
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return mCursor.getShort(column);
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}
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@Override
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public int getInt(int column) {
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return mCursor.getInt(column);
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}
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@Override
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public long getLong(int column) {
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return mCursor.getLong(column);
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}
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@Override
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public float getFloat(int column) {
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return mCursor.getFloat(column);
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}
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@Override
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public double getDouble(int column) {
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return mCursor.getDouble(column);
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}
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@Override
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public boolean isNull(int column) {
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return mCursor.isNull(column);
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}
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@Override
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public boolean onMove(int oldPosition, int newPosition) {
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if (newPosition >= 0 && newPosition < getCount()) {
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mCursor.moveToPosition(mOrderedPositions.get(newPosition));
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return true;
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}
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return false;
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}
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}
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