1 files changed, 125 insertions, 0 deletions
diff --git a/src/com/cyngn/eleven/loaders/SortedCursor.java b/src/com/cyngn/eleven/loaders/SortedCursor.java
new file mode 100644
index 0000000..ffd43b4
--- /dev/null
+++ b/src/com/cyngn/eleven/loaders/SortedCursor.java
@@ -0,0 +1,125 @@
+/*
+ * Copyright (C) 2014 Cyanogen, Inc.
+ */
+package com.cyngn.eleven.loaders;
+
+import android.database.AbstractCursor;
+import android.database.Cursor;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+
+/**
+ * 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;
+
+    /**
+     * @param cursor to wrap
+     * @param order the list of 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) {
+        if (cursor == null) {
+            throw new IllegalArgumentException("Non-null cursor is needed");
+        }
+
+        mCursor = cursor;
+        buildCursorPositionMapping(order, columnName);
+    }
+
+    /**
+     * 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
+     */
+    private void buildCursorPositionMapping(final long[] order, final String columnName) {
+        mOrderedPositions = new ArrayList<Integer>(mCursor.getCount());
+
+        HashMap<Long, Integer> mapCursorPositions = 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 {
+                mapCursorPositions.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 (long id : order) {
+                if (mapCursorPositions.containsKey(id)) {
+                    mOrderedPositions.add(mapCursorPositions.get(id));
+                }
+            }
+        }
+    }
+
+    @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;
+    }
+}