/*
 * Copyright (C) 2006 The Android Open Source 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 android.database;

A base class for Cursors that store their data in CursorWindows. 

The cursor owns the cursor window it uses.  When the cursor is closed,
its window is also closed.  Likewise, when the window used by the cursor is
changed, its old window is closed.  This policy of strict ownership ensures
that cursor windows are not leaked.
 Subclasses are responsible for filling the cursor window with data during AbstractCursor.onMove(int, int), allocating a new cursor window if necessary. During AbstractCursor.requery(), the existing cursor window should be cleared and filled with new data. 

If the contents of the cursor change or become invalid, the old window must be closed
(because it is owned by the cursor) and set to null.

/**
 * A base class for Cursors that store their data in {@link CursorWindow}s.
 * <p>
 * The cursor owns the cursor window it uses.  When the cursor is closed,
 * its window is also closed.  Likewise, when the window used by the cursor is
 * changed, its old window is closed.  This policy of strict ownership ensures
 * that cursor windows are not leaked.
 * </p><p>
 * Subclasses are responsible for filling the cursor window with data during
 * {@link #onMove(int, int)}, allocating a new cursor window if necessary.
 * During {@link #requery()}, the existing cursor window should be cleared and
 * filled with new data.
 * </p><p>
 * If the contents of the cursor change or become invalid, the old window must be closed
 * (because it is owned by the cursor) and set to null.
 * </p>
 */
public abstract class AbstractWindowedCursor extends AbstractCursor {
    
The cursor window owned by this cursor.
/**
     * The cursor window owned by this cursor.
     */
    protected CursorWindow mWindow;

    @Override
    public byte[] getBlob(int columnIndex) {
        checkPosition();
        return mWindow.getBlob(mPos, columnIndex);
    }

    @Override
    public String getString(int columnIndex) {
        checkPosition();
        return mWindow.getString(mPos, columnIndex);
    }

    @Override
    public void copyStringToBuffer(int columnIndex, CharArrayBuffer buffer) {
        checkPosition();
        mWindow.copyStringToBuffer(mPos, columnIndex, buffer);
    }

    @Override
    public short getShort(int columnIndex) {
        checkPosition();
        return mWindow.getShort(mPos, columnIndex);
    }

    @Override
    public int getInt(int columnIndex) {
        checkPosition();
        return mWindow.getInt(mPos, columnIndex);
    }

    @Override
    public long getLong(int columnIndex) {
        checkPosition();
        return mWindow.getLong(mPos, columnIndex);
    }

    @Override
    public float getFloat(int columnIndex) {
        checkPosition();
        return mWindow.getFloat(mPos, columnIndex);
    }

    @Override
    public double getDouble(int columnIndex) {
        checkPosition();
        return mWindow.getDouble(mPos, columnIndex);
    }

    @Override
    public boolean isNull(int columnIndex) {
        checkPosition();
        return mWindow.getType(mPos, columnIndex) == Cursor.FIELD_TYPE_NULL;
    }

    
Deprecated:
Use getType/**
     * @deprecated Use {@link #getType}
     */
    @Deprecated
    public boolean isBlob(int columnIndex) {
        return getType(columnIndex) == Cursor.FIELD_TYPE_BLOB;
    }

    
Deprecated:
Use getType/**
     * @deprecated Use {@link #getType}
     */
    @Deprecated
    public boolean isString(int columnIndex) {
        return getType(columnIndex) == Cursor.FIELD_TYPE_STRING;
    }

    
Deprecated:
Use getType/**
     * @deprecated Use {@link #getType}
     */
    @Deprecated
    public boolean isLong(int columnIndex) {
        return getType(columnIndex) == Cursor.FIELD_TYPE_INTEGER;
    }

    
Deprecated:
Use getType/**
     * @deprecated Use {@link #getType}
     */
    @Deprecated
    public boolean isFloat(int columnIndex) {
        return getType(columnIndex) == Cursor.FIELD_TYPE_FLOAT;
    }

    @Override
    public int getType(int columnIndex) {
        checkPosition();
        return mWindow.getType(mPos, columnIndex);
    }

    @Override
    protected void checkPosition() {
        super.checkPosition();
        
        if (mWindow == null) {
            throw new StaleDataException("Attempting to access a closed CursorWindow." +
                    "Most probable cause: cursor is deactivated prior to calling this method.");
        }
    }

    @Override
    public CursorWindow getWindow() {
        return mWindow;
    }

    
Sets a new cursor window for the cursor to use.

The cursor takes ownership of the provided cursor window; the cursor window
will be closed when the cursor is closed or when the cursor adopts a new
cursor window.

If the cursor previously had a cursor window, then it is closed when the
new cursor window is assigned.

Params:
window – The new cursor window, typically a remote cursor window./**
     * Sets a new cursor window for the cursor to use.
     * <p>
     * The cursor takes ownership of the provided cursor window; the cursor window
     * will be closed when the cursor is closed or when the cursor adopts a new
     * cursor window.
     * </p><p>
     * If the cursor previously had a cursor window, then it is closed when the
     * new cursor window is assigned.
     * </p>
     *
     * @param window The new cursor window, typically a remote cursor window.
     */
    public void setWindow(CursorWindow window) {
        if (window != mWindow) {
            closeWindow();
            mWindow = window;
        }
    }

    
Returns true if the cursor has an associated cursor window.
Returns:
True if the cursor has an associated cursor window./**
     * Returns true if the cursor has an associated cursor window.
     *
     * @return True if the cursor has an associated cursor window.
     */
    public boolean hasWindow() {
        return mWindow != null;
    }

    
Closes the cursor window and sets mWindow to null. 
@hide
/**
     * Closes the cursor window and sets {@link #mWindow} to null.
     * @hide
     */
    protected void closeWindow() {
        if (mWindow != null) {
            mWindow.close();
            mWindow = null;
        }
    }

    
If there is a window, clear it.
Otherwise, creates a new window.
Params:
name – The window name.
@hide
/**
     * If there is a window, clear it.
     * Otherwise, creates a new window.
     *
     * @param name The window name.
     * @hide
     */
    protected void clearOrCreateWindow(String name) {
        if (mWindow == null) {
            mWindow = new CursorWindow(name);
        } else {
            mWindow.clear();
        }
    }

    
@hide
/** @hide */
    @Override
    protected void onDeactivateOrClose() {
        super.onDeactivateOrClose();
        closeWindow();
    }
}