core/java/com/android/internal/content/SelectionBuilder.java

/*
 * Copyright (C) 2010 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 com.android.internal.content;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.text.TextUtils;

import java.util.ArrayList;

/**
 * Helper for building selection clauses for {@link SQLiteDatabase}. Each
 * appended clause is combined using {@code AND}. This class is <em>not</em>
 * thread safe.
 *
 * @hide
 */
public class SelectionBuilder {
    private StringBuilder mSelection = new StringBuilder();
    private ArrayList<String> mSelectionArgs = new ArrayList<String>();

    /**
     * Reset any internal state, allowing this builder to be recycled.
     */
    public SelectionBuilder reset() {
        mSelection.setLength(0);
        mSelectionArgs.clear();
        return this;
    }

    /**
     * Append the given selection clause to the internal state. Each clause is
     * surrounded with parenthesis and combined using {@code AND}.
     */
    public SelectionBuilder append(String selection, Object... selectionArgs) {
        if (TextUtils.isEmpty(selection)) {
            if (selectionArgs != null && selectionArgs.length > 0) {
                throw new IllegalArgumentException(
                        "Valid selection required when including arguments");
            }

            // Shortcut when clause is empty
            return this;
        }

        if (mSelection.length() > 0) {
            mSelection.append(" AND ");
        }

        mSelection.append("(").append(selection).append(")");
        if (selectionArgs != null) {
            for (Object arg : selectionArgs) {
                // TODO: switch to storing direct Object instances once
                // http://b/2464440 is fixed
                mSelectionArgs.add(String.valueOf(arg));
            }
        }

        return this;
    }

    /**
     * Return selection string for current internal state.
     *
     * @see #getSelectionArgs()
     */
    public String getSelection() {
        return mSelection.toString();
    }

    /**
     * Return selection arguments for current internal state.
     *
     * @see #getSelection()
     */
    public String[] getSelectionArgs() {
        return mSelectionArgs.toArray(new String[mSelectionArgs.size()]);
    }

    /**
     * Execute query using the current internal state as {@code WHERE} clause.
     * Missing arguments as treated as {@code null}.
     */
    public Cursor query(SQLiteDatabase db, String table, String[] columns, String orderBy) {
        return query(db, table, columns, null, null, orderBy, null);
    }

    /**
     * Execute query using the current internal state as {@code WHERE} clause.
     */
    public Cursor query(SQLiteDatabase db, String table, String[] columns, String groupBy,
            String having, String orderBy, String limit) {
        return db.query(table, columns, getSelection(), getSelectionArgs(), groupBy, having,
                orderBy, limit);
    }

    /**
     * Execute update using the current internal state as {@code WHERE} clause.
     */
    public int update(SQLiteDatabase db, String table, ContentValues values) {
        return db.update(table, values, getSelection(), getSelectionArgs());
    }

    /**
     * Execute delete using the current internal state as {@code WHERE} clause.
     */
    public int delete(SQLiteDatabase db, String table) {
        return db.delete(table, getSelection(), getSelectionArgs());
    }
}