Mercurial > hg > graal-jvmci-8
diff graal/Compiler/src/com/sun/c1x/util/ArrayMap.java @ 2507:9ec15d6914ca
Pull over of compiler from maxine repository.
author | Thomas Wuerthinger <thomas@wuerthinger.net> |
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date | Wed, 27 Apr 2011 11:43:22 +0200 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/graal/Compiler/src/com/sun/c1x/util/ArrayMap.java Wed Apr 27 11:43:22 2011 +0200 @@ -0,0 +1,117 @@ +/* + * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ +package com.sun.c1x.util; + +/** + * The {@code ArrayMap} class implements an efficient one-level map which is implemented + * as an array. Note that because of the one-level array inside, this data structure performs best + * when the range of integer keys is small and densely used. Note that the implementation can + * handle arbitrary intervals, including negative numbers, up to intervals of size 2^31 - 1. + * + * @author Ben L. Titzer + */ +public class ArrayMap<T> { + + private static final int INITIAL_SIZE = 5; // how big the initial array should be + private static final int EXTRA = 2; // how far on the left or right of a new element to grow + + Object[] map; + int low; + + /** + * Constructs a new {@code ArrayMap} with no initial assumptions. + */ + public ArrayMap() { + } + + /** + * Constructs a new {@code ArrayMap} that initially covers the specified interval. + * Note that this map will automatically expand if necessary later. + * @param low the low index, inclusive + * @param high the high index, exclusive + */ + public ArrayMap(int low, int high) { + this.low = low; + this.map = new Object[high - low + 1]; + } + + /** + * Puts a new value in the map at the specified index. + * @param i the index at which to store the value + * @param value the value to store at the specified index + */ + public void put(int i, T value) { + int index = i - low; + if (map == null) { + // no map yet + map = new Object[INITIAL_SIZE]; + low = index - 2; + map[INITIAL_SIZE / 2] = value; + } else if (index < 0) { + // grow backwards + growBackward(i, value); + } else if (index >= map.length) { + // grow forwards + growForward(i, value); + } else { + // no growth necessary + map[index] = value; + } + } + + /** + * Gets the value at the specified index in the map. + * @param i the index + * @return the value at the specified index; {@code null} if there is no value at the specified index, + * or if the index is out of the currently stored range + */ + public T get(int i) { + int index = i - low; + if (map == null || index < 0 || index >= map.length) { + return null; + } + Class<T> type = null; + return Util.uncheckedCast(type, map[index]); + } + + public int length() { + return map.length; + } + + private void growBackward(int i, T value) { + int nlow = i - EXTRA; + Object[] nmap = new Object[low - nlow + map.length]; + System.arraycopy(map, 0, nmap, low - nlow, map.length); + map = nmap; + low = nlow; + map[i - low] = value; + } + + private void growForward(int i, T value) { + int nlen = i - low + 1 + EXTRA; + Object[] nmap = new Object[nlen]; + System.arraycopy(map, 0, nmap, 0, map.length); + map = nmap; + map[i - low] = value; + } +}