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Java example source code file (ConsString.java)
The ConsString.java Java example source code/* * Copyright (c) 2010, 2013, 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. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * 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 jdk.nashorn.internal.runtime; import java.util.ArrayDeque; import java.util.Deque; /** * This class represents a string composed of two parts which may themselves be * instances of <tt>ConsString or {@link String}. Copying of characters to * a proper string is delayed until it becomes necessary. */ public final class ConsString implements CharSequence { private CharSequence left, right; final private int length; private boolean flat = false; /** * Constructor * * Takes two {@link CharSequence} instances that, concatenated, forms this {@code ConsString} * * @param left left char sequence * @param right right char sequence */ public ConsString(final CharSequence left, final CharSequence right) { assert left instanceof String || left instanceof ConsString; assert right instanceof String || right instanceof ConsString; this.left = left; this.right = right; length = left.length() + right.length(); } @Override public String toString() { return (String) flattened(); } @Override public int length() { return length; } @Override public char charAt(final int index) { return flattened().charAt(index); } @Override public CharSequence subSequence(final int start, final int end) { return flattened().subSequence(start, end); } private CharSequence flattened() { if (!flat) { flatten(); } return left; } private void flatten() { // We use iterative traversal as recursion may exceed the stack size limit. final char[] chars = new char[length]; int pos = length; // Strings are most often composed by appending to the end, which causes ConsStrings // to be very unbalanced, with mostly single string elements on the right and a long // linear list on the left. Traversing from right to left helps to keep the stack small // in this scenario. final Deque<CharSequence> stack = new ArrayDeque<>(); stack.addFirst(left); CharSequence cs = right; do { if (cs instanceof ConsString) { final ConsString cons = (ConsString) cs; stack.addFirst(cons.left); cs = cons.right; } else { final String str = (String) cs; pos -= str.length(); str.getChars(0, str.length(), chars, pos); cs = stack.isEmpty() ? null : stack.pollFirst(); } } while (cs != null); left = new String(chars); right = ""; flat = true; } } Other Java examples (source code examples)Here is a short list of links related to this Java ConsString.java source code file: |
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