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/*
 * Copyright 2008 Google Inc.
 *
 * 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 java.lang;

import static javaemul.internal.InternalPreconditions.checkStringElementIndex;

/**
 * A base class to share implementation between {@link StringBuffer} and {@link StringBuilder}.
 * 

* Most methods will give expected performance results. Exception is {@link #setCharAt(int, char)}, * which is O(n), and thus should not be used many times on the same StringBuffer. */ abstract class AbstractStringBuilder implements CharSequence, Appendable { String string; AbstractStringBuilder(String string) { this.string = string; } @Override public int length() { return string.length(); } public void setLength(int newLength) { int oldLength = length(); if (newLength < oldLength) { string = string.substring(0, newLength); } else if (newLength > oldLength) { string += String.valueOf(new char[newLength - oldLength]); } } public int capacity() { // This implementation does not track capacity. return Integer.MAX_VALUE; } @SuppressWarnings("unused") public void ensureCapacity(int ignoredCapacity) { // This implementation does not track capacity } public void trimToSize() { // This implementation does not track capacity } @Override public char charAt(int index) { return string.charAt(index); } public void getChars(int srcStart, int srcEnd, char[] dst, int dstStart) { string.getChars(srcStart, srcEnd, dst, dstStart); } /** * Warning! This method is much slower than the JRE implementation. If you need to do * character level manipulation, you are strongly advised to use a char[] directly. */ public void setCharAt(int index, char x) { replace0(index, index + 1, String.valueOf(x)); } @Override public CharSequence subSequence(int start, int end) { return string.substring(start, end); } public String substring(int begin) { return string.substring(begin); } public String substring(int begin, int end) { return string.substring(begin, end); } public int indexOf(String x) { return string.indexOf(x); } public int indexOf(String x, int start) { return string.indexOf(x, start); } public int lastIndexOf(String s) { return string.lastIndexOf(s); } public int lastIndexOf(String s, int start) { return string.lastIndexOf(s, start); } @Override public String toString() { return string; } void appendCodePoint0(int x) { string += String.fromCodePoint(x); } void replace0(int start, int end, String toInsert) { int length = string.length(); if (end > length) { end = length; } else { // Only checking for start > end; since rest is checked with substring. checkStringElementIndex(start, end + 1); } string = string.substring(0, start) + toInsert + string.substring(end); } void reverse0() { int length = string.length(); if (length <= 1) { return; } char[] buffer = new char[length]; buffer[0] = string.charAt(length - 1); for (int i = 1; i < length; i++) { buffer[i] = string.charAt(length - 1 - i); if (Character.isSurrogatePair(buffer[i], buffer[i - 1])) { swap(buffer, i - 1, i); } } string = new String(buffer); } private static void swap(char[] buffer, int f, int s) { char tmp = buffer[f]; buffer[f] = buffer[s]; buffer[s] = tmp; } }





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