1 /* 2 * Copyright (C) 2007 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.internal.util; 18 19 /** 20 * {@link CharSequence} utility methods. 21 */ 22 public class CharSequences { 23 24 /** 25 * Adapts {@link CharSequence} to an array of ASCII (7-bits per character) 26 * bytes. 27 * 28 * @param bytes ASCII bytes 29 */ 30 public static CharSequence forAsciiBytes(final byte[] bytes) { 31 return new CharSequence() { 32 public char charAt(int index) { 33 return (char) bytes[index]; 34 } 35 36 public int length() { 37 return bytes.length; 38 } 39 40 public CharSequence subSequence(int start, int end) { 41 return forAsciiBytes(bytes, start, end); 42 } 43 44 public String toString() { 45 return new String(bytes); 46 } 47 }; 48 } 49 50 /** 51 * Adapts {@link CharSequence} to an array of ASCII (7-bits per character) 52 * bytes. 53 * 54 * @param bytes ASCII bytes 55 * @param start index, inclusive 56 * @param end index, exclusive 57 * 58 * @throws IndexOutOfBoundsException if start or end are negative, if end 59 * is greater than length(), or if start is greater than end 60 */ 61 public static CharSequence forAsciiBytes(final byte[] bytes, 62 final int start, final int end) { 63 validate(start, end, bytes.length); 64 return new CharSequence() { 65 public char charAt(int index) { 66 return (char) bytes[index + start]; 67 } 68 69 public int length() { 70 return end - start; 71 } 72 73 public CharSequence subSequence(int newStart, int newEnd) { 74 newStart -= start; 75 newEnd -= start; 76 validate(newStart, newEnd, length()); 77 return forAsciiBytes(bytes, newStart, newEnd); 78 } 79 80 public String toString() { 81 return new String(bytes, start, length()); 82 } 83 }; 84 } 85 86 static void validate(int start, int end, int length) { 87 if (start < 0) throw new IndexOutOfBoundsException(); 88 if (end < 0) throw new IndexOutOfBoundsException(); 89 if (end > length) throw new IndexOutOfBoundsException(); 90 if (start > end) throw new IndexOutOfBoundsException(); 91 } 92 93 /** 94 * Compares two character sequences for equality. 95 */ 96 public static boolean equals(CharSequence a, CharSequence b) { 97 if (a.length() != b.length()) { 98 return false; 99 } 100 101 int length = a.length(); 102 for (int i = 0; i < length; i++) { 103 if (a.charAt(i) != b.charAt(i)) { 104 return false; 105 } 106 } 107 return true; 108 } 109 110 /** 111 * Compares two character sequences with API like {@link Comparable#compareTo}. 112 * 113 * @param me The CharSequence that receives the compareTo call. 114 * @param another The other CharSequence. 115 * @return See {@link Comparable#compareTo}. 116 */ 117 public static int compareToIgnoreCase(CharSequence me, CharSequence another) { 118 // Code adapted from String#compareTo 119 int myLen = me.length(), anotherLen = another.length(); 120 int myPos = 0, anotherPos = 0, result; 121 int end = (myLen < anotherLen) ? myLen : anotherLen; 122 123 while (myPos < end) { 124 if ((result = Character.toLowerCase(me.charAt(myPos++)) 125 - Character.toLowerCase(another.charAt(anotherPos++))) != 0) { 126 return result; 127 } 128 } 129 return myLen - anotherLen; 130 } 131 } 132
