001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.lang3.text.translate; 018 019 import java.io.IOException; 020 import java.io.Writer; 021 import java.io.StringWriter; 022 import java.util.Locale; 023 024 /** 025 * An API for translating text. 026 * Its core use is to escape and unescape text. Because escaping and unescaping 027 * is completely contextual, the API does not present two separate signatures. 028 * 029 * @author Apache Software Foundation 030 * @since 3.0 031 * @version $Id: CharSequenceTranslator.java 967237 2010-07-23 20:08:57Z mbenson $ 032 */ 033 public abstract class CharSequenceTranslator { 034 035 /** 036 * Translate a set of codepoints, represented by an int index into a CharSequence, 037 * into another set of codepoints. The number of codepoints consumed must be returned, 038 * and the only IOExceptions thrown must be from interacting with the Writer so that 039 * the top level API may reliable ignore StringWriter IOExceptions. 040 * 041 * @param input CharSequence that is being translated 042 * @param index int representing the current point of translation 043 * @param out Writer to translate the text to 044 * @return int count of codepoints consumed 045 * @throws IOException if and only if the Writer produces an IOException 046 */ 047 public abstract int translate(CharSequence input, int index, Writer out) throws IOException; 048 049 /** 050 * Helper for non-Writer usage. 051 * @param input CharSequence to be translated 052 * @return String output of translation 053 */ 054 public final String translate(CharSequence input) { 055 if (input == null) { 056 return null; 057 } 058 try { 059 StringWriter writer = new StringWriter(input.length() * 2); // TODO: Make the 2 part of the API??? 060 translate(input, writer); 061 return writer.toString(); 062 } catch (IOException ioe) { 063 // this should never ever happen while writing to a StringWriter 064 throw new RuntimeException(ioe); 065 } 066 } 067 068 // TODO: Point to CsvEscaper as a way to 'override'? 069 /** 070 * Translate an input onto a Writer. This is intentionally final as its algorithm is 071 * tightly coupled with the abstract method of this class. 072 * 073 * @param input CharSequence that is being translated 074 * @param out Writer to translate the text to 075 * @throws IOException if and only if the Writer produces an IOException 076 */ 077 public final void translate(CharSequence input, Writer out) throws IOException { 078 if (out == null) { 079 throw new IllegalArgumentException("The Writer must not be null"); 080 } 081 if (input == null) { 082 return; 083 } 084 int sz = Character.codePointCount(input, 0, input.length()); 085 for (int i = 0; i < sz; i++) { 086 087 // consumed is the number of codepoints consumed 088 int consumed = translate(input, i, out); 089 090 if(consumed == 0) { 091 out.write( Character.toChars( Character.codePointAt(input, i) ) ); 092 } else { 093 // contract with translators is that they have to understand codepoints and they just took care of a surrogate pair 094 for(int j=0; j<consumed; j++) { 095 if(i < sz - 2) { 096 i += Character.charCount( Character.codePointAt(input, i) ); 097 } else { 098 // If the String ends with a high surrogate, just add the 1 and don't worry about such things 099 i++; 100 } 101 } 102 // for loop will increment 1 anyway, so remove 1 to account for that 103 i--; 104 } 105 } 106 } 107 108 /** 109 * Helper method to create a merger of this translator with another set of 110 * translators. Useful in customizing the standard functionality. 111 * 112 * @param translators CharSequenceTranslator array of translators to merge with this one 113 * @return CharSequenceTranslator merging this translator with the others 114 */ 115 public final CharSequenceTranslator with(CharSequenceTranslator... translators) { 116 CharSequenceTranslator[] newArray = new CharSequenceTranslator[translators.length + 1]; 117 newArray[0] = this; 118 System.arraycopy(translators, 0, newArray, 1, translators.length); 119 return new AggregateTranslator(newArray); 120 } 121 122 /** 123 * <p>Returns an upper case hexadecimal <code>String</code> for the given 124 * character.</p> 125 * 126 * @param codepoint The codepoint to convert. 127 * @return An upper case hexadecimal <code>String</code> 128 */ 129 public static String hex(int codepoint) { 130 return Integer.toHexString(codepoint).toUpperCase(Locale.ENGLISH); 131 } 132 133 }