1 /* 2 * Copyright (C) 2012 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 5 * in compliance with the License. You may obtain a copy of the License at 6 * 7 * http://www.apache.org/licenses/LICENSE-2.0 8 * 9 * Unless required by applicable law or agreed to in writing, software distributed under the License 10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 11 * or implied. See the License for the specific language governing permissions and limitations under 12 * the License. 13 */ 14 15 package com.google.common.io; 16 17 import static com.google.common.base.Preconditions.checkNotNull; 18 19 import com.google.common.annotations.GwtCompatible; 20 21 import java.io.IOException; 22 23 /** 24 * Provides simple GWT-compatible substitutes for {@code InputStream}, {@code OutputStream}, 25 * {@code Reader}, and {@code Writer} so that {@code BaseEncoding} can use streaming implementations 26 * while remaining GWT-compatible. 27 * 28 * @author Louis Wasserman 29 */ 30 @GwtCompatible(emulated = true) 31 final class GwtWorkarounds { GwtWorkarounds()32 private GwtWorkarounds() {} 33 34 /** 35 * A GWT-compatible substitute for a {@code Reader}. 36 */ 37 interface CharInput { read()38 int read() throws IOException; close()39 void close() throws IOException; 40 } 41 42 /** 43 * Views a {@code CharSequence} as a {@code CharInput}. 44 */ asCharInput(final CharSequence chars)45 static CharInput asCharInput(final CharSequence chars) { 46 checkNotNull(chars); 47 return new CharInput() { 48 int index = 0; 49 50 @Override 51 public int read() { 52 if (index < chars.length()) { 53 return chars.charAt(index++); 54 } else { 55 return -1; 56 } 57 } 58 59 @Override 60 public void close() { 61 index = chars.length(); 62 } 63 }; 64 } 65 66 /** 67 * A GWT-compatible substitute for an {@code InputStream}. 68 */ 69 interface ByteInput { read()70 int read() throws IOException; close()71 void close() throws IOException; 72 } 73 74 /** 75 * A GWT-compatible substitute for an {@code OutputStream}. 76 */ 77 interface ByteOutput { write(byte b)78 void write(byte b) throws IOException; flush()79 void flush() throws IOException; close()80 void close() throws IOException; 81 } 82 83 /** 84 * A GWT-compatible substitute for a {@code Writer}. 85 */ 86 interface CharOutput { write(char c)87 void write(char c) throws IOException; flush()88 void flush() throws IOException; close()89 void close() throws IOException; 90 } 91 92 /** 93 * Returns a {@code CharOutput} whose {@code toString()} method can be used 94 * to get the combined output. 95 */ stringBuilderOutput(int initialSize)96 static CharOutput stringBuilderOutput(int initialSize) { 97 final StringBuilder builder = new StringBuilder(initialSize); 98 return new CharOutput() { 99 100 @Override 101 public void write(char c) { 102 builder.append(c); 103 } 104 105 @Override 106 public void flush() {} 107 108 @Override 109 public void close() {} 110 111 @Override 112 public String toString() { 113 return builder.toString(); 114 } 115 }; 116 } 117 } 118 119