1 /* 2 * Copyright (C) 2016 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.voicemail.impl.utils; 18 19 import java.io.PrintWriter; 20 import java.io.Writer; 21 import java.util.Arrays; 22 23 /** 24 * Lightweight wrapper around {@link PrintWriter} that automatically indents newlines based on 25 * internal state. It also automatically wraps long lines based on given line length. 26 * 27 * <p>Delays writing indent until first actual write on a newline, enabling indent modification 28 * after newline. 29 */ 30 public class IndentingPrintWriter extends PrintWriter { 31 32 private final String mSingleIndent; 33 private final int mWrapLength; 34 35 /** Mutable version of current indent */ 36 private StringBuilder mIndentBuilder = new StringBuilder(); 37 /** Cache of current {@link #mIndentBuilder} value */ 38 private char[] mCurrentIndent; 39 /** Length of current line being built, excluding any indent */ 40 private int mCurrentLength; 41 42 /** 43 * Flag indicating if we're currently sitting on an empty line, and that next write should be 44 * prefixed with the current indent. 45 */ 46 private boolean mEmptyLine = true; 47 48 private char[] mSingleChar = new char[1]; 49 IndentingPrintWriter(Writer writer, String singleIndent)50 public IndentingPrintWriter(Writer writer, String singleIndent) { 51 this(writer, singleIndent, -1); 52 } 53 IndentingPrintWriter(Writer writer, String singleIndent, int wrapLength)54 public IndentingPrintWriter(Writer writer, String singleIndent, int wrapLength) { 55 super(writer); 56 mSingleIndent = singleIndent; 57 mWrapLength = wrapLength; 58 } 59 increaseIndent()60 public void increaseIndent() { 61 mIndentBuilder.append(mSingleIndent); 62 mCurrentIndent = null; 63 } 64 decreaseIndent()65 public void decreaseIndent() { 66 mIndentBuilder.delete(0, mSingleIndent.length()); 67 mCurrentIndent = null; 68 } 69 printPair(String key, Object value)70 public void printPair(String key, Object value) { 71 print(key + "=" + String.valueOf(value) + " "); 72 } 73 printPair(String key, Object[] value)74 public void printPair(String key, Object[] value) { 75 print(key + "=" + Arrays.toString(value) + " "); 76 } 77 printHexPair(String key, int value)78 public void printHexPair(String key, int value) { 79 print(key + "=0x" + Integer.toHexString(value) + " "); 80 } 81 82 @Override println()83 public void println() { 84 write('\n'); 85 } 86 87 @Override write(int c)88 public void write(int c) { 89 mSingleChar[0] = (char) c; 90 write(mSingleChar, 0, 1); 91 } 92 93 @Override write(String s, int off, int len)94 public void write(String s, int off, int len) { 95 final char[] buf = new char[len]; 96 s.getChars(off, len - off, buf, 0); 97 write(buf, 0, len); 98 } 99 100 @Override write(char[] buf, int offset, int count)101 public void write(char[] buf, int offset, int count) { 102 final int indentLength = mIndentBuilder.length(); 103 final int bufferEnd = offset + count; 104 int lineStart = offset; 105 int lineEnd = offset; 106 107 // March through incoming buffer looking for newlines 108 while (lineEnd < bufferEnd) { 109 char ch = buf[lineEnd++]; 110 mCurrentLength++; 111 if (ch == '\n') { 112 maybeWriteIndent(); 113 super.write(buf, lineStart, lineEnd - lineStart); 114 lineStart = lineEnd; 115 mEmptyLine = true; 116 mCurrentLength = 0; 117 } 118 119 // Wrap if we've pushed beyond line length 120 if (mWrapLength > 0 && mCurrentLength >= mWrapLength - indentLength) { 121 if (!mEmptyLine) { 122 // Give ourselves a fresh line to work with 123 super.write('\n'); 124 mEmptyLine = true; 125 mCurrentLength = lineEnd - lineStart; 126 } else { 127 // We need more than a dedicated line, slice it hard 128 maybeWriteIndent(); 129 super.write(buf, lineStart, lineEnd - lineStart); 130 super.write('\n'); 131 mEmptyLine = true; 132 lineStart = lineEnd; 133 mCurrentLength = 0; 134 } 135 } 136 } 137 138 if (lineStart != lineEnd) { 139 maybeWriteIndent(); 140 super.write(buf, lineStart, lineEnd - lineStart); 141 } 142 } 143 maybeWriteIndent()144 private void maybeWriteIndent() { 145 if (mEmptyLine) { 146 mEmptyLine = false; 147 if (mIndentBuilder.length() != 0) { 148 if (mCurrentIndent == null) { 149 mCurrentIndent = mIndentBuilder.toString().toCharArray(); 150 } 151 super.write(mCurrentIndent, 0, mCurrentIndent.length); 152 } 153 } 154 } 155 } 156