/* * Copyright (C) 2012 The Android Open Source Project * * 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 com.android.internal.util; import java.io.PrintWriter; import java.io.Writer; /** * Lightweight wrapper around {@link PrintWriter} that automatically indents * newlines based on internal state. It also automatically wraps long lines * based on given line length. *
* Delays writing indent until first actual write on a newline, enabling indent * modification after newline. */ public class IndentingPrintWriter extends PrintWriter { private final String mSingleIndent; private final int mWrapLength; /** Mutable version of current indent */ private StringBuilder mIndentBuilder = new StringBuilder(); /** Cache of current {@link #mIndentBuilder} value */ private char[] mCurrentIndent; /** Length of current line being built, excluding any indent */ private int mCurrentLength; /** * Flag indicating if we're currently sitting on an empty line, and that * next write should be prefixed with the current indent. */ private boolean mEmptyLine = true; public IndentingPrintWriter(Writer writer, String singleIndent) { this(writer, singleIndent, -1); } public IndentingPrintWriter(Writer writer, String singleIndent, int wrapLength) { super(writer); mSingleIndent = singleIndent; mWrapLength = wrapLength; } public void increaseIndent() { mIndentBuilder.append(mSingleIndent); mCurrentIndent = null; } public void decreaseIndent() { mIndentBuilder.delete(0, mSingleIndent.length()); mCurrentIndent = null; } public void printPair(String key, Object value) { print(key + "=" + String.valueOf(value) + " "); } @Override public void write(char[] buf, int offset, int count) { final int indentLength = mIndentBuilder.length(); final int bufferEnd = offset + count; int lineStart = offset; int lineEnd = offset; // March through incoming buffer looking for newlines while (lineEnd < bufferEnd) { char ch = buf[lineEnd++]; mCurrentLength++; if (ch == '\n') { maybeWriteIndent(); super.write(buf, lineStart, lineEnd - lineStart); lineStart = lineEnd; mEmptyLine = true; mCurrentLength = 0; } // Wrap if we've pushed beyond line length if (mWrapLength > 0 && mCurrentLength >= mWrapLength - indentLength) { if (!mEmptyLine) { // Give ourselves a fresh line to work with super.write('\n'); mEmptyLine = true; mCurrentLength = lineEnd - lineStart; } else { // We need more than a dedicated line, slice it hard maybeWriteIndent(); super.write(buf, lineStart, lineEnd - lineStart); super.write('\n'); mEmptyLine = true; lineStart = lineEnd; mCurrentLength = 0; } } } if (lineStart != lineEnd) { maybeWriteIndent(); super.write(buf, lineStart, lineEnd - lineStart); } } private void maybeWriteIndent() { if (mEmptyLine) { mEmptyLine = false; if (mIndentBuilder.length() != 0) { if (mCurrentIndent == null) { mCurrentIndent = mIndentBuilder.toString().toCharArray(); } super.write(mCurrentIndent, 0, mCurrentIndent.length); } } } }