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/*
* Copyright (C) 2007 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.dx.util;
import java.io.FilterWriter;
import java.io.IOException;
import java.io.Writer;
/**
* Writer that wraps another writer and passes width-limited and
* optionally-prefixed output to its subordinate. When lines are
* wrapped they are automatically indented based on the start of the
* line.
*/
public final class IndentingWriter extends FilterWriter {
/** null-ok; optional prefix for every line */
private final String prefix;
/** > 0; the maximum output width */
private final int width;
/** > 0; the maximum indent */
private final int maxIndent;
/** >= 0; current output column (zero-based) */
private int column;
/** whether indent spaces are currently being collected */
private boolean collectingIndent;
/** >= 0; current indent amount */
private int indent;
/**
* Constructs an instance.
*
* @param out non-null; writer to send final output to
* @param width >= 0; the maximum output width (not including
* <code>prefix</code>), or <code>0</code> for no maximum
* @param prefix non-null; the prefix for each line
*/
public IndentingWriter(Writer out, int width, String prefix) {
super(out);
if (out == null) {
throw new NullPointerException("out == null");
}
if (width < 0) {
throw new IllegalArgumentException("width < 0");
}
if (prefix == null) {
throw new NullPointerException("prefix == null");
}
this.width = (width != 0) ? width : Integer.MAX_VALUE;
this.maxIndent = width >> 1;
this.prefix = (prefix.length() == 0) ? null : prefix;
bol();
}
/**
* Constructs a no-prefix instance.
*
* @param out non-null; writer to send final output to
* @param width >= 0; the maximum output width (not including
* <code>prefix</code>), or <code>0</code> for no maximum
*/
public IndentingWriter(Writer out, int width) {
this(out, width, "");
}
/** {@inheritDoc} */
@Override
public void write(int c) throws IOException {
synchronized (lock) {
if (collectingIndent) {
if (c == ' ') {
indent++;
if (indent >= maxIndent) {
indent = maxIndent;
collectingIndent = false;
}
} else {
collectingIndent = false;
}
}
if ((column == width) && (c != '\n')) {
out.write('\n');
column = 0;
/*
* Note: No else, so this should fall through to the next
* if statement.
*/
}
if (column == 0) {
if (prefix != null) {
out.write(prefix);
}
if (!collectingIndent) {
for (int i = 0; i < indent; i++) {
out.write(' ');
}
column = indent;
}
}
out.write(c);
if (c == '\n') {
bol();
} else {
column++;
}
}
}
/** {@inheritDoc} */
@Override
public void write(char[] cbuf, int off, int len) throws IOException {
synchronized (lock) {
while (len > 0) {
write(cbuf[off]);
off++;
len--;
}
}
}
/** {@inheritDoc} */
@Override
public void write(String str, int off, int len) throws IOException {
synchronized (lock) {
while (len > 0) {
write(str.charAt(off));
off++;
len--;
}
}
}
/**
* Indicates that output is at the beginning of a line.
*/
private void bol() {
column = 0;
collectingIndent = (maxIndent != 0);
indent = 0;
}
}
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