/*
* 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.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.StringWriter;
import java.io.Writer;
/**
* Class that takes a combined output destination and provides two
* output writers, one of which ends up writing to the left column and
* one which goes on the right.
*/
public final class TwoColumnOutput {
/** non-null; underlying writer for final output */
private final Writer out;
/** > 0; the left column width */
private final int leftWidth;
/** non-null; pending left column output */
private final StringBuffer leftBuf;
/** non-null; pending right column output */
private final StringBuffer rightBuf;
/** non-null; left column writer */
private final IndentingWriter leftColumn;
/** non-null; right column writer */
private final IndentingWriter rightColumn;
/**
* Turns the given two strings (with widths) and spacer into a formatted
* two-column string.
*
* @param s1 non-null; first string
* @param width1 > 0; width of the first column
* @param spacer non-null; spacer string
* @param s2 non-null; second string
* @param width2 > 0; width of the second column
* @return non-null; an appropriately-formatted string
*/
public static String toString(String s1, int width1, String spacer,
String s2, int width2) {
int len1 = s1.length();
int len2 = s2.length();
StringWriter sw = new StringWriter((len1 + len2) * 3);
TwoColumnOutput twoOut =
new TwoColumnOutput(sw, width1, width2, spacer);
try {
twoOut.getLeft().write(s1);
twoOut.getRight().write(s2);
} catch (IOException ex) {
throw new RuntimeException("shouldn't happen", ex);
}
twoOut.flush();
return sw.toString();
}
/**
* Constructs an instance.
*
* @param out non-null; writer to send final output to
* @param leftWidth > 0; width of the left column, in characters
* @param rightWidth > 0; width of the right column, in characters
* @param spacer non-null; spacer string to sit between the two columns
*/
public TwoColumnOutput(Writer out, int leftWidth, int rightWidth,
String spacer) {
if (out == null) {
throw new NullPointerException("out == null");
}
if (leftWidth < 1) {
throw new IllegalArgumentException("leftWidth < 1");
}
if (rightWidth < 1) {
throw new IllegalArgumentException("rightWidth < 1");
}
if (spacer == null) {
throw new NullPointerException("spacer == null");
}
StringWriter leftWriter = new StringWriter(1000);
StringWriter rightWriter = new StringWriter(1000);
this.out = out;
this.leftWidth = leftWidth;
this.leftBuf = leftWriter.getBuffer();
this.rightBuf = rightWriter.getBuffer();
this.leftColumn = new IndentingWriter(leftWriter, leftWidth);
this.rightColumn =
new IndentingWriter(rightWriter, rightWidth, spacer);
}
/**
* Constructs an instance.
*
* @param out non-null; stream to send final output to
* @param leftWidth >= 1; width of the left column, in characters
* @param rightWidth >= 1; width of the right column, in characters
* @param spacer non-null; spacer string to sit between the two columns
*/
public TwoColumnOutput(OutputStream out, int leftWidth, int rightWidth,
String spacer) {
this(new OutputStreamWriter(out), leftWidth, rightWidth, spacer);
}
/**
* Gets the writer to use to write to the left column.
*
* @return non-null; the left column writer
*/
public Writer getLeft() {
return leftColumn;
}
/**
* Gets the writer to use to write to the right column.
*
* @return non-null; the right column writer
*/
public Writer getRight() {
return rightColumn;
}
/**
* Flushes the output. If there are more lines of pending output in one
* column, then the other column will get filled with blank lines.
*/
public void flush() {
try {
appendNewlineIfNecessary(leftBuf, leftColumn);
appendNewlineIfNecessary(rightBuf, rightColumn);
outputFullLines();
flushLeft();
flushRight();
} catch (IOException ex) {
throw new RuntimeException(ex);
}
}
/**
* Outputs to the final destination as many full line pairs as
* there are in the pending output, removing those lines from
* their respective buffers. This method terminates when at
* least one of the two column buffers is empty.
*/
private void outputFullLines() throws IOException {
for (;;) {
int leftLen = leftBuf.indexOf("\n");
if (leftLen < 0) {
return;
}
int rightLen = rightBuf.indexOf("\n");
if (rightLen < 0) {
return;
}
if (leftLen != 0) {
out.write(leftBuf.substring(0, leftLen));
}
if (rightLen != 0) {
writeSpaces(out, leftWidth - leftLen);
out.write(rightBuf.substring(0, rightLen));
}
out.write('\n');
leftBuf.delete(0, leftLen + 1);
rightBuf.delete(0, rightLen + 1);
}
}
/**
* Flushes the left column buffer, printing it and clearing the buffer.
* If the buffer is already empty, this does nothing.
*/
private void flushLeft() throws IOException {
appendNewlineIfNecessary(leftBuf, leftColumn);
while (leftBuf.length() != 0) {
rightColumn.write('\n');
outputFullLines();
}
}
/**
* Flushes the right column buffer, printing it and clearing the buffer.
* If the buffer is already empty, this does nothing.
*/
private void flushRight() throws IOException {
appendNewlineIfNecessary(rightBuf, rightColumn);
while (rightBuf.length() != 0) {
leftColumn.write('\n');
outputFullLines();
}
}
/**
* Appends a newline to the given buffer via the given writer, but
* only if it isn't empty and doesn't already end with one.
*
* @param buf non-null; the buffer in question
* @param out non-null; the writer to use
*/
private static void appendNewlineIfNecessary(StringBuffer buf,
Writer out)
throws IOException {
int len = buf.length();
if ((len != 0) && (buf.charAt(len - 1) != '\n')) {
out.write('\n');
}
}
/**
* Writes the given number of spaces to the given writer.
*
* @param out non-null; where to write
* @param amt >= 0; the number of spaces to write
*/
private static void writeSpaces(Writer out, int amt) throws IOException {
while (amt > 0) {
out.write(' ');
amt--;
}
}
}
|
