IO: Add a method for reading lines
Change-Id: Ib7be76aa7ac889354ad4782e2b64d4221a0e25b9
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/*
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* Copyright (C) 2015, Google Inc.
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* and other copyright owners as documented in the project's IP log.
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*
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* This program and the accompanying materials are made available
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* under the terms of the Eclipse Distribution License v1.0 which
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* accompanies this distribution, is reproduced below, and is
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* available at http://www.eclipse.org/org/documents/edl-v10.php
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or
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* without modification, are permitted provided that the following
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* conditions are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials provided
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* with the distribution.
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*
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* - Neither the name of the Eclipse Foundation, Inc. nor the
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* names of its contributors may be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package org.eclipse.jgit.util;
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import static org.junit.Assert.assertEquals;
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import java.io.BufferedReader;
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import java.io.ByteArrayInputStream;
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import java.io.InputStreamReader;
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import java.io.Reader;
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import java.util.ArrayList;
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import java.util.Collection;
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import org.eclipse.jgit.lib.Constants;
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import org.junit.Test;
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import org.junit.runner.RunWith;
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import org.junit.runners.Parameterized;
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import org.junit.runners.Parameterized.Parameter;
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import org.junit.runners.Parameterized.Parameters;
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@RunWith(Parameterized.class)
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public class IOReadLineTest {
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@Parameter(0)
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public boolean buffered;
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@Parameter(1)
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public int sizeHint;
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@SuppressWarnings("boxing")
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@Parameters(name="buffered={0}, sizeHint={1}")
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public static Collection<Object[]> getParameters() {
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Boolean[] bv = {false, true};
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Integer[] sv = {-1, 0, 1, 2, 3, 4, 64};
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Collection<Object[]> params = new ArrayList<>(bv.length * sv.length);
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for (boolean b : bv) {
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for (Integer s : sv) {
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params.add(new Object[]{b, s});
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}
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}
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return params;
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}
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@Test
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public void testReadLine() throws Exception {
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Reader r = newReader("foo\nbar\nbaz\n");
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assertEquals("foo\n", readLine(r));
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assertEquals("bar\n", readLine(r));
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assertEquals("baz\n", readLine(r));
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assertEquals("", readLine(r));
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}
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@Test
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public void testReadLineNoTrailingNewline() throws Exception {
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Reader r = newReader("foo\nbar\nbaz");
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assertEquals("foo\n", readLine(r));
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assertEquals("bar\n", readLine(r));
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assertEquals("baz", readLine(r));
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assertEquals("", readLine(r));
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}
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private String readLine(Reader r) throws Exception {
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return IO.readLine(r, sizeHint);
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}
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private Reader newReader(String in) {
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Reader r = new InputStreamReader(
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new ByteArrayInputStream(Constants.encode(in)));
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if (buffered) {
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r = new BufferedReader(r);
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}
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assertEquals(Boolean.valueOf(buffered),
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Boolean.valueOf(r.markSupported()));
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return r;
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}
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}
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@ -51,6 +51,7 @@
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import java.io.FileNotFoundException;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.Reader;
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import java.nio.ByteBuffer;
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import java.nio.channels.ReadableByteChannel;
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import java.text.MessageFormat;
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@ -371,6 +372,74 @@ public static List<String> readLines(final String s) {
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return l;
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}
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/**
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* Read the next line from a reader.
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* <p>
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* Like {@link java.io.BufferedReader#readLine()}, but only treats {@code \n}
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* as end-of-line, and includes the trailing newline.
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*
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* @param in
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* the reader to read from.
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* @param sizeHint
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* hint for buffer sizing; 0 or negative for default.
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* @return the next line from the input, always ending in {@code \n} unless
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* EOF was reached.
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* @throws IOException
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* there was an error reading from the stream.
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*/
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public static String readLine(Reader in, int sizeHint) throws IOException {
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if (in.markSupported()) {
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if (sizeHint <= 0) {
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sizeHint = 1024;
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}
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StringBuilder sb = new StringBuilder(sizeHint);
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char[] buf = new char[sizeHint];
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while (true) {
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in.mark(sizeHint);
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int n = in.read(buf);
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if (n < 0) {
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in.reset();
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return sb.toString();
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}
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for (int i = 0; i < n; i++) {
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if (buf[i] == '\n') {
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resetAndSkipFully(in, ++i);
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sb.append(buf, 0, i);
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return sb.toString();
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}
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}
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if (n > 0) {
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sb.append(buf, 0, n);
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}
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resetAndSkipFully(in, n);
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}
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} else {
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StringBuilder buf = sizeHint > 0
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? new StringBuilder(sizeHint)
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: new StringBuilder();
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int i;
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while ((i = in.read()) != -1) {
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char c = (char) i;
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buf.append(c);
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if (c == '\n') {
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break;
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}
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}
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return buf.toString();
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}
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}
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private static void resetAndSkipFully(Reader fd, long toSkip) throws IOException {
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fd.reset();
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while (toSkip > 0) {
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long r = fd.skip(toSkip);
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if (r <= 0) {
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throw new EOFException(JGitText.get().shortSkipOfBlock);
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}
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toSkip -= r;
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}
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}
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private IO() {
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// Don't create instances of a static only utility.
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}
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