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Diffstat (limited to 'mobile/android/thirdparty/com/jakewharton/disklrucache/StrictLineReader.java')
-rw-r--r-- | mobile/android/thirdparty/com/jakewharton/disklrucache/StrictLineReader.java | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/mobile/android/thirdparty/com/jakewharton/disklrucache/StrictLineReader.java b/mobile/android/thirdparty/com/jakewharton/disklrucache/StrictLineReader.java new file mode 100644 index 000000000..c90691ce4 --- /dev/null +++ b/mobile/android/thirdparty/com/jakewharton/disklrucache/StrictLineReader.java @@ -0,0 +1,196 @@ +/* + * 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.jakewharton.disklrucache; + +import java.io.ByteArrayOutputStream; +import java.io.Closeable; +import java.io.EOFException; +import java.io.IOException; +import java.io.InputStream; +import java.io.UnsupportedEncodingException; +import java.nio.charset.Charset; + +/** + * Buffers input from an {@link InputStream} for reading lines. + * + * <p>This class is used for buffered reading of lines. For purposes of this class, a line ends + * with "\n" or "\r\n". End of input is reported by throwing {@code EOFException}. Unterminated + * line at end of input is invalid and will be ignored, the caller may use {@code + * hasUnterminatedLine()} to detect it after catching the {@code EOFException}. + * + * <p>This class is intended for reading input that strictly consists of lines, such as line-based + * cache entries or cache journal. Unlike the {@link java.io.BufferedReader} which in conjunction + * with {@link java.io.InputStreamReader} provides similar functionality, this class uses different + * end-of-input reporting and a more restrictive definition of a line. + * + * <p>This class supports only charsets that encode '\r' and '\n' as a single byte with value 13 + * and 10, respectively, and the representation of no other character contains these values. + * We currently check in constructor that the charset is one of US-ASCII, UTF-8 and ISO-8859-1. + * The default charset is US_ASCII. + */ +class StrictLineReader implements Closeable { + private static final byte CR = (byte) '\r'; + private static final byte LF = (byte) '\n'; + + private final InputStream in; + private final Charset charset; + + /* + * Buffered data is stored in {@code buf}. As long as no exception occurs, 0 <= pos <= end + * and the data in the range [pos, end) is buffered for reading. At end of input, if there is + * an unterminated line, we set end == -1, otherwise end == pos. If the underlying + * {@code InputStream} throws an {@code IOException}, end may remain as either pos or -1. + */ + private byte[] buf; + private int pos; + private int end; + + /** + * Constructs a new {@code LineReader} with the specified charset and the default capacity. + * + * @param in the {@code InputStream} to read data from. + * @param charset the charset used to decode data. Only US-ASCII, UTF-8 and ISO-8859-1 are + * supported. + * @throws NullPointerException if {@code in} or {@code charset} is null. + * @throws IllegalArgumentException if the specified charset is not supported. + */ + public StrictLineReader(InputStream in, Charset charset) { + this(in, 8192, charset); + } + + /** + * Constructs a new {@code LineReader} with the specified capacity and charset. + * + * @param in the {@code InputStream} to read data from. + * @param capacity the capacity of the buffer. + * @param charset the charset used to decode data. Only US-ASCII, UTF-8 and ISO-8859-1 are + * supported. + * @throws NullPointerException if {@code in} or {@code charset} is null. + * @throws IllegalArgumentException if {@code capacity} is negative or zero + * or the specified charset is not supported. + */ + public StrictLineReader(InputStream in, int capacity, Charset charset) { + if (in == null || charset == null) { + throw new NullPointerException(); + } + if (capacity < 0) { + throw new IllegalArgumentException("capacity <= 0"); + } + if (!(charset.equals(Util.US_ASCII))) { + throw new IllegalArgumentException("Unsupported encoding"); + } + + this.in = in; + this.charset = charset; + buf = new byte[capacity]; + } + + /** + * Closes the reader by closing the underlying {@code InputStream} and + * marking this reader as closed. + * + * @throws IOException for errors when closing the underlying {@code InputStream}. + */ + public void close() throws IOException { + synchronized (in) { + if (buf != null) { + buf = null; + in.close(); + } + } + } + + /** + * Reads the next line. A line ends with {@code "\n"} or {@code "\r\n"}, + * this end of line marker is not included in the result. + * + * @return the next line from the input. + * @throws IOException for underlying {@code InputStream} errors. + * @throws EOFException for the end of source stream. + */ + public String readLine() throws IOException { + synchronized (in) { + if (buf == null) { + throw new IOException("LineReader is closed"); + } + + // Read more data if we are at the end of the buffered data. + // Though it's an error to read after an exception, we will let {@code fillBuf()} + // throw again if that happens; thus we need to handle end == -1 as well as end == pos. + if (pos >= end) { + fillBuf(); + } + // Try to find LF in the buffered data and return the line if successful. + for (int i = pos; i != end; ++i) { + if (buf[i] == LF) { + int lineEnd = (i != pos && buf[i - 1] == CR) ? i - 1 : i; + String res = new String(buf, pos, lineEnd - pos, charset.name()); + pos = i + 1; + return res; + } + } + + // Let's anticipate up to 80 characters on top of those already read. + ByteArrayOutputStream out = new ByteArrayOutputStream(end - pos + 80) { + @Override + public String toString() { + int length = (count > 0 && buf[count - 1] == CR) ? count - 1 : count; + try { + return new String(buf, 0, length, charset.name()); + } catch (UnsupportedEncodingException e) { + throw new AssertionError(e); // Since we control the charset this will never happen. + } + } + }; + + while (true) { + out.write(buf, pos, end - pos); + // Mark unterminated line in case fillBuf throws EOFException or IOException. + end = -1; + fillBuf(); + // Try to find LF in the buffered data and return the line if successful. + for (int i = pos; i != end; ++i) { + if (buf[i] == LF) { + if (i != pos) { + out.write(buf, pos, i - pos); + } + pos = i + 1; + return out.toString(); + } + } + } + } + } + + public boolean hasUnterminatedLine() { + return end == -1; + } + + /** + * Reads new input data into the buffer. Call only with pos == end or end == -1, + * depending on the desired outcome if the function throws. + */ + private void fillBuf() throws IOException { + int result = in.read(buf, 0, buf.length); + if (result == -1) { + throw new EOFException(); + } + pos = 0; + end = result; + } +} + |