1bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor/* 21d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * Copyright (C) 2007 The Guava Authors 3bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * 4bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * Licensed under the Apache License, Version 2.0 (the "License"); 5bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * you may not use this file except in compliance with the License. 6bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * You may obtain a copy of the License at 7bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * 8bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * http://www.apache.org/licenses/LICENSE-2.0 9bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * 10bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * Unless required by applicable law or agreed to in writing, software 11bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * distributed under the License is distributed on an "AS IS" BASIS, 12bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * See the License for the specific language governing permissions and 14bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * limitations under the License. 15bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor */ 16bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 17bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnorpackage com.google.common.io; 18bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 191d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringertimport com.google.common.annotations.Beta; 20bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnorimport com.google.common.base.Preconditions; 21bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 22bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnorimport java.io.IOException; 23bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnorimport java.io.Reader; 24bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnorimport java.nio.CharBuffer; 25bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnorimport java.util.LinkedList; 26bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnorimport java.util.Queue; 27bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 28bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor/** 29bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * A class for reading lines of text. Provides the same functionality 30bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * as {@link java.io.BufferedReader#readLine()} but for all {@link Readable} 31bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * objects, not just instances of {@link Reader}. 32bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * 33bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * @author Chris Nokleberg 341d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * @since 1.0 35bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor */ 361d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert@Beta 37bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnorpublic final class LineReader { 38bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor private final Readable readable; 39bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor private final Reader reader; 40bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor private final char[] buf = new char[0x1000]; // 4K 41bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor private final CharBuffer cbuf = CharBuffer.wrap(buf); 42bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 43bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor private final Queue<String> lines = new LinkedList<String>(); 44bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor private final LineBuffer lineBuf = new LineBuffer() { 45bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor @Override protected void handleLine(String line, String end) { 46bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor lines.add(line); 47bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 48bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor }; 49bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 50bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor /** 51bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * Creates a new instance that will read lines from the given 52bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * {@code Readable} object. 53bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor */ 54bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor public LineReader(Readable readable) { 55bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor Preconditions.checkNotNull(readable); 56bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor this.readable = readable; 57bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor this.reader = (readable instanceof Reader) ? (Reader) readable : null; 58bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 59bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 60bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor /** 61bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * Reads a line of text. A line is considered to be terminated by any 62bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * one of a line feed ({@code '\n'}), a carriage return 63bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * ({@code '\r'}), or a carriage return followed immediately by a linefeed 64bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * ({@code "\r\n"}). 65bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * 66bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * @return a {@code String} containing the contents of the line, not 67bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * including any line-termination characters, or {@code null} if the 68bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * end of the stream has been reached. 69bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * @throws IOException if an I/O error occurs 70bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor */ 71bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor public String readLine() throws IOException { 72bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor while (lines.peek() == null) { 73bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor cbuf.clear(); 74bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor // The default implementation of Reader#read(CharBuffer) allocates a 75bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor // temporary char[], so we call Reader#read(char[], int, int) instead. 76bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor int read = (reader != null) 77bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor ? reader.read(buf, 0, buf.length) 78bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor : readable.read(cbuf); 79bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor if (read == -1) { 80bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor lineBuf.finish(); 81bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor break; 82bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 83bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor lineBuf.add(buf, 0, read); 84bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 85bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor return lines.poll(); 86bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 87bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor} 88