Update #0 - First Release

sources/main/java/com/google/common/io/LineReader.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2007 The Guava Authors
+ *
+ * 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.google.common.io;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.io.IOException;
+import java.io.Reader;
+import java.nio.CharBuffer;
+import java.util.LinkedList;
+import java.util.Queue;
+
+import com.google.common.annotations.Beta;
+
+/**
+ * A class for reading lines of text. Provides the same functionality as
+ * {@link java.io.BufferedReader#readLine()} but for all {@link Readable}
+ * objects, not just instances of {@link Reader}.
+ *
+ * @author Chris Nokleberg
+ * @since 1.0
+ */
+@Beta
+public final class LineReader {
+	private final Readable readable;
+	private final Reader reader;
+	private final char[] buf = new char[0x1000]; // 4K
+	private final CharBuffer cbuf = CharBuffer.wrap(buf);
+
+	private final Queue<String> lines = new LinkedList<String>();
+	private final LineBuffer lineBuf = new LineBuffer() {
+		@Override
+		protected void handleLine(String line, String end) {
+			lines.add(line);
+		}
+	};
+
+	/**
+	 * Creates a new instance that will read lines from the given {@code Readable}
+	 * object.
+	 */
+	public LineReader(Readable readable) {
+		this.readable = checkNotNull(readable);
+		this.reader = (readable instanceof Reader) ? (Reader) readable : null;
+	}
+
+	/**
+	 * Reads a line of text. A line is considered to be terminated by any one of a
+	 * line feed ({@code '\n'}), a carriage return ({@code '\r'}), or a carriage
+	 * return followed immediately by a linefeed ({@code "\r\n"}).
+	 *
+	 * @return a {@code String} containing the contents of the line, not including
+	 *         any line-termination characters, or {@code null} if the end of the
+	 *         stream has been reached.
+	 * @throws IOException if an I/O error occurs
+	 */
+	public String readLine() throws IOException {
+		while (lines.peek() == null) {
+			cbuf.clear();
+			// The default implementation of Reader#read(CharBuffer) allocates a
+			// temporary char[], so we call Reader#read(char[], int, int) instead.
+			int read = (reader != null) ? reader.read(buf, 0, buf.length) : readable.read(cbuf);
+			if (read == -1) {
+				lineBuf.finish();
+				break;
+			}
+			lineBuf.add(buf, 0, read);
+		}
+		return lines.poll();
+	}
+}