Update #0 - First Release

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

@@ -0,0 +1,117 @@
+/*
+ * 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 java.io.IOException;
+
+/**
+ * Package-protected abstract class that implements the line reading algorithm
+ * used by {@link LineReader}. Line separators are per
+ * {@link java.io.BufferedReader}: line feed, carriage return, or carriage
+ * return followed immediately by a linefeed.
+ *
+ * <p>
+ * Subclasses must implement {@link #handleLine}, call {@link #add} to pass
+ * character data, and call {@link #finish} at the end of stream.
+ *
+ * @author Chris Nokleberg
+ * @since 1.0
+ */
+abstract class LineBuffer {
+	/** Holds partial line contents. */
+	private StringBuilder line = new StringBuilder();
+	/** Whether a line ending with a CR is pending processing. */
+	private boolean sawReturn;
+
+	/**
+	 * Process additional characters from the stream. When a line separator is found
+	 * the contents of the line and the line separator itself are passed to the
+	 * abstract {@link #handleLine} method.
+	 *
+	 * @param cbuf the character buffer to process
+	 * @param off  the offset into the buffer
+	 * @param len  the number of characters to process
+	 * @throws IOException if an I/O error occurs
+	 * @see #finish
+	 */
+	protected void add(char[] cbuf, int off, int len) throws IOException {
+		int pos = off;
+		if (sawReturn && len > 0) {
+			// Last call to add ended with a CR; we can handle the line now.
+			if (finishLine(cbuf[pos] == '\n')) {
+				pos++;
+			}
+		}
+
+		int start = pos;
+		for (int end = off + len; pos < end; pos++) {
+			switch (cbuf[pos]) {
+			case '\r':
+				line.append(cbuf, start, pos - start);
+				sawReturn = true;
+				if (pos + 1 < end) {
+					if (finishLine(cbuf[pos + 1] == '\n')) {
+						pos++;
+					}
+				}
+				start = pos + 1;
+				break;
+
+			case '\n':
+				line.append(cbuf, start, pos - start);
+				finishLine(true);
+				start = pos + 1;
+				break;
+
+			default:
+				// do nothing
+			}
+		}
+		line.append(cbuf, start, off + len - start);
+	}
+
+	/** Called when a line is complete. */
+	private boolean finishLine(boolean sawNewline) throws IOException {
+		handleLine(line.toString(), sawReturn ? (sawNewline ? "\r\n" : "\r") : (sawNewline ? "\n" : ""));
+		line = new StringBuilder();
+		sawReturn = false;
+		return sawNewline;
+	}
+
+	/**
+	 * Subclasses must call this method after finishing character processing, in
+	 * order to ensure that any unterminated line in the buffer is passed to
+	 * {@link #handleLine}.
+	 *
+	 * @throws IOException if an I/O error occurs
+	 */
+	protected void finish() throws IOException {
+		if (sawReturn || line.length() > 0) {
+			finishLine(false);
+		}
+	}
+
+	/**
+	 * Called for each line found in the character data passed to {@link #add}.
+	 *
+	 * @param line a line of text (possibly empty), without any line separators
+	 * @param end  the line separator; one of {@code "\r"}, {@code "\n"},
+	 *             {@code "\r\n"}, or {@code ""}
+	 * @throws IOException if an I/O error occurs
+	 */
+	protected abstract void handleLine(String line, String end) throws IOException;
+}