Add writer that squelches duplicate lines.

diff --git a/src/main/java/net/pterodactylus/xdcc/ui/stdin/DuplicateLineSuppressingWriter.java b/src/main/java/net/pterodactylus/xdcc/ui/stdin/DuplicateLineSuppressingWriter.java
new file mode 100644 (file)
index 0000000..dfd9ed5
--- /dev/null
+++ b/src/main/java/net/pterodactylus/xdcc/ui/stdin/DuplicateLineSuppressingWriter.java
@@ -0,0 +1,119 @@
+/*
+ * XdccDownloader - DuplicateLineSuppressingWriter.java - Copyright © 2013 David Roden
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.xdcc.ui.stdin;
+
+import java.io.IOException;
+import java.io.Writer;
+
+/**
+ * {@link Writer} implementation that suppreses multiple identical lines written to it.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class DuplicateLineSuppressingWriter extends Writer {
+
+       private final Writer writer;
+       private String lastLine;
+       private final StringBuilder currentLine = new StringBuilder();
+
+       public DuplicateLineSuppressingWriter(Writer writer) {
+               this.writer = writer;
+       }
+
+       @Override
+       public void write(char[] cbuf) throws IOException {
+               write(cbuf, 0, cbuf.length);
+       }
+
+       @Override
+       public void write(String str) throws IOException {
+               write(str, 0, str.length());
+       }
+
+       @Override
+       public Writer append(CharSequence csq) throws IOException {
+               write(String.valueOf(csq));
+               return this;
+       }
+
+       @Override
+       public Writer append(CharSequence csq, int start, int end) throws IOException {
+               write(String.valueOf(csq).substring(start, end));
+               return this;
+       }
+
+       @Override
+       public Writer append(char c) throws IOException {
+               write(c);
+               return this;
+       }
+
+       @Override
+       public void flush() throws IOException {
+               writer.flush();
+       }
+
+       @Override
+       public void close() throws IOException {
+               writer.close();
+       }
+
+       @Override
+       public void write(int c) throws IOException {
+               currentLine.append((char) c);
+               writeCollectedLines();
+       }
+
+       @Override
+       public void write(char[] cbuf, int off, int len) throws IOException {
+               currentLine.append(cbuf, off, len);
+               writeCollectedLines();
+       }
+
+       @Override
+       public void write(String str, int off, int len) throws IOException {
+               currentLine.append(str, off, len);
+               writeCollectedLines();
+       }
+
+       private void writeCollectedLines() throws IOException {
+               while (currentLineContainsLineBreak()) {
+                       String nextLine = cutNextLine();
+                       maybeWriteNextLine(nextLine);
+               }
+       }
+
+       private void maybeWriteNextLine(String nextLine) throws IOException {
+               if (!nextLine.equals(lastLine)) {
+                       writer.write(nextLine);
+                       lastLine = nextLine;
+               }
+       }
+
+       private String cutNextLine() {
+               int indexOfLineBreak = currentLine.indexOf("\n");
+               String nextLine = currentLine.substring(0, indexOfLineBreak + 1);
+               currentLine.delete(0, indexOfLineBreak + 1);
+               return nextLine;
+       }
+
+       private boolean currentLineContainsLineBreak() {
+               return currentLine.indexOf("\n") > -1;
+       }
+
+}

diff --git a/src/test/java/net/pterodactylus/xdcc/ui/stdin/DuplicateLineSuppressingWriterTest.java b/src/test/java/net/pterodactylus/xdcc/ui/stdin/DuplicateLineSuppressingWriterTest.java
new file mode 100644 (file)
index 0000000..3465abb
--- /dev/null
+++ b/src/test/java/net/pterodactylus/xdcc/ui/stdin/DuplicateLineSuppressingWriterTest.java
@@ -0,0 +1,69 @@
+/*
+ * XdccDownloader - DuplicateLineSuppressingWriterTest.java - Copyright © 2013 David Roden
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.xdcc.ui.stdin;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+
+import java.io.IOException;
+import java.io.StringWriter;
+
+import org.junit.Test;
+
+/**
+ * Unit test for {@link DuplicateLineSuppressingWriter}.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class DuplicateLineSuppressingWriterTest {
+
+       private final StringWriter stringWriter = new StringWriter();
+       private final DuplicateLineSuppressingWriter duplicateLineSuppressingWriter = new DuplicateLineSuppressingWriter(stringWriter);
+
+       @Test
+       public void theFirstLineIsWrittenImmediately() throws IOException {
+               duplicateLineSuppressingWriter.write("First Line.\n");
+               assertThat(stringWriter.toString(), is("First Line.\n"));
+       }
+
+       @Test
+       public void twoDifferentLinesAreWrittenOut() throws IOException {
+               duplicateLineSuppressingWriter.write("First Line.\n");
+               duplicateLineSuppressingWriter.write("Second Line.\n");
+               assertThat(stringWriter.toString(), is("First Line.\nSecond Line.\n"));
+       }
+
+       @Test
+       public void twoEqualLinesAreOnlyWrittenOnce() throws IOException {
+               duplicateLineSuppressingWriter.write("First Line.\n");
+               duplicateLineSuppressingWriter.write("First Line.\n");
+               assertThat(stringWriter.toString(), is("First Line.\n"));
+       }
+
+       @Test
+       public void multipleLinesAreSuppressed() throws IOException {
+               duplicateLineSuppressingWriter.write("First Line.\n");
+               duplicateLineSuppressingWriter.write("Second Line.\n");
+               duplicateLineSuppressingWriter.write("Second Line.\n");
+               duplicateLineSuppressingWriter.write("Second Line.\n");
+               duplicateLineSuppressingWriter.write("First Line.\n");
+               duplicateLineSuppressingWriter.write("First Line.\n");
+               assertThat(stringWriter.toString(), is("First Line.\nSecond Line.\nFirst Line.\n"));
+       }
+
+}