1 files changed, 155 insertions, 0 deletions
diff --git a/plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/util/io/ReaderInputStream.java b/plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/util/io/ReaderInputStream.java
new file mode 100644
index 0000000000..b9291ef374
--- /dev/null
+++ b/plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/util/io/ReaderInputStream.java
@@ -0,0 +1,155 @@
+/*
+ * Copyright (c) 2020 Eike Stepper (Loehne, Germany) and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Eike Stepper - initial API and implementation
+ */
+package org.eclipse.net4j.util.io;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.Reader;
+import java.nio.Buffer;
+import java.nio.ByteBuffer;
+import java.nio.CharBuffer;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+
+/**
+ * An input stream for reading a {@link Reader}.
+ *
+ * @author Eike Stepper
+ * @since 3.13
+ */
+public class ReaderInputStream extends InputStream
+{
+  private static final int MASK = 0xFF;
+
+  private final Charset charset;
+
+  private Reader reader;
+
+  private CharBuffer chars = CharBuffer.allocate(IOUtil.DEFAULT_BUFFER_SIZE);
+
+  private ByteBuffer bytes;
+
+  public ReaderInputStream(Reader reader, String encoding) throws IOException
+  {
+    this.reader = reader;
+    charset = encoding == null ? StandardCharsets.UTF_8 : Charset.forName(encoding);
+  }
+
+  public ReaderInputStream(Reader reader) throws IOException
+  {
+    this(reader, null);
+  }
+
+  @Override
+  public int available() throws IOException
+  {
+    checkClosed();
+    ensureBytes();
+
+    if (bytes == null)
+    {
+      return 0;
+    }
+
+    return bytes.remaining();
+  }
+
+  @Override
+  public int read(byte[] b, int off, int len) throws IOException
+  {
+    checkClosed();
+
+    if (len == 0)
+    {
+      return 0;
+    }
+
+    ensureBytes();
+    if (bytes == null)
+    {
+      return IOUtil.EOF;
+    }
+
+    int count = 0;
+    do
+    {
+      ensureBytes();
+
+      if (bytes == null)
+      {
+        // No more to read.
+        break;
+      }
+
+      int toRead = Math.min(bytes.remaining(), len - count);
+      bytes.get(b, off + count, toRead);
+      count = count + toRead;
+    } while (count < len);
+
+    return count;
+  }
+
+  @Override
+  public int read() throws IOException
+  {
+    checkClosed();
+
+    ensureBytes();
+    if (bytes == null)
+    {
+      return IOUtil.EOF;
+    }
+
+    return bytes.get() & MASK;
+  }
+
+  @Override
+  public void close() throws IOException
+  {
+    if (reader != null)
+    {
+      reader.close();
+      reader = null;
+      bytes = null;
+      chars = null;
+    }
+  }
+
+  private void ensureBytes() throws IOException
+  {
+    if (bytes == null || !bytes.hasRemaining())
+    {
+      checkClosed();
+
+      Buffer buffer = chars;
+      buffer.rewind();
+
+      int count = reader.read(chars);
+      if (count > 0)
+      {
+        buffer.flip();
+        bytes = charset.encode(chars);
+      }
+      else
+      {
+        bytes = null;
+      }
+    }
+  }
+
+  private void checkClosed() throws IOException
+  {
+    if (reader == null)
+    {
+      throw new IOException("Reader is closed"); //$NON-NLS-1$
+    }
+  }
+}