moving files around

common/common-io/src/main/java/com/twelvemonkeys/io/CompoundReader.java

@@ -0,0 +1,218 @@
+/*
+ * Copyright (c) 2008, Harald Kuhr
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name "TwelveMonkeys" nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package com.twelvemonkeys.io;
+
+import com.twelvemonkeys.lang.Validate;
+
+import java.io.IOException;
+import java.io.Reader;
+import java.util.Iterator;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A Reader implementation that can read from multiple sources.
+ * <p/>
+ *
+ * @author <a href="mailto:harald.kuhr@gmail.com">Harald Kuhr</a>
+ * @author last modified by $Author: haku $
+ * @version $Id: //depot/branches/personal/haraldk/twelvemonkeys/release-2/twelvemonkeys-core/src/main/java/com/twelvemonkeys/io/CompoundReader.java#2 $
+ */
+public class CompoundReader extends Reader {
+
+    private Reader mCurrent;
+    private List<Reader> mReaders;
+    protected final Object mLock;
+
+    protected final boolean mMarkSupported;
+
+    private int mCurrentReader;
+    private int mMarkedReader;
+    private int mMark;
+    private int mNext;
+
+    /**
+     * Create a new compound reader.
+     *
+     * @param pReaders {@code Iterator} containting {@code Reader}s,
+     *        providing the character stream.
+     *
+     * @throws NullPointerException if {@code pReaders} is {@code null}, or
+     *         any of the elements in the iterator is {@code null}.
+     * @throws ClassCastException if any element of the iterator is not a
+     *         {@code java.io.Reader}
+     */
+    public CompoundReader(final Iterator<Reader> pReaders) {
+        super(Validate.notNull(pReaders, "readers"));
+
+        mLock = pReaders; // NOTE: It's ok to sync on pReaders, as the
+                          // reference can't change, only it's elements
+
+        mReaders = new ArrayList<Reader>();
+
+        boolean markSupported = true;
+        while (pReaders.hasNext()) {
+            Reader reader = pReaders.next();
+            if (reader == null) {
+                throw new NullPointerException("readers cannot contain null-elements");
+            }
+            mReaders.add(reader);
+            markSupported = markSupported && reader.markSupported();
+        }
+        mMarkSupported = markSupported;
+
+        mCurrent = nextReader();
+    }
+
+    protected final Reader nextReader() {
+        if (mCurrentReader >= mReaders.size()) {
+            mCurrent = new EmptyReader();
+        }
+        else {
+            mCurrent = mReaders.get(mCurrentReader++);
+        }
+        
+        // NOTE: Reset mNext for every reader, and record marked reader in mark/reset methods!
+        mNext = 0;
+        return mCurrent;
+    }
+
+    /**
+     * Check to make sure that the stream has not been closed
+     *
+     * @throws IOException if the stream is closed
+     */
+    protected final void ensureOpen() throws IOException {
+        if (mReaders == null) {
+            throw new IOException("Stream closed");
+        }
+    }
+
+    public void close() throws IOException {
+        // Close all readers
+        for (Reader reader : mReaders) {
+            reader.close();
+        }
+        mReaders = null;
+    }
+
+    @Override
+    public void mark(int pReadLimit) throws IOException {
+        if (pReadLimit < 0) {
+            throw new IllegalArgumentException("Read limit < 0");
+        }
+
+        // TODO: It would be nice if we could actually close some readers now
+
+        synchronized (mLock) {
+            ensureOpen();
+            mMark = mNext;
+            mMarkedReader = mCurrentReader;
+
+            mCurrent.mark(pReadLimit);
+        }
+    }
+
+    @Override
+    public void reset() throws IOException {
+        synchronized (mLock) {
+            ensureOpen();
+
+            if (mCurrentReader != mMarkedReader) {
+                // Reset any reader before this
+                for (int i = mCurrentReader; i >= mMarkedReader; i--) {
+                    mReaders.get(i).reset();
+                }
+
+                mCurrentReader = mMarkedReader - 1;
+                nextReader();
+            }
+            mCurrent.reset();
+
+            mNext = mMark;
+        }
+    }
+
+    @Override
+    public boolean markSupported() {
+        return mMarkSupported;
+    }
+
+    @Override
+    public int read() throws IOException {
+        synchronized (mLock) {
+            int read = mCurrent.read();
+
+            if (read < 0 && mCurrentReader < mReaders.size()) {
+                nextReader();
+                return read(); // In case of 0-length readers
+            }
+
+            mNext++;
+
+            return read;
+        }
+    }
+
+    public int read(char pBuffer[], int pOffset, int pLength) throws IOException {
+        synchronized (mLock) {
+            int read = mCurrent.read(pBuffer, pOffset, pLength);
+
+            if (read < 0 && mCurrentReader < mReaders.size()) {
+                nextReader();
+                return read(pBuffer, pOffset, pLength); // In case of 0-length readers
+            }
+
+            mNext += read;
+
+            return read;
+        }
+    }
+
+    @Override
+    public boolean ready() throws IOException {
+        return mCurrent.ready();
+    }
+
+    @Override
+    public long skip(long pChars) throws IOException {
+        synchronized (mLock) {
+            long skipped = mCurrent.skip(pChars);
+
+            if (skipped == 0 && mCurrentReader < mReaders.size()) {
+                nextReader();
+                return skip(pChars); // In case of 0-length readers
+            }
+
+            mNext += skipped;
+
+            return skipped;
+        }
+    }
+}