NextableInputStream: more options
authorNiki Roo <niki@nikiroo.be>
Thu, 25 Apr 2019 07:27:57 +0000 (09:27 +0200)
committerNiki Roo <niki@nikiroo.be>
Thu, 25 Apr 2019 07:27:57 +0000 (09:27 +0200)
src/be/nikiroo/utils/NextableInputStream.java
src/be/nikiroo/utils/test_code/NextableInputStreamTest.java

index 0def936c4247ea5019898d0862481713e8620c2b..69fd33b34244a7735fb2920b9153b1740573d208 100644 (file)
@@ -14,13 +14,18 @@ import java.io.InputStream;
  */
 public class NextableInputStream extends InputStream {
        private NextableInputStreamStep step;
+       private boolean started;
        private boolean stopped;
+       private boolean closed;
 
        private InputStream in;
+       private int openCounter;
        private boolean eof;
-       private int pos = 0;
-       private int len = 0;
-       private byte[] buffer = new byte[4096];
+       private int pos;
+       private int len;
+       private byte[] buffer;
+
+       private long bytesRead;
 
        /**
         * Create a new {@link NextableInputStream} that wraps the given
@@ -35,6 +40,84 @@ public class NextableInputStream extends InputStream {
        public NextableInputStream(InputStream in, NextableInputStreamStep step) {
                this.in = in;
                this.step = step;
+
+               this.buffer = new byte[4096];
+               this.pos = 0;
+               this.len = 0;
+       }
+
+       /**
+        * Create a new {@link NextableInputStream} that wraps the given bytes array
+        * as a data source.
+        * 
+        * @param in
+        *            the array to wrap, cannot be NULL
+        * @param step
+        *            how to separate it into sub-streams (can be NULL, but in that
+        *            case it will behave as a normal {@link InputStream})
+        */
+       public NextableInputStream(byte[] in, NextableInputStreamStep step) {
+               this(in, step, 0, in.length);
+       }
+
+       /**
+        * Create a new {@link NextableInputStream} that wraps the given bytes array
+        * as a data source.
+        * 
+        * @param in
+        *            the array to wrap, cannot be NULL
+        * @param step
+        *            how to separate it into sub-streams (can be NULL, but in that
+        *            case it will behave as a normal {@link InputStream})
+        * @param offset
+        *            the offset to start the reading at
+        * @param length
+        *            the number of bytes to take into account in the array,
+        *            starting from the offset
+        * 
+        * @throws NullPointerException
+        *             if the array is NULL
+        * @throws IndexOutOfBoundsException
+        *             if the offset and length do not correspond to the given array
+        */
+       public NextableInputStream(byte[] in, NextableInputStreamStep step,
+                       int offset, int length) {
+               if (in == null) {
+                       throw new NullPointerException();
+               } else if (offset < 0 || length < 0 || length > in.length - offset) {
+                       throw new IndexOutOfBoundsException();
+               }
+
+               this.in = null;
+               this.step = step;
+
+               this.buffer = in;
+               this.pos = offset;
+               this.len = length;
+
+               checkBuffer(true);
+       }
+
+       /**
+        * Return this very same {@link NextableInputStream}, but keep a counter of
+        * how many streams were open this way. When calling
+        * {@link NextableInputStream#close()}, decrease this counter if it is not
+        * already zero instead of actually closing the stream.
+        * <p>
+        * You are now responsible for it &mdash; you <b>must</b> close it.
+        * <p>
+        * This method allows you to use a wrapping stream around this one and still
+        * close the wrapping stream.
+        * 
+        * @return the same stream, but you are now responsible for closing it
+        * 
+        * @throws IOException
+        *             in case of I/O error or if the stream is closed
+        */
+       public synchronized InputStream open() throws IOException {
+               checkClose();
+               openCounter++;
+               return this;
        }
 
        /**
@@ -53,27 +136,61 @@ public class NextableInputStream extends InputStream {
         * @return TRUE if we unblocked the next sub-stream, FALSE if not
         * 
         * @throws IOException
-        *             in case of I/O error
+        *             in case of I/O error or if the stream is closed
         */
        public boolean next() throws IOException {
-               if (!hasMoreData() && stopped) {
-                       len = step.getResumeLen();
-                       pos += step.getResumeSkip();
-                       eof = false;
+               return next(false);
+       }
 
-                       if (!preRead()) {
-                               checkBuffer(false);
-                       }
+       /**
+        * Unblock the next sub-stream as would have done
+        * {@link NextableInputStream#next()}, but disable the sub-stream systems.
+        * <p>
+        * That is, the next stream, if any, will be the last one and will not be
+        * subject to the {@link NextableInputStreamStep}.
+        * 
+        * @return TRUE if we unblocked the next sub-stream, FALSE if not
+        * 
+        * @throws IOException
+        *             in case of I/O error or if the stream is closed
+        */
+       public boolean nextAll() throws IOException {
+               return next(true);
+       }
 
-                       // consider that if EOF, there is no next
-                       return hasMoreData();
-               }
+       public boolean startWith() {
+               // TODO
+               return false;
+       }
 
+       public boolean startWiths() {
+               // TODO
                return false;
        }
 
+       /**
+        * The number of bytes read from the under-laying {@link InputStream}.
+        * 
+        * @return the number of bytes
+        */
+       public long getBytesRead() {
+               return bytesRead;
+       }
+
+       /**
+        * Check if this stream is totally spent (no more data to read or to
+        * process).
+        * 
+        * @return TRUE if it is
+        */
+       public boolean eof() {
+               return closed || (len < 0 && !hasMoreData());
+       }
+
        @Override
        public int read() throws IOException {
+               checkClose();
+
                preRead();
                if (eof) {
                        return -1;
@@ -89,6 +206,8 @@ public class NextableInputStream extends InputStream {
 
        @Override
        public int read(byte[] b, int boff, int blen) throws IOException {
+               checkClose();
+
                if (b == null) {
                        throw new NullPointerException();
                } else if (boff < 0 || blen < 0 || blen > b.length - boff) {
@@ -113,10 +232,73 @@ public class NextableInputStream extends InputStream {
        }
 
        @Override
-       public int available() throws IOException {
+       public long skip(long n) throws IOException {
+               // TODO Auto-generated method stub
+               return super.skip(n);
+       }
+
+       @Override
+       public int available() {
+               if (closed) {
+                       return 0;
+               }
+
                return Math.max(0, len - pos);
        }
 
+       /**
+        * Closes this stream and releases any system resources associated with the
+        * stream.
+        * <p>
+        * Including the under-laying {@link InputStream}.
+        * <p>
+        * <b>Note:</b> if you called the {@link NextableInputStream#open()} method
+        * prior to this one, it will just decrease the internal count of how many
+        * open streams it held and do nothing else. The stream will actually be
+        * closed when you have called {@link NextableInputStream#close()} once more
+        * than {@link NextableInputStream#open()}.
+        * 
+        * @exception IOException
+        *                in case of I/O error
+        */
+       @Override
+       public synchronized void close() throws IOException {
+               close(true);
+       }
+
+       /**
+        * Closes this stream and releases any system resources associated with the
+        * stream.
+        * <p>
+        * Including the under-laying {@link InputStream} if
+        * <tt>incudingSubStream</tt> is true.
+        * <p>
+        * You can call this method multiple times, it will not cause an
+        * {@link IOException} for subsequent calls.
+        * <p>
+        * <b>Note:</b> if you called the {@link NextableInputStream#open()} method
+        * prior to this one, it will just decrease the internal count of how many
+        * open streams it held and do nothing else. The stream will actually be
+        * closed when you have called {@link NextableInputStream#close()} once more
+        * than {@link NextableInputStream#open()}.
+        * 
+        * @exception IOException
+        *                in case of I/O error
+        */
+       public synchronized void close(boolean includingSubStream)
+                       throws IOException {
+               if (!closed) {
+                       if (openCounter > 0) {
+                               openCounter--;
+                       } else {
+                               closed = true;
+                               if (includingSubStream && in != null) {
+                                       in.close();
+                               }
+                       }
+               }
+       }
+
        /**
         * Check if we still have some data in the buffer and, if not, fetch some.
         * 
@@ -131,6 +313,10 @@ public class NextableInputStream extends InputStream {
                if (!eof && in != null && pos >= len && !stopped) {
                        pos = 0;
                        len = in.read(buffer);
+                       if (len > 0) {
+                               bytesRead += len;
+                       }
+
                        checkBuffer(true);
                        hasRead = true;
                }
@@ -148,7 +334,7 @@ public class NextableInputStream extends InputStream {
         * @return TRUE if it is the case, FALSE if not
         */
        private boolean hasMoreData() {
-               return !(eof && pos >= len);
+               return !closed && started && !(eof && pos >= len);
        }
 
        /**
@@ -164,7 +350,7 @@ public class NextableInputStream extends InputStream {
         *            the {@link NextableInputStreamStep}
         */
        private void checkBuffer(boolean newBuffer) {
-               if (step != null) {
+               if (step != null && len > 0) {
                        if (newBuffer) {
                                step.clearBuffer();
                        }
@@ -177,4 +363,65 @@ public class NextableInputStream extends InputStream {
                        }
                }
        }
+
+       /**
+        * The implementation of {@link NextableInputStream#next()} and
+        * {@link NextableInputStream#nextAll()}.
+        * 
+        * @param all
+        *            TRUE for {@link NextableInputStream#nextAll()}, FALSE for
+        *            {@link NextableInputStream#next()}
+        * 
+        * @return TRUE if we unblocked the next sub-stream, FALSE if not
+        * 
+        * @throws IOException
+        *             in case of I/O error or if the stream is closed
+        */
+       private boolean next(boolean all) throws IOException {
+               checkClose();
+
+               if (!started) {
+                       // First call before being allowed to read
+                       started = true;
+
+                       if (all) {
+                               step = null;
+                       }
+
+                       return true;
+               }
+
+               if (step != null && !hasMoreData() && stopped) {
+                       len = step.getResumeLen();
+                       pos += step.getResumeSkip();
+                       eof = false;
+
+                       if (all) {
+                               step = null;
+                       }
+
+                       if (!preRead()) {
+                               checkBuffer(false);
+                       }
+
+                       // consider that if EOF, there is no next
+                       return hasMoreData();
+               }
+
+               return false;
+       }
+
+       /**
+        * Check that the stream was not closed, and throw an {@link IOException} if
+        * it was.
+        * 
+        * @throws IOException
+        *             if it was closed
+        */
+       private void checkClose() throws IOException {
+               if (closed) {
+                       throw new IOException(
+                                       "This NextableInputStream was closed, you cannot use it anymore.");
+               }
+       }
 }
index 87d64ac20d86cb10ef7941698f2ba69901fc9b2c..e57da84cf934c0e9bb311afe64988ac7d2511a5d 100644 (file)
@@ -18,6 +18,7 @@ public class NextableInputStreamTest extends TestLauncher {
                                byte[] expected = new byte[] { 42, 12, 0, 127 };
                                NextableInputStream in = new NextableInputStream(
                                                new ByteArrayInputStream(expected), null);
+                               in.next();
                                byte[] actual = IOUtils.toByteArray(in);
 
                                assertEquals(
@@ -38,7 +39,7 @@ public class NextableInputStreamTest extends TestLauncher {
                                                new ByteArrayInputStream(expected),
                                                new NextableInputStreamStep(12));
 
-                               checkNext(this, false, "FIRST", in, new byte[] { 42 });
+                               checkNext(this, "FIRST", in, new byte[] { 42 });
                        }
                });
 
@@ -50,9 +51,9 @@ public class NextableInputStreamTest extends TestLauncher {
                                                new ByteArrayInputStream(data),
                                                new NextableInputStreamStep(12));
 
-                               checkNext(this, false, "FIRST", in, new byte[] { 42 });
-                               checkNext(this, true, "SECOND", in, new byte[] { 0, 127 });
-                               checkNext(this, true, "THIRD", in, new byte[] { 51, 11 });
+                               checkNext(this, "FIRST", in, new byte[] { 42 });
+                               checkNext(this, "SECOND", in, new byte[] { 0, 127 });
+                               checkNext(this, "THIRD", in, new byte[] { 51, 11 });
                        }
                });
 
@@ -66,14 +67,14 @@ public class NextableInputStreamTest extends TestLauncher {
                                NextableInputStream subIn12 = new NextableInputStream(in4,
                                                new NextableInputStreamStep(12));
 
-                               checkNext(this, false, "SUB FIRST", subIn12, new byte[] { 42 });
-                               checkNext(this, true, "SUB SECOND", subIn12, new byte[] { 0 });
+                               in4.next();
+                               checkNext(this, "SUB FIRST", subIn12, new byte[] { 42 });
+                               checkNext(this, "SUB SECOND", subIn12, new byte[] { 0 });
 
                                assertEquals("The subIn still has some data", false,
                                                subIn12.next());
 
-                               checkNext(this, true, "MAIN LAST", in4,
-                                               new byte[] { 127, 12, 5 });
+                               checkNext(this, "MAIN LAST", in4, new byte[] { 127, 12, 5 });
                        }
                });
 
@@ -87,18 +88,73 @@ public class NextableInputStreamTest extends TestLauncher {
                                                new ByteArrayInputStream(data),
                                                new NextableInputStreamStep('\n'));
 
-                               checkNext(this, false, "FIRST", in, ln1.getBytes("UTF-8"));
-                               checkNext(this, true, "SECOND", in, ln2.getBytes("UTF-8"));
+                               checkNext(this, "FIRST", in, ln1.getBytes("UTF-8"));
+                               checkNext(this, "SECOND", in, ln2.getBytes("UTF-8"));
+                       }
+               });
+
+               addTest(new TestCase("nextAll()") {
+                       @Override
+                       public void test() throws Exception {
+                               byte[] data = new byte[] { 42, 12, 0, 127, 12, 51, 11, 12 };
+                               NextableInputStream in = new NextableInputStream(
+                                               new ByteArrayInputStream(data),
+                                               new NextableInputStreamStep(12));
+
+                               checkNext(this, "FIRST", in, new byte[] { 42 });
+                               checkNextAll(this, "REST", in, new byte[] { 0, 127, 12, 51, 11,
+                                               12 });
+                               assertEquals("The stream still has some data", false, in.next());
+                       }
+               });
+
+               addTest(new TestCase("getBytesRead()") {
+                       @Override
+                       public void test() throws Exception {
+                               byte[] data = new byte[] { 42, 12, 0, 127, 12, 51, 11, 12 };
+                               NextableInputStream in = new NextableInputStream(
+                                               new ByteArrayInputStream(data),
+                                               new NextableInputStreamStep(12));
+
+                               in.nextAll();
+                               IOUtils.toByteArray(in);
+
+                               assertEquals("The number of bytes read is not correct",
+                                               data.length, in.getBytesRead());
+                       }
+               });
+
+               addTest(new TestCase("bytes array input") {
+                       @Override
+                       public void test() throws Exception {
+                               byte[] data = new byte[] { 42, 12, 0, 127, 12, 51, 11, 12 };
+                               NextableInputStream in = new NextableInputStream(data,
+                                               new NextableInputStreamStep(12));
+
+                               checkNext(this, "FIRST", in, new byte[] { 42 });
+                               checkNext(this, "SECOND", in, new byte[] { 0, 127 });
+                               checkNext(this, "THIRD", in, new byte[] { 51, 11 });
                        }
                });
        }
 
-       static void checkNext(TestCase test, boolean callNext, String prefix,
-                       NextableInputStream in, byte[] expected) throws Exception {
-               if (callNext) {
-                       test.assertEquals("Cannot get " + prefix + " entry", true,
-                                       in.next());
+       static void checkNext(TestCase test, String prefix, NextableInputStream in,
+                       byte[] expected) throws Exception {
+               test.assertEquals("Cannot get " + prefix + " entry", true, in.next());
+               byte[] actual = IOUtils.toByteArray(in);
+               test.assertEquals("The " + prefix
+                               + " resulting array has not the correct number of items",
+                               expected.length, actual.length);
+               for (int i = 0; i < actual.length; i++) {
+                       test.assertEquals("Item " + i + " (0-based) is not the same",
+                                       expected[i], actual[i]);
                }
+       }
+
+       static void checkNextAll(TestCase test, String prefix,
+                       NextableInputStream in, byte[] expected) throws Exception {
+               test.assertEquals("Cannot get " + prefix + " entries", true,
+                               in.nextAll());
                byte[] actual = IOUtils.toByteArray(in);
                test.assertEquals("The " + prefix
                                + " resulting array has not the correct number of items",