import java.io.IOException;
import java.io.InputStream;
-import java.util.ArrayList;
-import java.util.List;
-public class NextableInputStream extends InputStream {
- private List<NextableInputStreamStep> steps = new ArrayList<NextableInputStreamStep>();
- private NextableInputStreamStep step = null;
-
- private InputStream in;
- private boolean eof;
- private int pos = 0;
- private int len = 0;
- private byte[] buffer = new byte[4096];
-
- public NextableInputStream(InputStream in) {
- this.in = in;
+/**
+ * This {@link InputStream} can be separated into sub-streams (you can process
+ * it as a normal {@link InputStream} but, when it is spent, you can call
+ * {@link NextableInputStream#next()} on it to unlock new data).
+ * <p>
+ * The separation in sub-streams is done via {@link NextableInputStreamStep}.
+ *
+ * @author niki
+ */
+public class NextableInputStream extends BufferedInputStream {
+ private NextableInputStreamStep step;
+ private boolean started;
+ private boolean stopped;
+
+ /**
+ * Create a new {@link NextableInputStream} that wraps the given
+ * {@link InputStream}.
+ *
+ * @param in
+ * the {@link InputStream} to wrap
+ * @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(InputStream in, NextableInputStreamStep step) {
+ super(in);
+ this.step = step;
}
- public void addStep(NextableInputStreamStep step) {
- steps.add(step);
+ /**
+ * 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);
}
- public boolean next() {
- if (!hasMoreData() && step != null) {
- len = step.getResumeLen();
- pos += step.getSkip();
- eof = false;
- step = null;
-
- checkNexts(false);
+ /**
+ * 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) {
+ super(in, offset, length);
+ this.step = step;
+ checkBuffer(true);
+ }
- return true;
- }
+ /**
+ * Unblock the processing of the next sub-stream.
+ * <p>
+ * It can only be called when the "current" stream is spent (i.e., you must
+ * first process the stream until it is spent).
+ * <p>
+ * We consider that when the under-laying {@link InputStream} is also spent,
+ * we cannot have a next sub-stream (it will thus return FALSE).
+ * <p>
+ * {@link IOException}s can happen when we have no data available in the
+ * buffer; in that case, we fetch more data to know if we can have a next
+ * sub-stream or not.
+ *
+ * @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 next() throws IOException {
+ return next(false);
+ }
- return 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);
}
+ /**
+ * Check if we still have some data in the buffer and, if not, fetch some.
+ *
+ * @return TRUE if we fetched some data, FALSE if there are still some in
+ * the buffer
+ *
+ * @throws IOException
+ * in case of I/O error
+ */
@Override
- public int read() throws IOException {
- preRead();
- if (eof) {
- return -1;
+ protected boolean preRead() throws IOException {
+ if (!stopped) {
+ boolean bufferChanged = super.preRead();
+ checkBuffer(true);
+ return bufferChanged;
}
- return buffer[pos++];
+ if (pos >= len) {
+ eof = true;
+ }
+
+ return false;
}
+ /**
+ * We have more data available in the buffer or we can fetch more.
+ *
+ * @return TRUE if it is the case, FALSE if not
+ */
@Override
- public int read(byte[] b) throws IOException {
- return read(b, 0, b.length);
+ protected boolean hasMoreData() {
+ return started && super.hasMoreData();
}
- @Override
- public int read(byte[] b, int boff, int blen) throws IOException {
- if (b == null) {
- throw new NullPointerException();
- } else if (boff < 0 || blen < 0 || blen > b.length - boff) {
- throw new IndexOutOfBoundsException();
- } else if (blen == 0) {
- return 0;
- }
+ /**
+ * Check that the buffer didn't overshot to the next item, and fix
+ * {@link NextableInputStream#len} if needed.
+ * <p>
+ * If {@link NextableInputStream#len} is fixed,
+ * {@link NextableInputStream#eof} and {@link NextableInputStream#stopped}
+ * are set to TRUE.
+ *
+ * @param newBuffer
+ * we changed the buffer, we need to clear some information in
+ * the {@link NextableInputStreamStep}
+ */
+ private void checkBuffer(boolean newBuffer) {
+ if (step != null && len > 0) {
+ if (newBuffer) {
+ step.clearBuffer();
+ }
- int done = 0;
- while (hasMoreData() && done < blen) {
- preRead();
- if (hasMoreData()) {
- for (int i = pos; i < blen && i < len; i++) {
- b[boff + done] = buffer[i];
- pos++;
- done++;
- }
+ int stopAt = step.stop(buffer, pos, len);
+ if (stopAt >= 0) {
+ len = stopAt;
+ eof = true;
+ stopped = true;
}
}
-
- return done > 0 ? done : -1;
}
- @Override
- public int available() throws IOException {
- return Math.max(0, len - pos);
- }
+ /**
+ * 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;
+ }
- private void preRead() throws IOException {
- if (!eof && in != null && pos >= len && step == null) {
- pos = 0;
- len = in.read(buffer);
- checkNexts(true);
+ return true;
}
- if (pos >= len) {
- eof = true;
- }
- }
+ if (step != null && !hasMoreData() && stopped) {
+ len = step.getResumeLen();
+ pos += step.getResumeSkip();
+ eof = false;
- private boolean hasMoreData() {
- return !(eof && pos >= len);
- }
+ if (all) {
+ step = null;
+ }
- private void checkNexts(boolean newBuffer) {
- if (!eof) {
- for (NextableInputStreamStep step : steps) {
- if (newBuffer) {
- step.clearBuffer();
- }
-
- int stopAt = step.stop(buffer, pos, len);
- if (stopAt >= 0) {
- this.step = step;
- len = stopAt;
- eof = true;
- break;
- }
+ if (!preRead()) {
+ checkBuffer(false);
}
+
+ // consider that if EOF, there is no next
+ return hasMoreData();
}
+
+ return false;
}
}
git://git.nikiroo.be / nikiroo-utils.git / blobdiff