import java.io.IOException;
import java.io.InputStream;
-import java.util.ArrayList;
-import java.util.List;
+/**
+ * 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 InputStream {
- private List<NextableInputStreamStep> steps = new ArrayList<NextableInputStreamStep>();
- private NextableInputStreamStep step = null;
+ private NextableInputStreamStep step;
+ private boolean stopped;
private InputStream in;
private boolean eof;
private int len = 0;
private byte[] buffer = new byte[4096];
- public NextableInputStream(InputStream in) {
+ /**
+ * 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) {
this.in = in;
+ this.step = step;
}
- public void addStep(NextableInputStreamStep step) {
- steps.add(step);
- }
-
- public boolean next() {
- if (!hasMoreData() && step != null) {
+ /**
+ * 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
+ */
+ public boolean next() throws IOException {
+ if (!hasMoreData() && stopped) {
len = step.getResumeLen();
- pos += step.getSkip();
+ pos += step.getResumeSkip();
eof = false;
- step = null;
-
- checkNexts(false);
- return true;
+ if (!preRead()) {
+ checkBuffer(false);
+ }
+
+ // consider that if EOF, there is no next
+ return hasMoreData();
}
return false;
return Math.max(0, len - pos);
}
- private void preRead() throws IOException {
- if (!eof && in != null && pos >= len && step == null) {
+ /**
+ * 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
+ */
+ private boolean preRead() throws IOException {
+ boolean hasRead = false;
+ if (!eof && in != null && pos >= len && !stopped) {
pos = 0;
len = in.read(buffer);
- checkNexts(true);
+ checkBuffer(true);
+ hasRead = true;
}
if (pos >= len) {
eof = true;
}
+
+ return hasRead;
}
+ /**
+ * We have more data available in the buffer or we can fetch more.
+ *
+ * @return TRUE if it is the case, FALSE if not
+ */
private boolean hasMoreData() {
return !(eof && pos >= len);
}
- private void checkNexts(boolean newBuffer) {
- if (!eof) {
- for (NextableInputStreamStep step : steps) {
- if (newBuffer) {
- step.clearBuffer();
- }
+ /**
+ * 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) {
+ if (newBuffer) {
+ step.clearBuffer();
+ }
- int stopAt = step.stop(buffer, pos, len);
- if (stopAt >= 0) {
- this.step = step;
- len = stopAt;
- eof = true;
- break;
- }
+ int stopAt = step.stop(buffer, pos, len);
+ if (stopAt >= 0) {
+ len = stopAt;
+ eof = true;
+ stopped = true;
}
}
}
package be.nikiroo.utils;
+import java.io.InputStream;
+
+/**
+ * Divide an {@link InputStream} into sub-streams.
+ *
+ * @author niki
+ */
public class NextableInputStreamStep {
private int stopAt;
- private boolean disabled;
- private int pos;
private int resumeLen;
private int last = -1;
private int skip;
+ /**
+ * Create a new divider that will separate the sub-streams each time it sees
+ * this byte.
+ * <p>
+ * Note that the byte will be bypassed by the {@link InputStream} as far as
+ * the consumers will be aware.
+ *
+ * @param byt
+ * the byte at which to separate two sub-streams
+ */
public NextableInputStreamStep(int byt) {
stopAt = byt;
}
- // do NOT stop twice on the same item
+ /**
+ * Check if we need to stop the {@link InputStream} reading at some point in
+ * the current buffer.
+ * <p>
+ * If we do, return the index at which to stop; if not, return -1.
+ * <p>
+ * This method will <b>not</b> return the same index a second time (unless
+ * we cleared the buffer).
+ *
+ * @param buffer
+ * the buffer to check
+ * @param pos
+ * the current position of what was read in the buffer
+ * @param len
+ * the maximum index to use in the buffer (anything above that is
+ * not to be used)
+ *
+ * @return the index at which to stop, or -1
+ */
public int stop(byte[] buffer, int pos, int len) {
for (int i = pos; i < len; i++) {
if (buffer[i] == stopAt) {
if (i > this.last) {
// we skip the sep
this.skip = 1;
-
- this.pos = pos;
+
this.resumeLen = len;
this.last = i;
return i;
return -1;
}
+ /**
+ * Get the maximum index to use in the buffer used in
+ * {@link NextableInputStreamStep#stop(byte[], int, int)} at resume time.
+ *
+ * @return the index
+ */
public int getResumeLen() {
return resumeLen;
}
-
- public int getSkip() {
+
+ /**
+ * Get the number of bytes to skip at resume time.
+ *
+ * @return the number of bytes to skip
+ */
+ public int getResumeSkip() {
return skip;
}
+ /**
+ * Clear the information we may have kept about the current buffer
+ * <p>
+ * You should call this method each time you change the content of the
+ * buffer used in {@link NextableInputStreamStep#stop(byte[], int, int)}.
+ */
public void clearBuffer() {
this.last = -1;
- this.pos = 0;
this.skip = 0;
this.resumeLen = 0;
}
-
- public boolean isEnabled() {
- return !disabled;
- }
}
package be.nikiroo.utils.test_code;
import java.io.ByteArrayInputStream;
-import java.io.InputStream;
import be.nikiroo.utils.IOUtils;
import be.nikiroo.utils.NextableInputStream;
@Override
public void test() throws Exception {
byte[] expected = new byte[] { 42, 12, 0, 127 };
- InputStream bin = new ByteArrayInputStream(expected);
- NextableInputStream in = new NextableInputStream(bin);
+ NextableInputStream in = new NextableInputStream(
+ new ByteArrayInputStream(expected), null);
byte[] actual = IOUtils.toByteArray(in);
assertEquals(
@Override
public void test() throws Exception {
byte[] expected = new byte[] { 42, 12, 0, 127 };
- InputStream bin = new ByteArrayInputStream(expected);
- NextableInputStream in = new NextableInputStream(bin);
- in.addStep(new NextableInputStreamStep(12));
- byte[] actual = IOUtils.toByteArray(in);
+ NextableInputStream in = new NextableInputStream(
+ new ByteArrayInputStream(expected),
+ new NextableInputStreamStep(12));
- assertEquals(
- "The resulting array has not the correct number of items",
- 1, actual.length);
- for (int i = 0; i < actual.length; i++) {
- assertEquals("Item " + i + " (0-based) is not the same",
- expected[i], actual[i]);
- }
+ checkNext(this, false, "FIRST", in, new byte[] { 42 });
}
});
addTest(new TestCase("Stop at 12, resume, stop again, resume") {
@Override
public void test() throws Exception {
- byte[] expected = new byte[] { 42, 12, 0, 127, 12, 51, 11, 12 };
+ byte[] data = new byte[] { 42, 12, 0, 127, 12, 51, 11, 12 };
NextableInputStream in = new NextableInputStream(
- new ByteArrayInputStream(expected));
- in.addStep(new NextableInputStreamStep(12));
+ new ByteArrayInputStream(data),
+ new NextableInputStreamStep(12));
- byte[] actual1 = IOUtils.toByteArray(in);
- byte[] expected1 = new byte[] { 42 };
- assertEquals(
- "The FIRST resulting array has not the correct number of items",
- expected1.length, actual1.length);
- for (int i = 0; i < actual1.length; i++) {
- assertEquals("Item " + i + " (0-based) is not the same",
- expected1[i], actual1[i]);
- }
+ 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 });
+ }
+ });
- assertEquals("Cannot get SECOND entry", true, in.next());
- byte[] actual2 = IOUtils.toByteArray(in);
- byte[] expected2 = new byte[] { 0, 127 };
- assertEquals(
- "The SECOND resulting array has not the correct number of items",
- expected2.length, actual2.length);
- for (int i = 0; i < actual2.length; i++) {
- assertEquals("Item " + i + " (0-based) is not the same",
- expected2[i], actual2[i]);
- }
+ addTest(new TestCase("Encapsulation") {
+ @Override
+ public void test() throws Exception {
+ byte[] data = new byte[] { 42, 12, 0, 4, 127, 12, 5 };
+ NextableInputStream in4 = new NextableInputStream(
+ new ByteArrayInputStream(data),
+ new NextableInputStreamStep(4));
+ NextableInputStream subIn12 = new NextableInputStream(in4,
+ new NextableInputStreamStep(12));
- assertEquals("Cannot get next THIRD entry", true, in.next());
- byte[] actual3 = IOUtils.toByteArray(in);
- byte[] expected3 = new byte[] { 51, 11 };
- assertEquals(
- "The THIRD resulting array has not the correct number of items",
- expected3.length, actual3.length);
- for (int i = 0; i < actual3.length; i++) {
- assertEquals("Item " + i + " (0-based) is not the same",
- expected3[i], actual3[i]);
- }
+ checkNext(this, false, "SUB FIRST", subIn12, new byte[] { 42 });
+ checkNext(this, true, "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 });
}
});
}
+
+ 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());
+ }
+ 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]);
+ }
+ }
}
git://git.nikiroo.be / nikiroo-utils.git / commitdiff