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8139414: java.util.Scanner hasNext() returns true, next() throws NoSuchElementException

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8072582: Scanner delimits incorrectly when delimiter spans a buffer boundary

Reviewed-by: smarks
This commit is contained in:
Xueming Shen 2016-06-14 16:56:27 -07:00
parent aa221e3a63
commit 5aad7937b7
2 changed files with 71 additions and 19 deletions
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39
jdk/src/java.base/share/classes/java/util/Scanner.java
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@ -793,7 +793,6 @@ public final class Scanner implements Iterator<String>, Closeable {
private void readInput() {
if (buf.limit() == buf.capacity())
makeSpace();
// Prepare to receive data
int p = buf.position();
buf.position(buf.limit());
@ -806,15 +805,12 @@ public final class Scanner implements Iterator<String>, Closeable {
lastException = ioe;
n = -1;
}
if (n == -1) {
sourceClosed = true;
needInput = false;
}
if (n > 0)
needInput = false;
// Restore current position and limit for reading
buf.limit(buf.position());
buf.position(p);
@ -871,15 +867,20 @@ public final class Scanner implements Iterator<String>, Closeable {
matchValid = false;
matcher.usePattern(delimPattern);
matcher.region(position, buf.limit());
// Skip delims first
if (matcher.lookingAt())
if (matcher.lookingAt()) {
if (matcher.hitEnd() && !sourceClosed) {
// more input might change the match of delims, in which
// might change whether or not if there is token left in
// buffer (don't update the "position" in this case)
needInput = true;
return false;
}
position = matcher.end();
}
// If we are sitting at the end, no more tokens in buffer
if (position == buf.limit())
return false;
return true;
}
@ -900,7 +901,6 @@ public final class Scanner implements Iterator<String>, Closeable {
*/
private String getCompleteTokenInBuffer(Pattern pattern) {
matchValid = false;
// Skip delims first
matcher.usePattern(delimPattern);
if (!skipped) { // Enforcing only one skip of leading delims
@ -941,13 +941,16 @@ public final class Scanner implements Iterator<String>, Closeable {
foundNextDelim = matcher.find();
}
if (foundNextDelim) {
// In the rare case that more input could cause the match
// to be lost and there is more input coming we must wait
// for more input. Note that hitting the end is okay as long
// as the match cannot go away. It is the beginning of the
// next delims we want to be sure about, we don't care if
// they potentially extend further.
if (matcher.requireEnd() && !sourceClosed) {
// In two rare cases that more input might cause the match to be
// lost or change.
// (1) if requireEnd() is true, more input might cause the match
// to be lost, we must wait for more input.
// (2) while hitting the end is okay IF the match does not
// go away AND the beginning of the next delims does not change
// (we don't care if they potentially extend further). But it's
// possible that more input could cause the beginning of the
// delims change, so have to wait for more input as well.
if ((matcher.requireEnd() || matcher.hitEnd()) && !sourceClosed) {
needInput = true;
return null;
}
@ -1341,8 +1344,9 @@ public final class Scanner implements Iterator<String>, Closeable {
saveState();
modCount++;
while (!sourceClosed) {
if (hasTokenInBuffer())
if (hasTokenInBuffer()) {
return revertState(true);
}
readInput();
}
boolean result = hasTokenInBuffer();
@ -1365,7 +1369,6 @@ public final class Scanner implements Iterator<String>, Closeable {
ensureOpen();
clearCaches();
modCount++;
while (true) {
String token = getCompleteTokenInBuffer(null);
if (token != null) {