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JBIterator: do not advance cursor iterator on each hasNext()

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This commit is contained in:
Gregory.Shrago
2016-11-16 06:45:58 +03:00
parent 5b5023467b
commit 656207eb3f
3 changed files with 108 additions and 42 deletions
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platform/platform-tests/testSrc/com/intellij/util/containers/TreeTraverserTest.java
+28 -3
View File
@@ -172,14 +172,39 @@ public class TreeTraverserTest extends TestCase {
assertEquals(new Integer(1), it.current());
}
public void testIteratorContractsCursor() {
public void testCursorIterableContract() {
List<Integer> list = ContainerUtil.newArrayList();
for (JBIterator<Integer> it : JBIterator.cursor(JBIterator.from(JBIterable.of(1, 2).iterator()))) {
JBIterable<Integer> orig = JBIterable.generate(1, INCREMENT).take(5);
for (JBIterator<Integer> it : JBIterator.cursor(JBIterator.from(orig.iterator()))) {
it.current();
it.hasNext();
list.add(it.current());
}
assertEquals(Arrays.asList(1, 2), list);
assertEquals(orig.toList(), list);
}
public void testCursorIteratorContract() {
JBIterable<Integer> orig = JBIterable.generate(1, INCREMENT).take(5);
JBIterator<JBIterator<Integer>> it = JBIterator.from(JBIterator.cursor(
JBIterator.from(orig.iterator())).iterator());
List<Integer> list = ContainerUtil.newArrayList();
while (it.advance()) {
it.hasNext();
list.add(it.current().current());
}
assertEquals(orig.toList(), list);
}
public void testCursorTransform() {
JBIterable<Integer> orig = JBIterable.generate(1, INCREMENT).take(5);
List<Integer> expected = ContainerUtil.newArrayList(1, 2, 3, 4, 5);
List<Integer> expectedOdd = ContainerUtil.newArrayList(1, 3, 5);
assertEquals(expected, JBIterator.cursor(JBIterator.from(orig.iterator())).transform(o -> o.current()).toList());
assertEquals(expected.size(), JBIterator.cursor(JBIterator.from(orig.iterator())).last().current().intValue());
assertEquals(expectedOdd, JBIterator.cursor(JBIterator.from(orig.iterator())).transform(o -> o.current()).filter(IS_ODD).toList());
assertEquals(expectedOdd, JBIterator.cursor(JBIterator.from(orig.iterator())).filter(o -> IS_ODD.value(o.current())).transform(o -> o.current()).toList());
assertEquals(expected.subList(0, 4), JBIterator.cursor(JBIterator.from(orig.iterator())).filter(o -> o.hasNext()).transform(o -> o.current()).toList());
}
public void testIteratorContractsSkipAndStop() {
platform/util/src/com/intellij/util/containers/JBIterable.java
+1 -1
View File
@@ -210,7 +210,7 @@ public abstract class JBIterable<E> implements Iterable<E> {
@NotNull
@Override
public String toString() {
return myIterable == this ? super.toString() : String.valueOf(myIterable);
return myIterable == this ? JBIterable.class.getSimpleName() : String.valueOf(myIterable);
}
/**
platform/util/src/com/intellij/util/containers/JBIterator.java
+79 -38
View File
@@ -46,16 +46,13 @@ import java.util.NoSuchElementException;
*
* @author gregsh
*
* @noinspection unchecked, AssignmentToForLoopParameter
* @noinspection unchecked, TypeParameterHidesVisibleType, AssignmentToForLoopParameter
*/
public abstract class JBIterator<E> implements Iterator<E> {
private static final Object NONE = new String("#none");
private static final Object STOP = new String("#stop");
private static final Object SKIP = new String("#skip");
@NotNull
public static <E extends JBIterator<?>> JBIterable<E> cursor(@NotNull E iterator) {
return JBIterable.generate(iterator, Functions.<E, E>identity()).takeWhile(ADVANCE);
return JBIterable.generate(iterator, Functions.<E>id()).intercept(CURSOR_NEXT);
}
@NotNull
@@ -73,10 +70,11 @@ public abstract class JBIterator<E> implements Iterator<E> {
};
}
private Object myCurrent = NONE;
private Object myNext = NONE;
private enum Do {INIT, STOP, SKIP}
private Object myCurrent = Do.INIT;
private Object myNext = Do.INIT;
private Op myFirstOp = new Op(null);
private Op myFirstOp = new NextOp();
private Op myLastOp = myFirstOp;
/**
@@ -94,7 +92,7 @@ public abstract class JBIterator<E> implements Iterator<E> {
*/
@Nullable
protected final E stop() {
myNext = STOP;
myNext = Do.STOP;
return null;
}
@@ -103,14 +101,14 @@ public abstract class JBIterator<E> implements Iterator<E> {
*/
@Nullable
protected final E skip() {
myNext = SKIP;
myNext = Do.SKIP;
return null;
}
@Override
public final boolean hasNext() {
peekNext();
return myNext != STOP;
return myNext != Do.STOP;
}
@Override
@@ -123,11 +121,14 @@ public abstract class JBIterator<E> implements Iterator<E> {
* Proceeds to the next element if any and returns true; otherwise false.
*/
public final boolean advance() {
myCurrent = NONE;
myCurrent = Do.INIT;
peekNext();
if (myNext == STOP) return false;
if (myNext == Do.STOP) return false;
myCurrent = myNext;
myNext = NONE;
myNext = Do.INIT;
if (myFirstOp instanceof JBIterator.CursorOp) {
((CursorOp)myFirstOp).advance(myCurrent);
}
currentChanged();
return true;
}
@@ -136,20 +137,22 @@ public abstract class JBIterator<E> implements Iterator<E> {
* Returns the current element if any; otherwise throws exception.
*/
public final E current() {
if (myCurrent == NONE) throw new NoSuchElementException();
if (myCurrent == Do.INIT) {
throw new NoSuchElementException();
}
return (E)myCurrent;
}
private void peekNext() {
if (myNext != NONE) return;
Object o = NONE;
if (myNext != Do.INIT) return;
Object o = Do.INIT;
for (Op op = myFirstOp; op != null; op = op == null ? myFirstOp : op.nextOp) {
o = op.impl == null ? nextImpl() : op.apply(o);
if (myNext == SKIP) {
o = myNext = NONE;
o = op.apply(op.impl == null ? nextImpl() : o);
if (myNext == Do.STOP) return;
if (myNext == Do.SKIP) {
o = myNext = Do.INIT;
op = null;
}
if (myNext == STOP) return;
}
myNext = o;
}
@@ -167,7 +170,7 @@ public abstract class JBIterator<E> implements Iterator<E> {
@NotNull
public final JBIterator<E> take(int count) {
// add first so that the underlying iterator stay on 'count' position
return addOp(myLastOp.impl != null, new WhileOp<E>(new CountDown<E>(count)));
return addOp(!(myLastOp instanceof NextOp), new WhileOp<E>(new CountDown<E>(count)));
}
@NotNull
@@ -187,7 +190,10 @@ public abstract class JBIterator<E> implements Iterator<E> {
@NotNull
private <T> T addOp(boolean last, @NotNull Op op) {
if (last) {
if (op.impl == null) {
myFirstOp = myLastOp = op;
}
else if (last) {
myLastOp.nextOp = op;
myLastOp = myLastOp.nextOp;
}
@@ -210,8 +216,8 @@ public abstract class JBIterator<E> implements Iterator<E> {
@Override
public String toString() {
JBIterable<Op> ops = operationsImpl();
return "{cur=" + myCurrent + "; next=" + myNext + (ops.isEmpty() ? "" : "; ops[" + ops.size() + "]=" + ops) + "}";
List<Op> ops = operationsImpl().toList();
return "{cur=" + myCurrent + "; next=" + myNext + (ops.size() < 2 ? "" : "; ops=" + ops) + "}";
}
@NotNull
@@ -226,7 +232,7 @@ public abstract class JBIterator<E> implements Iterator<E> {
@NotNull
private JBIterable<Op> operationsImpl() {
return JBIterable.generate(myFirstOp.nextOp, new Function<Op, Op>() {
return JBIterable.generate(myFirstOp, new Function<Op, Op>() {
@Override
public Op fun(Op op) {
return op.nextOp;
@@ -234,15 +240,20 @@ public abstract class JBIterator<E> implements Iterator<E> {
});
}
@NotNull
static String toShortString(@NotNull Object o) {
String fqn = o.getClass().getName();
return StringUtil.replace(o.toString(), fqn, StringUtil.getShortName(fqn, '.'));
String name = o.getClass().getName();
int idx = name.lastIndexOf('$');
if (idx > 0 && idx < name.length() && StringUtil.isJavaIdentifierStart(name.charAt(idx + 1))) {
return name.substring(idx + 1);
}
return name.substring(name.lastIndexOf('.') + 1);
}
private static final Condition<JBIterator<?>> ADVANCE = new Condition<JBIterator<?>>() {
private static final Function.Mono CURSOR_NEXT = new Function.Mono<JBIterator<?>>() {
@Override
public boolean value(JBIterator<?> it) {
return it.advance();
public JBIterator<?> fun(JBIterator<?> iterator) {
return iterator.addOp(false, iterator.new CursorOp());
}
};
@@ -260,7 +271,7 @@ public abstract class JBIterator<E> implements Iterator<E> {
@Override
public String toString() {
return impl == null ? "" : toShortString(impl);
return toShortString(impl == null ? this : impl);
}
}
@@ -283,7 +294,7 @@ public abstract class JBIterator<E> implements Iterator<E> {
}
@Override
public Object apply(Object o) {
Object apply(Object o) {
return impl.fun((E)o);
}
}
@@ -294,7 +305,7 @@ public abstract class JBIterator<E> implements Iterator<E> {
}
@Override
public Object apply(Object o) {
Object apply(Object o) {
return impl.value((E)o) ? o : skip();
}
}
@@ -305,24 +316,54 @@ public abstract class JBIterator<E> implements Iterator<E> {
super(condition);
}
@Override
public Object apply(Object o) {
Object apply(Object o) {
return impl.value((E)o) ? o : stop();
}
}
private class SkipOp<E> extends Op<Condition<? super E>> {
boolean active;
boolean active = true;
SkipOp(Condition<? super E> condition) {
super(condition);
active = true;
}
@Override
public Object apply(Object o) {
Object apply(Object o) {
if (active && impl.value((E)o)) return skip();
active = false;
return o;
}
}
private static class NextOp extends Op<Void> {
NextOp() {
super(null);
}
@Override
Object apply(Object o) {
return o;
}
}
private class CursorOp extends Op<Void> {
boolean advanced;
CursorOp() {
super(null);
}
@Override
Object apply(Object o) {
JBIterator<?> it = (JBIterator<?>)o;
return ((advanced = nextOp != null) ? it.advance() : it.hasNext()) ? it : stop();
}
void advance(Object o) {
if (advanced || !(o instanceof JBIterator)) return;
((JBIterator)o).advance();
advanced = true;
}
}
}