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IntervalSet perf: Use binary search for IntervalSet.contains(el)

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Ben Hamilton 2017-03-24 11:46:41 -07:00
parent 0713128d04
commit 850abe1c81
1 changed files with 13 additions and 19 deletions
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32
runtime/Java/src/org/antlr/v4/runtime/misc/IntervalSet.java
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@ -384,30 +384,24 @@ public class IntervalSet implements IntSet {
@Override
public boolean contains(int el) {
int n = intervals.size();
for (int i = 0; i < n; i++) {
Interval I = intervals.get(i);
int l = 0;
int r = n - 1;
// Binary search for the element in the (sorted,
// disjoint) array of intervals.
while (l <= r) {
int m = (l + r) / 2;
Interval I = intervals.get(m);
int a = I.a;
int b = I.b;
if ( el<a ) {
break; // list is sorted and el is before this interval; not here
}
if ( el>=a && el<=b ) {
return true; // found in this interval
if ( b<el ) {
l = m + 1;
} else if ( a>el ) {
r = m - 1;
} else { // el >= a && el <= b
return true;
}
}
return false;
/*
for (ListIterator iter = intervals.listIterator(); iter.hasNext();) {
Interval I = (Interval) iter.next();
if ( el<I.a ) {
break; // list is sorted and el is before this interval; not here
}
if ( el>=I.a && el<=I.b ) {
return true; // found in this interval
}
}
return false;
*/
}
/** {@inheritDoc} */