VersionConstraint.unionOf constructor
Creates a new version constraint that is the union of constraints
.
It allows any versions that any of those constraints allows. If
constraints
is empty, this returns a constraint that allows no versions.
Implementation
factory VersionConstraint.unionOf(Iterable<VersionConstraint> constraints) {
var flattened = constraints.expand((constraint) {
if (constraint.isEmpty) return [];
if (constraint is VersionUnion) return constraint.ranges;
return [constraint];
}).toList();
if (flattened.isEmpty) return VersionConstraint.empty;
if (flattened.any((constraint) => constraint.isAny)) {
return VersionConstraint.any;
}
// Only allow Versions and VersionRanges here so we can more easily reason
// about everything in [flattened]. _EmptyVersions and VersionUnions are
// filtered out above.
for (var constraint in flattened) {
if (constraint is VersionRange) continue;
throw new ArgumentError('Unknown VersionConstraint type $constraint.');
}
flattened.sort();
var merged = <VersionRange>[];
for (var constraint in flattened) {
// Merge this constraint with the previous one, but only if they touch.
if (merged.isEmpty ||
(!merged.last.allowsAny(constraint) &&
!areAdjacent(merged.last, constraint))) {
merged.add(constraint);
} else {
merged[merged.length - 1] = merged.last.union(constraint);
}
}
if (merged.length == 1) return merged.single;
return new VersionUnion.fromRanges(merged);
}