vendor filter iterator

vendor/github.com/hashicorp/go-memdb/filter.go

@@ -0,0 +1,33 @@
+package memdb
+
+// FilterFunc is a function that takes the results of an iterator and returns
+// whether the result should be filtered out.
+type FilterFunc func(interface{}) bool
+
+// FilterIterator is used to wrap a ResultIterator and apply a filter over it.
+type FilterIterator struct {
+	// filter is the filter function applied over the base iterator.
+	filter FilterFunc
+
+	// iter is the iterator that is being wrapped.
+	iter ResultIterator
+}
+
+func NewFilterIterator(wrap ResultIterator, filter FilterFunc) *FilterIterator {
+	return &FilterIterator{
+		filter: filter,
+		iter:   wrap,
+	}
+}
+
+// WatchCh returns the watch channel of the wrapped iterator.
+func (f *FilterIterator) WatchCh() <-chan struct{} { return f.iter.WatchCh() }
+
+// Next returns the next non-filtered result from the wrapped iterator
+func (f *FilterIterator) Next() interface{} {
+	for {
+		if value := f.iter.Next(); value == nil || !f.filter(value) {
+			return value
+		}
+	}
+}