/**
* @private
+ * Returns a new iterator over array, between indexes start and
+ * start + length, and only returns entries that pass the accept function
+ *
+ * @param array the array to iterate over.
+ * @param start the first index to iterate over
+ * @param length the number of elements in the array to iterate over.
+ * This, along with start, defines a slice of the array, and so length
+ * doesn't imply the number of elements in the iterator when accept
+ * doesn't always accept all values.
+ * @param predicate a function that takes parameters array and idx, which
+ * returns true when the element should be returned. If omitted, all
+ * elements are accepted.
+ *
+ * TODO(konigsberg): add default vlues to start and length.
+ */
+Dygraph.createIterator = function(array, start, length, predicate) {
+ predicate = predicate || function() { return true; };
+
+ var iter = new function() {
+ this.idx_ = start - 1; // use -1 so initial call to advance works.
+ this.end_ = Math.min(array.length, start + length);
+ this.nextIdx_ = this.idx_;
+ var self = this;
+
+ this.hasNext = function() {
+ return self.nextIdx_ < self.end_;
+ }
+ this.next = function() {
+ if (self.hasNext()) {
+ self.idx_ = self.nextIdx_;
+ self.advance_();
+ return array[self.idx_];
+ }
+ return null;
+ }
+ this.peek = function() {
+ if (self.hasNext()) {
+ return array[self.nextIdx_];
+ }
+ return null;
+ }
+ this.advance_ = function() {
+ self.nextIdx_++;
+ while(self.hasNext()) {
+ if (predicate(array, self.nextIdx_)) {
+ return;
+ }
+ self.nextIdx_++;
+ }
+ }
+ };
+ iter.advance_();
+ return iter;
+};
+
+/**
+ * @private
* Call a function N times at a given interval, then call a cleanup function
* once. repeat_fn is called once immediately, then (times - 1) times
* asynchronously. If times=1, then cleanup_fn() is also called synchronously.