X-Git-Url: https://adrianiainlam.tk/git/?a=blobdiff_plain;f=dygraph-utils.js;h=7aeca8d4e67b7b2c896d6ec80ca602124fde08d6;hb=ff1074cd53a1818d415c5da0a0acb516e6c02d65;hp=63411a599627809693bf15837ee47d466558f39c;hpb=c84d136cf6c4dac8e61f4a976487e14b72d4541a;p=dygraphs.git

diff --git a/dygraph-utils.js b/dygraph-utils.js
index 63411a5..7aeca8d 100644
--- a/dygraph-utils.js
+++ b/dygraph-utils.js
@@ -681,6 +681,61 @@ Dygraph.isAndroid = function() {
   return (/Android/).test(navigator.userAgent);
 };
 
+Dygraph.Iterator = function(array, start, length, predicate) {
+  start = start || 0;
+  length = length || array.length;
+  this.hasNext = true; // Use to identify if there's another element.
+  this.peek = null; // Use for look-ahead
+  this.array_ = array;
+  this.predicate_ = predicate;
+  this.end_ = Math.min(array.length, start + length);
+  this.nextIdx_ = start - 1; // use -1 so initial advance works.
+  this.next(); // ignoring result.
+}
+
+Dygraph.Iterator.prototype.next = function() {
+  if (!this.hasNext) {
+    return null;
+  }
+  var obj = this.peek;
+
+  var nextIdx = this.nextIdx_ + 1;
+  var found = false;
+  while (nextIdx < this.end_) {
+    if (!this.predicate_ || this.predicate_(this.array_, nextIdx)) {
+      this.peek = this.array_[nextIdx];
+      found = true;
+      break;
+    }
+    nextIdx++;
+  }
+  this.nextIdx_ = nextIdx;
+  if (!found) {
+    this.hasNext = false;
+    this.peek = null;
+  }
+  return obj;
+}
+
+/**
+ * @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, 0 if absent.
+ * @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. array.length when absent.
+ * @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.
+ */
+Dygraph.createIterator = function(array, start, length, predicate) {
+  return new Dygraph.Iterator(array, start, length, predicate);
+};
+
 /**
  * @private
  * Call a function N times at a given interval, then call a cleanup function