faster, a few tests failing

[dygraphs.git] / dygraph-utils.js

diff --git a/dygraph-utils.js b/dygraph-utils.js
index f65a7a6..d3a31d5 100644 (file)
--- a/dygraph-utils.js
+++ b/dygraph-utils.js
@@ -681,64 +681,60 @@ 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.start_ = start;
+  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
+ * @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.
+ * 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.
- *
- * 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_;
-    this.hasNext_ = true;
-    var self = this;
-
-    this.hasNext = function() {
-      return self.hasNext_;
-    }
-
-    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.nextIdx_ < self.end_) {
-        if (predicate(array, self.nextIdx_)) {
-          return;
-        }
-        self.nextIdx_++;
-      }
-      self.hasNext_ = false;
-    }
-  };
-  iter.advance_();
-  return iter;
+  return new Dygraph.Iterator(array, start, length, predicate);
 };
 
 /**