Roll Observatory packages and add a roll script

quiver/lib/src/iterables/range.dart

-// Copyright 2013 Google Inc. All Rights Reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-part of quiver.iterables;
-
-/**
- * Returns an [Iterable] sequence of [num]s.
- *
- * If only one argument is provided, [start_or_stop] is the upper bound for the
- * sequence. If two or more arguments are provided, [stop] is the upper bound.
- *
- * The sequence starts at 0 if one argument is provided, or [start_or_stop] if
- * two or more arguments are provided. The sequence increments by 1, or [step]
- * if provided. [step] can be negative, in which case the sequence counts down
- * from the starting point and [stop] must be less than the starting point so
- * that it becomes the lower bound.
- */
-Iterable<num> range(num start_or_stop, [num stop, num step]) =>
-    new _Range(start_or_stop, stop, step);
-
-class _Range extends IterableBase<num> {
-  final num start, stop, step;
-
-  _Range(num start_or_stop, num _stop, num _step)
-      : start = (_stop == null) ? 0 : start_or_stop,
-        stop = (_stop == null) ? start_or_stop : _stop,
-        step = (_step == null) ? 1 : _step {
-    if (step == 0) {
-      throw new ArgumentError("step cannot be 0");
-    }
-    if ((step > 0) && (stop < start)) {
-      throw new ArgumentError("if step is positive,"
-          " stop must be greater than start");
-    }
-    if ((step < 0) && (stop > start)) {
-      throw new ArgumentError("if step is negative,"
-          " stop must be less than start");
-    }
-  }
-
-  Iterator<num> get iterator => new _RangeIterator(start, stop, step);
-}
-
-class _RangeIterator implements Iterator<num> {
-  final num _stop, _step;
-  num _value;
-  bool _hasNext;
-  bool _inRange;
-
-  _RangeIterator(num start, num stop, this._step)
-      : _value = start,
-        _stop = stop,
-        _hasNext = true,
-        _inRange = false;
-
-  num get current => _inRange ? _value : null;
-
-  bool moveNext() {
-    if (_hasNext && _inRange) _value += _step;
-    _inRange = _hasNext = (_step > 0) ? (_value < _stop) : (_value > _stop);
-    return _hasNext;
-  }
-}