--- a/src/basics.h Thu Feb 09 23:51:42 2017 +0200
+++ b/src/basics.h Fri Feb 10 23:06:24 2017 +0200
@@ -217,6 +217,75 @@
double getRadialPoint(int segment, int divisions, double(*func)(double));
QVector<QLineF> makeCircle(int segments, int divisions, double radius);
+/*
+ * Implements a ring adapter over T. This class corrects indices given to the element-operator so that they're within bounds.
+ * The maximum amount can be specified manually.
+ *
+ * Example:
+ *
+ * int A[] = {10,20,30,40};
+ * ring(A)[0] == A[0 % 4] == A[0]
+ * ring(A)[5] == A[5 % 4] == A[1]
+ * ring(A)[-1] == ring(A)[-1 + 4] == A[3]
+ */
+template<typename T>
+class RingAdapter
+{
+private:
+ // The private section must come first because _collection is used in decltype() below.
+ T& _collection;
+ const int _count;
+
+public:
+ RingAdapter(T& collection, int count) :
+ _collection {collection},
+ _count {count} {}
+
+ template<typename IndexType>
+ decltype(_collection[IndexType()]) operator[](IndexType index)
+ {
+ if (_count == 0)
+ {
+ // Argh! ...let the collection deal with this case.
+ return _collection[0];
+ }
+ else
+ {
+ index %= _count;
+
+ // Fix negative modulus...
+ if (index < 0)
+ index += _count;
+
+ return _collection[index];
+ }
+ }
+
+ int size() const
+ {
+ return _count;
+ }
+};
+
+/*
+ * Convenience function for RingAdapter so that the template parameter does not have to be provided. The ring amount is assumed
+ * to be the amount of elements in the collection.
+ */
+template<typename T>
+RingAdapter<T> ring(T& collection)
+{
+ return RingAdapter<T> {collection, countof(collection)};
+}
+
+/*
+ * Version of ring() that allows manual specification of the count.
+ */
+template<typename T>
+RingAdapter<T> ring(T& collection, int count)
+{
+ return RingAdapter<T> {collection, count};
+}
+
//
// Get the amount of elements in something.
//
@@ -254,3 +323,9 @@
{
return vector.size();
}
+
+template<typename T>
+int countof(const RingAdapter<T>& ring)
+{
+ return ring.size();
+}