Merge pull request #13252 from marcemmers/span-add-begin-end

Implements iterators for the Span class to be compatible with std::span

platform/Span.h

@@ -19,6 +19,7 @@
 #define MBED_PLATFORM_SPAN_H_
 
 #include <algorithm>
+#include <iterator>
 #include <stddef.h>
 #include <stdint.h>
 
@@ -233,6 +234,16 @@ struct Span {
  */
  typedef element_type &reference;
 
+ /**
+ * Iterator to an ElementType
+ */
+ typedef pointer iterator;
+
+ /**
+ * Reverse iterator to an ElementType
+ */
+ typedef std::reverse_iterator<iterator> reverse_iterator;
+
  /**
  * Size of the Extent; -1 if dynamic.
  */
@@ -349,6 +360,46 @@ struct Span {
  return size() == 0;
  }
 
+ /**
+ * Return an iterator to the first element of the sequence.
+ *
+ * @return An iterator to the first element of the sequence.
+ */
+ iterator begin() const
+ {
+ return _data;
+ }
+
+ /**
+ * Return an iterator to the element following the last element of the sequence.
+ *
+ * @return An iterator to the element following the last element of the sequence.
+ */
+ iterator end() const
+ {
+ return _data + Extent;
+ }
+
+ /**
+ * Return a reverse_iterator to the first element of the reversed sequence.
+ *
+ * @return A reverse_iterator to the first element of the reversed sequence.
+ */
+ reverse_iterator rbegin() const
+ {
+ return reverse_iterator(end());
+ }
+
+ /**
+ * Return a reverse_iterator to the element following the last element of the reversed sequence.
+ *
+ * @return A reverse_iterator to the element following the last element of the reversed sequence.
+ */
+ reverse_iterator rend() const
+ {
+ return reverse_iterator(begin());
+ }
+
  /**
  * Returns a reference to the element at position @p index.
  *
@@ -534,6 +585,16 @@ struct Span<ElementType, SPAN_DYNAMIC_EXTENT> {
  */
  typedef element_type &reference;
 
+ /**
+ * Iterator to an ElementType
+ */
+ typedef pointer iterator;
+
+ /**
+ * Reverse iterator to an ElementType
+ */
+ typedef std::reverse_iterator<iterator> reverse_iterator;
+
  /**
  * Size of the Extent; -1 if dynamic.
  */
@@ -644,6 +705,46 @@ struct Span<ElementType, SPAN_DYNAMIC_EXTENT> {
  return size() == 0;
  }
 
+ /**
+ * Return an iterator to the first element of the sequence.
+ *
+ * @return An iterator to the first element of the sequence.
+ */
+ iterator begin() const
+ {
+ return _data;
+ }
+
+ /**
+ * Return an iterator to the element following the last element of the sequence.
+ *
+ * @return An iterator to the element following the last element of the sequence.
+ */
+ iterator end() const
+ {
+ return _data + _size;
+ }
+
+ /**
+ * Return a reverse_iterator to the first element of the reversed sequence.
+ *
+ * @return A reverse_iterator to the first element of the reversed sequence.
+ */
+ reverse_iterator rbegin() const
+ {
+ return reverse_iterator(end());
+ }
+
+ /**
+ * Return a reverse_iterator to the element following the last element of the reversed sequence.
+ *
+ * @return A reverse_iterator to the element following the last element of the reversed sequence.
+ */
+ reverse_iterator rend() const
+ {
+ return reverse_iterator(begin());
+ }
+
  /**
  * Access to an element of the sequence.
  *