Short live q20::fill{,_n}!

It just adds constexpr to it (we're ignoring the range version).

Apply it to QStaticByteArrayMatcher, where it replaces rather
lengthy initialization code.

Pick-to: 6.4
Change-Id: I1d60216fb04c94fa66fce5cc01313b3e9ba856ac
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 24 insertions, 0 deletions

diff --git a/src/corelib/global/q20algorithm.h b/src/corelib/global/q20algorithm.h
index 1d2e0117f4..69dc2d2446 100644
--- a/src/corelib/global/q20algorithm.h
+++ b/src/corelib/global/q20algorithm.h
@@ -32,6 +32,8 @@ namespace q20 {
 using std::copy;
 using std::copy_if;
 using std::copy_n;
+using std::fill;
+using std::fill_n;
 using std::is_sorted_until;
 using std::is_sorted;
 using std::transform;
@@ -75,6 +77,28 @@ copy_n(InputIterator first, Size n, OutputIterator dest)
     return dest;
 }
 
+template <typename ForwardIterator, typename Value>
+constexpr void
+fill(ForwardIterator first, ForwardIterator last, const Value &value)
+{
+    while (first != last) {
+        *first = value;
+        ++first;
+    }
+}
+
+template <typename OutputIterator, typename Size, typename Value>
+constexpr OutputIterator
+fill_n(OutputIterator first, Size n, const Value &value)
+{
+    while (n > Size{0}) {
+        *first = value;
+        ++first;
+        --n;
+    }
+    return first;
+}
+
 template <typename ForwardIterator, typename BinaryPredicate = std::less<>>
 constexpr ForwardIterator
 is_sorted_until(ForwardIterator first, ForwardIterator last, BinaryPredicate p = {})