Add support for creating ConstArrayRef from std::array

2 files changed, 25 insertions, 0 deletions

diff --git a/vespalib/src/tests/arrayref/arrayref_test.cpp b/vespalib/src/tests/arrayref/arrayref_test.cpp
index bd8646b2f99..8c41d38b292 100644
--- a/vespalib/src/tests/arrayref/arrayref_test.cpp
+++ b/vespalib/src/tests/arrayref/arrayref_test.cpp
@@ -53,4 +53,24 @@ TEST("require that references can be unconstified") {
     EXPECT_EQUAL(data[1], 5);
 }
 
+TEST("require that std::array references can be constified") {
+    std::array<int,3> data({1,2,3});
+    const ArrayRef<int> array_ref(data);
+    ConstArrayRef<int> const_ref(array_ref);
+    EXPECT_EQUAL(const_ref.size(), 3u);
+    EXPECT_EQUAL(const_ref.end() - const_ref.begin(), 3);
+    EXPECT_EQUAL(const_ref[2], 3);
+}
+
+TEST("require that references can be unconstified") {
+    std::array<int, 3> data({1,2,3});
+    const ConstArrayRef<int> const_ref(data);
+    ArrayRef<int> array_ref = unconstify(const_ref);
+    EXPECT_EQUAL(array_ref.size(), 3u);
+    EXPECT_EQUAL(array_ref.end() - array_ref.begin(), 3);
+    EXPECT_EQUAL(array_ref[1], 2);
+    array_ref[1] = 5;
+    EXPECT_EQUAL(data[1], 5);
+}
+
 TEST_MAIN() { TEST_RUN_ALL(); }
diff --git a/vespalib/src/vespa/vespalib/util/arrayref.h b/vespalib/src/vespa/vespalib/util/arrayref.h
index 319947e4cd9..9057f56fac0 100644
--- a/vespalib/src/vespa/vespalib/util/arrayref.h
+++ b/vespalib/src/vespa/vespalib/util/arrayref.h
@@ -3,6 +3,7 @@
 
 #include <cstddef>
 #include <vector>
+#include <array>
 
 namespace vespalib {
 
@@ -17,6 +18,8 @@ public:
     constexpr ArrayRef(T * v, size_t sz) noexcept : _v(v), _sz(sz) { }
     template<typename A=std::allocator<T>>
     ArrayRef(std::vector<T, A> & v) noexcept : _v(v.data()), _sz(v.size()) { }
+    template<size_t SZ>
+    ArrayRef(std::array<T, SZ> & v) noexcept : _v(v.data()), _sz(SZ) { }
     T & operator [] (size_t i) noexcept { return _v[i]; }
     const T & operator [] (size_t i) const noexcept { return _v[i]; }
     T * data() noexcept { return _v; }
@@ -36,6 +39,8 @@ public:
     constexpr ConstArrayRef(const T *v, size_t sz) noexcept : _v(v), _sz(sz) { }
     template<typename A=std::allocator<T>>
     ConstArrayRef(const std::vector<T, A> & v) noexcept : _v(v.data()), _sz(v.size()) { }
+    template<size_t SZ>
+    ConstArrayRef(const std::array<T, SZ> & v) noexcept : _v(v.data()), _sz(SZ) { }
     ConstArrayRef(const ArrayRef<T> & v) noexcept : _v(v.data()), _sz(v.size()) { }
     constexpr ConstArrayRef() noexcept : _v(nullptr), _sz(0) {}
     const T & operator [] (size_t i) const noexcept { return _v[i]; }