Start work on span

3 files changed, 74 insertions, 0 deletions

diff --git a/asl/BUILD.bazel b/asl/BUILD.bazel
index f0a9c38..d8810dd 100644
--- a/asl/BUILD.bazel
+++ b/asl/BUILD.bazel
@@ -14,6 +14,7 @@ cc_library(
         "meta.hpp",

         "option.hpp",

         "print.hpp",

+        "span.hpp",

         "utility.hpp",

     ],

     srcs = [

@@ -40,5 +41,6 @@ cc_library(
     "maybe_uninit",

     "meta",

     "option",

+    "span",

     "utility",

 ]]

diff --git a/asl/span.hpp b/asl/span.hpp
new file mode 100644
index 0000000..f3d4036
--- /dev/null
+++ b/asl/span.hpp
@@ -0,0 +1,44 @@
+#pragma once
+
+#include "asl/meta.hpp"
+#include "asl/annotations.hpp"
+#include "asl/layout.hpp"
+
+namespace asl
+{
+
+static constexpr int64_t dynamic_size = -1;
+
+template<is_object T, int64_t kSize = dynamic_size>
+class span
+{
+    static constexpr bool kIsDynamic = kSize < 0;
+
+    using SizeType = select_t<kIsDynamic, int64_t, empty>;
+
+    T* m_data{};
+    ASL_NO_UNIQUE_ADDRESS SizeType m_size{};
+
+public:
+    constexpr span() = default;
+
+    constexpr span(const span&) = default;
+    constexpr span(span&&) = default;
+    
+    constexpr span& operator=(const span&) = default;
+    constexpr span& operator=(span&&) = default;
+
+    ~span() = default;
+
+    constexpr int64_t size() const
+    {
+        if constexpr (kIsDynamic) { return m_size; }
+        else { return kSize; }
+    }
+
+    constexpr int64_t size_bytes() const { return size() * size_of<T>; }
+
+    constexpr bool is_empty() const { return size() == 0; }
+};
+
+} // namespace asl
diff --git a/asl/tests/span_tests.cpp b/asl/tests/span_tests.cpp
new file mode 100644
index 0000000..276d50a
--- /dev/null
+++ b/asl/tests/span_tests.cpp
@@ -0,0 +1,28 @@
+#include "asl/span.hpp"
+#include "asl/testing/testing.hpp"
+#include "asl/tests/test_types.hpp"
+
+static_assert(asl::trivially_destructible<asl::span<int>>);
+static_assert(asl::trivially_destructible<asl::span<HasDestructor>>);
+
+static_assert(asl::trivially_copyable<asl::span<int>>);
+static_assert(asl::trivially_copyable<asl::span<NonCopyConstructible>>);
+
+static_assert(asl::size_of<asl::span<int>> == asl::size_of<void*> * 2);
+static_assert(asl::size_of<asl::span<int, 2>> == asl::size_of<void*>);
+
+ASL_TEST(empty_dynamic)
+{
+    asl::span<int> s;
+    ASL_TEST_EXPECT(s.size() == 0);
+    ASL_TEST_EXPECT(s.size_bytes() == 0);
+    ASL_TEST_EXPECT(s.is_empty());
+}
+
+ASL_TEST(empty_static)
+{
+    asl::span<int, 0> s;
+    ASL_TEST_EXPECT(s.size() == 0);
+    ASL_TEST_EXPECT(s.size_bytes() == 0);
+    ASL_TEST_EXPECT(s.is_empty());
+}