From 78221946cc826980214e241eedc2a626f9e7b463 Mon Sep 17 00:00:00 2001
From: Lukas Tenbrink <lukas.tenbrink@gmail.com>
Date: Mon, 10 Mar 2025 18:55:09 +0100
Subject: [PATCH] Add C array constructor to `Span`. [skip ci]

---
 core/templates/span.h            | 19 +++++++++++++++++++
 tests/core/templates/test_span.h | 19 ++++++++++++-------
 2 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/core/templates/span.h b/core/templates/span.h
index c8f8591347..5aa9b3dab1 100644
--- a/core/templates/span.h
+++ b/core/templates/span.h
@@ -43,10 +43,29 @@ class Span {
 	uint64_t _len = 0;
 
 public:
+	static constexpr bool is_string = std::disjunction_v<
+		std::is_same<T, char>,
+		std::is_same<T, char16_t>,
+		std::is_same<T, char32_t>,
+		std::is_same<T, wchar_t>
+	>;
+
 	_FORCE_INLINE_ constexpr Span() = default;
 	_FORCE_INLINE_ constexpr Span(const T *p_ptr, uint64_t p_len) :
 			_ptr(p_ptr), _len(p_len) {}
 
+	// Allows creating Span directly from C arrays and string literals.
+	template <size_t N>
+	_FORCE_INLINE_ constexpr Span(const T (&p_array)[N]) :
+			_ptr(p_array), _len(N) {
+		if constexpr (is_string) {
+			// Cut off the \0 terminator implicitly added to string literals.
+			if (N > 0 && p_array[N - 1] == '\0') {
+				_len--;
+			}
+		}
+	}
+
 	_FORCE_INLINE_ constexpr uint64_t size() const { return _len; }
 	_FORCE_INLINE_ constexpr bool is_empty() const { return _len == 0; }
 
diff --git a/tests/core/templates/test_span.h b/tests/core/templates/test_span.h
index 94ce8183fa..9fe0b03058 100644
--- a/tests/core/templates/test_span.h
+++ b/tests/core/templates/test_span.h
@@ -48,17 +48,22 @@ TEST_CASE("[Span] Constexpr Validators") {
 	static_assert(span_value.size() == 1);
 	static_assert(!span_value.is_empty());
 
-	constexpr static char32_t array[] = U"122345";
-	constexpr Span<char32_t> span_array(array, strlen(array));
-	static_assert(span_array.ptr() == &array[0]);
+	static constexpr int ints[] = { 0, 1, 2, 3, 4, 5 };
+	constexpr Span<int> span_array = ints;
 	static_assert(span_array.size() == 6);
 	static_assert(!span_array.is_empty());
-	static_assert(span_array[0] == U'1');
-	static_assert(span_array[span_array.size() - 1] == U'5');
+	static_assert(span_array[0] == 0);
+	static_assert(span_array[span_array.size() - 1] == 5);
+
+	constexpr Span<char32_t> span_string = U"122345";
+	static_assert(span_string.size() == 6);
+	static_assert(!span_string.is_empty());
+	static_assert(span_string[0] == U'1');
+	static_assert(span_string[span_string.size() - 1] == U'5');
 
 	int idx = 0;
-	for (const char32_t &chr : span_array) {
-		CHECK_EQ(chr, span_array[idx++]);
+	for (const char32_t &chr : span_string) {
+		CHECK_EQ(chr, span_string[idx++]);
 	}
 }