Merge pull request #1749 from evoskuil/master

Add literal_length() constexprs.

Author: evoskuil

include/bitcoin/system/types.hpp

@@ -175,7 +175,7 @@ using unsigned_exact_type =
                     iif<Bytes == sizeof(uint64_t), uint64_t,
                         uintx_t<Bytes * 8u>>>>>>;
 
-/// Text capture.
+/// Literal capture.
 /// ---------------------------------------------------------------------------
 
 // Implementation requires c-style array.
@@ -200,6 +200,21 @@ struct text_t
     }
 };
 
+template <size_t Size, typename Byte,
+    std::enable_if_t<std::is_same_v<Byte, char>, bool> = true>
+constexpr size_t literal_length(const Byte(&)[Size]) noexcept
+{
+    // Excludes literal string null terminator.
+    return Size - 1;
+}
+
+template <size_t Size, typename Byte,
+    std::enable_if_t<std::is_same_v<Byte, uint8_t>, bool> = true>
+constexpr size_t literal_length(const Byte(&)[Size]) noexcept
+{
+    return Size;
+}
+
 BC_POP_WARNING()
 BC_POP_WARNING()
 

test/types.cpp

@@ -236,3 +236,22 @@ static_assert(is_same_type<unsigned_exact_type<256>, uintx_t<to_bits(256u)>>);
 static_assert(is_same_type<unsigned_exact_type<512>, uintx_t<to_bits(512u)>>);
 static_assert(is_same_type<unsigned_exact_type<1024>, uintx_t<to_bits(1024u)>>);
 static_assert(is_same_type<unsigned_exact_type<2048>, uintx_t<to_bits(2048u)>>);
+
+// literal_length
+// ----------------------------------------------------------------------------
+
+static_assert(literal_length("") == 0_size);
+static_assert(literal_length("abc") == 3_size);
+static_assert(literal_length("a\0c") == 3_size);
+
+static constexpr const char empty_text[] = "";
+static_assert(literal_length(empty_text) == 0_size);
+
+static constexpr const char double_terminated[] = "abc\0";
+static_assert(literal_length(double_terminated) == 4_size);
+
+static constexpr const char middle_terminated[] = "a\0c";
+static_assert(literal_length(middle_terminated) == 3_size);
+
+static constexpr const uint8_t not_empty_bytes[] = { 0x42, 0x00, 0x42, 0x00 };
+static_assert(literal_length(not_empty_bytes) == 4_size);