Added static assert of std::string::value_type size

* CodepointIterator only supports UTF-8 encoded single-byte input strings
** this should prevent CodepointIterator from compiling on systems with larger char sizes while providing a helpful error message
* improved const-correctness by marking currByte (iterator dereferencing cache) and helper method arguments as const

1 files changed, 4 insertions, 4 deletions

diff --git a/src/utility.h b/src/utility.h
index 8aa46a0..75811f5 100644
--- a/src/utility.h
+++ b/src/utility.h
@@ -20,14 +20,14 @@ enum class CodePoint : std::uint8_t {
 	FOUR         = (UINT8_MAX >> 5), // 00000111
 };
 
-inline bool match(std::uint8_t unit, CodeUnitType type) {
+inline bool match(const std::uint8_t unit, const CodeUnitType type) {
 	return unit & static_cast<std::uint8_t>(type);
 }
 
 inline void write(char32_t& point,
-                  std::uint8_t unit,
-                  CodePoint mask,
-                  std::uint8_t offset) {
+                  const std::uint8_t unit,
+                  const CodePoint mask,
+                  const std::uint8_t offset) {
 	point += (unit & static_cast<std::uint8_t>(mask)) << offset;
 }