From f3025691d12727bbab138c13680cc21a451626b6 Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Sun, 19 Dec 2021 20:09:38 +0100
Subject: Simplify append_utf in output iterator

---
 include/unicode.h | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/include/unicode.h b/include/unicode.h
index 6d8aac5..7965a6e 100644
--- a/include/unicode.h
+++ b/include/unicode.h
@@ -284,7 +284,8 @@ namespace unicode::detail {
     return trailing_byte<m - n - 1>(value);
   }
 
-  void append_utf8(const char32_t& value)
+  template<class X = T, typename std::enable_if<(sizeof(X) == 1), bool>::type = true>
+  inline void append_utf(const char32_t& value)
   {
    if (value < 0x80) { // 1 byte
     s.push_back(static_cast<value_type>(value));
@@ -304,9 +305,10 @@ namespace unicode::detail {
     throw std::runtime_error("Invalid internal Unicode value: "s + std::to_string(static_cast<uint32_t>(value)));
   }
 
-  void append_utf16(const char32_t& value)
+  template<class X = T, typename std::enable_if<(sizeof(X) == 2), bool>::type = true>
+  inline void append_utf(const char32_t& value)
   {
-   if (value <= 0xFFFF) { // expect value to be already valid Unicode values
+   if (value <= 0xFFFF) { // expect value to be already valid Unicode values (checked in input iterator)
     s.push_back(static_cast<value_type>(value));
    } else {
     char32_t value_reduced{value - 0x10000};
@@ -315,23 +317,16 @@ namespace unicode::detail {
    }
   }
 
-  void append_utf32(const char32_t& value)
+  template<class X = T, typename std::enable_if<(sizeof(X) == 4), bool>::type = true>
+  inline void append_utf(const char32_t& value)
   {
-   // expect value to be already valid Unicode values
+   // expect value to be already valid Unicode values (checked in input iterator)
    s.push_back(value);
   }
 
   reference operator=(const char32_t& value)
   {
-   static_assert(sizeof(T) == 1 || sizeof(T) == 2 || sizeof(T) == 4);
-
-   if constexpr(sizeof(T) == 1) {
-    append_utf8(value);
-   } else if constexpr(sizeof(T) == 2) {
-    append_utf16(value);
-   } else if constexpr(sizeof(T) == 4) {
-    append_utf32(value);
-   }
+   append_utf(value);
    return *this;
   }
 
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