From d234c1ca09af512e9a13579a6fff8d5834d7b36c Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Mon, 3 Jan 2022 16:08:38 +0100
Subject: Separated out remaining functions from unicode.h, documentation

---
 include/unicode/conversion.h | 113 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 include/unicode/conversion.h

(limited to 'include/unicode/conversion.h')

diff --git a/include/unicode/conversion.h b/include/unicode/conversion.h
new file mode 100644
index 0000000..dc57084
--- /dev/null
+++ b/include/unicode/conversion.h
@@ -0,0 +1,113 @@
+//
+// Reichwein.IT Unicode Library
+//
+// Functions for conversion between UTF and ISO encodings
+//
+
+#pragma once
+
+#include "unicode/endian.h"
+#include "unicode/iso.h"
+#include "unicode/optimization.h"
+#include "unicode/predicate.h"
+#include "unicode/types.h"
+#include "unicode/type_traits.h"
+#include "unicode/utf.h"
+
+#include <algorithm>
+#include <array>
+#include <cstdint>
+#include <iterator>
+#include <memory>
+#include <stdexcept>
+#include <string>
+#include <type_traits>
+#include <utility>
+
+namespace unicode {
+
+ // First variant of convert(): Specification of encodings explicitly
+ //
+ // e.g.
+ // unicode::UTF_8
+ // unicode::UTF_16
+ // unicode::UTF_32
+ // unicode::ISO_8859_1
+ // unicode::ISO_8859_15
+ //
+ // see also utf.h and iso.h
+ //
+ // From and To are Encodings
+ //
+ // throws std::invalid_argument on conversion error
+ template<typename From, typename To, std::enable_if_t<is_encoding_v<From> && is_encoding_v<To>, bool> = true>
+ typename To::string_type convert(const typename From::string_type& s)
+ {
+  // At compile time, decide which optimization to use, with fallback to
+  // iterating with std::copy()
+
+  // if input type == output type, only validate and return input, if appropriate
+  if constexpr(sizeof(typename From::value_type) == sizeof(typename To::value_type) &&
+               is_utf_encoding_v<From> && is_utf_encoding_v<To>) {
+   if (validate_utf<typename From::value_type>(s)) {
+    return s;
+   } else {
+    throw std::invalid_argument("Invalid UTF input");
+   }
+  } else if constexpr(accu_size == 8 && is_little_endian() && is_utf_8_v<typename From::value_type> &&
+                      is_utf_encoding_v<From> && is_utf_encoding_v<To>) { // endian specific optimization
+   return convert_optimized_utf<From, To>(s);
+  } else if constexpr(accu_size == 4 || accu_size == 8) { // accu size specific optimization with speedup for 7bit input
+   return convert_optimized<From, To>(s);
+  } else {
+   typename To::string_type result;
+   std::copy(From::begin(s), From::end(s), To::back_inserter(result));
+   return result;
+  }
+ }
+
+ // Second variant of convert(): Specification of encodings via character type
+ //
+ // see also type_traits.h for is_char
+ //
+ // From and To are from: utf8_t (i.e. char or char8_t (C++20)), char16_t and char32_t, char, wchar_t, uint8_t, uint16_t, uint32_t
+ //
+ // throws std::invalid_argument on conversion error
+ template<typename From, typename To,
+  typename FromContainer=std::basic_string<From>,
+  typename ToContainer=std::basic_string<To>,
+  std::enable_if_t<is_char_v<From> && is_char_v<To>, bool> = true>
+ ToContainer convert(const FromContainer& s)
+ {
+  typedef UTF<utf_iterator<From>, utf_back_insert_iterator<To>> UTF_Trait;
+
+  ToContainer result;
+
+  std::copy(UTF_Trait::begin(s), UTF_Trait::end(s), UTF_Trait::back_inserter(result));
+
+  return result;
+ }
+
+ // Third variant of convert(): Specification of encodings via container type
+ //
+ // see also type_traits.h for is_container
+ //
+ // From and To are containers
+ //
+ // throws std::invalid_argument on conversion error
+ template<typename FromContainer, typename ToContainer,
+  std::enable_if_t<is_container_v<FromContainer> && is_container_v<ToContainer>, bool> = true
+ >
+ ToContainer convert(const FromContainer& s)
+ {
+  typedef UTF<utf_iterator<typename FromContainer::value_type, FromContainer>, utf_back_insert_iterator<typename ToContainer::value_type, ToContainer>> UTF_Trait;
+  
+  ToContainer result;
+
+  std::copy(UTF_Trait::begin(s), UTF_Trait::end(s), UTF_Trait::back_inserter(result));
+
+  return result;
+ }
+
+} // namespace unicode
+
-- 
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