Range experiment

.clang-format

@@ -3,7 +3,7 @@ AccessModifierOffset: -1
 ConstructorInitializerIndentWidth: 4
 AlignTrailingComments: true
 AllowAllParametersOfDeclarationOnNextLine: true
-AllowShortIfStatementsOnASingleLine: WithoutElse
+#AllowShortIfStatementsOnASingleLine: WithoutElse
 AllowShortLoopsOnASingleLine: true
 AlwaysBreakTemplateDeclarations: Yes
 AlwaysBreakBeforeMultilineStrings: true
@@ -31,4 +31,3 @@ BreakBeforeBraces: Attach
 SpacesInParentheses: false
 SpaceInEmptyParentheses: false
 SpacesInCStyleCastParentheses: false
-

include/skyr/unicode/code_point.hpp

@@ -0,0 +1,310 @@
+// Copyright 2019 Glyn Matthews.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef SKYR_UNICODE_CODE_POINT_HPP
+#define SKYR_UNICODE_CODE_POINT_HPP
+
+#include <tl/expected.hpp>
+#include <skyr/unicode/errors.hpp>
+#include <skyr/unicode/constants.hpp>
+#include <skyr/unicode/core.hpp>
+
+namespace skyr::unicode {
+/// This class defines a range over a code point in raw bytes,
+/// according to UTF-8.
+/// \tparam OctetIterator An iterator type over the raw bytes
+template<typename OctetIterator>
+class u8_code_point_t {
+ public:
+
+  ///
+  using const_iterator = OctetIterator;
+  ///
+  using iterator = const_iterator;
+  ///
+  using value_type = char;
+  ///
+  using const_reference = value_type;
+  ///
+  using reference = const_reference;
+  ///
+  using size_type = std::size_t;
+
+  /// \brief Constructor
+  /// \param first An iterator at the beginning of the code point
+  /// \param last An iterator at the end of the code point
+  constexpr u8_code_point_t(
+      OctetIterator first,
+      OctetIterator last)
+      : first(first), last(last) {}
+
+  /// \brief Constructor. The length of the code point sequence is
+  ///        inferred from the first code point value.
+  /// \param first An iterator at the beginning of the code point
+  explicit constexpr u8_code_point_t(OctetIterator first)
+      : u8_code_point_t(first, first + sequence_length(*first)) {}
+
+  /// \brief Copy constructor.
+  constexpr u8_code_point_t(const u8_code_point_t &) = default;
+  /// \brief Move constructor.
+  constexpr u8_code_point_t(u8_code_point_t &&) noexcept = default;
+  /// \brief Copy assignment operator.
+  constexpr u8_code_point_t &operator=(const u8_code_point_t &) = default;
+  /// \brief Move assignment operator.
+  constexpr u8_code_point_t &operator=(u8_code_point_t &&) noexcept = default;
+  /// \brief Destructor.
+  ~u8_code_point_t() = default;
+
+  /// Returns an iterator to the beginning
+  /// \return \c const_iterator
+  [[nodiscard]] constexpr const_iterator begin() const noexcept {
+    return first;
+  }
+
+  /// Returns an iterator to the end
+  /// \return \c const_iterator
+  [[nodiscard]] constexpr const_iterator end() const noexcept {
+    return last;
+  }
+
+  /// Returns an iterator to the beginning
+  /// \return \c const_iterator
+  [[nodiscard]] constexpr auto cbegin() const noexcept {
+    return begin();
+  }
+
+  /// Returns an iterator to the end
+  /// \return \c const_iterator
+  [[nodiscard]] constexpr auto cend() const noexcept {
+    return end();
+  }
+
+  /// \brief Returns the length in bytes of this code point.
+  /// \return
+  [[nodiscard]] constexpr auto size() const noexcept -> size_type {
+    return sequence_length(*first);
+  }
+
+ private:
+
+  OctetIterator first, last;
+
+};
+
+///
+/// \tparam OctetRange
+/// \param range
+/// \return
+template<typename OctetRange>
+inline tl::expected<u8_code_point_t<typename OctetRange::const_iterator>, std::error_code> u8_code_point(
+    const OctetRange &range) {
+  auto first = std::begin(range), last = std::end(range);
+  if (std::distance(first, last) > sequence_length(*first)) {
+    return tl::make_unexpected(make_error_code(unicode_errc::overflow));
+  }
+  return u8_code_point_t<typename OctetRange::const_iterator>(
+      first,
+      first + sequence_length(*first));
+}
+
+
+/// Tests if the code point value is valid.
+/// \returns \c true if the value is a valid code point, \c false otherwise
+template <typename OctetIterator>
+inline bool is_valid(const u8_code_point_t<OctetIterator> &code_point) {
+  return static_cast<bool>(find_code_point(std::begin(code_point)));
+}
+
+///
+/// \tparam OctetRange
+/// \param range
+/// \return
+template <typename OctetRange>
+inline tl::expected<u8_code_point_t<typename OctetRange::const_iterator>, std::error_code> valid_u8_code_point(
+    const OctetRange &range) {
+  using result_type = tl::expected<u8_code_point_t<typename OctetRange::const_iterator>, std::error_code>;
+
+  auto check_code_point = [] (auto &&code_point) -> result_type {
+    return find_code_point(std::begin(code_point))
+        .and_then([=] (auto) -> result_type {
+          return code_point;
+        });
+  };
+
+  return
+      u8_code_point(range)
+          .and_then(check_code_point);
+}
+
+///
+class u16_code_point_t {
+
+ public:
+
+  ///
+  /// \param code_point
+  explicit constexpr u16_code_point_t(char32_t code_point)
+  : code_point_(code_point) {}
+
+  ///
+  /// \param code_point
+  explicit constexpr u16_code_point_t(char16_t code_point)
+  : code_point_(code_point) {}
+
+  constexpr u16_code_point_t(char16_t lead_value, char16_t trail_value)
+  : code_point_((lead_value << 10) + trail_value + constants::surrogates::offset) {}
+
+  ///
+  constexpr u16_code_point_t(const u16_code_point_t &) = default;
+  ///
+  constexpr u16_code_point_t(u16_code_point_t &&) noexcept = default;
+  ///
+  u16_code_point_t &operator=(const u16_code_point_t &) = default;
+  ///
+  u16_code_point_t &operator=(u16_code_point_t &&) noexcept = default;
+  ///
+  ~u16_code_point_t() = default;
+
+  ///
+  /// \return
+  [[nodiscard]] uint16_t lead_value() const {
+    return is_surrogate_pair()?
+           static_cast<char16_t>((code_point_ >> 10U) + constants::surrogates::lead_offset) :
+           static_cast<char16_t>(code_point_);
+  }
+
+  ///
+  /// \return
+  [[nodiscard]] uint16_t trail_value() const {
+    return is_surrogate_pair()?
+           static_cast<char16_t>((code_point_ & 0x3ffU) + constants::surrogates::trail_min) :
+           0;
+  }
+
+  ///
+  /// \return
+  [[nodiscard]] constexpr bool is_surrogate_pair() const noexcept {
+    return code_point_ > 0xffffU;
+  }
+
+  tl::expected<char32_t, std::error_code> u32_value() const noexcept {
+    return code_point_;
+  }
+
+ private:
+
+  char32_t code_point_;
+
+};
+
+///
+/// \param code_point
+/// \return
+inline u16_code_point_t u16_code_point(char32_t code_point) {
+  return u16_code_point_t(code_point);
+}
+
+///
+/// \param code_point
+/// \return
+inline u16_code_point_t u16_code_point(char16_t code_point) {
+  return u16_code_point_t(code_point);
+}
+
+///
+/// \param lead
+/// \param value
+/// \return
+inline u16_code_point_t u16_code_point(char16_t lead, char16_t value) {
+  return u16_code_point_t(lead, value);
+}
+
+///
+/// \tparam OctetIterator
+/// \param code_point
+/// \return
+template <typename OctetIterator>
+inline tl::expected<char32_t, std::error_code> u32_value(
+    u8_code_point_t<OctetIterator> code_point) noexcept {
+  return find_code_point(code_point.begin())
+      .and_then([] (auto state) -> tl::expected<char32_t, std::error_code> {
+        return state.value;
+      });
+}
+
+///
+/// \tparam OctetIterator
+/// \param code_point
+/// \return
+template <typename OctetIterator>
+inline tl::expected<char32_t, std::error_code> u32_value(
+    tl::expected<u8_code_point_t<OctetIterator>, std::error_code> code_point) noexcept {
+  return code_point
+  .and_then([] (auto code_point) -> tl::expected<char32_t , std::error_code> {
+    return u32_value(code_point);
+  });
+}
+
+///
+/// \param code_point
+/// \return
+inline tl::expected<char32_t, std::error_code> u32_value(
+    u16_code_point_t code_point) noexcept {
+  return code_point.u32_value();
+}
+
+///
+/// \param code_point
+/// \return
+inline tl::expected<char32_t, std::error_code> u32_value(
+    tl::expected<u16_code_point_t, std::error_code> code_point) noexcept {
+  return code_point
+  .and_then([] (auto code_point) -> tl::expected<char32_t, std::error_code> {
+    return code_point.u32_value();
+  });
+}
+
+///
+/// \param code_point
+/// \return
+inline tl::expected<char32_t, std::error_code> u32_value(
+    char32_t code_point) noexcept {
+  return code_point;
+}
+
+///
+/// \param code_point
+/// \return
+inline tl::expected<char32_t, std::error_code> u32_value(
+    tl::expected<char32_t, std::error_code> code_point) noexcept {
+  return code_point;
+}
+
+///
+/// \tparam OctetIterator
+/// \param code_point
+/// \return
+template <typename OctetIterator>
+inline tl::expected<u16_code_point_t, std::error_code> u16_value(
+    u8_code_point_t<OctetIterator> code_point) {
+  return u16_code_point(u32_value(code_point));
+}
+
+///
+/// \tparam OctetIterator
+/// \param code_point
+/// \return
+template <typename OctetIterator>
+inline tl::expected<u16_code_point_t, std::error_code> u16_value(
+    tl::expected<u8_code_point_t<OctetIterator>, std::error_code> code_point) {
+  return u32_value(code_point)
+  .and_then([] (auto code_point) -> tl::expected<u16_code_point_t, std::error_code> {
+    return u16_code_point(code_point);
+  });
+}
+}  // namespace skyr::unicode
+
+
+#endif //SKYR_UNICODE_CODE_POINT_HPP

include/skyr/unicode/constants.hpp

@@ -3,8 +3,8 @@
 // (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef SKYR_CONSTANTS_HPP
-#define SKYR_CONSTANTS_HPP
+#ifndef SKYR_UNICODE_CONSTANTS_HPP
+#define SKYR_UNICODE_CONSTANTS_HPP
 
 namespace skyr::unicode::constants {
 namespace surrogates {
@@ -22,6 +22,8 @@ namespace code_points {
 // Maximum valid value for a Unicode code point
 constexpr char32_t max = 0x0010ffffu;
 }  // namespace code_points
+
+constexpr char bom[] = {'\xef', '\xbb', '\xbf'};
 }  // namespace skyr::unicode::constants
 
-#endif //SKYR_CONSTANTS_HPP
+#endif //SKYR_UNICODE_CONSTANTS_HPP