1 files changed, 139 insertions, 0 deletions
diff --git a/src/third-party/scnlib/include/scn/unicode/utf16.h b/src/third-party/scnlib/include/scn/unicode/utf16.h
new file mode 100644
index 0000000..8d8a400
--- /dev/null
+++ b/src/third-party/scnlib/include/scn/unicode/utf16.h
@@ -0,0 +1,139 @@
+// Copyright 2017 Elias Kosunen
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// This file is a part of scnlib:
+//     https://github.com/eliaskosunen/scnlib
+//
+// The contents of this file are based on utfcpp:
+//     https://github.com/nemtrif/utfcpp
+//     Copyright (c) 2006 Nemanja Trifunovic
+//     Distributed under the Boost Software License, version 1.0
+
+#ifndef SCN_UNICODE_UTF16_H
+#define SCN_UNICODE_UTF16_H
+
+#include "../detail/error.h"
+#include "../util/expected.h"
+#include "common.h"
+
+namespace scn {
+    SCN_BEGIN_NAMESPACE
+
+    namespace detail {
+        namespace utf16 {
+            template <typename U16>
+            SCN_CONSTEXPR14 int get_sequence_length(U16 ch)
+            {
+                uint16_t lead = mask16(ch);
+                if (is_lead_surrogate(lead)) {
+                    return 2;
+                }
+                if (SCN_UNLIKELY(is_trail_surrogate(lead))) {
+                    return 0;
+                }
+                return 1;
+            }
+
+            template <typename I, typename S>
+            SCN_CONSTEXPR14 error validate_next(I& it, S end, code_point& cp)
+            {
+                SCN_EXPECT(it != end);
+
+                uint16_t lead = mask16(*it);
+                if (is_lead_surrogate(lead)) {
+                    ++it;
+                    if (it == end) {
+                        return {error::invalid_encoding,
+                                "Lone utf16 lead surrogate"};
+                    }
+                    uint16_t trail = mask16(*it);
+                    if (!is_trail_surrogate(trail)) {
+                        return {error::invalid_encoding,
+                                "Invalid utf16 trail surrogate"};
+                    }
+                    ++it;
+                    cp = static_cast<code_point>(
+                        static_cast<uint32_t>(lead << 10u) + trail +
+                        surrogate_offset);
+                    return {};
+                }
+                if (is_trail_surrogate(lead)) {
+                    return {error::invalid_encoding,
+                            "Lone utf16 trail surrogate"};
+                }
+
+                cp = static_cast<code_point>(*it);
+                ++it;
+                return {};
+            }
+
+            template <typename I, typename S>
+            SCN_CONSTEXPR14 expected<I> parse_code_point(I begin,
+                                                         S end,
+                                                         code_point& cp)
+            {
+                auto e = validate_next(begin, end, cp);
+                if (!e) {
+                    return e;
+                }
+                return {begin};
+            }
+
+            template <typename I, typename S>
+            SCN_CONSTEXPR14 expected<I> encode_code_point(I begin,
+                                                          S end,
+                                                          code_point cp)
+            {
+                SCN_EXPECT(begin + 2 <= end);
+
+                if (!is_valid_code_point(cp)) {
+                    return error(error::invalid_encoding,
+                                 "Invalid code point, cannot encode in UTF-16");
+                }
+
+                if (cp > 0xffffu) {
+                    *begin++ = static_cast<uint16_t>(
+                        (static_cast<uint32_t>(cp) >> 10u) + lead_offset);
+                    *begin++ = static_cast<uint16_t>(
+                        (static_cast<uint32_t>(cp) & 0x3ffu) +
+                        trail_surrogate_min);
+                }
+                else {
+                    *begin++ = static_cast<uint16_t>(cp);
+                }
+                return {begin};
+            }
+
+            template <typename I, typename S>
+            SCN_CONSTEXPR14 expected<std::ptrdiff_t> code_point_distance(
+                I begin,
+                S end)
+            {
+                std::ptrdiff_t dist{};
+                code_point cp{};
+                for (; begin < end; ++dist) {
+                    auto e = validate_next(begin, end, cp);
+                    if (!e) {
+                        return e;
+                    }
+                }
+                return {dist};
+            }
+        }  // namespace utf16
+    }      // namespace detail
+
+    SCN_END_NAMESPACE
+}  // namespace scn
+
+#endif