1 files changed, 171 insertions, 0 deletions
diff --git a/src/ww898/cp_utf8.hpp b/src/ww898/cp_utf8.hpp
new file mode 100644
index 0000000..8eaa133
--- /dev/null
+++ b/src/ww898/cp_utf8.hpp
@@ -0,0 +1,171 @@
+/*
+ * MIT License
+ * 
+ * Copyright (c) 2017-2019 Mikhail Pilin
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *  
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *  
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#pragma once
+
+#include <cstdint>
+#include <utility>
+#include <stdexcept>
+
+#include "base/result.h"
+
+namespace ww898 {
+namespace utf {
+
+// Supported combinations:
+//   0xxx_xxxx
+//   110x_xxxx 10xx_xxxx
+//   1110_xxxx 10xx_xxxx 10xx_xxxx
+//   1111_0xxx 10xx_xxxx 10xx_xxxx 10xx_xxxx
+//   1111_10xx 10xx_xxxx 10xx_xxxx 10xx_xxxx 10xx_xxxx
+//   1111_110x 10xx_xxxx 10xx_xxxx 10xx_xxxx 10xx_xxxx 10xx_xxxx
+struct utf8 final
+{
+    static size_t const max_unicode_symbol_size = 4;
+    static size_t const max_supported_symbol_size = 6;
+
+    static uint32_t const max_supported_code_point = 0x7FFFFFFF;
+
+    using char_type = uint8_t;
+
+    template<typename PeekFn>
+    static Result<size_t, const char *> char_size(PeekFn && peek_fn)
+    {
+        const std::pair<char_type, size_t> peek_res = std::forward<PeekFn>(peek_fn)();
+        const auto ch0 = peek_res.first;
+        const auto remaining = peek_res.second;
+        size_t retval = 0;
+
+        if (ch0 < 0x80) { // 0xxx_xxxx
+            retval = 1;
+        } else if (ch0 < 0xC0) {
+            return Err("The utf8 first char in sequence is incorrect");
+        } else if (ch0 < 0xE0) { // 110x_xxxx 10xx_xxxx
+            retval = 2;
+        } else if (ch0 < 0xF0) { // 1110_xxxx 10xx_xxxx 10xx_xxxx
+            retval = 3;
+        } else if (ch0 < 0xF8) { // 1111_0xxx 10xx_xxxx 10xx_xxxx 10xx_xxxx
+            retval = 4;
+        } else if (ch0 < 0xFC) { // 1111_10xx 10xx_xxxx 10xx_xxxx 10xx_xxxx 10xx_xxxx
+            retval = 5;
+        } else if (ch0 < 0xFE) { // 1111_110x 10xx_xxxx 10xx_xxxx 10xx_xxxx 10xx_xxxx 10xx_xxxx
+            retval = 6;
+        } else {
+            return Err("The utf8 first char in sequence is incorrect");
+        }
+        if (retval - 1 > remaining) {
+            return Err("Truncated utf8 sequence");
+        }
+        return Ok(retval);
+    }
+
+    template<typename ReadFn>
+    static uint32_t read(ReadFn && read_fn)
+    {
+        char_type const ch0 = read_fn();
+        if (ch0 < 0x80) // 0xxx_xxxx
+            return ch0;
+        if (ch0 < 0xC0)
+            throw std::runtime_error("The utf8 first char in sequence is incorrect");
+        if (ch0 < 0xE0) // 110x_xxxx 10xx_xxxx
+        {
+            char_type const ch1 = read_fn(); if (ch1 >> 6 != 2) goto _err;
+            return (ch0 << 6) + ch1 - 0x3080;
+        }
+        if (ch0 < 0xF0) // 1110_xxxx 10xx_xxxx 10xx_xxxx
+        {
+            char_type const ch1 = read_fn(); if (ch1 >> 6 != 2) goto _err;
+            char_type const ch2 = read_fn(); if (ch2 >> 6 != 2) goto _err;
+            return (ch0 << 12) + (ch1 << 6) + ch2 - 0xE2080;
+        }
+        if (ch0 < 0xF8) // 1111_0xxx 10xx_xxxx 10xx_xxxx 10xx_xxxx
+        {
+            char_type const ch1 = read_fn(); if (ch1 >> 6 != 2) goto _err;
+            char_type const ch2 = read_fn(); if (ch2 >> 6 != 2) goto _err;
+            char_type const ch3 = read_fn(); if (ch3 >> 6 != 2) goto _err;
+            return (ch0 << 18) + (ch1 << 12) + (ch2 << 6) + ch3 - 0x3C82080;
+        }
+        if (ch0 < 0xFC) // 1111_10xx 10xx_xxxx 10xx_xxxx 10xx_xxxx 10xx_xxxx
+        {
+            char_type const ch1 = read_fn(); if (ch1 >> 6 != 2) goto _err;
+            char_type const ch2 = read_fn(); if (ch2 >> 6 != 2) goto _err;
+            char_type const ch3 = read_fn(); if (ch3 >> 6 != 2) goto _err;
+            char_type const ch4 = read_fn(); if (ch4 >> 6 != 2) goto _err;
+            return (ch0 << 24) + (ch1 << 18) + (ch2 << 12) + (ch3 << 6) + ch4 - 0xFA082080;
+        }
+        if (ch0 < 0xFE) // 1111_110x 10xx_xxxx 10xx_xxxx 10xx_xxxx 10xx_xxxx 10xx_xxxx
+        {
+            char_type const ch1 = read_fn(); if (ch1 >> 6 != 2) goto _err;
+            char_type const ch2 = read_fn(); if (ch2 >> 6 != 2) goto _err;
+            char_type const ch3 = read_fn(); if (ch3 >> 6 != 2) goto _err;
+            char_type const ch4 = read_fn(); if (ch4 >> 6 != 2) goto _err;
+            char_type const ch5 = read_fn(); if (ch5 >> 6 != 2) goto _err;
+            return (ch0 << 30) + (ch1 << 24) + (ch2 << 18) + (ch3 << 12) + (ch4 << 6) + ch5 - 0x82082080;
+        }
+        throw std::runtime_error("The utf8 first char in sequence is incorrect");
+        _err: throw std::runtime_error("The utf8 slave char in sequence is incorrect");
+    }
+
+    template<typename WriteFn>
+    static void write(uint32_t const cp, WriteFn && write_fn)
+    {
+        if (cp < 0x80)          // 0xxx_xxxx
+            write_fn(static_cast<char_type>(cp));
+        else if (cp < 0x800)    // 110x_xxxx 10xx_xxxx
+        {
+            write_fn(static_cast<char_type>(0xC0 | cp >>  6));
+            goto _1;
+        }
+        else if (cp < 0x10000)  // 1110_xxxx 10xx_xxxx 10xx_xxxx
+        {
+            write_fn(static_cast<char_type>(0xE0 | cp >> 12));
+            goto _2;
+        }
+        else if (cp < 0x200000) // 1111_0xxx 10xx_xxxx 10xx_xxxx 10xx_xxxx
+        {
+            write_fn(static_cast<char_type>(0xF0 | cp >> 18));
+            goto _3;
+        }
+        else if (cp < 0x4000000) // 1111_10xx 10xx_xxxx 10xx_xxxx 10xx_xxxx 10xx_xxxx
+        {
+            write_fn(static_cast<char_type>(0xF8 | cp >> 24));
+            goto _4;
+        }
+        else if (cp < 0x80000000) // 1111_110x 10xx_xxxx 10xx_xxxx 10xx_xxxx 10xx_xxxx 10xx_xxxx
+        {
+            write_fn(static_cast<char_type>(0xFC | cp >> 30));
+            goto _5;
+        }
+        else
+            throw std::runtime_error("Tool large UTF8 code point");
+        return;
+        _5: write_fn(static_cast<char_type>(0x80 | (cp >> 24 & 0x3F)));
+        _4: write_fn(static_cast<char_type>(0x80 | (cp >> 18 & 0x3F)));
+        _3: write_fn(static_cast<char_type>(0x80 | (cp >> 12 & 0x3F)));
+        _2: write_fn(static_cast<char_type>(0x80 | (cp >>  6 & 0x3F)));
+        _1: write_fn(static_cast<char_type>(0x80 | (cp       & 0x3F)));
+    }
+};
+
+}}