Добавлена третья задача пятой главы

Занимательное программирование/5/3_context/main.cpp

@@ -0,0 +1,67 @@
+#include <iostream>
+#include <cstdlib>
+#include <array>
+#include "utf8.h"
+#include "context.hpp"
+#include "utf8/checked.h"
+
+static
+context_model process_input()
+{
+    std::array<char, 4096> buffer;
+    std::ptrdiff_t left_over{ 0 };
+    context_model context;
+
+    while (!std::cin.eof())
+    {
+        std::cin.read(buffer.data() + left_over, buffer.size() - left_over);
+
+        std::array<char, 4096>::iterator octet_iterator = std::begin(buffer);
+        std::array<char, 4096>::iterator start_iterator = octet_iterator;
+        std::array<char, 4096>::iterator end_iterator = octet_iterator + std::cin.gcount() + left_over;
+
+        try
+        {
+            while (start_iterator != end_iterator)
+            {
+                utf8::utfchar32_t character = utf8::next(start_iterator, end_iterator);
+
+                context.add(character);
+                octet_iterator = start_iterator;
+            }
+            left_over = 0;
+        }
+        catch (const utf8::not_enough_room&)
+        {
+            std::copy(octet_iterator, end_iterator, std::begin(buffer));
+            left_over = std::distance(octet_iterator, end_iterator);
+        }
+    }
+    return context;
+}
+
+/*
+ * Reads a UTF-8 file from stdin, analyzes it and prints context information.
+ */
+int main(int argc, char **argv)
+{
+    context_model context = process_input();
+
+    std::size_t i{ 0 };
+    for (auto [context_characters, occurrence]: context)
+    {
+        ++i;
+        std::cout << i << ". " << context_characters << ": ";
+
+        for (auto [character, count]: occurrence)
+        {
+            std::string character_bytes;
+            utf8::append(character, character_bytes);
+
+            std::cout << character_bytes << " - " << count << "; ";
+        }
+        std::cout  << std::endl;
+    }
+
+    return EXIT_SUCCESS;
+}