Command done

src/Command.cpp

@@ -0,0 +1,51 @@
+#include "Command.h"
+
+#include <iostream>
+
+
+namespace Command {
+    Command readCommand() {
+        if (!std::cin)
+            return {Exit{}};
+        std::string line;
+        if (!std::getline(std::cin, line))
+            return {Exit{}};
+
+        // Trim leading and trailing whitespaces
+        constexpr std::string_view TO_TRIM = " \t\n\r";
+        const size_t start = line.find_first_not_of(TO_TRIM);
+        const size_t end = line.find_last_not_of(TO_TRIM);
+        if (start == std::string::npos) return None{};
+        const std::string_view line_trimmed(line.data() + start, end - start + 1);
+
+        using namespace std::string_view_literals;
+        if (line_trimmed == "r"sv || line_trimmed == "refresh"sv)
+            return Refresh{};
+        if (line_trimmed == "n"sv || line_trimmed == ">"sv || line_trimmed == "next"sv)
+            return Next{};
+        if (line_trimmed == "p"sv || line_trimmed == "<"sv || line_trimmed == "previous"sv)
+            return Previous{};
+        if (line_trimmed == "x"sv || line_trimmed == "exit"sv || line_trimmed == "q"sv || line_trimmed == "quit"sv)
+            return Exit{};
+        if (line_trimmed == "help"sv || line_trimmed == "?"sv || line_trimmed == "?"sv)
+            return Help{};
+
+        if (line_trimmed.starts_with("seek") || line.starts_with("s ")) {
+            const size_t space = line_trimmed.find(' ');
+            if (space == std::string::npos)
+                throw NoNumberException();
+            int number = 0;
+            const size_t size = line.size();
+            for (size_t i = space + 1; i < size; ++i) {
+                const char c = line_trimmed[i];
+                if (!std::isdigit(c))
+                    throw NoNumberException();
+                number = number * 10 + (c - '0');
+            }
+
+            return {Seek{number}};
+        }
+
+        return {None{}};
+    }
+}