Merge GCC frontend into the branch

frontend/driver.cc

@@ -0,0 +1,124 @@
+/* Parsing driver.
+   Copyright (C) 2025 Free Software Foundation, Inc.
+
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "elna/frontend/driver.h"
+
+namespace elna::frontend
+{
+    position make_position(const yy::location& location)
+    {
+        position result;
+        result.line = static_cast<std::size_t>(location.begin.line);
+        result.column = static_cast<std::size_t>(location.begin.column);
+
+        return result;
+    }
+
+    syntax_error::syntax_error(const std::string& message,
+            const char *input_file, const yy::location& location)
+        : error(input_file, make_position(location)), message(message)
+    {
+    }
+
+    std::string syntax_error::what() const
+    {
+        return message;
+    }
+
+    driver::driver(const char *input_file)
+        : error_container(input_file)
+    {
+    }
+
+    char escape_char(char escape)
+    {
+        switch (escape)
+        {
+        case 'n':
+            return '\n';
+        case 'a':
+            return '\a';
+        case 'b':
+            return '\b';
+        case 't':
+            return '\t';
+        case 'f':
+            return '\f';
+        case 'r':
+            return '\r';
+        case 'v':
+            return '\v';
+        case '\\':
+            return '\\';
+        case '\'':
+            return '\'';
+        case '"':
+            return '"';
+        case '?':
+            return '\?';
+        case '0':
+            return '\0';
+        default:
+            return escape_invalid_char;
+        }
+    }
+
+    std::optional<std::string> escape_string(const char *escape)
+    {
+        std::string result;
+        const char *current_position = escape + 1;
+
+        while (*current_position != '\0')
+        {
+            if (*current_position == '\\' && *(current_position + 1) == 'x')
+            {
+                current_position += 2;
+
+                std::size_t processed;
+                char character = static_cast<char>(std::stoi(current_position, &processed, 16));
+                if (processed == 0)
+                {
+                    return std::nullopt;
+                }
+                else
+                {
+                    current_position += processed - 1;
+                    result.push_back(character);
+                }
+            }
+            else if (*current_position == '\\')
+            {
+                ++current_position;
+
+                char escape = escape_char(*current_position);
+                if (escape == escape_invalid_char)
+                {
+                    return std::nullopt;
+                }
+                result.push_back(escape);
+            }
+            else
+            {
+                result.push_back(*current_position);
+            }
+            ++current_position;
+        }
+        result.pop_back(); // Remove the terminating quote character.
+
+        return result;
+    }
+}