Move source reading into a function

boot/dependency.cc

@@ -0,0 +1,62 @@
+/* Dependency graph analysis.
+   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/boot/dependency.h"
+
+#include "elna/boot/driver.h"
+#include "parser.hh"
+
+namespace elna::boot
+{
+    dependency_graph::dependency_graph()
+    {
+    }
+
+    dependency_graph::dependency_graph(error_list&& errors)
+        : m_errors(std::move(errors))
+    {
+    }
+
+    bool dependency_graph::has_errors() const
+    {
+        return !errors().empty();
+    }
+
+    const error_list& dependency_graph::errors() const
+    {
+        return m_errors;
+    }
+
+    dependency_graph read_sources(std::istream& entry_point, const char *entry_path)
+    {
+        driver parse_driver{ entry_path };
+        lexer tokenizer(entry_point);
+        yy::parser parser(tokenizer, parse_driver);
+
+        if (parser())
+        {
+            return dependency_graph(std::move(parse_driver.errors()));
+        }
+        else
+        {
+            dependency_graph outcome;
+            outcome.modules.emplace_back(std::move(parse_driver.tree));
+
+            return outcome;
+        }
+    }
+}