Add support for include_directive in C

Fixes #46

Add support for processing `include_directive` in C files.

* **api/analyzers/c/analyzer.py**
  - Add `process_include_directive` method to handle `include_directive` nodes and create edges between files.
  - Modify `first_pass` method to process `include_directive` nodes and create edges between files.

* **tests/test_c_analyzer.py**
  - Add test case to verify the creation of edges between files for `include_directive`.

---

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Author: gkorland

api/analyzers/c/analyzer.py

@@ -315,6 +315,36 @@ def process_struct_specifier(self, parent: File, node: Node, path: Path,
             # Connect parent to entity
             graph.connect_entities('DEFINES', parent.id, entity.id)
 
+    def process_include_directive(self, parent: File, node: Node, path: Path, graph: Graph) -> None:
+        """
+        Processes an include directive node to create an edge between files.
+
+        Args:
+            parent (File): The parent File object.
+            node (Node): The AST node representing the include directive.
+            path (Path): The file path where the include directive is found.
+            graph (Graph): The Graph object to which the file entities and edges will be added.
+
+        Returns:
+            None
+        """
+
+        assert(node.type == 'include_directive')
+
+        # Extract the included file path
+        included_file_node = node.child_by_field_name('path')
+        if included_file_node is None:
+            return
+
+        included_file_path = included_file_node.text.decode('utf-8').strip('"<>')
+
+        # Create file entity for the included file
+        included_file = File(os.path.dirname(path), included_file_path, os.path.splitext(included_file_path)[1])
+        graph.add_file(included_file)
+
+        # Connect the parent file to the included file
+        graph.connect_entities('INCLUDES', parent.id, included_file.id)
+
     def first_pass(self, path: Path, f: io.TextIOWrapper, graph:Graph) -> None:
         """
         Perform the first pass processing of a C source file or header file.
@@ -388,6 +418,15 @@ def first_pass(self, path: Path, f: io.TextIOWrapper, graph:Graph) -> None:
             for node in structs:
                 self.process_struct_specifier(file, node, path, graph)
 
+        # Process include directives
+        query = C_LANGUAGE.query("(preprocessor_directive (include_directive) @include)")
+        captures = query.captures(tree.root_node)
+
+        if 'include' in captures:
+            includes = captures['include']
+            for node in includes:
+                self.process_include_directive(file, node, path, graph)
+
     def second_pass(self, path: Path, f: io.TextIOWrapper, graph: Graph) -> None:
         """
         Perform the second pass processing of a C source file or header file to establish function call relationships.

tests/test_c_analyzer.py

@@ -60,3 +60,10 @@ def test_analyzer(self):
         self.assertIn('add', callers)
         self.assertIn('main', callers)
 
+        # Test for include_directive edge creation
+        included_file = g.get_file('', 'myheader.h', '.h')
+        self.assertIsNotNone(included_file)
+
+        includes = g.get_neighbors([f.id], rel='INCLUDES')
+        included_files = [node['properties']['name'] for node in includes['nodes']]
+        self.assertIn('myheader.h', included_files)