Add support for custom code generators (#66)

Author: LM-robynka

src/objdictgen/__main__.py

@@ -141,6 +141,7 @@ def main(debugopts: DebugOpts, args: Sequence[str]|None = None):
                         help="Store in internal format (json only)")
     subp.add_argument('--no-sort', action="store_true",
                         help="Don't order of parameters in output OD")
+    subp.add_argument('--generate-with', type=str, help="Pass a .py file for custom code generation")
 
     # -- DIFF --
     subp = subparser.add_parser('diff', parents=[common_opts], help="""
@@ -263,7 +264,7 @@ def main(debugopts: DebugOpts, args: Sequence[str]|None = None):
         od.DumpFile(opts.out,
             filetype=opts.type,
             # These additional options are only used for JSON output
-            sort=not opts.no_sort, internal=opts.internal, validate=not opts.novalidate
+            sort=not opts.no_sort, internal=opts.internal, validate=not opts.novalidate, custom_genfile=opts.generate_with
         )
 
 

src/objdictgen/node.py

@@ -21,6 +21,10 @@
 
 import copy
 import logging
+import importlib.util
+import sys
+import os
+
 from pathlib import Path
 from typing import Any, Generator, Iterable, Iterator
 
@@ -33,6 +37,26 @@
 log = logging.getLogger('objdictgen')
 
 
+def executeCustomGenerator(filename: str, filepath: TPath, node: NodeProtocol) -> None:
+    """Execute custom python file for code generation"""
+    parent_dir = os.path.dirname(os.path.abspath(filename))
+    sys.path.append(parent_dir)
+    spec = importlib.util.spec_from_file_location("CustomGenerator", filename)
+    customModule = importlib.util.module_from_spec(spec)
+    sys.modules["CustomGenerator"] = customModule
+    # Handle errors coming from custom code
+    try:
+        spec.loader.exec_module(customModule)
+    except Exception as e:
+        print(f"error executing {filename}: {e}")
+        return
+
+    if hasattr(customModule, 'GenerateFile'):
+        customModule.GenerateFile(filepath, node)
+    else:
+        raise AttributeError(f"{filename} does not have a 'GenerateFile' function.")
+
+
 # ------------------------------------------------------------------------------
 #                          Definition of Node Object
 # ------------------------------------------------------------------------------
@@ -192,7 +216,7 @@ def LoadJson(contents: str, validate=True) -> Node:
         """ Import a new Node from a JSON string """
         return jsonod.generate_node(contents, validate=validate)
 
-    def DumpFile(self, filepath: TPath, filetype: str|None = "jsonc", **kwargs):
+    def DumpFile(self, filepath: TPath, filetype: str|None = "jsonc", custom_genfile: TPath|None = None, **kwargs):
         """ Save node into file """
 
         # Attempt to determine the filetype from the filepath
@@ -223,6 +247,15 @@ def DumpFile(self, filepath: TPath, filetype: str|None = "jsonc", **kwargs):
             with open(filepath, "w", encoding="utf-8") as f:
                 f.write(jdata)
             return
+        
+        if custom_genfile is not None:
+            log.debug("Invoking custom generator: %s", custom_genfile)
+            try:
+                executeCustomGenerator(custom_genfile, filepath, self)
+                return
+            except (ImportError, ModuleNotFoundError):
+                log.debug("Failed to load custom generator: %s", custom_genfile)
+                raise
 
         if filetype == 'c':
             log.debug("Writing C files '%s'", filepath)

tests/conftest.py

@@ -282,6 +282,11 @@ def basepath():
     """ Fixture returning the base of the project """
     return (HERE / '..').resolve()
 
+@pytest.fixture
+def testspath():
+    """ Fixture returning the path to the tests directory """
+    return (HERE).resolve()
+
 
 @pytest.fixture
 def fn():

tests/test_generators/bad_generator.py

@@ -0,0 +1,7 @@
+"""Example of an invalid .py file you could pass with the --generate-with arg.
+In this case the function name does not match the expected name"""
+
+from objdictgen.typing import NodeProtocol, TPath
+
+def Generate_File(filepath: TPath, node: NodeProtocol):
+    return ""

tests/test_generators/generator.py

@@ -0,0 +1,6 @@
+"""Example of a valid .py file you could pass with the --generate-with arg"""
+
+from objdictgen.typing import NodeProtocol, TPath
+
+def GenerateFile(filepath: TPath, node: NodeProtocol):
+    print("success")

tests/test_node.py

@@ -1,11 +1,26 @@
 """Tests for node.py"""
 import pytest
 
-from objdictgen.node import Node
+from objdictgen.node import Node, NodeProtocol, executeCustomGenerator
 
 @pytest.mark.parametrize("file", ['master', 'slave'])
 def test_node_LoadFile(odpath, file):
 
     od = Node.LoadFile(odpath / (file + '.json'))
     assert isinstance(od, Node)
     assert od.Name == 'master' if file == 'master' else 'slave'
+
+@pytest.mark.parametrize("filename", ["this_file_does_not_exist.py", "bad_generator.py", "generator.py"])
+def test_node_execute_custom_generator(filename: str, testspath):
+    full_path = testspath.joinpath("test_generators").joinpath(filename)
+    mock_path = "/mock"
+    if filename == "bad_generator.py":
+        with pytest.raises(AttributeError):
+            executeCustomGenerator(full_path, mock_path, NodeProtocol)
+    elif filename == "this_file_does_not_exist.py":
+        executeCustomGenerator(full_path, mock_path, NodeProtocol)
+    elif filename == "generator.py":
+        try:
+            executeCustomGenerator(full_path, mock_path, NodeProtocol) == "success"
+        except Exception:
+            pytest.fail("failed to execute generator.py")