Add Python-Protobuf generator

We add a generator for a library which allows conversion from model
instance to and from corresponding Protocol Buffers.

Author: mristin

README.rst

@@ -139,7 +139,7 @@ Call the generator with the appropriate target:
 
     usage: aas-core-codegen [-h] --model_path MODEL_PATH --snippets_dir
                             SNIPPETS_DIR --output_dir OUTPUT_DIR --target
-                            {csharp,cpp,golang,java,jsonschema,python,typescript,rdf_shacl,xsd,jsonld_context,protobuf}
+                            {csharp,cpp,golang,java,jsonschema,python,typescript,rdf_shacl,xsd,jsonld_context,protobuf,python_protobuf}
                             [--version]
 
     Generate implementations and schemas based on an AAS meta-model.
@@ -153,7 +153,7 @@ Call the generator with the appropriate target:
                             specific code snippets
       --output_dir OUTPUT_DIR
                             path to the generated code
-      --target {csharp,cpp,golang,java,jsonschema,python,typescript,rdf_shacl,xsd,jsonld_context,protobuf}
+      --target {csharp,cpp,golang,java,jsonschema,python,typescript,rdf_shacl,xsd,jsonld_context,protobuf,python_protobuf}
                             target language or schema
       --version             show the current version and exit
 

aas_core_codegen/main.py

@@ -18,6 +18,7 @@
 import aas_core_codegen.xsd.main as xsd_main
 import aas_core_codegen.jsonld.main as jsonld_main
 import aas_core_codegen.protobuf.main as protobuf_main
+import aas_core_codegen.python_protobuf.main as python_protobuf_main
 from aas_core_codegen import run, specific_implementations
 from aas_core_codegen.common import LinenoColumner, assert_never
 
@@ -38,6 +39,7 @@ class Target(enum.Enum):
     XSD = "xsd"
     JSONLD_CONTEXT = "jsonld_context"
     PROTOBUF = "protobuf"
+    PYTHON_PROTOBUF = "python_protobuf"
 
 
 class Parameters:
@@ -169,6 +171,9 @@ def execute(params: Parameters, stdout: TextIO, stderr: TextIO) -> int:
     elif params.target is Target.PROTOBUF:
         return protobuf_main.execute(run_context, stdout=stdout, stderr=stderr)
 
+    elif params.target is Target.PYTHON_PROTOBUF:
+        return python_protobuf_main.execute(run_context, stdout=stdout, stderr=stderr)
+
     else:
         assert_never(params.target)
 

aas_core_codegen/python_protobuf/__init__.py

@@ -0,0 +1 @@
+"""Generate the code for conversion from and to Protocol Buffers."""