feat: Implement modelling rules and validation

Note that this feature is distinct from the "Validate Model" option in
the Capella GUI. Validation in capellambse uses its own custom set of
rules.

Also note that this is only an initial version, which still has a lot of
limitations. In future iterations, the applied ruleset may be extended,
modified, or made more configurable from a user's perspective.

Co-authored-by: Ernst Würger <ernst.wuerger@deutschebahn.com>
Co-authored-by: Martin Lehmann <martin.lehmann@deutschebahn.com>
Co-authored-by: Viktor Kravchenko <viktor.kravchenko@deutschebahn.com>

.pre-commit-config.yaml

@@ -108,6 +108,7 @@ repos:
           - mypy==1.10.0
           - click==8.1.7
           - diskcache==5.0
+          - jinja2==3.1.3
           - markupsafe==2.0
           - platformdirs==4.2.0
           - pytest-cov

capellambse/extensions/validation/__init__.py

@@ -0,0 +1,37 @@
+# SPDX-FileCopyrightText: Copyright DB InfraGO AG
+# SPDX-License-Identifier: Apache-2.0
+"""The module provides management and evaluation of validation rules.
+
+Validation rules are conditions ensuring that specific modeling
+guidelines are followed. These rules apply to particular types of model
+elements or to diagrams, and values of metrics. By evaluating each rule,
+the module generates validation results, indicating whether the
+corresponding guideline has been satisfied or not. This way, the module
+helps maintain the quality and consistency of the model.
+"""
+
+from ._validate import *
+
+from . import rules  # isort: skip
+
+
+def init() -> None:
+    # pylint: disable=redefined-outer-name # false-positive
+    import capellambse
+    from capellambse.model import common as c
+
+    c.set_accessor(
+        capellambse.MelodyModel,
+        "validation",
+        c.AlternateAccessor(ModelValidation),
+    )
+    capellambse.MelodyModel.validate = property(  # type: ignore[attr-defined]
+        lambda self: self.validation.validate
+    )
+
+    c.set_accessor(
+        c.GenericElement, "validation", c.AlternateAccessor(ElementValidation)
+    )
+    c.GenericElement.validate = property(  # type: ignore[attr-defined]
+        lambda self: self.validation.validate
+    )

capellambse/extensions/validation/__main__.py

@@ -0,0 +1,47 @@
+# SPDX-FileCopyrightText: Copyright DB InfraGO AG
+# SPDX-License-Identifier: Apache-2.0
+from __future__ import annotations
+
+import logging
+import typing as t
+
+import click
+import jinja2
+
+import capellambse
+
+
+@click.command()
+@click.option("-m", "--model", required=True, type=capellambse.ModelCLI())
+@click.option(
+    "-o",
+    "--output",
+    type=click.File("w", atomic=True),
+    required=True,
+    help="Output file to render the template into",
+)
+@click.option("-t", "--template", help="An optional custom template to render")
+def _main(
+    model: capellambse.MelodyModel,
+    template: str | None,
+    output: t.IO[str],
+) -> None:
+    logging.basicConfig()
+
+    loader: jinja2.BaseLoader
+    if template is None:
+        loader = jinja2.PackageLoader("capellambse", "extensions/validation")
+        template = "report-template.html.jinja"
+    else:
+        loader = jinja2.FileSystemLoader(".")
+    env = jinja2.Environment(loader=loader)
+
+    with output:
+        env.get_template(template).stream(
+            model=model,
+            results=model.validation.validate(),
+        ).dump(output)
+
+
+if __name__ == "__main__":
+    _main()