add method to check SHACL constraints

- add `constraints` module
- migrate constraint exception from bdd-dsl
- add method to load a dict of SHACL paths and check a graph against
  these constraints
- resolve #5

src/rdf_utils/constraints.py

@@ -0,0 +1,32 @@
+# SPDX-License-Identifier:  MPL-2.0
+from typing import Dict
+from rdflib import ConjunctiveGraph, Graph
+import pyshacl
+
+
+class ConstraintViolation(Exception):
+    def __init__(self, domain, message):
+        super().__init__(f"{domain} constraint violated: {message}")
+
+
+class SHACLViolation(ConstraintViolation):
+    def __init__(self, violation_str: str):
+        super().__init__("SHACL", violation_str)
+
+
+def check_shacl_constraints(graph: Graph, shacl_dict: Dict[str, str], quiet=False) -> bool:
+    """
+    :param graph: rdfl.Graph to be checked
+    :param shacl_dict: mapping from SHACL path to graph format, e.g. URL -> "turtle"
+    :param quiet: if true will not throw an exception
+    """
+    shacl_g = ConjunctiveGraph()
+    for mm_url, fmt in shacl_dict.items():
+        shacl_g.parse(mm_url, format=fmt)
+
+    conforms, _, report_text = pyshacl.validate(graph, shacl_graph=shacl_g, inference="rdfs")
+
+    if not conforms and not quiet:
+        raise SHACLViolation(report_text)
+
+    return conforms