Type StringBasedConstraintBase

Note: Extra type assertions are entered because broader type in
`StringBasedConstraintBase` can't be narrowed in child classes.

Signed-off-by: Alex Nelson <[email protected]>

pyshacl/constraints/core/string_based_constraints.py

@@ -2,6 +2,7 @@
 """
 https://www.w3.org/TR/shacl/#core-components-string
 """
+import logging
 import re
 from typing import Dict, List
 
@@ -11,7 +12,7 @@
 from pyshacl.constraints.constraint_component import ConstraintComponent
 from pyshacl.consts import RDF, SH, XSD_WHOLE_INTEGERS
 from pyshacl.errors import ConstraintLoadError, ReportableRuntimeError
-from pyshacl.pytypes import GraphLike, SHACLExecutor
+from pyshacl.pytypes import GraphLike, RDFNode, SHACLExecutor
 from pyshacl.rdfutil import stringify_node
 from pyshacl.shape import Shape
 
@@ -38,9 +39,9 @@ class StringBasedConstraintBase(ConstraintComponent):
 
     shacl_constraint_component = rdflib.URIRef("urn:notimplemented")
 
-    def __init__(self, shape):
+    def __init__(self, shape: Shape) -> None:
         super(StringBasedConstraintBase, self).__init__(shape)
-        self.string_rules = []
+        self.string_rules: List[RDFNode] = []
         self.allow_multi_rules = True
 
     @classmethod
@@ -260,18 +261,19 @@ class PatternConstraintComponent(StringBasedConstraintBase):
 
     def __init__(self, shape: Shape) -> None:
         super(PatternConstraintComponent, self).__init__(shape)
-        patterns_found = list(self.shape.objects(SH_pattern))
+        patterns_found: List[RDFNode] = []
+        for pattern_found in self.shape.objects(SH_pattern):
+            if not isinstance(pattern_found, rdflib.Literal):
+                raise ConstraintLoadError(
+                    "PatternConstraintComponent sh:pattern must be a RDF Literal node.",
+                    "https://www.w3.org/TR/shacl/#PatternConstraintComponent",
+                )
+            patterns_found.append(pattern_found)
         if len(patterns_found) < 1:
             raise ConstraintLoadError(
                 "PatternConstraintComponent must have at least one sh:pattern predicate.",
                 "https://www.w3.org/TR/shacl/#PatternConstraintComponent",
             )
-        for p in patterns_found:
-            if not isinstance(p, rdflib.Literal):
-                raise ConstraintLoadError(
-                    "PatternConstraintComponent sh:pattern must be a RDF Literal node.",
-                    "https://www.w3.org/TR/shacl/#PatternConstraintComponent",
-                )
         self.string_rules = patterns_found
         flags_found = set(self.shape.objects(SH_flags))
         if len(flags_found) > 0:
@@ -290,9 +292,19 @@ def constraint_name(cls):
 
     def make_generic_messages(self, datagraph: GraphLike, focus_node, value_node) -> List[rdflib.Literal]:
         if len(self.string_rules) < 2:
-            m = "Value does not match pattern '{}'".format(str(self.string_rules[0].value))
+            string_rule = self.string_rules[0]
+            assert isinstance(string_rule, rdflib.Literal)
+            m = "Value does not match pattern '{}'".format(str(string_rule.value))
         else:
-            rules = "', '".join(str(c.value) for c in self.string_rules)
+            # Inform type system that all the string rules are Literals.
+            _string_rules: List[rdflib.Literal] = []
+            for string_rule in self.string_rules:
+                if not isinstance(string_rule, rdflib.Literal):
+                    logging.debug("string_rule = %r.", string_rule)
+                    logging.debug("type(string_rule) = %r.", type(string_rule))
+                    raise TypeError("Non-Literal entered string_rules list.")
+                _string_rules.append(string_rule)
+            rules = "', '".join(str(c.value) for c in _string_rules)
             m = "Value does not match every pattern in ('{}')".format(rules)
         return [rdflib.Literal(m)]