Fix infinite recursion in directory layout (#708)

# Description
Fix infinite recursion in directory layout

## Type of change
<!-- Put an `x` in the box that applies. -->
- [x] Bug fix.
- [ ] New feature.
- [ ] Documentation update.
- [ ] Test update.

ontopy/utils.py

@@ -786,12 +786,8 @@ def directory_layout(onto):
 
         where `ontoA`, `ontoB` and `ontoC` are imported Ontology objects.
     """
-    layout = {}
 
     def recur(o):
-        for imported in o.imported_ontologies:
-            if imported not in layout:
-                recur(imported)
         baseiri = o.base_iri.rstrip("/#")
 
         # Some heuristics here to reproduce the EMMO layout.
@@ -809,7 +805,11 @@ def recur(o):
         layout[o] = (
             baseiri + "/" + os.path.basename(baseiri) if emmolayout else baseiri
         )
+        for imported in o.imported_ontologies:
+            if imported not in layout:
+                recur(imported)
 
+    layout = {}
     recur(onto)
 
     # Strip off initial common prefix from all paths

tests/test_utils_directory_layout.py

@@ -71,3 +71,19 @@ def test_local_directory_layout():
 
     assert layout[omap["http://emmo.info/models#"]] == "models"
     assert layout[omap["http://emmo.info/testonto#"]] == "testonto"
+
+
+def test_local_directory_layout_recursive():
+    thisdir = Path(__file__).resolve().parent
+    ontopath = thisdir / "testonto" / "testonto-recursive.ttl"
+    onto = get_ontology(ontopath).load()
+    layout = directory_layout(onto)
+    omap = {o.base_iri: o for o in layout.keys()}
+
+    assert (
+        layout[omap["http://emmo.info/models-recursive#"]] == "models-recursive"
+    )
+    assert (
+        layout[omap["http://emmo.info/testonto-recursive#"]]
+        == "testonto-recursive"
+    )

tests/testonto/catalog-v001.xml

@@ -1,7 +1,9 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <catalog prefer="public" xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog">
     <group id="Folder Repository, directory=, recursive=true, Auto-Update=false, version=2" prefer="public" xml:base="">
-	    <uri name="http://emmo.info/testonto/0.1.0" uri="ontology.ttl"/>
+	    <uri name="http://emmo.info/testonto/0.1.0" uri="testonto.ttl"/>
 	    <uri name="http://emmo.info/testonto/0.1.0/models" uri="models.ttl"/>
+	    <uri name="http://emmo.info/testonto-recursive/0.1.0" uri="testonto-recursive.ttl"/>
+	    <uri name="http://emmo.info/testonto/0.1.0/models-recursive" uri="models-recursive.ttl"/>
     </group>
 </catalog>

tests/testonto/models-recursive.ttl

@@ -0,0 +1,23 @@
+@prefix : <http://emmo.info/models-recursive#> .
+@prefix owl: <http://www.w3.org/2002/07/owl#> .
+@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
+@prefix xml: <http://www.w3.org/XML/1998/namespace> .
+@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
+@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
+@base <http://emmo.info/models-recursive> .
+
+<http://emmo.info/models-recursive> rdf:type owl:Ontology ;
+    owl:imports <http://emmo.info/testonto-recursive/0.1.0> ;
+    owl:versionIRI <http://emmo.info/testonto/0.1.0/models-recursive> .
+
+
+# Annotations
+skos:prefLabel rdf:type owl:AnnotationProperty .
+skos:altLabel rdf:type owl:AnnotationProperty .
+
+
+:testclass rdf:type owl:Class ;
+    rdfs:subClassOf owl:Thing ;
+    skos:prefLabel "TestClass"@en ;
+    skos:altLabel 25517 . # Test that values given as integers are accepted by ontodoc

tests/testonto/testonto-recursive.ttl

@@ -0,0 +1,33 @@
+@prefix : <http://emmo.info/testonto-recursive#> .
+@prefix owl: <http://www.w3.org/2002/07/owl#> .
+@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
+@prefix xml: <http://www.w3.org/XML/1998/namespace> .
+@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
+@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
+@base <http://emmo.info/testonto-recursive> .
+
+<http://emmo.info/testonto-recursive> rdf:type owl:Ontology ;
+                             owl:versionIRI <http://emmo.info/testonto-recursive/0.1.0> ;
+                             owl:imports <http://emmo.info/testonto/0.1.0/models-recursive> ;
+			     owl:versionInfo "0.1.0" .
+
+
+:testclass rdf:type owl:Class ;
+    rdfs:subClassOf owl:Thing ;
+    skos:prefLabel "TestClass"@en .
+
+:testobjectproperty rdf:type owl:ObjectProperty ;
+    rdfs:domain :testclass ;
+    rdfs:range :testclass ;
+    skos:prefLabel "hasObjectProperty"@en .
+
+:testannotationproperty rdf:type owl:AnnotationProperty ;
+    rdfs:domain :testclass ;
+    rdfs:range rdfs:Literal ;
+    skos:prefLabel "hasAnnotationProperty"@en .
+
+:testdatatypeproperty rdf:type owl:DatatypeProperty ;
+    rdfs:domain :testclass ;
+    rdfs:range xsd:string ;
+    skos:prefLabel "hasDataProperty"@en .