fixes https://github.com/zazuko/rdf-validate-shacl/issues/136

src/validation-engine.js

@@ -15,6 +15,7 @@ class ValidationEngine {
     this.violationsCount = 0
     this.validationError = null
     this.nestedResults = {}
+    this.checkedNodes = new Set()
   }
 
   clone() {
@@ -42,6 +43,7 @@ class ValidationEngine {
     this.validationError = null
     try {
       this.initReport()
+      this.checkedNodes.clear()
       let foundError = false
       const shapes = this.context.shapesGraph.shapesWithTarget
       for (const shape of shapes) {
@@ -67,6 +69,14 @@ class ValidationEngine {
 
     if (shape.deactivated) return false
 
+    // have we already checked this focusNode against the shape? If so, don't check again to prevent possible recursion.
+    let id = JSON.stringify([focusNode, shape.shapeNode])
+    if (this.checkedNodes.has(id)) {
+      return false
+    }
+    // mark given focusNode/shape pair as 'checked'.
+    this.checkedNodes.add(id)
+
     const valueNodes = shape.getValueNodes(focusNode, dataGraph)
     let errorFound = false
     for (const constraint of shape.constraints) {

test/data/data-shapes/custom/circularReferences.ttl

@@ -0,0 +1,48 @@
+@prefix dash: <http://datashapes.org/dash#> .
+@prefix ex: <http://example.org#> .
+@prefix mf: <http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#> .
+@prefix owl: <http://www.w3.org/2002/07/owl#> .
+@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
+@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
+@prefix sh: <http://www.w3.org/ns/shacl#> .
+@prefix sht: <http://www.w3.org/ns/shacl-test#> .
+@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+
+<>
+  rdf:type mf:Manifest ;
+  mf:entries (
+      <circularReferences>
+    ) ;
+.
+
+<circularReferences>
+  rdf:type sht:Validate ;
+  rdfs:label "Test of circular references in data graph" ;
+  mf:action [
+      sht:dataGraph <> ;
+      sht:shapesGraph <> ;
+    ] ;
+  mf:result [
+      rdf:type sh:ValidationReport ;
+      sh:conforms "true"^^xsd:boolean ;
+  ] ;
+.
+
+ex:Thing
+    a sh:NodeShape,rdfs:Class ;
+    sh:property [
+                  sh:path         ex:references ;
+                  sh:node         ex:Thing
+                ] ;
+    sh:targetClass <Thing>
+.
+
+<thing1>
+    a <Thing> ;
+    ex:references <thing2>
+.
+
+<thing2>
+    a <Thing> ;
+    ex:references <thing1> ;
+.

test/data/data-shapes/custom/manifest.ttl

@@ -11,4 +11,5 @@
 	mf:include <multiLevelInheritanceWithImplicitTarget.ttl> ;
 	mf:include <targetNodeDoesNotExist.ttl> ;
 	mf:include <lessThan-moreTypes.ttl> ;
+	mf:include <circularReferences.ttl> ;
 	.