Remove unnecessary inverse paths

lib/ShapesGraph.ts

@@ -142,10 +142,11 @@ export class ShapesGraph {
       alreadyProcessedPaths.push(p);
       p = this.cleanPath(p);
 
-      if (p.startsWith('^')) {
-        p = p.substring(1);
+      if (this.isRealInversePath(p)) {
+        p = this.getRealPath(p);
         mermaid += `  S${shapedId}_${this.counter}[ ]${link}|"${p}"|S${shapedId}\n`;
       } else {
+        p = this.getRealPath(p);
         mermaid += `  S${shapedId}${link}|"${p}"|S${shapedId}_${this.counter}[ ]\n`;
       }
 
@@ -155,6 +156,26 @@ export class ShapesGraph {
     return mermaid;
   }
 
+  private isRealInversePath(path: string) {
+    const found = path.match(/^(\^+)[^\^]+/);
+
+    if (!found) {
+      return false;
+    }
+
+    return found[1].length % 2 !== 0;
+  }
+
+  private getRealPath(path: string) {
+    const found = path.match(/^\^*([^\^]+)/);
+
+    if (!found) {
+      return ''; //TODO: throw error.
+    }
+
+    return found[1];
+  }
+
   protected constructPathPattern(shapeStore: RdfStore, listItem: Term): Path {
     if (listItem.termType === "BlankNode") {
       //Look for special types

tests/07 - mermaid/double-inverse-path.txt

@@ -1,3 +1,3 @@
 flowchart TD
   S1((Shape))
-  S1_0[ ]-->|http://example.org/p2|S1
+  S1-->|"http://example.org/p1"|S1_0[ ]

tests/07 - mermaid/mermaid.test.ts

@@ -54,12 +54,24 @@ describe("Test whether the correct Mermaid text is generated for a ShapesGraph",
     assert.equal(actualMermaid, expectedMermaid);
   });
 
-  it.skip("Double inverse path", async () => {
+  it("Double inverse path", async () => {
     const actualMermaid = shapesGraph.toMermaid(df.namedNode("http://example.org/DoubleInversePathShape"));
     const expectedMermaid = await fs.readFile('./tests/07 - mermaid/double-inverse-path.txt', 'utf-8');
     assert.equal(actualMermaid, expectedMermaid);
   });
 
+  it("Triple inverse path", async () => {
+    const actualMermaid = shapesGraph.toMermaid(df.namedNode("http://example.org/TripleInversePathShape"));
+    const expectedMermaid = await fs.readFile('./tests/07 - mermaid/triple-inverse-path.txt', 'utf-8');
+    assert.equal(actualMermaid, expectedMermaid);
+  });
+
+  it("Quadruple inverse path", async () => {
+    const actualMermaid = shapesGraph.toMermaid(df.namedNode("http://example.org/DoubleInversePathShape"));
+    const expectedMermaid = await fs.readFile('./tests/07 - mermaid/quadruple-inverse-path.txt', 'utf-8');
+    assert.equal(actualMermaid, expectedMermaid);
+  });
+
   it("Zero or more path", async () => {
     const actualMermaid = shapesGraph.toMermaid(df.namedNode("http://example.org/ZeroOrMorePathShape"));
     const expectedMermaid = await fs.readFile('./tests/07 - mermaid/zero-or-more-path.txt', 'utf-8');

tests/07 - mermaid/quadruple-inverse-path.txt

@@ -0,0 +1,3 @@
+flowchart TD
+  S1((Shape))
+  S1-->|"http://example.org/p1"|S1_0[ ]

tests/07 - mermaid/shape.ttl

@@ -40,14 +40,30 @@ ex:SequenceAndInversePathShape a sh:NodeShape ;
         sh:minCount 1
     ] .
 
- # Double inverse path
+# Double inverse path
 ex:DoubleInversePathShape a sh:NodeShape ;
     sh:closed true;
     sh:property [
         sh:path ([sh:inversePath [sh:inversePath ex:p1 ] ]) ;
         sh:minCount 1
     ] .
 
+# Triple inverse path
+ex:TripleInversePathShape a sh:NodeShape ;
+    sh:closed true;
+    sh:property [
+        sh:path ([sh:inversePath [sh:inversePath [sh:inversePath ex:p1 ] ] ]) ;
+        sh:minCount 1
+    ] .
+
+# Quadruple inverse path
+ex:QuadrupleInversePathShape a sh:NodeShape ;
+    sh:closed true;
+    sh:property [
+        sh:path ([sh:inversePath [sh:inversePath [sh:inversePath [sh:inversePath ex:p1 ] ] ] ]) ;
+        sh:minCount 1
+    ] .
+
 # Zero or More path
 ex:ZeroOrMorePathShape a sh:NodeShape ;
     sh:closed true;

tests/07 - mermaid/triple-inverse-path.txt

@@ -0,0 +1,3 @@
+flowchart TD
+  S1((Shape))
+  S1_0[ ]-->|"http://example.org/p1"|S1