feat(flowchart): implement double circle node

The implementation uses two circles, inside each other.
A double circle node is opend with `()(` and closed with `)()`.

src/diagrams/flowchart/flowRenderer-v2.js

@@ -131,6 +131,9 @@ export const addVertices = function (vert, g, svgId) {
       case 'group':
         _shape = 'rect';
         break;
+      case 'doublecircle':
+        _shape = 'doublecircle';
+        break;
       default:
         _shape = 'rect';
     }

src/diagrams/flowchart/flowRenderer.spec.js

@@ -26,6 +26,7 @@ describe('the flowchart renderer', function () {
       ['subroutine', 'subroutine'],
       ['cylinder', 'cylinder'],
       ['group', 'rect'],
+      ['doublecircle', 'doublecircle'],
     ].forEach(function ([type, expectedShape, expectedRadios = 0]) {
       it(`should add the correct shaped node to the graph for vertex type ${type}`, function () {
         const addedNodes = [];

src/diagrams/flowchart/parser/flow-singlenode.spec.js

@@ -159,6 +159,40 @@ describe('[Singlenodes] when parsing', () => {
     expect(vert['a'].text).toBe('A <br> end');
   });
 
+  it('should handle a single double circle node', function () {
+    // Silly but syntactically correct
+    const res = flow.parser.parse('graph TD;a()(A)();');
+
+    const vert = flow.parser.yy.getVertices();
+    const edges = flow.parser.yy.getEdges();
+
+    expect(edges.length).toBe(0);
+    expect(vert['a'].type).toBe('doublecircle');
+  });
+
+  it('should handle a single double circle node with whitespace after it', function () {
+    // Silly but syntactically correct
+    const res = flow.parser.parse('graph TD;a()(A)()   ;');
+
+    const vert = flow.parser.yy.getVertices();
+    const edges = flow.parser.yy.getEdges();
+
+    expect(edges.length).toBe(0);
+    expect(vert['a'].type).toBe('doublecircle');
+  });
+
+  it('should handle a single double circle node with html in it (SN3)', function () {
+    // Silly but syntactically correct
+    const res = flow.parser.parse('graph TD;a()(A <br> end)();');
+
+    const vert = flow.parser.yy.getVertices();
+    const edges = flow.parser.yy.getEdges();
+
+    expect(edges.length).toBe(0);
+    expect(vert['a'].type).toBe('doublecircle');
+    expect(vert['a'].text).toBe('A <br> end');
+  });
+
   it('should handle a single node with alphanumerics starting on a char', function () {
     // Silly but syntactically correct
     const res = flow.parser.parse('graph TD;id1;');

src/diagrams/flowchart/parser/flow.jison

@@ -121,6 +121,8 @@ that id.
 "[|"                  return 'VERTEX_WITH_PROPS_START';
 "[("                  return 'CYLINDERSTART';
 ")]"                  return 'CYLINDEREND';
+"()("                 return 'DOUBLECIRCLESTART';
+")()"                 return 'DOUBLECIRCLEEND';
 \-                    return 'MINUS';
 "."                   return 'DOT';
 [\_]                  return 'UNDERSCORE';
@@ -373,6 +375,8 @@ node: vertex
 
 vertex:  idString SQS text SQE
         {$$ = $1;yy.addVertex($1,$3,'square');}
+    | idString DOUBLECIRCLESTART text DOUBLECIRCLEEND
+        {$$ = $1;yy.addVertex($1,$3,'doublecircle');}
     | idString PS PS text PE PE
         {$$ = $1;yy.addVertex($1,$4,'circle');}
     | idString '(-' text '-)'