add shape datastore (for nodes of data flow diagram)

See https://github.com/mermaid-js/mermaid/issues/1893

src/diagrams/flowchart/flowChartShapes.js

@@ -176,6 +176,24 @@ function subroutine(parent, bbox, node) {
   return shapeSvg;
 }
 
+function datastore(parent, bbox, node) {
+  const shapeSvg = parent
+    .insert('rect', ':first-child')
+    .attr('class', 'basic label-container')
+    .attr('style', node.style)
+    .attr('rx', node.rx)
+    .attr('ry', node.ry)
+    .attr('x', -bbox.width / 2)
+    .attr('y', -bbox.height / 2)
+    .attr('width', bbox.width)
+    .attr('height', bbox.height)
+    .attr('stroke-dasharray', bbox.width + ' ' + bbox.height);
+  node.intersect = function (point) {
+    return dagreD3.intersect.rect(node, point);
+  };
+  return shapeSvg;
+}
+
 function cylinder(parent, bbox, node) {
   const w = bbox.width;
   const rx = w / 2;
@@ -244,6 +262,7 @@ export function addToRender(render) {
   render.shapes().hexagon = hexagon;
   render.shapes().stadium = stadium;
   render.shapes().subroutine = subroutine;
+  render.shapes().datastore = datastore;
   render.shapes().cylinder = cylinder;
 
   // Add custom shape for box with inverted arrow on left side
@@ -270,6 +289,7 @@ export function addToRenderV2(addShape) {
   addShape({ hexagon });
   addShape({ stadium });
   addShape({ subroutine });
+  addShape({ datastore });
   addShape({ cylinder });
 
   // Add custom shape for box with inverted arrow on left side

src/diagrams/flowchart/flowRenderer.js

@@ -123,6 +123,9 @@ export const addVertices = function (vert, g, svgId) {
       case 'subroutine':
         _shape = 'subroutine';
         break;
+      case 'datastore':
+        _shape = 'datastore';
+        break;
       case 'cylinder':
         _shape = 'cylinder';
         break;