parser and editor use same code for figuring out what is connected to what

src/statecharts/detect_connections.ts

@@ -0,0 +1,84 @@
+import { findNearestArrow, findNearestHistory, findNearestSide, findRountangle, RountanglePart, VisualEditorState } from "./concrete_syntax";
+
+export type Connections = {
+  arrow2SideMap: Map<string,[{ uid: string; part: RountanglePart; } | undefined, { uid: string; part: RountanglePart; } | undefined]>,
+  side2ArrowMap: Map<string, Set<["start"|"end", string]>>,
+  text2ArrowMap: Map<string,string>,
+  arrow2TextMap: Map<string,string[]>,
+  arrow2HistoryMap: Map<string,string>,
+  text2RountangleMap: Map<string, string>,
+  rountangle2TextMap: Map<string, string[]>,
+  history2ArrowMap: Map<string, string[]>,
+}
+
+export function detectConnections(state: VisualEditorState): Connections {
+  // detect what is 'connected'
+  const arrow2SideMap = new Map<string,[{ uid: string; part: RountanglePart; } | undefined, { uid: string; part: RountanglePart; } | undefined]>();
+  const side2ArrowMap = new Map<string, Set<["start"|"end", string]>>();
+  const text2ArrowMap = new Map<string,string>();
+  const arrow2TextMap = new Map<string,string[]>();
+  const arrow2HistoryMap = new Map<string,string>();
+  const text2RountangleMap = new Map<string, string>();
+  const rountangle2TextMap = new Map<string, string[]>();
+  const history2ArrowMap = new Map<string, string[]>();
+
+  // arrow <-> (rountangle | diamond)
+  for (const arrow of state.arrows) {
+    // snap to history:
+    const historyTarget = findNearestHistory(arrow.end, state.history);
+    if (historyTarget) {
+      arrow2HistoryMap.set(arrow.uid, historyTarget.uid);
+      history2ArrowMap.set(historyTarget.uid, [...(history2ArrowMap.get(historyTarget.uid) || []), arrow.uid]);
+    }
+
+    // snap to rountangle/diamon side:
+    const sides = [...state.rountangles, ...state.diamonds];
+    const startSide = findNearestSide(arrow, "start", sides);
+    const endSide = historyTarget ? undefined : findNearestSide(arrow, "end", sides);
+    if (startSide || endSide) {
+      arrow2SideMap.set(arrow.uid, [startSide, endSide]);
+    }
+    if (startSide) {
+      const arrowConns = side2ArrowMap.get(startSide.uid + '/' + startSide.part) || new Set();
+      arrowConns.add(["start", arrow.uid]);
+      side2ArrowMap.set(startSide.uid + '/' + startSide.part, arrowConns);
+    }
+    if (endSide) {
+      const arrowConns = side2ArrowMap.get(endSide.uid + '/' + endSide.part) || new Set();
+      arrowConns.add(["end", arrow.uid]);
+      side2ArrowMap.set(endSide.uid + '/' + endSide.part, arrowConns);
+    }
+  }
+  // text <-> arrow
+  for (const text of state.texts) {
+    const nearestArrow = findNearestArrow(text.topLeft, state.arrows);
+    if (nearestArrow) {
+      // prioritize text belonging to arrows:
+      text2ArrowMap.set(text.uid, nearestArrow.uid);
+      const textsOfArrow = arrow2TextMap.get(nearestArrow.uid) || [];
+      textsOfArrow.push(text.uid);
+      arrow2TextMap.set(nearestArrow.uid, textsOfArrow);
+    }
+    else {
+      // text <-> rountangle
+      const rountangle = findRountangle(text.topLeft, state.rountangles);
+      if (rountangle) {
+        text2RountangleMap.set(text.uid, rountangle.uid);
+        const texts = rountangle2TextMap.get(rountangle.uid) || [];
+        texts.push(text.uid);
+        rountangle2TextMap.set(rountangle.uid, texts);
+      }
+    }
+  }
+
+  return {
+    arrow2SideMap,
+    side2ArrowMap,
+    text2ArrowMap,
+    arrow2TextMap,
+    arrow2HistoryMap,
+    text2RountangleMap,
+    rountangle2TextMap,
+    history2ArrowMap,
+  };
+}