增加 Symbol，history 增加 isModified

packages/designer/src/document/history.ts

@@ -174,6 +174,10 @@ export class History {
     this.emitter.removeAllListeners();
     this.records = [];
   }
+
+  isModified() {
+    return this.point !== this.session.cursor;
+  }
 }
 
 class Session {

packages/vision-preset/src/index.ts

@@ -25,6 +25,7 @@ import DragEngine from './drag-engine';
 import Viewport from './viewport';
 import Project from './project';
 import { designer, editor } from './editor';
+import Symbols from './symbols';
 
 import './vision.less';
 
@@ -109,6 +110,7 @@ const VisualEngine = {
   Version,
   Project,
   logger,
+  Symbols,
 };
 
 (window as any).VisualEngine = VisualEngine;
@@ -156,6 +158,7 @@ export {
   Version,
   Project,
   logger,
+  Symbols,
 };
 
 

packages/vision-preset/src/symbols.ts

@@ -0,0 +1,17 @@
+export class SymbolManager {
+  private symbolMap: { [symbolName: string]: symbol } = {};
+
+  public create(name: string): symbol {
+    if (this.symbolMap[name]) {
+      return this.symbolMap[name];
+    }
+    this.symbolMap[name] = Symbol(name);
+    return this.symbolMap[name];
+  }
+
+  public get(name: string) {
+    return this.symbolMap[name];
+  }
+}
+
+export default new SymbolManager();