From 984a76993fe2ea6e7a47e5e2052d4b6748b70842 Mon Sep 17 00:00:00 2001
From: "mario.gk" <mario.gk@alibaba-inc.com>
Date: Thu, 7 May 2020 21:38:47 +0800
Subject: [PATCH] =?UTF-8?q?=E5=A2=9E=E5=8A=A0=20Symbol=EF=BC=8Chistory=20?=
 =?UTF-8?q?=E5=A2=9E=E5=8A=A0=20=20isModified?=
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---
 packages/designer/src/document/history.ts |  4 ++++
 packages/vision-preset/src/index.ts       |  3 +++
 packages/vision-preset/src/symbols.ts     | 17 +++++++++++++++++
 3 files changed, 24 insertions(+)
 create mode 100644 packages/vision-preset/src/symbols.ts

diff --git a/packages/designer/src/document/history.ts b/packages/designer/src/document/history.ts
index 0f283b65b..8a37f1032 100644
--- a/packages/designer/src/document/history.ts
+++ b/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 {
diff --git a/packages/vision-preset/src/index.ts b/packages/vision-preset/src/index.ts
index 23dbe607a..ed632b3ef 100644
--- a/packages/vision-preset/src/index.ts
+++ b/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,
 };
 
 
diff --git a/packages/vision-preset/src/symbols.ts b/packages/vision-preset/src/symbols.ts
new file mode 100644
index 000000000..81091e371
--- /dev/null
+++ b/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();