docs: op and change

Author: zxch3n

10_op_and_change.ts

@@ -0,0 +1,80 @@
+import { Change, Loro, LoroList, LoroText } from "npm:[email protected]";
+import { expect } from "npm:[email protected]";
+
+Deno.test("op and change", () => {
+  const docA = new Loro();
+  docA.setPeerId("0");
+  const textA = docA.getText("text");
+  // This create 3 operations
+  textA.insert(0, "123");
+  // This create a new Change
+  docA.commit();
+  // This create 2 operations
+  textA.insert(0, "ab");
+  // This will NOT create a new Change
+  docA.commit();
+
+  {
+    const changeMap: Map<`${number}`, Change[]> = docA.getAllChanges();
+    expect(changeMap.size).toBe(1);
+    expect(changeMap.get("0")).toStrictEqual([
+      {
+        lamport: 0,
+        length: 5,
+        peer: "0",
+        counter: 0,
+        deps: [],
+        timestamp: 0,
+      },
+    ]);
+  }
+
+  // Create docB from doc
+  const docB = Loro.fromSnapshot(docA.exportSnapshot());
+  docB.setPeerId("1");
+  const textB = docB.getText("text");
+  // This create 2 operations
+  textB.insert(0, "cd");
+
+  // Import the Change from docB to doc
+  const bytes = docB.exportFrom(); // Exporting has implicit commit
+  docA.import(bytes);
+
+  // This create 1 operations
+  textA.insert(0, "1");
+  // Because doc import a Change from docB, it will create a new Change for
+  // new commit to record this causal order
+  docA.commit();
+  {
+    const changeMap: Map<`${number}`, Change[]> = docA.getAllChanges();
+    expect(changeMap.size).toBe(2);
+    expect(changeMap.get("0")).toStrictEqual([
+      {
+        lamport: 0,
+        length: 5,
+        peer: "0",
+        counter: 0,
+        deps: [],
+        timestamp: 0,
+      },
+      {
+        lamport: 7,
+        length: 1,
+        peer: "0",
+        counter: 5,
+        deps: [{ peer: "1", counter: 1 }],
+        timestamp: 0,
+      },
+    ]);
+    expect(changeMap.get("1")).toStrictEqual([
+      {
+        lamport: 5,
+        length: 2,
+        peer: "1",
+        counter: 0,
+        deps: [{ peer: "0", counter: 4 }],
+        timestamp: 0,
+      },
+    ]);
+  }
+});