Diffing tools

package.json

@@ -89,7 +89,7 @@
     "@jsonjoy.com/json-pack": "^1.1.0",
     "@jsonjoy.com/json-pointer": "^1.0.0",
     "@jsonjoy.com/json-type": "^1.0.0",
-    "@jsonjoy.com/util": "^1.4.0",
+    "@jsonjoy.com/util": "^1.6.0",
     "arg": "^5.0.2",
     "hyperdyperid": "^1.2.0",
     "nano-css": "^5.6.2",
@@ -108,6 +108,7 @@
     "benchmark": "^2.1.4",
     "config-galore": "^1.0.0",
     "editing-traces": "https://github.com/streamich/editing-traces#6494020428530a6e382378b98d1d7e31334e2d7b",
+    "fast-diff": "^1.3.0",
     "fast-json-patch": "^3.1.1",
     "html-webpack-plugin": "^5.6.0",
     "jest": "^29.7.0",
@@ -152,6 +153,7 @@
           "",
           "demo",
           "json-cli",
+          "json-crdt-diff",
           "json-crdt-patch",
           "json-crdt-extensions",
           "json-crdt-peritext-ui",
@@ -160,6 +162,7 @@
           "json-ot",
           "json-patch-ot",
           "json-patch",
+          "json-patch-diff",
           "json-stable",
           "json-text",
           "json-walk",

src/json-crdt-diff/JsonCrdtDiff.ts

@@ -0,0 +1,215 @@
+import {deepEqual} from '@jsonjoy.com/util/lib/json-equal/deepEqual';
+import {cmpUint8Array} from '@jsonjoy.com/util/lib/buffers/cmpUint8Array';
+import {type ITimespanStruct, type ITimestampStruct, type Patch, PatchBuilder, Timespan} from '../json-crdt-patch';
+import {ArrNode, BinNode, ConNode, ObjNode, StrNode, ValNode, VecNode, type JsonNode} from '../json-crdt/nodes';
+import * as str from '../util/diff/str';
+import * as bin from '../util/diff/bin';
+import * as line from '../util/diff/line';
+import {structHashCrdt} from '../json-hash/structHashCrdt';
+import {structHash} from '../json-hash';
+import type {Model} from '../json-crdt/model';
+
+export class DiffError extends Error {
+  constructor(message: string = 'DIFF') {
+    super(message);
+  }
+}
+
+export class JsonCrdtDiff {
+  protected builder: PatchBuilder;
+
+  public constructor(protected readonly model: Model<any>) {
+    this.builder = new PatchBuilder(model.clock.clone());
+  }
+
+  protected diffStr(src: StrNode, dst: string): void {
+    const view = src.view();
+    if (view === dst) return;
+    const builder = this.builder;
+    str.apply(
+      str.diff(view, dst),
+      view.length,
+      (pos, txt) => builder.insStr(src.id, !pos ? src.id : src.find(pos - 1)!, txt),
+      (pos, len) => builder.del(src.id, src.findInterval(pos, len)),
+    );
+  }
+
+  protected diffBin(src: BinNode, dst: Uint8Array): void {
+    const view = src.view();
+    if (cmpUint8Array(view, dst)) return;
+    const builder = this.builder;
+    bin.apply(
+      bin.diff(view, dst),
+      view.length,
+      (pos, txt) => builder.insBin(src.id, !pos ? src.id : src.find(pos - 1)!, txt),
+      (pos, len) => builder.del(src.id, src.findInterval(pos, len)),
+    );
+  }
+
+  protected diffArr(src: ArrNode, dst: unknown[]): void {
+    const srcLines: string[] = [];
+    src.children((node) => {
+      srcLines.push(structHashCrdt(node));
+    });
+    const dstLines: string[] = [];
+    const dstLength = dst.length;
+    for (let i = 0; i < dstLength; i++) dstLines.push(structHash(dst[i]));
+    const linePatch = line.diff(srcLines, dstLines);
+    if (!linePatch.length) return;
+    const inserts: [after: ITimestampStruct, views: unknown[]][] = [];
+    const deletes: ITimespanStruct[] = [];
+    const patchLength = linePatch.length;
+    for (let i = patchLength - 1; i >= 0; i--) {
+      const [type, posSrc, posDst] = linePatch[i];
+      switch (type) {
+        case line.LINE_PATCH_OP_TYPE.EQL:
+          break;
+        case line.LINE_PATCH_OP_TYPE.INS: {
+          const view = dst[posDst];
+          const after = posSrc >= 0 ? src.find(posSrc) : src.id;
+          if (!after) throw new DiffError();
+          inserts.push([after, [view]]);
+          break;
+        }
+        case line.LINE_PATCH_OP_TYPE.DEL: {
+          const span = src.findInterval(posSrc, 1);
+          if (!span || !span.length) throw new DiffError();
+          deletes.push(...span);
+          break;
+        }
+        case line.LINE_PATCH_OP_TYPE.MIX: {
+          const view = dst[posDst];
+          try {
+            this.diffAny(src.getNode(posSrc)!, view);
+          } catch (error) {
+            if (error instanceof DiffError) {
+              const span = src.findInterval(posSrc, 1)!;
+              deletes.push(...span);
+              const after = posSrc ? src.find(posSrc - 1) : src.id;
+              if (!after) throw new DiffError();
+              inserts.push([after, [view]]);
+            } else throw error;
+          }
+        }
+      }
+    }
+    const builder = this.builder;
+    const length = inserts.length;
+    for (let i = 0; i < length; i++) {
+      const [after, views] = inserts[i];
+      builder.insArr(
+        src.id,
+        after,
+        views.map((view) => builder.json(view)),
+      );
+    }
+    if (deletes.length) builder.del(src.id, deletes);
+  }
+
+  protected diffObj(src: ObjNode, dst: Record<string, unknown>): void {
+    const builder = this.builder;
+    const inserts: [key: string, value: ITimestampStruct][] = [];
+    const srcKeys = new Set<string>();
+    // biome-ignore lint: .forEach is fastest here
+    src.forEach((key) => {
+      srcKeys.add(key);
+      const dstValue = dst[key];
+      if (dstValue === void 0) inserts.push([key, builder.const(undefined)]);
+    });
+    const keys = Object.keys(dst);
+    const length = keys.length;
+    for (let i = 0; i < length; i++) {
+      const key = keys[i];
+      const dstValue = dst[key];
+      if (srcKeys.has(key)) {
+        const child = src.get(key);
+        if (child) {
+          try {
+            this.diffAny(child, dstValue);
+            continue;
+          } catch (error) {
+            if (!(error instanceof DiffError)) throw error;
+          }
+        }
+      }
+      inserts.push([key, src.get(key) instanceof ConNode ? builder.const(dstValue) : builder.constOrJson(dstValue)]);
+    }
+    if (inserts.length) builder.insObj(src.id, inserts);
+  }
+
+  protected diffVec(src: VecNode, dst: unknown[]): void {
+    const builder = this.builder;
+    const edits: [key: number, value: ITimestampStruct][] = [];
+    const elements = src.elements;
+    const srcLength = elements.length;
+    const dstLength = dst.length;
+    const index = src.doc.index;
+    const min = Math.min(srcLength, dstLength);
+    for (let i = dstLength; i < srcLength; i++) {
+      const id = elements[i];
+      if (id) {
+        const child = index.get(id);
+        const isDeleted = !child || (child instanceof ConNode && child.val === void 0);
+        if (isDeleted) return;
+        edits.push([i, builder.const(void 0)]);
+      }
+    }
+    for (let i = 0; i < min; i++) {
+      const value = dst[i];
+      const child = src.get(i);
+      if (child) {
+        try {
+          this.diffAny(child, value);
+          continue;
+        } catch (error) {
+          if (!(error instanceof DiffError)) throw error;
+        }
+      }
+      edits.push([i, builder.constOrJson(value)]);
+    }
+    for (let i = srcLength; i < dstLength; i++) edits.push([i, builder.constOrJson(dst[i])]);
+    if (edits.length) builder.insVec(src.id, edits);
+  }
+
+  protected diffVal(src: ValNode, dst: unknown): void {
+    try {
+      this.diffAny(src.node(), dst);
+    } catch (error) {
+      if (error instanceof DiffError) {
+        const builder = this.builder;
+        builder.setVal(src.id, builder.constOrJson(dst));
+      } else throw error;
+    }
+  }
+
+  public diffAny(src: JsonNode, dst: unknown): void {
+    if (src instanceof ConNode) {
+      const val = src.val;
+      if (val !== dst && !deepEqual(src.val, dst)) throw new DiffError();
+    } else if (src instanceof StrNode) {
+      if (typeof dst !== 'string') throw new DiffError();
+      this.diffStr(src, dst);
+    } else if (src instanceof ObjNode) {
+      if (!dst || typeof dst !== 'object' || Array.isArray(dst)) throw new DiffError();
+      this.diffObj(src, dst as Record<string, unknown>);
+    } else if (src instanceof ValNode) {
+      this.diffVal(src, dst);
+    } else if (src instanceof ArrNode) {
+      if (!Array.isArray(dst)) throw new DiffError();
+      this.diffArr(src, dst as unknown[]);
+    } else if (src instanceof VecNode) {
+      if (!Array.isArray(dst)) throw new DiffError();
+      this.diffVec(src, dst as unknown[]);
+    } else if (src instanceof BinNode) {
+      if (!(dst instanceof Uint8Array)) throw new DiffError();
+      this.diffBin(src, dst);
+    } else {
+      throw new DiffError();
+    }
+  }
+
+  public diff(src: JsonNode, dst: unknown): Patch {
+    this.diffAny(src, dst);
+    return this.builder.flush();
+  }
+}

src/json-crdt-diff/__tests__/JsonCrdtDiff-fuzzing.spec.ts

@@ -0,0 +1,53 @@
+import {JsonCrdtDiff} from '../JsonCrdtDiff';
+import {Model} from '../../json-crdt/model';
+import {RandomJson} from '@jsonjoy.com/util/lib/json-random';
+
+const assertDiff = (src: unknown, dst: unknown) => {
+  const model = Model.create();
+  model.api.root(src);
+  const patch1 = new JsonCrdtDiff(model).diff(model.root, dst);
+  // console.log(model + '');
+  // console.log(patch1 + '');
+  model.applyPatch(patch1);
+  // console.log(model + '');
+  expect(model.view()).toEqual(dst);
+  const patch2 = new JsonCrdtDiff(model).diff(model.root, dst);
+  expect(patch2.ops.length).toBe(0);
+};
+
+const iterations = 1000;
+
+test('from random JSON to random JSON', () => {
+  for (let i = 0; i < iterations; i++) {
+    const src = RandomJson.generate();
+    const dst = RandomJson.generate();
+    // console.log(src);
+    // console.log(dst);
+    assertDiff(src, dst);
+  }
+});
+
+test('two random arrays of integers', () => {
+  const iterations = 100;
+
+  const randomArray = () => {
+    const len = Math.floor(Math.random() * 10);
+    const arr: unknown[] = [];
+    for (let i = 0; i < len; i++) {
+      arr.push(Math.ceil(Math.random() * 13));
+    }
+    return arr;
+  };
+
+  for (let i = 0; i < iterations; i++) {
+    const src = randomArray();
+    const dst = randomArray();
+    try {
+      assertDiff(src, dst);
+    } catch (error) {
+      console.error('src', src);
+      console.error('dst', dst);
+      throw error;
+    }
+  }
+});