@tldraw/sync-core/dist-esm/lib/diff.mjs.map

tldraw infinite canvas SDK (multiplayer sync).

{
  "version": 3,
  "sources": ["../../src/lib/diff.ts"],
  "sourcesContent": ["import { RecordsDiff, UnknownRecord } from '@tldraw/store'\nimport { isEqual, objectMapEntries, objectMapValues } from '@tldraw/utils'\n\n/** @internal */\nexport const RecordOpType = {\n\tPut: 'put',\n\tPatch: 'patch',\n\tRemove: 'remove',\n} as const\n\n/** @internal */\nexport type RecordOpType = (typeof RecordOpType)[keyof typeof RecordOpType]\n\n/** @internal */\nexport type RecordOp<R extends UnknownRecord> =\n\t| [typeof RecordOpType.Put, R]\n\t| [typeof RecordOpType.Patch, ObjectDiff]\n\t| [typeof RecordOpType.Remove]\n\n/**\n * A one-way (non-reversible) diff designed for small json footprint. These are mainly intended to\n * be sent over the wire. Either as push requests from the client to the server, or as patch\n * operations in the opposite direction.\n *\n * Each key in this object is the id of a record that has been added, updated, or removed.\n *\n * @internal\n */\nexport interface NetworkDiff<R extends UnknownRecord> {\n\t[id: string]: RecordOp<R>\n}\n\n/**\n * Converts a (reversible, verbose) RecordsDiff into a (non-reversible, concise) NetworkDiff\n *\n *@internal\n */\nexport function getNetworkDiff<R extends UnknownRecord>(\n\tdiff: RecordsDiff<R>\n): NetworkDiff<R> | null {\n\tlet res: NetworkDiff<R> | null = null\n\n\tfor (const [k, v] of objectMapEntries(diff.added)) {\n\t\tif (!res) res = {}\n\t\tres[k] = [RecordOpType.Put, v]\n\t}\n\n\tfor (const [from, to] of objectMapValues(diff.updated)) {\n\t\tconst diff = diffRecord(from, to)\n\t\tif (diff) {\n\t\t\tif (!res) res = {}\n\t\t\tres[to.id] = [RecordOpType.Patch, diff]\n\t\t}\n\t}\n\n\tfor (const removed of Object.keys(diff.removed)) {\n\t\tif (!res) res = {}\n\t\tres[removed] = [RecordOpType.Remove]\n\t}\n\n\treturn res\n}\n\n/** @internal */\nexport const ValueOpType = {\n\tPut: 'put',\n\tDelete: 'delete',\n\tAppend: 'append',\n\tPatch: 'patch',\n} as const\n/** @internal */\nexport type ValueOpType = (typeof ValueOpType)[keyof typeof ValueOpType]\n\n/** @internal */\nexport type PutOp = [type: typeof ValueOpType.Put, value: unknown]\n/** @internal */\nexport type AppendOp = [type: typeof ValueOpType.Append, values: unknown[], offset: number]\n/** @internal */\nexport type PatchOp = [type: typeof ValueOpType.Patch, diff: ObjectDiff]\n/** @internal */\nexport type DeleteOp = [type: typeof ValueOpType.Delete]\n\n/** @internal */\nexport type ValueOp = PutOp | AppendOp | PatchOp | DeleteOp\n\n/** @internal */\nexport interface ObjectDiff {\n\t[k: string]: ValueOp\n}\n\n/** @internal */\nexport function diffRecord(prev: object, next: object): ObjectDiff | null {\n\treturn diffObject(prev, next, new Set(['props']))\n}\n\nfunction diffObject(prev: object, next: object, nestedKeys?: Set<string>): ObjectDiff | null {\n\tif (prev === next) {\n\t\treturn null\n\t}\n\tlet result: ObjectDiff | null = null\n\tfor (const key of Object.keys(prev)) {\n\t\t// if key is not in next then it was deleted\n\t\tif (!(key in next)) {\n\t\t\tif (!result) result = {}\n\t\t\tresult[key] = [ValueOpType.Delete]\n\t\t\tcontinue\n\t\t}\n\t\t// if key is in both places, then compare values\n\t\tconst prevVal = (prev as any)[key]\n\t\tconst nextVal = (next as any)[key]\n\t\tif (!isEqual(prevVal, nextVal)) {\n\t\t\tif (nestedKeys?.has(key) && prevVal && nextVal) {\n\t\t\t\tconst diff = diffObject(prevVal, nextVal)\n\t\t\t\tif (diff) {\n\t\t\t\t\tif (!result) result = {}\n\t\t\t\t\tresult[key] = [ValueOpType.Patch, diff]\n\t\t\t\t}\n\t\t\t} else if (Array.isArray(nextVal) && Array.isArray(prevVal)) {\n\t\t\t\tconst op = diffArray(prevVal, nextVal)\n\t\t\t\tif (op) {\n\t\t\t\t\tif (!result) result = {}\n\t\t\t\t\tresult[key] = op\n\t\t\t\t}\n\t\t\t} else {\n\t\t\t\tif (!result) result = {}\n\t\t\t\tresult[key] = [ValueOpType.Put, nextVal]\n\t\t\t}\n\t\t}\n\t}\n\tfor (const key of Object.keys(next)) {\n\t\t// if key is in next but not in prev then it was added\n\t\tif (!(key in prev)) {\n\t\t\tif (!result) result = {}\n\t\t\tresult[key] = [ValueOpType.Put, (next as any)[key]]\n\t\t}\n\t}\n\treturn result\n}\n\nfunction diffValue(valueA: unknown, valueB: unknown): ValueOp | null {\n\tif (Object.is(valueA, valueB)) return null\n\tif (Array.isArray(valueA) && Array.isArray(valueB)) {\n\t\treturn diffArray(valueA, valueB)\n\t} else if (!valueA || !valueB || typeof valueA !== 'object' || typeof valueB !== 'object') {\n\t\treturn isEqual(valueA, valueB) ? null : [ValueOpType.Put, valueB]\n\t} else {\n\t\tconst diff = diffObject(valueA, valueB)\n\t\treturn diff ? [ValueOpType.Patch, diff] : null\n\t}\n}\n\nfunction diffArray(prevArray: unknown[], nextArray: unknown[]): PutOp | AppendOp | PatchOp | null {\n\tif (Object.is(prevArray, nextArray)) return null\n\t// if lengths are equal, check for patch operation\n\tif (prevArray.length === nextArray.length) {\n\t\t// bail out if more than len/5 items need patching\n\t\tconst maxPatchIndexes = Math.max(prevArray.length / 5, 1)\n\t\tconst toPatchIndexes = []\n\t\tfor (let i = 0; i < prevArray.length; i++) {\n\t\t\tif (!isEqual(prevArray[i], nextArray[i])) {\n\t\t\t\ttoPatchIndexes.push(i)\n\t\t\t\tif (toPatchIndexes.length > maxPatchIndexes) {\n\t\t\t\t\treturn [ValueOpType.Put, nextArray]\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\t\tif (toPatchIndexes.length === 0) {\n\t\t\t// same length and no items changed, so no diff\n\t\t\treturn null\n\t\t}\n\t\tconst diff: ObjectDiff = {}\n\t\tfor (const i of toPatchIndexes) {\n\t\t\tconst prevItem = prevArray[i]\n\t\t\tconst nextItem = nextArray[i]\n\t\t\tif (!prevItem || !nextItem) {\n\t\t\t\tdiff[i] = [ValueOpType.Put, nextItem]\n\t\t\t} else if (typeof prevItem === 'object' && typeof nextItem === 'object') {\n\t\t\t\tconst op = diffValue(prevItem, nextItem)\n\t\t\t\tif (op) {\n\t\t\t\t\tdiff[i] = op\n\t\t\t\t}\n\t\t\t} else {\n\t\t\t\tdiff[i] = [ValueOpType.Put, nextItem]\n\t\t\t}\n\t\t}\n\t\treturn [ValueOpType.Patch, diff]\n\t}\n\n\t// if lengths are not equal, check for append operation, and bail out\n\t// to replace whole array if any shared elems changed\n\tfor (let i = 0; i < prevArray.length; i++) {\n\t\tif (!isEqual(prevArray[i], nextArray[i])) {\n\t\t\treturn [ValueOpType.Put, nextArray]\n\t\t}\n\t}\n\n\treturn [ValueOpType.Append, nextArray.slice(prevArray.length), prevArray.length]\n}\n\n/** @internal */\nexport function applyObjectDiff<T extends object>(object: T, objectDiff: ObjectDiff): T {\n\t// don't patch nulls\n\tif (!object || typeof object !== 'object') return object\n\tconst isArray = Array.isArray(object)\n\tlet newObject: any | undefined = undefined\n\tconst set = (k: any, v: any) => {\n\t\tif (!newObject) {\n\t\t\tif (isArray) {\n\t\t\t\tnewObject = [...object]\n\t\t\t} else {\n\t\t\t\tnewObject = { ...object }\n\t\t\t}\n\t\t}\n\t\tif (isArray) {\n\t\t\tnewObject[Number(k)] = v\n\t\t} else {\n\t\t\tnewObject[k] = v\n\t\t}\n\t}\n\tfor (const [key, op] of Object.entries(objectDiff)) {\n\t\tswitch (op[0]) {\n\t\t\tcase ValueOpType.Put: {\n\t\t\t\tconst value = op[1]\n\t\t\t\tif (!isEqual(object[key as keyof T], value)) {\n\t\t\t\t\tset(key, value)\n\t\t\t\t}\n\t\t\t\tbreak\n\t\t\t}\n\t\t\tcase ValueOpType.Append: {\n\t\t\t\tconst values = op[1]\n\t\t\t\tconst offset = op[2]\n\t\t\t\tconst arr = object[key as keyof T]\n\t\t\t\tif (Array.isArray(arr) && arr.length === offset) {\n\t\t\t\t\tset(key, [...arr, ...values])\n\t\t\t\t}\n\t\t\t\tbreak\n\t\t\t}\n\t\t\tcase ValueOpType.Patch: {\n\t\t\t\tif (object[key as keyof T] && typeof object[key as keyof T] === 'object') {\n\t\t\t\t\tconst diff = op[1]\n\t\t\t\t\tconst patched = applyObjectDiff(object[key as keyof T] as object, diff)\n\t\t\t\t\tif (patched !== object[key as keyof T]) {\n\t\t\t\t\t\tset(key, patched)\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\tbreak\n\t\t\t}\n\t\t\tcase ValueOpType.Delete: {\n\t\t\t\tif (key in object) {\n\t\t\t\t\tif (!newObject) {\n\t\t\t\t\t\tif (isArray) {\n\t\t\t\t\t\t\tconsole.error(\"Can't delete array item yet (this should never happen)\")\n\t\t\t\t\t\t\tnewObject = [...object]\n\t\t\t\t\t\t} else {\n\t\t\t\t\t\t\tnewObject = { ...object }\n\t\t\t\t\t\t}\n\t\t\t\t\t}\n\t\t\t\t\tdelete newObject[key]\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\t}\n\n\treturn newObject ?? object\n}\n"],
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