@tldraw/store/dist-esm/lib/RecordsDiff.mjs.map

tldraw infinite canvas SDK (store).

{
  "version": 3,
  "sources": ["../../src/lib/RecordsDiff.ts"],
  "sourcesContent": ["import { objectMapEntries } from '@tldraw/utils'\nimport { IdOf, UnknownRecord } from './BaseRecord'\n\n/**\n * A diff describing the changes to records, containing collections of records that were added,\n * updated, or removed. This is the fundamental data structure used throughout the store system\n * to track and communicate changes.\n *\n * @example\n * ```ts\n * const diff: RecordsDiff<Book> = {\n *   added: {\n *     'book:1': { id: 'book:1', typeName: 'book', title: 'New Book' }\n *   },\n *   updated: {\n *     'book:2': [\n *       { id: 'book:2', typeName: 'book', title: 'Old Title' }, // from\n *       { id: 'book:2', typeName: 'book', title: 'New Title' }  // to\n *     ]\n *   },\n *   removed: {\n *     'book:3': { id: 'book:3', typeName: 'book', title: 'Deleted Book' }\n *   }\n * }\n * ```\n *\n * @public\n */\nexport interface RecordsDiff<R extends UnknownRecord> {\n\t/** Records that were created, keyed by their ID */\n\tadded: Record<IdOf<R>, R>\n\t/** Records that were modified, keyed by their ID. Each entry contains [from, to] tuple */\n\tupdated: Record<IdOf<R>, [from: R, to: R]>\n\t/** Records that were deleted, keyed by their ID */\n\tremoved: Record<IdOf<R>, R>\n}\n\n/**\n * Creates an empty RecordsDiff with no added, updated, or removed records.\n * This is useful as a starting point when building diffs programmatically.\n *\n * @returns An empty RecordsDiff with all collections initialized to empty objects\n * @example\n * ```ts\n * const emptyDiff = createEmptyRecordsDiff<Book>()\n * // Result: { added: {}, updated: {}, removed: {} }\n * ```\n *\n * @internal\n */\nexport function createEmptyRecordsDiff<R extends UnknownRecord>(): RecordsDiff<R> {\n\treturn { added: {}, updated: {}, removed: {} } as RecordsDiff<R>\n}\n\n/**\n * Creates the inverse of a RecordsDiff, effectively reversing all changes.\n * Added records become removed, removed records become added, and updated records\n * have their from/to values swapped. This is useful for implementing undo operations.\n *\n * @param diff - The diff to reverse\n * @returns A new RecordsDiff that represents the inverse of the input diff\n * @example\n * ```ts\n * const originalDiff: RecordsDiff<Book> = {\n *   added: { 'book:1': newBook },\n *   updated: { 'book:2': [oldBook, updatedBook] },\n *   removed: { 'book:3': deletedBook }\n * }\n *\n * const reversedDiff = reverseRecordsDiff(originalDiff)\n * // Result: {\n * //   added: { 'book:3': deletedBook },\n * //   updated: { 'book:2': [updatedBook, oldBook] },\n * //   removed: { 'book:1': newBook }\n * // }\n * ```\n *\n * @public\n */\nexport function reverseRecordsDiff(diff: RecordsDiff<any>) {\n\tconst result: RecordsDiff<any> = { added: diff.removed, removed: diff.added, updated: {} }\n\tfor (const [from, to] of Object.values(diff.updated)) {\n\t\tresult.updated[from.id] = [to, from]\n\t}\n\treturn result\n}\n\n/**\n * Checks whether a RecordsDiff contains any changes. A diff is considered empty\n * if it has no added, updated, or removed records.\n *\n * @param diff - The diff to check\n * @returns True if the diff contains no changes, false otherwise\n * @example\n * ```ts\n * const emptyDiff = createEmptyRecordsDiff<Book>()\n * console.log(isRecordsDiffEmpty(emptyDiff)) // true\n *\n * const nonEmptyDiff: RecordsDiff<Book> = {\n *   added: { 'book:1': someBook },\n *   updated: {},\n *   removed: {}\n * }\n * console.log(isRecordsDiffEmpty(nonEmptyDiff)) // false\n * ```\n *\n * @public\n */\nexport function isRecordsDiffEmpty<T extends UnknownRecord>(diff: RecordsDiff<T>) {\n\treturn (\n\t\tObject.keys(diff.added).length === 0 &&\n\t\tObject.keys(diff.updated).length === 0 &&\n\t\tObject.keys(diff.removed).length === 0\n\t)\n}\n\n/**\n * Combines multiple RecordsDiff objects into a single consolidated diff.\n * This function intelligently merges changes, handling cases where the same record\n * is modified multiple times across different diffs. For example, if a record is\n * added in one diff and then updated in another, the result will show it as added\n * with the final state.\n *\n * @param diffs - An array of diffs to combine into a single diff\n * @param options - Configuration options for the squashing operation\n *   - mutateFirstDiff - If true, modifies the first diff in place instead of creating a new one\n * @returns A single diff that represents the cumulative effect of all input diffs\n * @example\n * ```ts\n * const diff1: RecordsDiff<Book> = {\n *   added: { 'book:1': { id: 'book:1', title: 'New Book' } },\n *   updated: {},\n *   removed: {}\n * }\n *\n * const diff2: RecordsDiff<Book> = {\n *   added: {},\n *   updated: { 'book:1': [{ id: 'book:1', title: 'New Book' }, { id: 'book:1', title: 'Updated Title' }] },\n *   removed: {}\n * }\n *\n * const squashed = squashRecordDiffs([diff1, diff2])\n * // Result: {\n * //   added: { 'book:1': { id: 'book:1', title: 'Updated Title' } },\n * //   updated: {},\n * //   removed: {}\n * // }\n * ```\n *\n * @public\n */\nexport function squashRecordDiffs<T extends UnknownRecord>(\n\tdiffs: RecordsDiff<T>[],\n\toptions?: {\n\t\tmutateFirstDiff?: boolean\n\t}\n): RecordsDiff<T> {\n\tconst result = options?.mutateFirstDiff\n\t\t? diffs[0]\n\t\t: ({ added: {}, removed: {}, updated: {} } as RecordsDiff<T>)\n\n\tsquashRecordDiffsMutable(result, options?.mutateFirstDiff ? diffs.slice(1) : diffs)\n\treturn result\n}\n\n/**\n * Applies an array of diffs to a target diff by mutating the target in-place.\n * This is the core implementation used by squashRecordDiffs. It handles complex\n * scenarios where records move between added/updated/removed states across multiple diffs.\n *\n * The function processes each diff sequentially, applying the following logic:\n * - Added records: If the record was previously removed, convert to an update; otherwise add it\n * - Updated records: Chain updates together, preserving the original 'from' state\n * - Removed records: If the record was added in this sequence, cancel both operations\n *\n * @param target - The diff to modify in-place (will be mutated)\n * @param diffs - Array of diffs to apply to the target\n * @example\n * ```ts\n * const targetDiff: RecordsDiff<Book> = {\n *   added: {},\n *   updated: {},\n *   removed: { 'book:1': oldBook }\n * }\n *\n * const newDiffs = [{\n *   added: { 'book:1': newBook },\n *   updated: {},\n *   removed: {}\n * }]\n *\n * squashRecordDiffsMutable(targetDiff, newDiffs)\n * // targetDiff is now: {\n * //   added: {},\n * //   updated: { 'book:1': [oldBook, newBook] },\n * //   removed: {}\n * // }\n * ```\n *\n * @internal\n */\nexport function squashRecordDiffsMutable<T extends UnknownRecord>(\n\ttarget: RecordsDiff<T>,\n\tdiffs: RecordsDiff<T>[]\n): void {\n\tfor (const diff of diffs) {\n\t\tfor (const [id, value] of objectMapEntries(diff.added)) {\n\t\t\tif (target.removed[id]) {\n\t\t\t\tconst original = target.removed[id]\n\t\t\t\tdelete target.removed[id]\n\t\t\t\tif (original !== value) {\n\t\t\t\t\ttarget.updated[id] = [original, value]\n\t\t\t\t}\n\t\t\t} else {\n\t\t\t\ttarget.added[id] = value\n\t\t\t}\n\t\t}\n\n\t\tfor (const [id, [_from, to]] of objectMapEntries(diff.updated)) {\n\t\t\tif (target.added[id]) {\n\t\t\t\ttarget.added[id] = to\n\t\t\t\tdelete target.updated[id]\n\t\t\t\tdelete target.removed[id]\n\t\t\t\tcontinue\n\t\t\t}\n\t\t\tif (target.updated[id]) {\n\t\t\t\ttarget.updated[id] = [target.updated[id][0], to]\n\t\t\t\tdelete target.removed[id]\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\t\ttarget.updated[id] = diff.updated[id]\n\t\t\tdelete target.removed[id]\n\t\t}\n\n\t\tfor (const [id, value] of objectMapEntries(diff.removed)) {\n\t\t\t// the same record was added in this diff sequence, just drop it\n\t\t\tif (target.added[id]) {\n\t\t\t\tdelete target.added[id]\n\t\t\t} else if (target.updated[id]) {\n\t\t\t\ttarget.removed[id] = target.updated[id][0]\n\t\t\t\tdelete target.updated[id]\n\t\t\t} else {\n\t\t\t\ttarget.removed[id] = value\n\t\t\t}\n\t\t}\n\t}\n}\n"],
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