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import {type ITimestampStruct, ts, printTs, Timestamp} from './clock';
import {printTree} from 'tree-dump/lib/printTree';
import {encode, decode} from './codec/binary';
import type {Printable} from 'tree-dump/lib/types';
/**
* A union type of all possible JSON CRDT patch operations.
*/
export type JsonCrdtPatchOperation =
| operations.NewConOp
| operations.NewValOp
| operations.NewVecOp
| operations.NewObjOp
| operations.NewStrOp
| operations.NewBinOp
| operations.NewArrOp
| operations.InsValOp
| operations.InsObjOp
| operations.InsVecOp
| operations.InsStrOp
| operations.InsBinOp
| operations.InsArrOp
| operations.DelOp
| operations.NopOp;
/**
* Represents a JSON CRDT patch.
*
* Normally, you would create a new patch using the {@link PatchBuilder} class.
*
* ```ts
* import {Patch, PatchBuilder, LogicalClock} from 'json-joy/lib/json-crdt-patch';
*
* const clock = new LogicalClock(3, 100);
* const builder = new PatchBuilder(clock);
* const patch = builder.flush();
* ```
*
* Save patch to a binary representation:
*
* ```ts
* const binary = patch.toBinary();
* ```
*
* Load patch from a binary representation:
*
* ```ts
* const patch = Patch.fromBinary(binary);
* ```
*
* @category Patch
*/
export class Patch implements Printable {
/**
* Un-marshals a JSON CRDT patch from a binary representation.
*/
public static fromBinary(data: Uint8Array): Patch {
return decode(data);
}
/**
* A list of operations in the patch.
*/
public ops: JsonCrdtPatchOperation[] = [];
/**
* Arbitrary metadata associated with the patch, which is not used by the
* library.
*/
public meta: unknown = undefined;
/**
* Returns the patch ID, which is equal to the ID of the first operation
* in the patch.
*
* @returns The ID of the first operation in the patch.
*/
public getId(): ITimestampStruct | undefined {
const op = this.ops[0];
if (!op) return undefined;
return op.id;
}
/**
* Returns the total time span of the patch, which is the sum of all
* operation spans.
*
* @returns The length of the patch.
*/
public span(): number {
let span = 0;
for (const op of this.ops) span += op.span();
return span;
}
/**
* Returns the expected time of the next inserted operation.
*/
public nextTime(): number {
const ops = this.ops;
const length = ops.length;
if (!length) return 0;
const lastOp = ops[length - 1];
return lastOp.id.time + lastOp.span();
}
/**
* Creates a new patch where all timestamps are transformed using the
* provided function.
*
* @param ts Timestamp transformation function.
* @returns A new patch with transformed timestamps.
*/
public rewriteTime(ts: (id: ITimestampStruct) => ITimestampStruct): Patch {
const patch = new Patch();
const ops = this.ops;
const length = ops.length;
const patchOps = patch.ops;
for (let i = 0; i < length; i++) {
const op = ops[i];
Iif (op instanceof operations.DelOp) patchOps.push(new operations.DelOp(ts(op.id), ts(op.obj), op.what));
else if (op instanceof operations.NewConOp)
patchOps.push(new operations.NewConOp(ts(op.id), op.val instanceof Timestamp ? ts(op.val) : op.val));
else if (op instanceof operations.NewVecOp) patchOps.push(new operations.NewVecOp(ts(op.id)));
else if (op instanceof operations.NewValOp) patchOps.push(new operations.NewValOp(ts(op.id)));
else if (op instanceof operations.NewObjOp) patchOps.push(new operations.NewObjOp(ts(op.id)));
else if (op instanceof operations.NewStrOp) patchOps.push(new operations.NewStrOp(ts(op.id)));
else if (op instanceof operations.NewBinOp) patchOps.push(new operations.NewBinOp(ts(op.id)));
else if (op instanceof operations.NewArrOp) patchOps.push(new operations.NewArrOp(ts(op.id)));
else if (op instanceof operations.InsArrOp)
patchOps.push(new operations.InsArrOp(ts(op.id), ts(op.obj), ts(op.ref), op.data.map(ts)));
else if (op instanceof operations.InsStrOp)
patchOps.push(new operations.InsStrOp(ts(op.id), ts(op.obj), ts(op.ref), op.data));
else if (op instanceof operations.InsBinOp)
patchOps.push(new operations.InsBinOp(ts(op.id), ts(op.obj), ts(op.ref), op.data));
else if (op instanceof operations.InsValOp)
patchOps.push(new operations.InsValOp(ts(op.id), ts(op.obj), ts(op.val)));
else if (op instanceof operations.InsObjOp)
patchOps.push(
new operations.InsObjOp(
ts(op.id),
ts(op.obj),
op.data.map(([key, value]) => [key, ts(value)]),
),
);
else if (op instanceof operations.InsVecOp)
patchOps.push(
new operations.InsVecOp(
ts(op.id),
ts(op.obj),
op.data.map(([key, value]) => [key, ts(value)]),
),
);
else IEif (op instanceof operations.NopOp) patchOps.push(new operations.NopOp(ts(op.id), op.len));
}
return patch;
}
/**
* The `.rebase()` operation is meant to be applied to patches which have not
* yet been advertised to the server (other peers), or when
* the server clock is used and concurrent change on the server happened.
*
* The .rebase() operation returns a new `Patch` with the IDs recalculated
* such that the first operation has the `time` equal to `newTime`.
*
* @param newTime Time where the patch ID should begin (ID of the first operation).
* @param transformAfter Time after (and including) which the IDs should be
* transformed. If not specified, equals to the time of the first operation.
*/
public rebase(newTime: number, transformAfter?: number): Patch {
const id = this.getId();
Iif (!id) throw new Error('EMPTY_PATCH');
const sid = id.sid;
const patchStartTime = id.time;
transformAfter ??= patchStartTime;
Iif (patchStartTime === newTime) return this;
const delta = newTime - patchStartTime;
return this.rewriteTime((id: ITimestampStruct): ITimestampStruct => {
if (id.sid !== sid) return id;
const time = id.time;
if (time < transformAfter) return id;
return ts(sid, time + delta);
});
}
/**
* Creates a deep clone of the patch.
*
* @returns A deep clone of the patch.
*/
public clone(): Patch {
return this.rewriteTime((id) => id);
}
/**
* Marshals the patch into a binary representation.
*
* @returns A binary representation of the patch.
*/
public toBinary() {
return encode(this);
}
// ---------------------------------------------------------------- Printable
/**
* Returns a textual human-readable representation of the patch. This can be
* used for debugging purposes.
*
* @param tab Start string for each line.
* @returns Text representation of the patch.
*/
public toString(tab: string = ''): string {
const id = this.getId();
const header = `Patch ${id ? printTs(id) : '(nil)'}!${this.span()}`;
return (
header +
printTree(
tab,
this.ops.map((op) => (tab) => op.toString(tab)),
)
);
}
}
|