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August 6, 2024 20:49
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patch applier
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| type Patch = [path: PathPart[], obj: any, range: PatchRange, val?: any] | |
| /** | |
| * walk a path in an obj, optionally mutating it to insert missing parts | |
| * @see https://github.com/braid-org/braid-spec/blob/aea85367d60793c113bdb305a4b4ecf55d38061d/draft-toomim-httpbis-range-patch-01.txt | |
| * | |
| * to insert a string in an array, you need to wrap it in [] | |
| * | |
| * to insert an array in an array you need to wrap it in [] | |
| */ | |
| export function patch<T>( | |
| path: PathPart[], | |
| obj: any, | |
| range: PatchRange, | |
| val?: any, | |
| reviver?: ( | |
| value: any, | |
| key: any, | |
| parent: any, | |
| path: PathPart[], | |
| obj: T, | |
| range: PatchRange, | |
| ) => void, | |
| ) { | |
| let originalObject = obj | |
| let p = [...path] | |
| while (true) { | |
| let key = p.shift() | |
| if (!p.length) { | |
| if (typeof reviver == "function") { | |
| val = reviver(val, key, obj, path, originalObject, range) | |
| } | |
| if (Array.isArray(range) || typeof range == "number") { | |
| if (typeof key == "undefined") { | |
| throw new Error("cant treat top level as a seq") | |
| } | |
| key = key! | |
| // splice | |
| let [start, end] = Array.isArray(range) ? range : [range, range + 1] | |
| const ZERO_LENGTH = Array.isArray(range) && range.length == 0 | |
| if (!ZERO_LENGTH && (start == null || end == null)) { | |
| throw new RangeError("it's all or nothing, no half measures") | |
| } | |
| const DELETE = typeof val == "undefined" | |
| const INSERT = start === end && !DELETE | |
| const APPEND = ZERO_LENGTH && !DELETE | |
| let op = DELETE | |
| ? ("del" as const) | |
| : APPEND | |
| ? ("add" as const) | |
| : INSERT | |
| ? ("ins" as const) | |
| : ("replace" as const) | |
| if (typeof obj[key] == "undefined") { | |
| // todo what if it's a function that would return a string? | |
| if (typeof val == "string") { | |
| obj[key] = "" | |
| } else { | |
| obj[key] = [] | |
| } | |
| } | |
| let seq = obj[key] | |
| if (Array.isArray(seq)) { | |
| switch (op) { | |
| case "add": { | |
| Array.isArray(val) ? seq.push(...val) : seq.push(val) | |
| return | |
| } | |
| case "replace": | |
| case "ins": { | |
| Array.isArray(val) | |
| ? seq.splice(start!, end! - 1, ...val) | |
| : seq.splice(start!, end! - 1, val) | |
| return | |
| } | |
| case "del": { | |
| seq.splice(start!, end! - start!) | |
| return | |
| } | |
| default: { | |
| throw new Error("i don't know what happened") | |
| } | |
| } | |
| } | |
| if (typeof seq == "string") { | |
| switch (op) { | |
| case "add": { | |
| obj[key] = seq + val | |
| return | |
| } | |
| case "replace": | |
| case "ins": { | |
| obj[key] = seq.slice(0, start) + val + seq.slice(end) | |
| return | |
| } | |
| case "del": { | |
| obj[key] = seq.slice(0, start) + seq.slice(end) | |
| return | |
| } | |
| default: { | |
| throw new Error("i don't know what happened") | |
| } | |
| } | |
| } | |
| // todo should impl for typed arrays? | |
| throw new Error("not implemented") | |
| } | |
| if (typeof key == "undefined") { | |
| if (typeof range != "string") { | |
| throw new Error(`can't index top-level map with ${range}`) | |
| } | |
| obj[range] = val | |
| return | |
| } | |
| if (typeof obj[key] == "undefined") { | |
| obj[key] = {} | |
| } | |
| // put/delete | |
| if (typeof val == "undefined") { | |
| delete obj[key][range] | |
| } else { | |
| obj[key][range] = val | |
| } | |
| return | |
| } | |
| if (typeof key == "undefined") { | |
| throw new Error("cant treat top level as a seq") | |
| } | |
| key = key! | |
| let nextkey = p[0] | |
| if (typeof obj[key] == "undefined") { | |
| if (typeof nextkey == "string") { | |
| obj[key] = {} | |
| } else if (typeof nextkey == "number") { | |
| obj[key] = [] | |
| } else { | |
| throw new Error(`can't go down this road ${obj}.${key}.${nextkey}`) | |
| } | |
| } | |
| obj = obj[key] | |
| } | |
| } | |
| export function fromAutomerge(autopatch: AutomergePatch, obj: any): Patch { | |
| let path = autopatch.path.slice(0, -1) | |
| let key = autopatch.path[autopatch.path.length - 1] | |
| // @ts-expect-error | |
| let [range, val]: PatchRange = (() => { | |
| switch (autopatch.action) { | |
| case "conflict": { | |
| return [ | |
| key!, | |
| { | |
| $type: type("automerge:conflict"), | |
| }, | |
| ] | |
| } | |
| case "inc": { | |
| return [ | |
| key as number, | |
| { | |
| $type: type("automerge:inc"), | |
| $value: autopatch.value, | |
| }, | |
| ] | |
| } | |
| case "mark": { | |
| return [ | |
| key, | |
| { | |
| $type: type("automerge:mark"), | |
| $meta: { | |
| marks: autopatch.marks, | |
| }, | |
| }, | |
| ] | |
| } | |
| case "unmark": { | |
| return [ | |
| key!, | |
| { | |
| $type: type("automerge:unmark"), | |
| $meta: { | |
| start: autopatch.start, | |
| end: autopatch.end, | |
| name: autopatch.name, | |
| }, | |
| }, | |
| ] | |
| } | |
| case "del": { | |
| return [[key as number, +key + (autopatch.length || 0)]] | |
| } | |
| case "insert": { | |
| if (autopatch.marks || autopatch.conflicts) { | |
| return { | |
| $type: type("automerge:insert"), | |
| $value: autopatch.values, | |
| $meta: { | |
| marks: autopatch.marks, | |
| conflicts: autopatch.conflicts, | |
| }, | |
| } | |
| } | |
| return [[key as number, key as number], autopatch.values] | |
| } | |
| case "splice": { | |
| if (autopatch.marks) { | |
| return { | |
| $type: type("automerge:splice"), | |
| $value: autopatch.value, | |
| $meta: { | |
| marks: autopatch.marks, | |
| }, | |
| } | |
| } | |
| return [[key as number, key as number], [autopatch.value]] | |
| } | |
| case "put": { | |
| return [key!, autopatch.value] | |
| } | |
| } | |
| })() | |
| return [path, obj, range, val] | |
| } |
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