/**
* std/json/stream - incremental JSON stream validation
*
* Import with: import { stream_validator } from "std/json"
*/
pub enum JsonStreamStatus {
Pending
Valid
Invalid(error)
}
type JsonStreamValidator = {
feed: fn(any) -> JsonStreamStatus,
value: fn() -> any,
status: fn() -> JsonStreamStatus,
partial: fn() -> any,
}
/**
* Create an incremental validator for UTF-8 JSON string or bytes chunks.
* `feed(chunk)` returns JsonStreamStatus.Pending, JsonStreamStatus.Valid, or
* JsonStreamStatus.Invalid({reason, path}). `value()` returns the parsed JSON
* value after Valid and nil otherwise. `partial()` returns the best-effort
* partially-filled value from the bytes seen so far (Vercel `streamObject` /
* Instructor `Partial[T]`): the frontier's open string/containers are closed
* and any half-typed trailing member is dropped, so it grows monotonically as
* chunks arrive — nil until the first complete member is present.
*
* @effects: []
* @errors: []
*/
pub fn stream_validator(schema) -> JsonStreamValidator {
const handle = __json_stream_validator(schema)
return {
_namespace: "json_stream_validator",
feed: fn(chunk) { return __json_stream_validator_feed(handle, chunk) },
value: fn() { return __json_stream_validator_value(handle) },
status: fn() { return __json_stream_validator_status(handle) },
partial: fn() { return __json_stream_validator_partial(handle) },
}
}
fn __stream_object_text(chunk) -> string {
if type_of(chunk) == "string" {
return chunk
}
if type_of(chunk) == "dict" {
return to_string(chunk?.delta ?? chunk?.text ?? chunk?.content ?? "")
}
return to_string(chunk)
}
/**
* Stream partial typed objects from a chunked JSON `source` (Vercel
* `streamObject`). Feeds each chunk of `source` — strings, or dicts carrying a
* `delta`/`text`/`content` field (so an `llm_stream_call` stream composes
* directly) — into a `stream_validator`, and emits the current best-effort
* partial object every time it grows, ending with the fully parsed object.
*
* Returns a `Stream<any>`, so it composes with `for`, `.next()`, and the
* stream combinators. By default consecutive identical partials are
* de-duplicated, so a chunk that does not complete a new member emits nothing;
* pass `options.dedupe: false` to emit one partial per source chunk instead.
* `schema` (optional, default permissive) gates final validation and early
* invalidation exactly as `stream_validator` does; the streamed partials
* themselves are structural (schema is not enforced mid-stream, since a partial
* is legitimately incomplete). A truncated stream still yields its best-effort
* final partial rather than throwing — use `stream_validator` directly when you
* need strict completion.
*
* @effects: []
* @errors: []
*/
pub gen fn stream_object(source, schema = nil, options = nil) -> Stream<any> {
const dedupe = (options ?? {})?.dedupe ?? true
const validator = stream_validator(schema ?? {})
let last_emitted = nil
let emitted_any = false
for chunk in source {
const text = __stream_object_text(chunk)
if text != "" {
validator.feed(text)
}
const partial = validator.partial()
if partial != nil {
const key = json_stringify(partial)
if !dedupe || !emitted_any || key != last_emitted {
last_emitted = key
emitted_any = true
emit partial
}
}
}
const final_value = validator.value() ?? validator.partial()
if final_value != nil {
const final_key = json_stringify(final_value)
if !emitted_any || final_key != last_emitted {
emit final_value
}
}
}
/**
* `std/json/stream_validate` — standalone partial-JSON validation API.
*
* Verdict shape (plain dict, stable for agents to dispatch on):
* {verdict: "pending"}
* {verdict: "valid"}
* {verdict: "invalid", reason: <string>, path: <jsonpointer-ish>}
*
* `stream_validate_create(schema)` returns an opaque validator handle.
* `stream_validate_chunk(handle, chunk)` returns the verdict after
* consuming `chunk` (string or bytes). Once a validator reaches
* `"invalid"` further chunks are ignored and the same verdict is
* surfaced. `stream_validate_finalize(handle)` flushes the stream — a
* still-pending validator with a partial document transitions to
* `"invalid"` with `reason: "incomplete JSON document at end of stream"`.
* The trio is also exposed as the `stream_validate` namespace record so
* callers can write `stream_validate.create(schema)`.
*/
/**
* Create a `stream_validate` handle for a JSON schema.
*
* @effects: []
* @errors: []
*/
pub fn stream_validate_create(schema) -> string {
return __json_stream_validate_create(schema)
}
/**
* Feed the next chunk into a `stream_validate` handle. Returns the new
* verdict dict.
*
* @effects: []
* @errors: []
*/
pub fn stream_validate_chunk(handle: string, chunk) -> dict {
return __json_stream_validate_chunk(handle, chunk)
}
/**
* Flush a `stream_validate` handle. If the stream is still pending with
* a partial document the verdict transitions to invalid; an already
* valid or invalid verdict is returned unchanged.
*
* @effects: []
* @errors: []
*/
pub fn stream_validate_finalize(handle: string) -> dict {
return __json_stream_validate_finalize(handle)
}
/**
* Namespace accessor for the `stream_validate.*` API. Returns a record
* holding the create/chunk/finalize closures so scripts can write
* `let sv = stream_validate(); let v = sv.create(schema)` or destructure
* via `let {create, chunk, finalize} = stream_validate()`.
*
* @effects: []
* @errors: []
*/
pub fn stream_validate() -> dict {
return {
create: fn(schema) { return __json_stream_validate_create(schema) },
chunk: fn(handle, chunk) { return __json_stream_validate_chunk(handle, chunk) },
finalize: fn(handle) { return __json_stream_validate_finalize(handle) },
}
}