| 248 | * @since 4.0.0 |
| 249 | */ |
| 250 | export function makeParser(onParse: (event: AnyEvent) => void, options?: DecodeOptions): Parser { |
| 251 | const maxEventSize = options?.maxEventSize ?? defaultMaxEventSize |
| 252 | |
| 253 | // Processing state |
| 254 | let isFirstChunk: boolean |
| 255 | let buffer: string |
| 256 | let startingPosition: number |
| 257 | let startingFieldLength: number |
| 258 | let discardTrailingNewline: boolean |
| 259 | |
| 260 | // Event state |
| 261 | let lastEventId: string | undefined |
| 262 | let eventName: string | undefined |
| 263 | let data: string |
| 264 | |
| 265 | reset() |
| 266 | return { feed, reset } |
| 267 | |
| 268 | function reset(): void { |
| 269 | isFirstChunk = true |
| 270 | buffer = "" |
| 271 | startingPosition = 0 |
| 272 | startingFieldLength = -1 |
| 273 | discardTrailingNewline = false |
| 274 | |
| 275 | lastEventId = undefined |
| 276 | eventName = undefined |
| 277 | data = "" |
| 278 | } |
| 279 | |
| 280 | function feed(chunk: string): SseError | undefined { |
| 281 | buffer = buffer ? buffer + chunk : chunk |
| 282 | |
| 283 | // Strip any UTF-8 byte order mark (BOM) at the start of the stream. |
| 284 | // Note that we do not strip any non - UTF8 BOM, as eventsource streams are |
| 285 | // always decoded as UTF8 as per the specification. |
| 286 | if (isFirstChunk && buffer.startsWith(BOM)) { |
| 287 | buffer = buffer.slice(BOM.length) |
| 288 | } |
| 289 | |
| 290 | isFirstChunk = false |
| 291 | |
| 292 | // Set up chunk-specific processing state |
| 293 | const length = buffer.length |
| 294 | let position = 0 |
| 295 | |
| 296 | // Read the current buffer byte by byte |
| 297 | while (position < length) { |
| 298 | // EventSource allows for carriage return + line feed, which means we |
| 299 | // need to ignore a linefeed character if the previous character was a |
| 300 | // carriage return |
| 301 | // @todo refactor to reduce nesting, consider checking previous byte? |
| 302 | // @todo but consider multiple chunks etc |
| 303 | if (discardTrailingNewline) { |
| 304 | if (buffer[position] === "\n") { |
| 305 | ++position |
| 306 | } |
| 307 | discardTrailingNewline = false |