eventsource-parser - npm Package Compare versions

Comparing version 3.0.8 to 3.1.0

dist/index.cjs

@@ -11,13 +11,17 @@ "use strict";
 }
-function createParser(callbacks) {
-  if (typeof callbacks == "function")
+function createParser(config) {
+  if (typeof config == "function")
     throw new TypeError(
-      "`callbacks` must be an object, got a function instead. Did you mean `{onEvent: fn}`?"
+      "`config` must be an object, got a function instead. Did you mean `createParser({onEvent: fn})`?"
     );
-  const { onEvent = noop, onError = noop, onRetry = noop, onComment } = callbacks, pendingFragments = [];
-  let isFirstChunk = !0, id, data = "", dataLines = 0, eventType;
+  const { onEvent = noop, onError = noop, onRetry = noop, onComment, maxBufferSize } = config, pendingFragments = [];
+  let pendingFragmentsLength = 0, isFirstChunk = !0, id, data = "", dataLines = 0, eventType, terminated = !1;
   function feed(chunk) {
+    if (terminated)
+      throw new Error(
+        "Cannot feed parser: it was terminated after exceeding the configured max buffer size. Call `reset()` to resume parsing."
+      );
     if (isFirstChunk && (isFirstChunk = !1, chunk.charCodeAt(0) === 239 && chunk.charCodeAt(1) === 187 && chunk.charCodeAt(2) === 191 && (chunk = chunk.slice(3))), pendingFragments.length === 0) {
       const trailing2 = processLines(chunk);
-      trailing2 !== "" && pendingFragments.push(trailing2);
+      trailing2 !== "" && (pendingFragments.push(trailing2), pendingFragmentsLength = trailing2.length), checkBufferSize();
       return;
@@ -27,3 +31,3 @@ }
 `) === -1 && chunk.indexOf("\r") === -1) {
-      pendingFragments.push(chunk);
+      pendingFragments.push(chunk), pendingFragmentsLength += chunk.length, checkBufferSize();
       return;
@@ -33,6 +37,13 @@ }
     const input = pendingFragments.join("");
-    pendingFragments.length = 0;
+    pendingFragments.length = 0, pendingFragmentsLength = 0;
     const trailing = processLines(input);
-    trailing !== "" && pendingFragments.push(trailing);
+    trailing !== "" && (pendingFragments.push(trailing), pendingFragmentsLength = trailing.length), checkBufferSize();
   }
+  function checkBufferSize() {
+    maxBufferSize !== void 0 && (pendingFragmentsLength + data.length <= maxBufferSize || (terminated = !0, pendingFragments.length = 0, pendingFragmentsLength = 0, id = void 0, data = "", dataLines = 0, eventType = void 0, onError(
+      new ParseError(`Buffered data exceeded max buffer size of ${maxBufferSize} characters`, {
+        type: "max-buffer-size-exceeded"
+      })
+    )));
+  }
   function processLines(chunk) {
@@ -157,3 +168,3 @@ let searchIndex = 0;
     }
-    isFirstChunk = !0, id = void 0, data = "", dataLines = 0, eventType = void 0, pendingFragments.length = 0;
+    isFirstChunk = !0, id = void 0, data = "", dataLines = 0, eventType = void 0, pendingFragments.length = 0, pendingFragmentsLength = 0, terminated = !1;
   }
@@ -160,0 +171,0 @@ return { feed, reset };

dist/index.cjs.map

@@ -1,1 +0,1 @@
-{"version":3,"file":"index.cjs","sources":["../src/errors.ts","../src/parse.ts"],"sourcesContent":["/**\n * The type of error that occurred.\n * @public\n */\nexport type ErrorType = 'invalid-retry' | 'unknown-field'\n\n/**\n * Error thrown when encountering an issue during parsing.\n *\n * @public\n */\nexport class ParseError extends Error {\n  /**\n   * The type of error that occurred.\n   */\n  type: ErrorType\n\n  /**\n   * In the case of an unknown field encountered in the stream, this will be the field name.\n   */\n  field?: string | undefined\n\n  /**\n   * In the case of an unknown field encountered in the stream, this will be the value of the field.\n   */\n  value?: string | undefined\n\n  /**\n   * The line that caused the error, if available.\n   */\n  line?: string | undefined\n\n  constructor(\n    message: string,\n    options: {type: ErrorType; field?: string; value?: string; line?: string},\n  ) {\n    super(message)\n    this.name = 'ParseError'\n    this.type = options.type\n    this.field = options.field\n    this.value = options.value\n    this.line = options.line\n  }\n}\n","/**\n * EventSource/Server-Sent Events parser\n * @see https://html.spec.whatwg.org/multipage/server-sent-events.html\n */\nimport {ParseError} from './errors.ts'\nimport type {EventSourceParser, ParserCallbacks} from './types.ts'\n\n// ASCII codes used in the hot parsing paths.\nconst LF = 10\nconst CR = 13\nconst SPACE = 32\n\n// oxlint-disable-next-line no-unused-vars\nfunction noop(_arg: unknown) {\n  // intentional noop\n}\n\n/**\n * Creates a new EventSource parser.\n *\n * @param callbacks - Callbacks to invoke on different parsing events:\n *   - `onEvent` when a new event is parsed\n *   - `onError` when an error occurs\n *   - `onRetry` when a new reconnection interval has been sent from the server\n *   - `onComment` when a comment is encountered in the stream\n *\n * @returns A new EventSource parser, with `parse` and `reset` methods.\n * @public\n */\nexport function createParser(callbacks: ParserCallbacks): EventSourceParser {\n  if (typeof callbacks === 'function') {\n    throw new TypeError(\n      '`callbacks` must be an object, got a function instead. Did you mean `{onEvent: fn}`?',\n    )\n  }\n\n  const {onEvent = noop, onError = noop, onRetry = noop, onComment} = callbacks\n\n  // Trailing bytes from prior `feed()` calls that did not yet form a complete line.\n  // Stored as an array of fragments and only joined when a line terminator arrives.\n  // Concatenating per-feed (`prefix + chunk`) is O(N²) when a single SSE line spans\n  // many chunks (e.g. a large `data:` payload streamed in tiny slices, or an MCP-style\n  // server that emits one giant content block). Buffering as fragments + joining once\n  // makes the same workload linear.\n  const pendingFragments: string[] = []\n\n  let isFirstChunk = true\n  let id: string | undefined\n  let data = ''\n  let dataLines = 0\n  let eventType: string | undefined\n\n  /**\n   * Feeds a chunk of the SSE stream to the parser. Any trailing bytes that do\n   * not yet form a complete line are held back and prepended to the next chunk,\n   * so callers can pass arbitrary slices of the stream without worrying about\n   * line boundaries.\n   *\n   * Per the SSE spec, a UTF-8 BOM (0xEF 0xBB 0xBF) at the start of the very\n   * first chunk is stripped before parsing.\n   *\n   * @see https://html.spec.whatwg.org/multipage/server-sent-events.html#parsing-an-event-stream\n   */\n  function feed(chunk: string) {\n    if (isFirstChunk) {\n      isFirstChunk = false\n      // Match and strip UTF-8 BOM from the start of the stream, if present.\n      // (Per the spec, this is only valid at the very start of the stream)\n      if (\n        chunk.charCodeAt(0) === 0xef &&\n        chunk.charCodeAt(1) === 0xbb &&\n        chunk.charCodeAt(2) === 0xbf\n      ) {\n        chunk = chunk.slice(3)\n      }\n    }\n\n    // Hot path: no buffered prefix from a prior partial line. Hand the chunk\n    // straight to `processLines`, exactly like the original implementation.\n    // Zero new work in the common case (every chunk ends with `\\n\\n`).\n    if (pendingFragments.length === 0) {\n      const trailing = processLines(chunk)\n      if (trailing !== '') pendingFragments.push(trailing)\n      return\n    }\n\n    // We have a buffered prefix. If this chunk also has no terminator, append\n    // to the buffer without concatenating — that's the O(N²) trap we're\n    // avoiding (large single `data:` payload split across many tiny chunks).\n    if (chunk.indexOf('\\n') === -1 && chunk.indexOf('\\r') === -1) {\n      pendingFragments.push(chunk)\n      return\n    }\n\n    // Terminator arrived. Join the accumulated fragments + this chunk once,\n    // process, and buffer any new trailing partial line.\n    pendingFragments.push(chunk)\n    const input = pendingFragments.join('')\n    pendingFragments.length = 0\n    const trailing = processLines(input)\n    if (trailing !== '') pendingFragments.push(trailing)\n  }\n\n  /**\n   * Splits `chunk` into SSE lines and dispatches each to the appropriate handler.\n   * Returns any trailing bytes that did not terminate with a line break, so the\n   * caller can prepend them to the next chunk.\n   *\n   * The SSE spec permits three line terminators: `\\n`, `\\r`, and `\\r\\n`. Real-world\n   * streams almost always use plain `\\n`, so we take a fast path when no `\\r` is\n   * present in the chunk. The slow path is spec-correct but does more work per line.\n   */\n  function processLines(chunk: string): string {\n    let searchIndex = 0\n\n    // Fast path: LF-only chunk (the common case for typical SSE servers).\n    // We can scan forward with a single `indexOf('\\n')` per line and inline\n    // the hot-path branches for `data:` and `event:` without the CR bookkeeping\n    // the slow path needs.\n    if (chunk.indexOf('\\r') === -1) {\n      let lfIndex = chunk.indexOf('\\n', searchIndex)\n      while (lfIndex !== -1) {\n        // Blank line: end-of-event marker. Dispatch the accumulated event (if any)\n        // and reset the buffered fields. This is hoisted out of `parseLine` because\n        // it's the single most common line shape after `data:` lines.\n        if (searchIndex === lfIndex) {\n          if (dataLines > 0) {\n            onEvent({id, event: eventType, data})\n          }\n          id = undefined\n          data = ''\n          dataLines = 0\n          eventType = undefined\n          searchIndex = lfIndex + 1\n          lfIndex = chunk.indexOf('\\n', searchIndex)\n          continue\n        }\n        const firstCharCode = chunk.charCodeAt(searchIndex)\n        if (isDataPrefix(chunk, searchIndex, firstCharCode)) {\n          // `data:` line — append the value to the event's data buffer.\n          // 'data:'.length === 5, 'data: '.length === 6\n          const valueStart =\n            chunk.charCodeAt(searchIndex + 5) === SPACE ? searchIndex + 6 : searchIndex + 5\n          const value = chunk.slice(valueStart, lfIndex)\n          // Fast path within a fast path: if this is the first data line AND the\n          // next char is another LF (i.e. `data:foo\\n\\n`), dispatch immediately\n          // without ever writing to the `data` buffer. This is the shape of a\n          // typical single-line SSE event (ChatGPT-style streams, etc.) and is\n          // hot enough to be worth the duplication.\n          if (dataLines === 0 && chunk.charCodeAt(lfIndex + 1) === LF) {\n            onEvent({id, event: eventType, data: value})\n            id = undefined\n            data = ''\n            eventType = undefined\n            searchIndex = lfIndex + 2\n            lfIndex = chunk.indexOf('\\n', searchIndex)\n            continue\n          }\n          // Multi-line data: concatenate with newline separator per spec.\n          data = dataLines === 0 ? value : `${data}\\n${value}`\n          dataLines++\n        } else if (isEventPrefix(chunk, searchIndex, firstCharCode)) {\n          // `event:` line — set the event type for the next dispatch. Per spec,\n          // an empty value resets `event type` to its default (undefined here).\n          // 'event:'.length === 6, 'event: '.length === 7\n          eventType =\n            chunk.slice(\n              chunk.charCodeAt(searchIndex + 6) === SPACE ? searchIndex + 7 : searchIndex + 6,\n              lfIndex,\n            ) || undefined\n        } else {\n          // Everything else: `id:`, `retry:`, comment lines (`:` prefix), unknown\n          // fields, or malformed lines. These are rarer and go through the full\n          // per-line parser, which handles the SSE field grammar in detail.\n          parseLine(chunk, searchIndex, lfIndex)\n        }\n        searchIndex = lfIndex + 1\n        lfIndex = chunk.indexOf('\\n', searchIndex)\n      }\n      return chunk.slice(searchIndex)\n    }\n\n    // Slow path: the chunk contains at least one `\\r`, so lines may be terminated\n    // by `\\r`, `\\n`, or `\\r\\n`. We locate the next terminator by looking at both\n    // the nearest `\\r` and `\\n` and picking whichever comes first.\n    while (searchIndex < chunk.length) {\n      const crIndex = chunk.indexOf('\\r', searchIndex)\n      const lfIndex = chunk.indexOf('\\n', searchIndex)\n\n      let lineEnd = -1\n      if (crIndex !== -1 && lfIndex !== -1) {\n        lineEnd = crIndex < lfIndex ? crIndex : lfIndex\n      } else if (crIndex !== -1) {\n        // A trailing `\\r` at the very end of the chunk is ambiguous: it could be\n        // a bare-CR terminator, or the first half of a `\\r\\n` whose `\\n` arrives\n        // in the next chunk. Defer until we see more input.\n        if (crIndex === chunk.length - 1) {\n          lineEnd = -1\n        } else {\n          lineEnd = crIndex\n        }\n      } else if (lfIndex !== -1) {\n        lineEnd = lfIndex\n      }\n\n      if (lineEnd === -1) {\n        break\n      }\n\n      parseLine(chunk, searchIndex, lineEnd)\n      searchIndex = lineEnd + 1\n      // If we just consumed a `\\r` and the next char is `\\n`, skip it so the\n      // pair is treated as a single terminator rather than an empty line.\n      if (chunk.charCodeAt(searchIndex - 1) === CR && chunk.charCodeAt(searchIndex) === LF) {\n        searchIndex++\n      }\n    }\n\n    return chunk.slice(searchIndex)\n  }\n\n  function parseLine(chunk: string, start: number, end: number) {\n    if (start === end) {\n      dispatchEvent()\n      return\n    }\n\n    const firstCharCode = chunk.charCodeAt(start)\n\n    if (isDataPrefix(chunk, start, firstCharCode)) {\n      // 'data:'.length === 5, 'data: '.length === 6\n      const valueStart = chunk.charCodeAt(start + 5) === SPACE ? start + 6 : start + 5\n      const value = chunk.slice(valueStart, end)\n      data = dataLines === 0 ? value : `${data}\\n${value}`\n      dataLines++\n      return\n    }\n\n    if (isEventPrefix(chunk, start, firstCharCode)) {\n      // 'event:'.length === 6, 'event: '.length === 7\n      eventType =\n        chunk.slice(chunk.charCodeAt(start + 6) === SPACE ? start + 7 : start + 6, end) || undefined\n      return\n    }\n\n    // Fast path for \"id:\" — 'i' = 105, 'd' = 100, ':' = 58\n    if (\n      firstCharCode === 105 &&\n      chunk.charCodeAt(start + 1) === 100 &&\n      chunk.charCodeAt(start + 2) === 58\n    ) {\n      // 'id:'.length === 3, 'id: '.length === 4\n      const value = chunk.slice(chunk.charCodeAt(start + 3) === SPACE ? start + 4 : start + 3, end)\n      id = value.includes('\\0') ? undefined : value\n      return\n    }\n\n    // Comment line — ':' = 58\n    if (firstCharCode === 58) {\n      if (onComment) {\n        const line = chunk.slice(start, end)\n        // skip ':' (+1), or ': ' (+2) when a space follows\n        onComment(line.slice(chunk.charCodeAt(start + 1) === SPACE ? 2 : 1))\n      }\n      return\n    }\n\n    const line = chunk.slice(start, end)\n    const fieldSeparatorIndex = line.indexOf(':')\n    if (fieldSeparatorIndex === -1) {\n      processField(line, '', line)\n      return\n    }\n\n    const field = line.slice(0, fieldSeparatorIndex)\n    // skip ':' (+1), or ': ' (+2) when a space follows\n    const offset = line.charCodeAt(fieldSeparatorIndex + 1) === SPACE ? 2 : 1\n    const value = line.slice(fieldSeparatorIndex + offset)\n    processField(field, value, line)\n  }\n\n  function processField(field: string, value: string, line: string) {\n    // Field names must be compared literally, with no case folding performed.\n    switch (field) {\n      case 'event':\n        // Set the `event type` buffer to field value\n        eventType = value || undefined\n        break\n      case 'data':\n        data = dataLines === 0 ? value : `${data}\\n${value}`\n        dataLines++\n        break\n      case 'id':\n        // If the field value does not contain U+0000 NULL, then set the `ID` buffer to\n        // the field value. Otherwise, ignore the field.\n        id = value.includes('\\0') ? undefined : value\n        break\n      case 'retry':\n        // If the field value consists of only ASCII digits, then interpret the field value as an\n        // integer in base ten, and set the event stream's reconnection time to that integer.\n        // Otherwise, ignore the field.\n        if (/^\\d+$/.test(value)) {\n          onRetry(parseInt(value, 10))\n        } else {\n          onError(\n            new ParseError(`Invalid \\`retry\\` value: \"${value}\"`, {\n              type: 'invalid-retry',\n              value,\n              line,\n            }),\n          )\n        }\n        break\n      default:\n        // Otherwise, the field is ignored.\n        onError(\n          new ParseError(\n            `Unknown field \"${field.length > 20 ? `${field.slice(0, 20)}…` : field}\"`,\n            {type: 'unknown-field', field, value, line},\n          ),\n        )\n        break\n    }\n  }\n\n  function dispatchEvent() {\n    if (dataLines > 0) {\n      onEvent({\n        id,\n        event: eventType,\n        data,\n      })\n    }\n\n    id = undefined\n    data = ''\n    dataLines = 0\n    eventType = undefined\n  }\n\n  function reset(options: {consume?: boolean} = {}) {\n    if (options.consume && pendingFragments.length > 0) {\n      const incompleteLine = pendingFragments.join('')\n      parseLine(incompleteLine, 0, incompleteLine.length)\n    }\n\n    isFirstChunk = true\n    id = undefined\n    data = ''\n    dataLines = 0\n    eventType = undefined\n    pendingFragments.length = 0\n  }\n\n  return {feed, reset}\n}\n\n/**\n * Checks if `chunk` starts with the literal `data:` at index `i`.\n *\n * Equivalent to `chunk.startsWith('data:', i)`, but benchmarks show this\n * hand-unrolled char-code comparison is ~20% faster on common event types.\n * The caller passes `firstCharCode` (the code at `i`) so it can be reused\n * across prefix checks.\n *\n * ASCII: 'd' = 100, 'a' = 97, 't' = 116, 'a' = 97, ':' = 58\n */\nfunction isDataPrefix(chunk: string, i: number, firstCharCode: number): boolean {\n  return (\n    firstCharCode === 100 &&\n    chunk.charCodeAt(i + 1) === 97 &&\n    chunk.charCodeAt(i + 2) === 116 &&\n    chunk.charCodeAt(i + 3) === 97 &&\n    chunk.charCodeAt(i + 4) === 58\n  )\n}\n\n/**\n * Checks if `chunk` starts with the literal `event:` at index `i`.\n *\n * See {@link isDataPrefix} for why this is hand-unrolled rather than using\n * `String.prototype.startsWith`.\n *\n * ASCII: 'e' = 101, 'v' = 118, 'e' = 101, 'n' = 110, 't' = 116, ':' = 58\n */\nfunction isEventPrefix(chunk: string, i: number, firstCharCode: number): boolean {\n  return (\n    firstCharCode === 101 &&\n    chunk.charCodeAt(i + 1) === 118 &&\n    chunk.charCodeAt(i + 2) === 101 &&\n    chunk.charCodeAt(i + 3) === 110 &&\n    chunk.charCodeAt(i + 4) === 116 &&\n    chunk.charCodeAt(i + 5) === 58\n  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dist/index.d.cts

 /**
  * Creates a new EventSource parser.
  *
- * @param callbacks - Callbacks to invoke on different parsing events:
- *   - `onEvent` when a new event is parsed
- *   - `onError` when an error occurs
- *   - `onRetry` when a new reconnection interval has been sent from the server
- *   - `onComment` when a comment is encountered in the stream
+ * @param config - Parser configuration. Accepts callbacks (see {@link ParserCallbacks})
+ *   and options like `maxBufferSize` (see {@link ParserConfig}).
  *
- * @returns A new EventSource parser, with `parse` and `reset` methods.
+ * @returns A new EventSource parser, with `feed` and `reset` methods.
  * @public
  */
-export declare function createParser(
-  callbacks: ParserCallbacks,
-): EventSourceParser;
+export declare function createParser(config: ParserConfig): EventSourceParser;
 
@@ -21,3 +16,6 @@ /**
  */
-export declare type ErrorType = "invalid-retry" | "unknown-field";
+export declare type ErrorType =
+  | "invalid-retry"
+  | "unknown-field"
+  | "max-buffer-size-exceeded";
 
@@ -147,2 +145,27 @@ /**
 
+/**
+ * Configuration accepted by {@link createParser}. Extends {@link ParserCallbacks} with
+ * additional options that control parser behavior.
+ *
+ * @public
+ */
+export declare interface ParserConfig extends ParserCallbacks {
+  /**
+   * Maximum number of characters the parser is allowed to buffer across calls to `feed()`.
+   *
+   * Two unbounded surfaces exist in a streaming SSE parser:
+   * - A partial line that has not yet been terminated by `\n`, `\r`, or `\r\n`.
+   * - A multi-line event whose terminating blank line has not yet arrived (each `data:`
+   *   field gets appended to the buffered event).
+   *
+   * When the combined size of these buffers exceeds `maxBufferSize`, the parser emits a
+   * `ParseError` with `type: 'max-buffer-size-exceeded'` to `onError` and becomes
+   * terminated — subsequent calls to `feed()` will throw until `reset()` is called.
+   * This protects against unbounded memory growth from malformed or malicious streams.
+   *
+   * @defaultValue `undefined` (unbounded)
+   */
+  maxBufferSize?: number | undefined;
+}
+
 export {};

dist/index.d.ts

 /**
  * Creates a new EventSource parser.
  *
- * @param callbacks - Callbacks to invoke on different parsing events:
- *   - `onEvent` when a new event is parsed
- *   - `onError` when an error occurs
- *   - `onRetry` when a new reconnection interval has been sent from the server
- *   - `onComment` when a comment is encountered in the stream
+ * @param config - Parser configuration. Accepts callbacks (see {@link ParserCallbacks})
+ *   and options like `maxBufferSize` (see {@link ParserConfig}).
  *
- * @returns A new EventSource parser, with `parse` and `reset` methods.
+ * @returns A new EventSource parser, with `feed` and `reset` methods.
  * @public
  */
-export declare function createParser(
-  callbacks: ParserCallbacks,
-): EventSourceParser;
+export declare function createParser(config: ParserConfig): EventSourceParser;
 
@@ -21,3 +16,6 @@ /**
  */
-export declare type ErrorType = "invalid-retry" | "unknown-field";
+export declare type ErrorType =
+  | "invalid-retry"
+  | "unknown-field"
+  | "max-buffer-size-exceeded";
 
@@ -147,2 +145,27 @@ /**
 
+/**
+ * Configuration accepted by {@link createParser}. Extends {@link ParserCallbacks} with
+ * additional options that control parser behavior.
+ *
+ * @public
+ */
+export declare interface ParserConfig extends ParserCallbacks {
+  /**
+   * Maximum number of characters the parser is allowed to buffer across calls to `feed()`.
+   *
+   * Two unbounded surfaces exist in a streaming SSE parser:
+   * - A partial line that has not yet been terminated by `\n`, `\r`, or `\r\n`.
+   * - A multi-line event whose terminating blank line has not yet arrived (each `data:`
+   *   field gets appended to the buffered event).
+   *
+   * When the combined size of these buffers exceeds `maxBufferSize`, the parser emits a
+   * `ParseError` with `type: 'max-buffer-size-exceeded'` to `onError` and becomes
+   * terminated — subsequent calls to `feed()` will throw until `reset()` is called.
+   * This protects against unbounded memory growth from malformed or malicious streams.
+   *
+   * @defaultValue `undefined` (unbounded)
+   */
+  maxBufferSize?: number | undefined;
+}
+
 export {};

dist/index.js

@@ -9,13 +9,17 @@ class ParseError extends Error {
 }
-function createParser(callbacks) {
-  if (typeof callbacks == "function")
+function createParser(config) {
+  if (typeof config == "function")
     throw new TypeError(
-      "`callbacks` must be an object, got a function instead. Did you mean `{onEvent: fn}`?"
+      "`config` must be an object, got a function instead. Did you mean `createParser({onEvent: fn})`?"
     );
-  const { onEvent = noop, onError = noop, onRetry = noop, onComment } = callbacks, pendingFragments = [];
-  let isFirstChunk = !0, id, data = "", dataLines = 0, eventType;
+  const { onEvent = noop, onError = noop, onRetry = noop, onComment, maxBufferSize } = config, pendingFragments = [];
+  let pendingFragmentsLength = 0, isFirstChunk = !0, id, data = "", dataLines = 0, eventType, terminated = !1;
   function feed(chunk) {
+    if (terminated)
+      throw new Error(
+        "Cannot feed parser: it was terminated after exceeding the configured max buffer size. Call `reset()` to resume parsing."
+      );
     if (isFirstChunk && (isFirstChunk = !1, chunk.charCodeAt(0) === 239 && chunk.charCodeAt(1) === 187 && chunk.charCodeAt(2) === 191 && (chunk = chunk.slice(3))), pendingFragments.length === 0) {
       const trailing2 = processLines(chunk);
-      trailing2 !== "" && pendingFragments.push(trailing2);
+      trailing2 !== "" && (pendingFragments.push(trailing2), pendingFragmentsLength = trailing2.length), checkBufferSize();
       return;
@@ -25,3 +29,3 @@ }
 `) === -1 && chunk.indexOf("\r") === -1) {
-      pendingFragments.push(chunk);
+      pendingFragments.push(chunk), pendingFragmentsLength += chunk.length, checkBufferSize();
       return;
@@ -31,6 +35,13 @@ }
     const input = pendingFragments.join("");
-    pendingFragments.length = 0;
+    pendingFragments.length = 0, pendingFragmentsLength = 0;
     const trailing = processLines(input);
-    trailing !== "" && pendingFragments.push(trailing);
+    trailing !== "" && (pendingFragments.push(trailing), pendingFragmentsLength = trailing.length), checkBufferSize();
   }
+  function checkBufferSize() {
+    maxBufferSize !== void 0 && (pendingFragmentsLength + data.length <= maxBufferSize || (terminated = !0, pendingFragments.length = 0, pendingFragmentsLength = 0, id = void 0, data = "", dataLines = 0, eventType = void 0, onError(
+      new ParseError(`Buffered data exceeded max buffer size of ${maxBufferSize} characters`, {
+        type: "max-buffer-size-exceeded"
+      })
+    )));
+  }
   function processLines(chunk) {
@@ -155,3 +166,3 @@ let searchIndex = 0;
     }
-    isFirstChunk = !0, id = void 0, data = "", dataLines = 0, eventType = void 0, pendingFragments.length = 0;
+    isFirstChunk = !0, id = void 0, data = "", dataLines = 0, eventType = void 0, pendingFragments.length = 0, pendingFragmentsLength = 0, terminated = !1;
   }
@@ -158,0 +169,0 @@ return { feed, reset };

dist/index.js.map

@@ -1,1 +0,1 @@
-{"version":3,"file":"index.js","sources":["../src/errors.ts","../src/parse.ts"],"sourcesContent":["/**\n * The type of error that occurred.\n * @public\n */\nexport type ErrorType = 'invalid-retry' | 'unknown-field'\n\n/**\n * Error thrown when encountering an issue during parsing.\n *\n * @public\n */\nexport class ParseError extends Error {\n  /**\n   * The type of error that occurred.\n   */\n  type: ErrorType\n\n  /**\n   * In the case of an unknown field encountered in the stream, this will be the field name.\n   */\n  field?: string | undefined\n\n  /**\n   * In the case of an unknown field encountered in the stream, this will be the value of the field.\n   */\n  value?: string | undefined\n\n  /**\n   * The line that caused the error, if available.\n   */\n  line?: string | undefined\n\n  constructor(\n    message: string,\n    options: {type: ErrorType; field?: string; value?: string; line?: string},\n  ) {\n    super(message)\n    this.name = 'ParseError'\n    this.type = options.type\n    this.field = options.field\n    this.value = options.value\n    this.line = options.line\n  }\n}\n","/**\n * EventSource/Server-Sent Events parser\n * @see https://html.spec.whatwg.org/multipage/server-sent-events.html\n */\nimport {ParseError} from './errors.ts'\nimport type {EventSourceParser, ParserCallbacks} from './types.ts'\n\n// ASCII codes used in the hot parsing paths.\nconst LF = 10\nconst CR = 13\nconst SPACE = 32\n\n// oxlint-disable-next-line no-unused-vars\nfunction noop(_arg: unknown) {\n  // intentional noop\n}\n\n/**\n * Creates a new EventSource parser.\n *\n * @param callbacks - Callbacks to invoke on different parsing events:\n *   - `onEvent` when a new event is parsed\n *   - `onError` when an error occurs\n *   - `onRetry` when a new reconnection interval has been sent from the server\n *   - `onComment` when a comment is encountered in the stream\n *\n * @returns A new EventSource parser, with `parse` and `reset` methods.\n * @public\n */\nexport function createParser(callbacks: ParserCallbacks): EventSourceParser {\n  if (typeof callbacks === 'function') {\n    throw new TypeError(\n      '`callbacks` must be an object, got a function instead. Did you mean `{onEvent: fn}`?',\n    )\n  }\n\n  const {onEvent = noop, onError = noop, onRetry = noop, onComment} = callbacks\n\n  // Trailing bytes from prior `feed()` calls that did not yet form a complete line.\n  // Stored as an array of fragments and only joined when a line terminator arrives.\n  // Concatenating per-feed (`prefix + chunk`) is O(N²) when a single SSE line spans\n  // many chunks (e.g. a large `data:` payload streamed in tiny slices, or an MCP-style\n  // server that emits one giant content block). Buffering as fragments + joining once\n  // makes the same workload linear.\n  const pendingFragments: string[] = []\n\n  let isFirstChunk = true\n  let id: string | undefined\n  let data = ''\n  let dataLines = 0\n  let eventType: string | undefined\n\n  /**\n   * Feeds a chunk of the SSE stream to the parser. Any trailing bytes that do\n   * not yet form a complete line are held back and prepended to the next chunk,\n   * so callers can pass arbitrary slices of the stream without worrying about\n   * line boundaries.\n   *\n   * Per the SSE spec, a UTF-8 BOM (0xEF 0xBB 0xBF) at the start of the very\n   * first chunk is stripped before parsing.\n   *\n   * @see https://html.spec.whatwg.org/multipage/server-sent-events.html#parsing-an-event-stream\n   */\n  function feed(chunk: string) {\n    if (isFirstChunk) {\n      isFirstChunk = false\n      // Match and strip UTF-8 BOM from the start of the stream, if present.\n      // (Per the spec, this is only valid at the very start of the stream)\n      if (\n        chunk.charCodeAt(0) === 0xef &&\n        chunk.charCodeAt(1) === 0xbb &&\n        chunk.charCodeAt(2) === 0xbf\n      ) {\n        chunk = chunk.slice(3)\n      }\n    }\n\n    // Hot path: no buffered prefix from a prior partial line. Hand the chunk\n    // straight to `processLines`, exactly like the original implementation.\n    // Zero new work in the common case (every chunk ends with `\\n\\n`).\n    if (pendingFragments.length === 0) {\n      const trailing = processLines(chunk)\n      if (trailing !== '') pendingFragments.push(trailing)\n      return\n    }\n\n    // We have a buffered prefix. If this chunk also has no terminator, append\n    // to the buffer without concatenating — that's the O(N²) trap we're\n    // avoiding (large single `data:` payload split across many tiny chunks).\n    if (chunk.indexOf('\\n') === -1 && chunk.indexOf('\\r') === -1) {\n      pendingFragments.push(chunk)\n      return\n    }\n\n    // Terminator arrived. Join the accumulated fragments + this chunk once,\n    // process, and buffer any new trailing partial line.\n    pendingFragments.push(chunk)\n    const input = pendingFragments.join('')\n    pendingFragments.length = 0\n    const trailing = processLines(input)\n    if (trailing !== '') pendingFragments.push(trailing)\n  }\n\n  /**\n   * Splits `chunk` into SSE lines and dispatches each to the appropriate handler.\n   * Returns any trailing bytes that did not terminate with a line break, so the\n   * caller can prepend them to the next chunk.\n   *\n   * The SSE spec permits three line terminators: `\\n`, `\\r`, and `\\r\\n`. Real-world\n   * streams almost always use plain `\\n`, so we take a fast path when no `\\r` is\n   * present in the chunk. The slow path is spec-correct but does more work per line.\n   */\n  function processLines(chunk: string): string {\n    let searchIndex = 0\n\n    // Fast path: LF-only chunk (the common case for typical SSE servers).\n    // We can scan forward with a single `indexOf('\\n')` per line and inline\n    // the hot-path branches for `data:` and `event:` without the CR bookkeeping\n    // the slow path needs.\n    if (chunk.indexOf('\\r') === -1) {\n      let lfIndex = chunk.indexOf('\\n', searchIndex)\n      while (lfIndex !== -1) {\n        // Blank line: end-of-event marker. Dispatch the accumulated event (if any)\n        // and reset the buffered fields. This is hoisted out of `parseLine` because\n        // it's the single most common line shape after `data:` lines.\n        if (searchIndex === lfIndex) {\n          if (dataLines > 0) {\n            onEvent({id, event: eventType, data})\n          }\n          id = undefined\n          data = ''\n          dataLines = 0\n          eventType = undefined\n          searchIndex = lfIndex + 1\n          lfIndex = chunk.indexOf('\\n', searchIndex)\n          continue\n        }\n        const firstCharCode = chunk.charCodeAt(searchIndex)\n        if (isDataPrefix(chunk, searchIndex, firstCharCode)) {\n          // `data:` line — append the value to the event's data buffer.\n          // 'data:'.length === 5, 'data: '.length === 6\n          const valueStart =\n            chunk.charCodeAt(searchIndex + 5) === SPACE ? searchIndex + 6 : searchIndex + 5\n          const value = chunk.slice(valueStart, lfIndex)\n          // Fast path within a fast path: if this is the first data line AND the\n          // next char is another LF (i.e. `data:foo\\n\\n`), dispatch immediately\n          // without ever writing to the `data` buffer. This is the shape of a\n          // typical single-line SSE event (ChatGPT-style streams, etc.) and is\n          // hot enough to be worth the duplication.\n          if (dataLines === 0 && chunk.charCodeAt(lfIndex + 1) === LF) {\n            onEvent({id, event: eventType, data: value})\n            id = undefined\n            data = ''\n            eventType = undefined\n            searchIndex = lfIndex + 2\n            lfIndex = chunk.indexOf('\\n', searchIndex)\n            continue\n          }\n          // Multi-line data: concatenate with newline separator per spec.\n          data = dataLines === 0 ? value : `${data}\\n${value}`\n          dataLines++\n        } else if (isEventPrefix(chunk, searchIndex, firstCharCode)) {\n          // `event:` line — set the event type for the next dispatch. Per spec,\n          // an empty value resets `event type` to its default (undefined here).\n          // 'event:'.length === 6, 'event: '.length === 7\n          eventType =\n            chunk.slice(\n              chunk.charCodeAt(searchIndex + 6) === SPACE ? searchIndex + 7 : searchIndex + 6,\n              lfIndex,\n            ) || undefined\n        } else {\n          // Everything else: `id:`, `retry:`, comment lines (`:` prefix), unknown\n          // fields, or malformed lines. These are rarer and go through the full\n          // per-line parser, which handles the SSE field grammar in detail.\n          parseLine(chunk, searchIndex, lfIndex)\n        }\n        searchIndex = lfIndex + 1\n        lfIndex = chunk.indexOf('\\n', searchIndex)\n      }\n      return chunk.slice(searchIndex)\n    }\n\n    // Slow path: the chunk contains at least one `\\r`, so lines may be terminated\n    // by `\\r`, `\\n`, or `\\r\\n`. We locate the next terminator by looking at both\n    // the nearest `\\r` and `\\n` and picking whichever comes first.\n    while (searchIndex < chunk.length) {\n      const crIndex = chunk.indexOf('\\r', searchIndex)\n      const lfIndex = chunk.indexOf('\\n', searchIndex)\n\n      let lineEnd = -1\n      if (crIndex !== -1 && lfIndex !== -1) {\n        lineEnd = crIndex < lfIndex ? crIndex : lfIndex\n      } else if (crIndex !== -1) {\n        // A trailing `\\r` at the very end of the chunk is ambiguous: it could be\n        // a bare-CR terminator, or the first half of a `\\r\\n` whose `\\n` arrives\n        // in the next chunk. Defer until we see more input.\n        if (crIndex === chunk.length - 1) {\n          lineEnd = -1\n        } else {\n          lineEnd = crIndex\n        }\n      } else if (lfIndex !== -1) {\n        lineEnd = lfIndex\n      }\n\n      if (lineEnd === -1) {\n        break\n      }\n\n      parseLine(chunk, searchIndex, lineEnd)\n      searchIndex = lineEnd + 1\n      // If we just consumed a `\\r` and the next char is `\\n`, skip it so the\n      // pair is treated as a single terminator rather than an empty line.\n      if (chunk.charCodeAt(searchIndex - 1) === CR && chunk.charCodeAt(searchIndex) === LF) {\n        searchIndex++\n      }\n    }\n\n    return chunk.slice(searchIndex)\n  }\n\n  function parseLine(chunk: string, start: number, end: number) {\n    if (start === end) {\n      dispatchEvent()\n      return\n    }\n\n    const firstCharCode = chunk.charCodeAt(start)\n\n    if (isDataPrefix(chunk, start, firstCharCode)) {\n      // 'data:'.length === 5, 'data: '.length === 6\n      const valueStart = chunk.charCodeAt(start + 5) === SPACE ? start + 6 : start + 5\n      const value = chunk.slice(valueStart, end)\n      data = dataLines === 0 ? value : `${data}\\n${value}`\n      dataLines++\n      return\n    }\n\n    if (isEventPrefix(chunk, start, firstCharCode)) {\n      // 'event:'.length === 6, 'event: '.length === 7\n      eventType =\n        chunk.slice(chunk.charCodeAt(start + 6) === SPACE ? start + 7 : start + 6, end) || undefined\n      return\n    }\n\n    // Fast path for \"id:\" — 'i' = 105, 'd' = 100, ':' = 58\n    if (\n      firstCharCode === 105 &&\n      chunk.charCodeAt(start + 1) === 100 &&\n      chunk.charCodeAt(start + 2) === 58\n    ) {\n      // 'id:'.length === 3, 'id: '.length === 4\n      const value = chunk.slice(chunk.charCodeAt(start + 3) === SPACE ? start + 4 : start + 3, end)\n      id = value.includes('\\0') ? undefined : value\n      return\n    }\n\n    // Comment line — ':' = 58\n    if (firstCharCode === 58) {\n      if (onComment) {\n        const line = chunk.slice(start, end)\n        // skip ':' (+1), or ': ' (+2) when a space follows\n        onComment(line.slice(chunk.charCodeAt(start + 1) === SPACE ? 2 : 1))\n      }\n      return\n    }\n\n    const line = chunk.slice(start, end)\n    const fieldSeparatorIndex = line.indexOf(':')\n    if (fieldSeparatorIndex === -1) {\n      processField(line, '', line)\n      return\n    }\n\n    const field = line.slice(0, fieldSeparatorIndex)\n    // skip ':' (+1), or ': ' (+2) when a space follows\n    const offset = line.charCodeAt(fieldSeparatorIndex + 1) === SPACE ? 2 : 1\n    const value = line.slice(fieldSeparatorIndex + offset)\n    processField(field, value, line)\n  }\n\n  function processField(field: string, value: string, line: string) {\n    // Field names must be compared literally, with no case folding performed.\n    switch (field) {\n      case 'event':\n        // Set the `event type` buffer to field value\n        eventType = value || undefined\n        break\n      case 'data':\n        data = dataLines === 0 ? value : `${data}\\n${value}`\n        dataLines++\n        break\n      case 'id':\n        // If the field value does not contain U+0000 NULL, then set the `ID` buffer to\n        // the field value. Otherwise, ignore the field.\n        id = value.includes('\\0') ? undefined : value\n        break\n      case 'retry':\n        // If the field value consists of only ASCII digits, then interpret the field value as an\n        // integer in base ten, and set the event stream's reconnection time to that integer.\n        // Otherwise, ignore the field.\n        if (/^\\d+$/.test(value)) {\n          onRetry(parseInt(value, 10))\n        } else {\n          onError(\n            new ParseError(`Invalid \\`retry\\` value: \"${value}\"`, {\n              type: 'invalid-retry',\n              value,\n              line,\n            }),\n          )\n        }\n        break\n      default:\n        // Otherwise, the field is ignored.\n        onError(\n          new ParseError(\n            `Unknown field \"${field.length > 20 ? `${field.slice(0, 20)}…` : field}\"`,\n            {type: 'unknown-field', field, value, line},\n          ),\n        )\n        break\n    }\n  }\n\n  function dispatchEvent() {\n    if (dataLines > 0) {\n      onEvent({\n        id,\n        event: eventType,\n        data,\n      })\n    }\n\n    id = undefined\n    data = ''\n    dataLines = 0\n    eventType = undefined\n  }\n\n  function reset(options: {consume?: boolean} = {}) {\n    if (options.consume && pendingFragments.length > 0) {\n      const incompleteLine = pendingFragments.join('')\n      parseLine(incompleteLine, 0, incompleteLine.length)\n    }\n\n    isFirstChunk = true\n    id = undefined\n    data = ''\n    dataLines = 0\n    eventType = undefined\n    pendingFragments.length = 0\n  }\n\n  return {feed, reset}\n}\n\n/**\n * Checks if `chunk` starts with the literal `data:` at index `i`.\n *\n * Equivalent to `chunk.startsWith('data:', i)`, but benchmarks show this\n * hand-unrolled char-code comparison is ~20% faster on common event types.\n * The caller passes `firstCharCode` (the code at `i`) so it can be reused\n * across prefix checks.\n *\n * ASCII: 'd' = 100, 'a' = 97, 't' = 116, 'a' = 97, ':' = 58\n */\nfunction isDataPrefix(chunk: string, i: number, firstCharCode: number): boolean {\n  return (\n    firstCharCode === 100 &&\n    chunk.charCodeAt(i + 1) === 97 &&\n    chunk.charCodeAt(i + 2) === 116 &&\n    chunk.charCodeAt(i + 3) === 97 &&\n    chunk.charCodeAt(i + 4) === 58\n  )\n}\n\n/**\n * Checks if `chunk` starts with the literal `event:` at index `i`.\n *\n * See {@link isDataPrefix} for why this is hand-unrolled rather than using\n * `String.prototype.startsWith`.\n *\n * ASCII: 'e' = 101, 'v' = 118, 'e' = 101, 'n' = 110, 't' = 116, ':' = 58\n */\nfunction isEventPrefix(chunk: string, i: number, firstCharCode: number): boolean {\n  return (\n    firstCharCode === 101 &&\n    chunk.charCodeAt(i + 1) === 118 &&\n    chunk.charCodeAt(i + 2) === 101 &&\n    chunk.charCodeAt(i + 3) === 110 &&\n    chunk.charCodeAt(i + 4) === 116 &&\n    chunk.charCodeAt(i + 5) === 58\n  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Any trailing bytes that do\n   * not yet form a complete line are held back and prepended to the next chunk,\n   * so callers can pass arbitrary slices of the stream without worrying about\n   * line boundaries.\n   *\n   * Per the SSE spec, a UTF-8 BOM (0xEF 0xBB 0xBF) at the start of the very\n   * first chunk is stripped before parsing.\n   *\n   * @see https://html.spec.whatwg.org/multipage/server-sent-events.html#parsing-an-event-stream\n   */\n  function feed(chunk: string) {\n    if (terminated) {\n      throw new Error(\n        'Cannot feed parser: it was terminated after exceeding the configured max buffer size. 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)\n}\n"],"names":["trailing","value","line"],"mappings":"AAWO,MAAM,mBAAmB,MAAM;AAAA,EAqBpC,YACE,SACA,SACA;AACA,UAAM,OAAO,GACb,KAAK,OAAO,cACZ,KAAK,OAAO,QAAQ,MACpB,KAAK,QAAQ,QAAQ,OACrB,KAAK,QAAQ,QAAQ,OACrB,KAAK,OAAO,QAAQ;AAAA,EACtB;AACF;ACnCA,MAAM,KAAK,IACL,KAAK,IACL,QAAQ;AAGd,SAAS,KAAK,MAAe;AAE7B;AAWO,SAAS,aAAa,QAAyC;AACpE,MAAI,OAAO,UAAW;AACpB,UAAM,IAAI;AAAA,MACR;AAAA,IAAA;AAIJ,QAAM,EAAC,UAAU,MAAM,UAAU,MAAM,UAAU,MAAM,WAAW,cAAA,IAAiB,QAQ7E,mBAA6B,CAAA;AAInC,MAAI,yBAAyB,GAEzB,eAAe,IACf,IACA,OAAO,IACP,YAAY,GACZ,WAIA,aAAa;AAajB,WAAS,KAAK,OAAe;AAC3B,QAAI;AACF,YAAM,IAAI;AAAA,QACR;AAAA,MAAA;AAoBJ,QAhBI,iBACF,eAAe,IAIb,MAAM,WAAW,CAAC,MAAM,OACxB,MAAM,WAAW,CAAC,MAAM,OACxB,MAAM,WAAW,CAAC,MAAM,QAExB,QAAQ,MAAM,MAAM,CAAC,KAOrB,iBAAiB,WAAW,GAAG;AACjC,YAAMA,YAAW,aAAa,KAAK;AAC/BA,oBAAa,OACf,iBAAiB,KAAKA,SAAQ,GAC9B,yBAAyBA,UAAS,SAEpC,gBAAA;AACA;AAAA,IACF;AAKA,QAAI,MAAM,QAAQ;AAAA,CAAI,MAAM,MAAM,MAAM,QAAQ,IAAI,MAAM,IAAI;AAC5D,uBAAiB,KAAK,KAAK,GAC3B,0BAA0B,MAAM,QAChC,gBAAA;AACA;AAAA,IACF;AAIA,qBAAiB,KAAK,KAAK;AAC3B,UAAM,QAAQ,iBAAiB,KAAK,EAAE;AACtC,qBAAiB,SAAS,GAC1B,yBAAyB;AACzB,UAAM,WAAW,aAAa,KAAK;AAC/B,iBAAa,OACf,iBAAiB,KAAK,QAAQ,GAC9B,yBAAyB,SAAS,SAEpC,gBAAA;AAAA,EACF;AAEA,WAAS,kBAAkB;AACrB,sBAAkB,WAClB,yBAAyB,KAAK,UAAU,kBAE5C,aAAa,IACb,iBAAiB,SAAS,GAC1B,yBAAyB,GACzB,KAAK,QACL,OAAO,IACP,YAAY,GACZ,YAAY,QACZ;AAAA,MACE,IAAI,WAAW,6CAA6C,aAAa,eAAe;AAAA,QACtF,MAAM;AAAA,MAAA,CACP;AAAA,IAAA;AAAA,EAEL;AAWA,WAAS,aAAa,OAAuB;AAC3C,QAAI,cAAc;AAMlB,QAAI,MAAM,QAAQ,IAAI,MAAM,IAAI;AAC9B,UAAI,UAAU,MAAM,QAAQ;AAAA,GAAM,WAAW;AAC7C,aAAO,YAAY,MAAI;AAIrB,YAAI,gBAAgB,SAAS;AACvB,sBAAY,KACd,QAAQ,EAAC,IAAI,OAAO,WAAW,KAAA,CAAK,GAEtC,KAAK,QACL,OAAO,IACP,YAAY,GACZ,YAAY,QACZ,cAAc,UAAU,GACxB,UAAU,MAAM,QAAQ;AAAA,GAAM,WAAW;AACzC;AAAA,QACF;AACA,cAAM,gBAAgB,MAAM,WAAW,WAAW;AAClD,YAAI,aAAa,OAAO,aAAa,aAAa,GAAG;AAGnD,gBAAM,aACJ,MAAM,WAAW,cAAc,CAAC,MAAM,QAAQ,cAAc,IAAI,cAAc,GAC1E,QAAQ,MAAM,MAAM,YAAY,OAAO;AAM7C,cAAI,cAAc,KAAK,MAAM,WAAW,UAAU,CAAC,MAAM,IAAI;AAC3D,oBAAQ,EAAC,IAAI,OAAO,WAAW,MAAM,MAAA,CAAM,GAC3C,KAAK,QACL,OAAO,IACP,YAAY,QACZ,cAAc,UAAU,GACxB,UAAU,MAAM,QAAQ;AAAA,GAAM,WAAW;AACzC;AAAA,UACF;AAEA,iBAAO,cAAc,IAAI,QAAQ,GAAG,IAAI;AAAA,EAAK,KAAK,IAClD;AAAA,QACF,MAAW,eAAc,OAAO,aAAa,aAAa,IAIxD,YACE,MAAM;AAAA,UACJ,MAAM,WAAW,cAAc,CAAC,MAAM,QAAQ,cAAc,IAAI,cAAc;AAAA,UAC9E;AAAA,QAAA,KACG,SAKP,UAAU,OAAO,aAAa,OAAO;AAEvC,sBAAc,UAAU,GACxB,UAAU,MAAM,QAAQ;AAAA,GAAM,WAAW;AAAA,MAC3C;AACA,aAAO,MAAM,MAAM,WAAW;AAAA,IAChC;AAKA,WAAO,cAAc,MAAM,UAAQ;AACjC,YAAM,UAAU,MAAM,QAAQ,MAAM,WAAW,GACzC,UAAU,MAAM,QAAQ;AAAA,GAAM,WAAW;AAE/C,UAAI,UAAU;AAgBd,UAfI,YAAY,MAAM,YAAY,KAChC,UAAU,UAAU,UAAU,UAAU,UAC/B,YAAY,KAIjB,YAAY,MAAM,SAAS,IAC7B,UAAU,KAEV,UAAU,UAEH,YAAY,OACrB,UAAU,UAGR,YAAY;AACd;AAGF,gBAAU,OAAO,aAAa,OAAO,GACrC,cAAc,UAAU,GAGpB,MAAM,WAAW,cAAc,CAAC,MAAM,MAAM,MAAM,WAAW,WAAW,MAAM,MAChF;AAAA,IAEJ;AAEA,WAAO,MAAM,MAAM,WAAW;AAAA,EAChC;AAEA,WAAS,UAAU,OAAe,OAAe,KAAa;AAC5D,QAAI,UAAU,KAAK;AACjB,oBAAA;AACA;AAAA,IACF;AAEA,UAAM,gBAAgB,MAAM,WAAW,KAAK;AAE5C,QAAI,aAAa,OAAO,OAAO,aAAa,GAAG;AAE7C,YAAM,aAAa,MAAM,WAAW,QAAQ,CAAC,MAAM,QAAQ,QAAQ,IAAI,QAAQ,GACzEC,SAAQ,MAAM,MAAM,YAAY,GAAG;AACzC,aAAO,cAAc,IAAIA,SAAQ,GAAG,IAAI;AAAA,EAAKA,MAAK,IAClD;AACA;AAAA,IACF;AAEA,QAAI,cAAc,OAAO,OAAO,aAAa,GAAG;AAE9C,kBACE,MAAM,MAAM,MAAM,WAAW,QAAQ,CAAC,MAAM,QAAQ,QAAQ,IAAI,QAAQ,GAAG,GAAG,KAAK;AACrF;AAAA,IACF;AAGA,QACE,kBAAkB,OAClB,MAAM,WAAW,QAAQ,CAAC,MAAM,OAChC,MAAM,WAAW,QAAQ,CAAC,MAAM,IAChC;AAEA,YAAMA,SAAQ,MAAM,MAAM,MAAM,WAAW,QAAQ,CAAC,MAAM,QAAQ,QAAQ,IAAI,QAAQ,GAAG,GAAG;AAC5F,WAAKA,OAAM,SAAS,IAAI,IAAI,SAAYA;AACxC;AAAA,IACF;AAGA,QAAI,kBAAkB,IAAI;AACxB,UAAI,WAAW;AACb,cAAMC,QAAO,MAAM,MAAM,OAAO,GAAG;AAEnC,kBAAUA,MAAK,MAAM,MAAM,WAAW,QAAQ,CAAC,MAAM,QAAQ,IAAI,CAAC,CAAC;AAAA,MACrE;AACA;AAAA,IACF;AAEA,UAAM,OAAO,MAAM,MAAM,OAAO,GAAG,GAC7B,sBAAsB,KAAK,QAAQ,GAAG;AAC5C,QAAI,wBAAwB,IAAI;AAC9B,mBAAa,MAAM,IAAI,IAAI;AAC3B;AAAA,IACF;AAEA,UAAM,QAAQ,KAAK,MAAM,GAAG,mBAAmB,GAEzC,SAAS,KAAK,WAAW,sBAAsB,CAAC,MAAM,QAAQ,IAAI,GAClE,QAAQ,KAAK,MAAM,sBAAsB,MAAM;AACrD,iBAAa,OAAO,OAAO,IAAI;AAAA,EACjC;AAEA,WAAS,aAAa,OAAe,OAAe,MAAc;AAEhE,YAAQ,OAAA;AAAA,MACN,KAAK;AAEH,oBAAY,SAAS;AACrB;AAAA,MACF,KAAK;AACH,eAAO,cAAc,IAAI,QAAQ,GAAG,IAAI;AAAA,EAAK,KAAK,IAClD;AACA;AAAA,MACF,KAAK;AAGH,aAAK,MAAM,SAAS,IAAI,IAAI,SAAY;AACxC;AAAA,MACF,KAAK;AAIC,gBAAQ,KAAK,KAAK,IACpB,QAAQ,SAAS,OAAO,EAAE,CAAC,IAE3B;AAAA,UACE,IAAI,WAAW,6BAA6B,KAAK,KAAK;AAAA,YACpD,MAAM;AAAA,YACN;AAAA,YACA;AAAA,UAAA,CACD;AAAA,QAAA;AAGL;AAAA,MACF;AAEE;AAAA,UACE,IAAI;AAAA,YACF,kBAAkB,MAAM,SAAS,KAAK,GAAG,MAAM,MAAM,GAAG,EAAE,CAAC,WAAM,KAAK;AAAA,YACtE,EAAC,MAAM,iBAAiB,OAAO,OAAO,KAAA;AAAA,UAAI;AAAA,QAC5C;AAEF;AAAA,IAAA;AAAA,EAEN;AAEA,WAAS,gBAAgB;AACnB,gBAAY,KACd,QAAQ;AAAA,MACN;AAAA,MACA,OAAO;AAAA,MACP;AAAA,IAAA,CACD,GAGH,KAAK,QACL,OAAO,IACP,YAAY,GACZ,YAAY;AAAA,EACd;AAEA,WAAS,MAAM,UAA+B,IAAI;AAChD,QAAI,QAAQ,WAAW,iBAAiB,SAAS,GAAG;AAClD,YAAM,iBAAiB,iBAAiB,KAAK,EAAE;AAC/C,gBAAU,gBAAgB,GAAG,eAAe,MAAM;AAAA,IACpD;AAEA,mBAAe,IACf,KAAK,QACL,OAAO,IACP,YAAY,GACZ,YAAY,QACZ,iBAAiB,SAAS,GAC1B,yBAAyB,GACzB,aAAa;AAAA,EACf;AAEA,SAAO,EAAC,MAAM,MAAA;AAChB;AAYA,SAAS,aAAa,OAAe,GAAW,eAAgC;AAC9E,SACE,kBAAkB,OAClB,MAAM,WAAW,IAAI,CAAC,MAAM,MAC5B,MAAM,WAA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dist/stream.cjs

@@ -5,3 +5,3 @@ "use strict";
 class EventSourceParserStream extends TransformStream {
-  constructor({ onError, onRetry, onComment } = {}) {
+  constructor({ onError, onRetry, onComment, maxBufferSize } = {}) {
     let parser;
@@ -15,6 +15,7 @@ super({
           onError(error) {
-            onError === "terminate" ? controller.error(error) : typeof onError == "function" && onError(error);
+            typeof onError == "function" && onError(error), (onError === "terminate" || error.type === "max-buffer-size-exceeded") && controller.error(error);
           },
           onRetry,
-          onComment
+          onComment,
+          maxBufferSize
         });
@@ -21,0 +22,0 @@ },

dist/stream.cjs.map

@@ -1,1 +0,1 @@
-{"version":3,"file":"stream.cjs","sources":["../src/stream.ts"],"sourcesContent":["import {createParser} from './parse.ts'\nimport type {EventSourceMessage, EventSourceParser} from './types.ts'\n\n/**\n * Options for the EventSourceParserStream.\n *\n * @public\n */\nexport interface StreamOptions {\n  /**\n   * Behavior when a parsing error occurs.\n   *\n   * - A custom function can be provided to handle the error.\n   * - `'terminate'` will error the stream and stop parsing.\n   * - Any other value will ignore the error and continue parsing.\n   *\n   * @defaultValue `undefined`\n   */\n  onError?: ('terminate' | ((error: Error) => void)) | undefined\n\n  /**\n   * Callback for when a reconnection interval is sent from the server.\n   *\n   * @param retry - The number of milliseconds to wait before reconnecting.\n   */\n  onRetry?: ((retry: number) => void) | undefined\n\n  /**\n   * Callback for when a comment is encountered in the stream.\n   *\n   * @param comment - The comment encountered in the stream.\n   */\n  onComment?: ((comment: string) => void) | undefined\n}\n\n/**\n * A TransformStream that ingests a stream of strings and produces a stream of `EventSourceMessage`.\n *\n * @example Basic usage\n * ```\n * const eventStream =\n *   response.body\n *     .pipeThrough(new TextDecoderStream())\n *     .pipeThrough(new EventSourceParserStream())\n * ```\n *\n * @example Terminate stream on parsing errors\n * ```\n * const eventStream =\n *  response.body\n *   .pipeThrough(new TextDecoderStream())\n *   .pipeThrough(new EventSourceParserStream({terminateOnError: true}))\n * ```\n *\n * @public\n */\nexport class EventSourceParserStream extends TransformStream<string, EventSourceMessage> {\n  constructor({onError, onRetry, onComment}: StreamOptions = {}) {\n    let parser!: EventSourceParser\n\n    super({\n      start(controller) {\n        parser = createParser({\n          onEvent: (event) => {\n            controller.enqueue(event)\n          },\n          onError(error) {\n            if (onError === 'terminate') {\n              controller.error(error)\n            } else if (typeof onError === 'function') {\n              onError(error)\n            }\n\n            // Ignore by default\n          },\n          onRetry,\n          onComment,\n        })\n      },\n      transform(chunk) {\n        parser.feed(chunk)\n      },\n    })\n  }\n}\n\nexport {type ErrorType, ParseError} from './errors.ts'\nexport type {EventSourceMessage} from './types.ts'\n"],"names":["createParser"],"mappings":";;;AAwDO,MAAM,gCAAgC,gBAA4C;AAAA,EACvF,YAAY,EAAC,SAAS,SAAS,UAAA,IAA4B,CAAA,GAAI;AAC7D,QAAI;AAEJ,UAAM;AAAA,MACJ,MAAM,YAAY;AAChB,iBAASA,MAAAA,aAAa;AAAA,UACpB,SAAS,CAAC,UAAU;AAClB,uBAAW,QAAQ,KAAK;AAAA,UAC1B;AAAA,UACA,QAAQ,OAAO;AACT,wBAAY,cACd,WAAW,MAAM,KAAK,IACb,OAAO,WAAY,cAC5B,QAAQ,KAAK;AAAA,UAIjB;AAAA,UACA;AAAA,UACA;AAAA,QAAA,CACD;AAAA,MACH;AAAA,MACA,UAAU,OAAO;AACf,eAAO,KAAK,KAAK;AAAA,MACnB;AAAA,IAAA,CACD;AAAA,EACH;AACF;;;"}
+{"version":3,"file":"stream.cjs","sources":["../src/stream.ts"],"sourcesContent":["import {createParser} from './parse.ts'\nimport type {EventSourceMessage, EventSourceParser} from './types.ts'\n\n/**\n * Options for the EventSourceParserStream.\n *\n * @public\n */\nexport interface StreamOptions {\n  /**\n   * Behavior when a parsing error occurs.\n   *\n   * - A custom function can be provided to handle the error.\n   * - `'terminate'` will error the stream and stop parsing.\n   * - Any other value will ignore the error and continue parsing.\n   *\n   * @defaultValue `undefined`\n   */\n  onError?: ('terminate' | ((error: Error) => void)) | undefined\n\n  /**\n   * Callback for when a reconnection interval is sent from the server.\n   *\n   * @param retry - The number of milliseconds to wait before reconnecting.\n   */\n  onRetry?: ((retry: number) => void) | undefined\n\n  /**\n   * Callback for when a comment is encountered in the stream.\n   *\n   * @param comment - The comment encountered in the stream.\n   */\n  onComment?: ((comment: string) => void) | undefined\n\n  /**\n   * Maximum number of characters the parser is allowed to buffer across calls to `feed()`.\n   * See {@link ParserConfig.maxBufferSize} for details.\n   *\n   * When the limit is exceeded, the stream is always errored (regardless of the `onError`\n   * setting) since the underlying parser is unrecoverable without a `reset()`.\n   *\n   * @defaultValue `undefined` (unbounded)\n   */\n  maxBufferSize?: number | undefined\n}\n\n/**\n * A TransformStream that ingests a stream of strings and produces a stream of `EventSourceMessage`.\n *\n * @example Basic usage\n * ```\n * const eventStream =\n *   response.body\n *     .pipeThrough(new TextDecoderStream())\n *     .pipeThrough(new EventSourceParserStream())\n * ```\n *\n * @example Terminate stream on parsing errors\n * ```\n * const eventStream =\n *  response.body\n *   .pipeThrough(new TextDecoderStream())\n *   .pipeThrough(new EventSourceParserStream({onError: 'terminate'}))\n * ```\n *\n * @public\n */\nexport class EventSourceParserStream extends TransformStream<string, EventSourceMessage> {\n  constructor({onError, onRetry, onComment, maxBufferSize}: StreamOptions = {}) {\n    let parser!: EventSourceParser\n\n    super({\n      start(controller) {\n        parser = createParser({\n          onEvent: (event) => {\n            controller.enqueue(event)\n          },\n          onError(error) {\n            if (typeof onError === 'function') {\n              onError(error)\n            }\n\n            // `max-buffer-size-exceeded` is fatal — the parser is unusable until\n            // `reset()`, which the stream wrapper has no way to call. Always\n            // terminate the stream in that case so consumers see the meaningful\n            // `ParseError` instead of an opaque \"cannot feed terminated parser\"\n            // throw from the next chunk.\n            if (onError === 'terminate' || error.type === 'max-buffer-size-exceeded') {\n              controller.error(error)\n            }\n\n            // Ignore by default\n          },\n          onRetry,\n          onComment,\n          maxBufferSize,\n        })\n      },\n      transform(chunk) {\n        parser.feed(chunk)\n      },\n    })\n  }\n}\n\nexport {type ErrorType, ParseError} from './errors.ts'\nexport type {EventSourceMessage} from './types.ts'\n"],"names":["createParser"],"mappings":";;;AAmEO,MAAM,gCAAgC,gBAA4C;AAAA,EACvF,YAAY,EAAC,SAAS,SAAS,WAAW,cAAA,IAAgC,IAAI;AAC5E,QAAI;AAEJ,UAAM;AAAA,MACJ,MAAM,YAAY;AAChB,iBAASA,MAAAA,aAAa;AAAA,UACpB,SAAS,CAAC,UAAU;AAClB,uBAAW,QAAQ,KAAK;AAAA,UAC1B;AAAA,UACA,QAAQ,OAAO;AACT,mBAAO,WAAY,cACrB,QAAQ,KAAK,IAQX,YAAY,eAAe,MAAM,SAAS,+BAC5C,WAAW,MAAM,KAAK;AAAA,UAI1B;AAAA,UACA;AAAA,UACA;AAAA,UACA;AAAA,QAAA,CACD;AAAA,MACH;AAAA,MACA,UAAU,OAAO;AACf,eAAO,KAAK,KAAK;AAAA,MACnB;AAAA,IAAA,CACD;AAAA,EACH;AACF;;;"}

dist/stream.d.cts

@@ -5,3 +5,6 @@ /**
  */
-export declare type ErrorType = "invalid-retry" | "unknown-field";
+export declare type ErrorType =
+  | "invalid-retry"
+  | "unknown-field"
+  | "max-buffer-size-exceeded";
 
@@ -47,3 +50,3 @@ /**
  *   .pipeThrough(new TextDecoderStream())
- *   .pipeThrough(new EventSourceParserStream({terminateOnError: true}))
+ *   .pipeThrough(new EventSourceParserStream({onError: 'terminate'}))
  * ```
@@ -57,3 +60,3 @@ *
 > {
-  constructor({ onError, onRetry, onComment }?: StreamOptions);
+  constructor({ onError, onRetry, onComment, maxBufferSize }?: StreamOptions);
 }
@@ -122,4 +125,14 @@
   onComment?: ((comment: string) => void) | undefined;
+  /**
+   * Maximum number of characters the parser is allowed to buffer across calls to `feed()`.
+   * See {@link ParserConfig.maxBufferSize} for details.
+   *
+   * When the limit is exceeded, the stream is always errored (regardless of the `onError`
+   * setting) since the underlying parser is unrecoverable without a `reset()`.
+   *
+   * @defaultValue `undefined` (unbounded)
+   */
+  maxBufferSize?: number | undefined;
 }
 
 export {};

dist/stream.d.ts

@@ -5,3 +5,6 @@ /**
  */
-export declare type ErrorType = "invalid-retry" | "unknown-field";
+export declare type ErrorType =
+  | "invalid-retry"
+  | "unknown-field"
+  | "max-buffer-size-exceeded";
 
@@ -47,3 +50,3 @@ /**
  *   .pipeThrough(new TextDecoderStream())
- *   .pipeThrough(new EventSourceParserStream({terminateOnError: true}))
+ *   .pipeThrough(new EventSourceParserStream({onError: 'terminate'}))
  * ```
@@ -57,3 +60,3 @@ *
 > {
-  constructor({ onError, onRetry, onComment }?: StreamOptions);
+  constructor({ onError, onRetry, onComment, maxBufferSize }?: StreamOptions);
 }
@@ -122,4 +125,14 @@
   onComment?: ((comment: string) => void) | undefined;
+  /**
+   * Maximum number of characters the parser is allowed to buffer across calls to `feed()`.
+   * See {@link ParserConfig.maxBufferSize} for details.
+   *
+   * When the limit is exceeded, the stream is always errored (regardless of the `onError`
+   * setting) since the underlying parser is unrecoverable without a `reset()`.
+   *
+   * @defaultValue `undefined` (unbounded)
+   */
+  maxBufferSize?: number | undefined;
 }
 
 export {};

dist/stream.js

 import { createParser } from "./index.js";
 import { ParseError } from "./index.js";
 class EventSourceParserStream extends TransformStream {
-  constructor({ onError, onRetry, onComment } = {}) {
+  constructor({ onError, onRetry, onComment, maxBufferSize } = {}) {
     let parser;
@@ -13,6 +13,7 @@ super({
           onError(error) {
-            onError === "terminate" ? controller.error(error) : typeof onError == "function" && onError(error);
+            typeof onError == "function" && onError(error), (onError === "terminate" || error.type === "max-buffer-size-exceeded") && controller.error(error);
           },
           onRetry,
-          onComment
+          onComment,
+          maxBufferSize
         });
@@ -19,0 +20,0 @@ },

dist/stream.js.map

@@ -1,1 +0,1 @@
-{"version":3,"file":"stream.js","sources":["../src/stream.ts"],"sourcesContent":["import {createParser} from './parse.ts'\nimport type {EventSourceMessage, EventSourceParser} from './types.ts'\n\n/**\n * Options for the EventSourceParserStream.\n *\n * @public\n */\nexport interface StreamOptions {\n  /**\n   * Behavior when a parsing error occurs.\n   *\n   * - A custom function can be provided to handle the error.\n   * - `'terminate'` will error the stream and stop parsing.\n   * - Any other value will ignore the error and continue parsing.\n   *\n   * @defaultValue `undefined`\n   */\n  onError?: ('terminate' | ((error: Error) => void)) | undefined\n\n  /**\n   * Callback for when a reconnection interval is sent from the server.\n   *\n   * @param retry - The number of milliseconds to wait before reconnecting.\n   */\n  onRetry?: ((retry: number) => void) | undefined\n\n  /**\n   * Callback for when a comment is encountered in the stream.\n   *\n   * @param comment - The comment encountered in the stream.\n   */\n  onComment?: ((comment: string) => void) | undefined\n}\n\n/**\n * A TransformStream that ingests a stream of strings and produces a stream of `EventSourceMessage`.\n *\n * @example Basic usage\n * ```\n * const eventStream =\n *   response.body\n *     .pipeThrough(new TextDecoderStream())\n *     .pipeThrough(new EventSourceParserStream())\n * ```\n *\n * @example Terminate stream on parsing errors\n * ```\n * const eventStream =\n *  response.body\n *   .pipeThrough(new TextDecoderStream())\n *   .pipeThrough(new EventSourceParserStream({terminateOnError: true}))\n * ```\n *\n * @public\n */\nexport class EventSourceParserStream extends TransformStream<string, EventSourceMessage> {\n  constructor({onError, onRetry, onComment}: StreamOptions = {}) {\n    let parser!: EventSourceParser\n\n    super({\n      start(controller) {\n        parser = createParser({\n          onEvent: (event) => {\n            controller.enqueue(event)\n          },\n          onError(error) {\n            if (onError === 'terminate') {\n              controller.error(error)\n            } else if (typeof onError === 'function') {\n              onError(error)\n            }\n\n            // Ignore by default\n          },\n          onRetry,\n          onComment,\n        })\n      },\n      transform(chunk) {\n        parser.feed(chunk)\n      },\n    })\n  }\n}\n\nexport {type ErrorType, ParseError} from './errors.ts'\nexport type {EventSourceMessage} from './types.ts'\n"],"names":[],"mappings":";;AAwDO,MAAM,gCAAgC,gBAA4C;AAAA,EACvF,YAAY,EAAC,SAAS,SAAS,UAAA,IAA4B,CAAA,GAAI;AAC7D,QAAI;AAEJ,UAAM;AAAA,MACJ,MAAM,YAAY;AAChB,iBAAS,aAAa;AAAA,UACpB,SAAS,CAAC,UAAU;AAClB,uBAAW,QAAQ,KAAK;AAAA,UAC1B;AAAA,UACA,QAAQ,OAAO;AACT,wBAAY,cACd,WAAW,MAAM,KAAK,IACb,OAAO,WAAY,cAC5B,QAAQ,KAAK;AAAA,UAIjB;AAAA,UACA;AAAA,UACA;AAAA,QAAA,CACD;AAAA,MACH;AAAA,MACA,UAAU,OAAO;AACf,eAAO,KAAK,KAAK;AAAA,MACnB;AAAA,IAAA,CACD;AAAA,EACH;AACF;"}
+{"version":3,"file":"stream.js","sources":["../src/stream.ts"],"sourcesContent":["import {createParser} from './parse.ts'\nimport type {EventSourceMessage, EventSourceParser} from './types.ts'\n\n/**\n * Options for the EventSourceParserStream.\n *\n * @public\n */\nexport interface StreamOptions {\n  /**\n   * Behavior when a parsing error occurs.\n   *\n   * - A custom function can be provided to handle the error.\n   * - `'terminate'` will error the stream and stop parsing.\n   * - Any other value will ignore the error and continue parsing.\n   *\n   * @defaultValue `undefined`\n   */\n  onError?: ('terminate' | ((error: Error) => void)) | undefined\n\n  /**\n   * Callback for when a reconnection interval is sent from the server.\n   *\n   * @param retry - The number of milliseconds to wait before reconnecting.\n   */\n  onRetry?: ((retry: number) => void) | undefined\n\n  /**\n   * Callback for when a comment is encountered in the stream.\n   *\n   * @param comment - The comment encountered in the stream.\n   */\n  onComment?: ((comment: string) => void) | undefined\n\n  /**\n   * Maximum number of characters the parser is allowed to buffer across calls to `feed()`.\n   * See {@link ParserConfig.maxBufferSize} for details.\n   *\n   * When the limit is exceeded, the stream is always errored (regardless of the `onError`\n   * setting) since the underlying parser is unrecoverable without a `reset()`.\n   *\n   * @defaultValue `undefined` (unbounded)\n   */\n  maxBufferSize?: number | undefined\n}\n\n/**\n * A TransformStream that ingests a stream of strings and produces a stream of `EventSourceMessage`.\n *\n * @example Basic usage\n * ```\n * const eventStream =\n *   response.body\n *     .pipeThrough(new TextDecoderStream())\n *     .pipeThrough(new EventSourceParserStream())\n * ```\n *\n * @example Terminate stream on parsing errors\n * ```\n * const eventStream =\n *  response.body\n *   .pipeThrough(new TextDecoderStream())\n *   .pipeThrough(new EventSourceParserStream({onError: 'terminate'}))\n * ```\n *\n * @public\n */\nexport class EventSourceParserStream extends TransformStream<string, EventSourceMessage> {\n  constructor({onError, onRetry, onComment, maxBufferSize}: StreamOptions = {}) {\n    let parser!: EventSourceParser\n\n    super({\n      start(controller) {\n        parser = createParser({\n          onEvent: (event) => {\n            controller.enqueue(event)\n          },\n          onError(error) {\n            if (typeof onError === 'function') {\n              onError(error)\n            }\n\n            // `max-buffer-size-exceeded` is fatal — the parser is unusable until\n            // `reset()`, which the stream wrapper has no way to call. Always\n            // terminate the stream in that case so consumers see the meaningful\n            // `ParseError` instead of an opaque \"cannot feed terminated parser\"\n            // throw from the next chunk.\n            if (onError === 'terminate' || error.type === 'max-buffer-size-exceeded') {\n              controller.error(error)\n            }\n\n            // Ignore by default\n          },\n          onRetry,\n          onComment,\n          maxBufferSize,\n        })\n      },\n      transform(chunk) {\n        parser.feed(chunk)\n      },\n    })\n  }\n}\n\nexport {type ErrorType, ParseError} from './errors.ts'\nexport type {EventSourceMessage} from './types.ts'\n"],"names":[],"mappings":";;AAmEO,MAAM,gCAAgC,gBAA4C;AAAA,EACvF,YAAY,EAAC,SAAS,SAAS,WAAW,cAAA,IAAgC,IAAI;AAC5E,QAAI;AAEJ,UAAM;AAAA,MACJ,MAAM,YAAY;AAChB,iBAAS,aAAa;AAAA,UACpB,SAAS,CAAC,UAAU;AAClB,uBAAW,QAAQ,KAAK;AAAA,UAC1B;AAAA,UACA,QAAQ,OAAO;AACT,mBAAO,WAAY,cACrB,QAAQ,KAAK,IAQX,YAAY,eAAe,MAAM,SAAS,+BAC5C,WAAW,MAAM,KAAK;AAAA,UAI1B;AAAA,UACA;AAAA,UACA;AAAA,UACA;AAAA,QAAA,CACD;AAAA,MACH;AAAA,MACA,UAAU,OAAO;AACf,eAAO,KAAK,KAAK;AAAA,MACnB;AAAA,IAAA,CACD;AAAA,EACH;AACF;"}

package.json

 {
   "name": "eventsource-parser",
-  "version": "3.0.8",
+  "version": "3.1.0",
   "description": "Streaming, source-agnostic EventSource/Server-Sent Events parser",
@@ -66,17 +66,17 @@ "keywords": [
   "devDependencies": {
-    "@sanity/pkg-utils": "^10.4.15",
+    "@sanity/pkg-utils": "^10.4.18",
     "@sanity/semantic-release-preset": "^6.0.0",
     "@sanity/tsconfig": "^2.1.0",
     "@types/node": "^20.19.0",
-    "eventsource-encoder": "^1.0.1",
-    "knip": "^6.4.1",
+    "eventsource-encoder": "^1.0.2",
+    "knip": "^6.7.0",
     "mitata": "^1.0.34",
-    "oxfmt": "^0.45.0",
-    "oxlint": "^1.60.0",
+    "oxfmt": "^0.47.0",
+    "oxlint": "^1.62.0",
     "rimraf": "^6.1.3",
     "rollup-plugin-visualizer": "^6.0.3",
     "semantic-release": "^25.0.3",
-    "terser": "^5.46.1",
+    "terser": "^5.46.2",
     "typescript": "^5.9.3",
-    "vitest": "^4.1.4"
+    "vitest": "^4.1.5"
   },
@@ -83,0 +83,0 @@ "browserslist": [

README.md

@@ -112,2 +112,24 @@ # eventsource-parser
 
+### Limiting buffered memory (`maxBufferSize`)
+
+By default the parser buffers data indefinitely until a server completes an event. A server (or proxy) that never terminates a line, or that keeps appending `data:` lines without ever sending a blank line to dispatch the event, can therefore grow the parser's buffers without bound.
+
+Pass a `maxBufferSize` (in characters) to `createParser` to cap this. If the combined size of the pending line buffer and the in-progress event's data buffer exceeds the limit, the parser emits a `ParseError` with `type: 'max-buffer-size-exceeded'` and becomes terminated: subsequent calls to `feed()` will throw until `reset()` is called.
+
+```ts
+const parser = createParser({
+  maxBufferSize: 1024 * 1024, // 1 MB
+  onEvent(event) {
+    // …
+  },
+  onError(error) {
+    if (error.type === 'max-buffer-size-exceeded') {
+      // Stream peer is misbehaving — typically you'd close the connection.
+    }
+  },
+})
+```
+
+The same option is available on the [stream variant](#stream-usage); the stream is always errored when this limit is exceeded, regardless of the `onError` setting (since the underlying parser is unrecoverable without a `reset()`).
+
 ## Stream usage
@@ -123,2 +145,11 @@
 
+The stream constructor accepts a subset of the `createParser` options (`onComment`, `onRetry`, `maxBufferSize`) plus an `onError` that can either be a function or set to `'terminate'` to error the stream on parse errors. Events are delivered through the stream itself rather than via an `onEvent` callback:
+
+```ts
+new EventSourceParserStream({
+  maxBufferSize: 1024 * 1024,
+  onError: 'terminate',
+})
+```
+
 Note that the TransformStream is exposed under a separate export (`eventsource-parser/stream`), in order to maximize compatibility with environments that do not have the `TransformStream` constructor available.
@@ -125,0 +156,0 @@

src/errors.ts

@@ -5,3 +5,3 @@ /**
  */
-export type ErrorType = 'invalid-retry' | 'unknown-field'
+export type ErrorType = 'invalid-retry' | 'unknown-field' | 'max-buffer-size-exceeded'
 
@@ -8,0 +8,0 @@ /**

src/index.ts

 export {type ErrorType, ParseError} from './errors.ts'
 export {createParser} from './parse.ts'
-export type {EventSourceMessage, EventSourceParser, ParserCallbacks} from './types.ts'
+export type {
+  EventSourceMessage,
+  EventSourceParser,
+  ParserCallbacks,
+  ParserConfig,
+} from './types.ts'

src/parse.ts

@@ -6,3 +6,3 @@ /**
 import {ParseError} from './errors.ts'
-import type {EventSourceParser, ParserCallbacks} from './types.ts'
+import type {EventSourceParser, ParserConfig} from './types.ts'
 
@@ -22,19 +22,16 @@ // ASCII codes used in the hot parsing paths.
  *
- * @param callbacks - Callbacks to invoke on different parsing events:
- *   - `onEvent` when a new event is parsed
- *   - `onError` when an error occurs
- *   - `onRetry` when a new reconnection interval has been sent from the server
- *   - `onComment` when a comment is encountered in the stream
+ * @param config - Parser configuration. Accepts callbacks (see {@link ParserCallbacks})
+ *   and options like `maxBufferSize` (see {@link ParserConfig}).
  *
- * @returns A new EventSource parser, with `parse` and `reset` methods.
+ * @returns A new EventSource parser, with `feed` and `reset` methods.
  * @public
  */
-export function createParser(callbacks: ParserCallbacks): EventSourceParser {
-  if (typeof callbacks === 'function') {
+export function createParser(config: ParserConfig): EventSourceParser {
+  if (typeof config === 'function') {
     throw new TypeError(
-      '`callbacks` must be an object, got a function instead. Did you mean `{onEvent: fn}`?',
+      '`config` must be an object, got a function instead. Did you mean `createParser({onEvent: fn})`?',
     )
   }
 
-  const {onEvent = noop, onError = noop, onRetry = noop, onComment} = callbacks
+  const {onEvent = noop, onError = noop, onRetry = noop, onComment, maxBufferSize} = config
 
@@ -49,2 +46,6 @@ // Trailing bytes from prior `feed()` calls that did not yet form a complete line.
 
+  // Running total of `pendingFragments` lengths, kept in sync with the array so the
+  // `maxBufferSize` check doesn't have to walk the fragment list on every feed.
+  let pendingFragmentsLength = 0
+
   let isFirstChunk = true
@@ -56,2 +57,6 @@ let id: string | undefined
 
+  // Set after a `maxBufferSize` overflow. Once tripped, `feed()` throws until
+  // `reset()` is called — see the comment on `maxBufferSize` in `ParserConfig`.
+  let terminated = false
+
   /**
@@ -69,2 +74,8 @@ * Feeds a chunk of the SSE stream to the parser. Any trailing bytes that do
   function feed(chunk: string) {
+    if (terminated) {
+      throw new Error(
+        'Cannot feed parser: it was terminated after exceeding the configured max buffer size. Call `reset()` to resume parsing.',
+      )
+    }
+
     if (isFirstChunk) {
@@ -88,3 +99,7 @@ isFirstChunk = false
       const trailing = processLines(chunk)
-      if (trailing !== '') pendingFragments.push(trailing)
+      if (trailing !== '') {
+        pendingFragments.push(trailing)
+        pendingFragmentsLength = trailing.length
+      }
+      checkBufferSize()
       return
@@ -98,2 +113,4 @@ }
       pendingFragments.push(chunk)
+      pendingFragmentsLength += chunk.length
+      checkBufferSize()
       return
@@ -107,6 +124,29 @@ }
     pendingFragments.length = 0
+    pendingFragmentsLength = 0
     const trailing = processLines(input)
-    if (trailing !== '') pendingFragments.push(trailing)
+    if (trailing !== '') {
+      pendingFragments.push(trailing)
+      pendingFragmentsLength = trailing.length
+    }
+    checkBufferSize()
   }
 
+  function checkBufferSize() {
+    if (maxBufferSize === undefined) return
+    if (pendingFragmentsLength + data.length <= maxBufferSize) return
+
+    terminated = true
+    pendingFragments.length = 0
+    pendingFragmentsLength = 0
+    id = undefined
+    data = ''
+    dataLines = 0
+    eventType = undefined
+    onError(
+      new ParseError(`Buffered data exceeded max buffer size of ${maxBufferSize} characters`, {
+        type: 'max-buffer-size-exceeded',
+      }),
+    )
+  }
+
   /**
@@ -361,2 +401,4 @@ * Splits `chunk` into SSE lines and dispatches each to the appropriate handler.
     pendingFragments.length = 0
+    pendingFragmentsLength = 0
+    terminated = false
   }
@@ -363,0 +405,0 @@

src/stream.ts

@@ -34,2 +34,13 @@ import {createParser} from './parse.ts'
   onComment?: ((comment: string) => void) | undefined
+
+  /**
+   * Maximum number of characters the parser is allowed to buffer across calls to `feed()`.
+   * See {@link ParserConfig.maxBufferSize} for details.
+   *
+   * When the limit is exceeded, the stream is always errored (regardless of the `onError`
+   * setting) since the underlying parser is unrecoverable without a `reset()`.
+   *
+   * @defaultValue `undefined` (unbounded)
+   */
+  maxBufferSize?: number | undefined
 }
@@ -53,3 +64,3 @@
  *   .pipeThrough(new TextDecoderStream())
- *   .pipeThrough(new EventSourceParserStream({terminateOnError: true}))
+ *   .pipeThrough(new EventSourceParserStream({onError: 'terminate'}))
  * ```
@@ -60,3 +71,3 @@ *
 export class EventSourceParserStream extends TransformStream<string, EventSourceMessage> {
-  constructor({onError, onRetry, onComment}: StreamOptions = {}) {
+  constructor({onError, onRetry, onComment, maxBufferSize}: StreamOptions = {}) {
     let parser!: EventSourceParser
@@ -71,8 +82,15 @@
           onError(error) {
-            if (onError === 'terminate') {
-              controller.error(error)
-            } else if (typeof onError === 'function') {
+            if (typeof onError === 'function') {
               onError(error)
             }
 
+            // `max-buffer-size-exceeded` is fatal — the parser is unusable until
+            // `reset()`, which the stream wrapper has no way to call. Always
+            // terminate the stream in that case so consumers see the meaningful
+            // `ParseError` instead of an opaque "cannot feed terminated parser"
+            // throw from the next chunk.
+            if (onError === 'terminate' || error.type === 'max-buffer-size-exceeded') {
+              controller.error(error)
+            }
+
             // Ignore by default
@@ -82,2 +100,3 @@ },
           onComment,
+          maxBufferSize,
         })
@@ -84,0 +103,0 @@ },

src/types.ts

@@ -98,1 +98,26 @@ import type {ParseError} from './errors.ts'
 }
+
+/**
+ * Configuration accepted by {@link createParser}. Extends {@link ParserCallbacks} with
+ * additional options that control parser behavior.
+ *
+ * @public
+ */
+export interface ParserConfig extends ParserCallbacks {
+  /**
+   * Maximum number of characters the parser is allowed to buffer across calls to `feed()`.
+   *
+   * Two unbounded surfaces exist in a streaming SSE parser:
+   * - A partial line that has not yet been terminated by `\n`, `\r`, or `\r\n`.
+   * - A multi-line event whose terminating blank line has not yet arrived (each `data:`
+   *   field gets appended to the buffered event).
+   *
+   * When the combined size of these buffers exceeds `maxBufferSize`, the parser emits a
+   * `ParseError` with `type: 'max-buffer-size-exceeded'` to `onError` and becomes
+   * terminated — subsequent calls to `feed()` will throw until `reset()` is called.
+   * This protects against unbounded memory growth from malformed or malicious streams.
+   *
+   * @defaultValue `undefined` (unbounded)
+   */
+  maxBufferSize?: number | undefined
+}

New alerts

Long strings

Supply chain risk

Contains long string literals, which may be a sign of obfuscated or packed code.

Found 1 instance in 1 package

URL strings

Supply chain risk

Package contains fragments of external URLs or IP addresses, which the package may be accessing at runtime.

Found 1 instance in 1 package

Improved metrics

Total package byte prevSize

123218

13.91%

Lines of code

1362

11.64%

Number of lines in readme file

158

24.41%

Worsened metrics

Number of low supply chain risk alerts

2

Infinity%

No dependency changes