class ParseError extends Error {
  constructor(message, options) {
    super(message), this.name = "ParseError", this.type = options.type, this.field = options.field, this.value = options.value, this.line = options.line;
  }
}
function noop(_arg) {
}
function createParser(callbacks) {
  if (typeof callbacks == "function")
    throw new TypeError(
      "`callbacks` must be an object, got a function instead. Did you mean `{onEvent: fn}`?"
    );
  const { onEvent = noop, onError = noop, onRetry = noop, onComment } = callbacks;
  let incompleteLine = "", isFirstChunk = true, id, data = "", eventType = "";
  function feed(newChunk) {
    const chunk = isFirstChunk ? newChunk.replace(/^\xEF\xBB\xBF/, "") : newChunk, [complete, incomplete] = splitLines(`${incompleteLine}${chunk}`);
    for (const line of complete)
      parseLine(line);
    incompleteLine = incomplete, isFirstChunk = false;
  }
  function parseLine(line) {
    if (line === "") {
      dispatchEvent();
      return;
    }
    if (line.startsWith(":")) {
      onComment && onComment(line.slice(line.startsWith(": ") ? 2 : 1));
      return;
    }
    const fieldSeparatorIndex = line.indexOf(":");
    if (fieldSeparatorIndex !== -1) {
      const field = line.slice(0, fieldSeparatorIndex), offset = line[fieldSeparatorIndex + 1] === " " ? 2 : 1, value = line.slice(fieldSeparatorIndex + offset);
      processField(field, value, line);
      return;
    }
    processField(line, "", line);
  }
  function processField(field, value, line) {
    switch (field) {
      case "event":
        eventType = value;
        break;
      case "data":
        data = `${data}${value}
`;
        break;
      case "id":
        id = value.includes("\0") ? void 0 : value;
        break;
      case "retry":
        /^\d+$/.test(value) ? onRetry(parseInt(value, 10)) : onError(
          new ParseError(`Invalid \`retry\` value: "${value}"`, {
            type: "invalid-retry",
            value,
            line
          })
        );
        break;
      default:
        onError(
          new ParseError(
            `Unknown field "${field.length > 20 ? `${field.slice(0, 20)}…` : field}"`,
            { type: "unknown-field", field, value, line }
          )
        );
        break;
    }
  }
  function dispatchEvent() {
    data.length > 0 && onEvent({
      id,
      event: eventType || void 0,
      // If the data buffer's last character is a U+000A LINE FEED (LF) character,
      // then remove the last character from the data buffer.
      data: data.endsWith(`
`) ? data.slice(0, -1) : data
    }), id = void 0, data = "", eventType = "";
  }
  function reset(options = {}) {
    incompleteLine && options.consume && parseLine(incompleteLine), isFirstChunk = true, id = void 0, data = "", eventType = "", incompleteLine = "";
  }
  return { feed, reset };
}
function splitLines(chunk) {
  const lines = [];
  let incompleteLine = "", searchIndex = 0;
  for (; searchIndex < chunk.length; ) {
    const crIndex = chunk.indexOf("\r", searchIndex), lfIndex = chunk.indexOf(`
`, searchIndex);
    let lineEnd = -1;
    if (crIndex !== -1 && lfIndex !== -1 ? lineEnd = Math.min(crIndex, lfIndex) : crIndex !== -1 ? crIndex === chunk.length - 1 ? lineEnd = -1 : lineEnd = crIndex : lfIndex !== -1 && (lineEnd = lfIndex), lineEnd === -1) {
      incompleteLine = chunk.slice(searchIndex);
      break;
    } else {
      const line = chunk.slice(searchIndex, lineEnd);
      lines.push(line), searchIndex = lineEnd + 1, chunk[searchIndex - 1] === "\r" && chunk[searchIndex] === `
` && searchIndex++;
    }
  }
  return [lines, incompleteLine];
}
export {
  ParseError,
  createParser
};
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