Function readCodePoint

packages/babel-helper-string-parser/src/index.ts:406–450

(
  input: string,
  pos: number,
  lineStart: number,
  curLine: number,
  throwOnInvalid: boolean,
  errors: CodePointErrorHandlers,
)

};

export function readCodePoint(
  input: string,
  pos: number,
  lineStart: number,
  curLine: number,
  throwOnInvalid: boolean,
  errors: CodePointErrorHandlers,
) {
  const ch = input.charCodeAt(pos);
  let code;

  if (ch === charCodes.leftCurlyBrace) {
    ++pos;
    ({ code, pos } = readHexChar(
      input,
      pos,
      lineStart,
      curLine,
      input.indexOf("}", pos) - pos,
      true,
      throwOnInvalid,
      errors,
    ));
    ++pos;
    if (code !== null && code > 0x10ffff) {
      if (throwOnInvalid) {
        errors.invalidCodePoint(pos, lineStart, curLine);
      } else {
        return { code: null, pos };
      }
    }
  } else {
    ({ code, pos } = readHexChar(
      input,
      pos,
      lineStart,
      curLine,
      4,
      false,
      throwOnInvalid,
      errors,
    ));
  }
  return { code, pos };
}