Function isValidEncName

xml/_common.ts:127–154

* Validates an EncName per XML 1.0 §4.3.3. * EncName ::= [A-Za-z] ([A-Za-z0-9._] | '-')* * * @returns true if valid, false otherwise

(encoding: string)

 * @returns true if valid, false otherwise
 */
function isValidEncName(encoding: string): boolean {
  if (encoding.length === 0) {
    return false;
  }
  // First character must be a letter
  const first = encoding.charCodeAt(0);
  if (
    !(first >= 0x41 && first <= 0x5A) && // A-Z
    !(first >= 0x61 && first <= 0x7A) // a-z
  ) {
    return false;
  }
  // Rest can be letter, digit, '.', '_', '-'
  for (let i = 1; i < encoding.length; i++) {
    const code = encoding.charCodeAt(i);
    if (
      !(code >= 0x41 && code <= 0x5A) && // A-Z
      !(code >= 0x61 && code <= 0x7A) && // a-z
      !(code >= 0x30 && code <= 0x39) && // 0-9
      code !== 0x2E && // .
      code !== 0x5F && // _
      code !== 0x2D // -
    ) {
      return false;
    }
  }
  return true;
}

/**
 * Validates and parses an XML declaration content string.