sverweij/state-machine-cat

/*
 * In the XML spec we read: https://www.w3.org/TR/xml/#NT-Name:
 *
 * NameStartChar ::= ":" | [A-Z] | "_" | [a-z] | [#xC0-#xD6] | [#xD8-#xF6] | [#xF8-#x2FF] | [#x370-#x37D] |
 *                   [#x37F-#x1FFF] | [#x200C-#x200D] | [#x2070-#x218F] | [#x2C00-#x2FEF] | [#x3001-#xD7FF] |
 *                   [#xF900-#xFDCF] | [#xFDF0-#xFFFD] | [#x10000-#xEFFFF]
 * NameChar      ::= NameStartChar | "-" | "." | [0-9] | #xB7 | [#x0300-#x036F] | [#x203F-#x2040]
 * Name          ::= NameStartChar (NameChar)*
 *
 * This means that these characters are forbidden for NameStartChar
 * #xD7, #xF7, #x300 - #x36F, #x37E, #x2000 - #x200B, #x200E - #x206F, #x2190 - #x2BFF, #x2FF0 - #x3000,
 * #xD800 - #xF8FF, #xFDD0 - #xFDEF, #xFFFE - #xFFFF
 */

/* eslint no-control-regex: 0, max-len: 0, no-misleading-character-class: 0 */
const NAME_CHAR_FORBIDDEN_RE =
  /[\u0000-\u002C\u002F\u003B-\u0040\u005B-\u0060\u007B-\u00BF\u00D7\u00F7\u0300-\u036F\u037E\u2000-\u200B\u200E-\u206F\u2190-\u2BFF\u2FF0-\u3000\uD800-\uF8FF\uFDD0-\uFDEF\uFFFE-\uFFFF]/g;
const START_NAME_CHAR_FORBIDDEN_EXTRA_RE =
  /[-.0-9\u00B7\u0300-\u036F\u203F-\u2040]/g;

function makeValidNameChars(pCandidateNameTail: string): string {
  return pCandidateNameTail.replace(NAME_CHAR_FORBIDDEN_RE, "_");
}

/**
 * if it's an invalid NameStartChar but a valid NameChar smack a '_' in front of it
 * if it's an invalid NameChar as well - run it through the makeValidNameChars replacer
 */
function makeValidNameStartChar(pCandidateChar: string): string {
  let lReturnValue = makeValidNameChars(pCandidateChar);

  if (lReturnValue.match(START_NAME_CHAR_FORBIDDEN_EXTRA_RE)) {
    lReturnValue = `_${pCandidateChar}`;
  }
  return lReturnValue;
}

/**
 * Takes any string and returns a valid XMLName using these rules:
 *
 * If pCandidateName is not empty:
 *   For all characters in pCandidateName:
 *    if it's not a valid NameChar, replace it with '_'
 *   For the first character:
 *     If it's a valid NameChar, but not a valid NameStartChar, add an '_' in front of the pCandidateName
 *
 * If pCandidateName is empty:
 *  return the string '__empty'
 */
export default (pCandidateName: string): string => {
  pCandidateName = pCandidateName || "";

  if (pCandidateName.length === 0) {
    return `__empty`;
  }
  return makeValidNameStartChar(pCandidateName[0]).concat(
    makeValidNameChars(pCandidateName.slice(1)),
  );
};