libphonenumber-js/es6/helpers/extension/createExtensionPattern.js

A simpler (and smaller) rewrite of Google Android's libphonenumber library in javascript

import { VALID_DIGITS } from '../../constants.js'; // The RFC 3966 format for extensions.

var RFC3966_EXTN_PREFIX = ';ext=';
/**
 * Helper method for constructing regular expressions for parsing. Creates
 * an expression that captures up to max_length digits.
 * @return {string} RegEx pattern to capture extension digits.
 */

var getExtensionDigitsPattern = function getExtensionDigitsPattern(maxLength) {
  return "([".concat(VALID_DIGITS, "]{1,").concat(maxLength, "})");
};
/**
 * Helper initialiser method to create the regular-expression pattern to match
 * extensions.
 * Copy-pasted from Google's `libphonenumber`:
 * https://github.com/google/libphonenumber/blob/55b2646ec9393f4d3d6661b9c82ef9e258e8b829/javascript/i18n/phonenumbers/phonenumberutil.js#L759-L766
 * @return {string} RegEx pattern to capture extensions.
 */


export default function createExtensionPattern(purpose) {
  // We cap the maximum length of an extension based on the ambiguity of the way
  // the extension is prefixed. As per ITU, the officially allowed length for
  // extensions is actually 40, but we don't support this since we haven't seen real
  // examples and this introduces many false interpretations as the extension labels
  // are not standardized.

  /** @type {string} */
  var extLimitAfterExplicitLabel = '20';
  /** @type {string} */

  var extLimitAfterLikelyLabel = '15';
  /** @type {string} */

  var extLimitAfterAmbiguousChar = '9';
  /** @type {string} */

  var extLimitWhenNotSure = '6';
  /** @type {string} */

  var possibleSeparatorsBetweenNumberAndExtLabel = "[ \xA0\\t,]*"; // Optional full stop (.) or colon, followed by zero or more spaces/tabs/commas.

  /** @type {string} */

  var possibleCharsAfterExtLabel = "[:\\.\uFF0E]?[ \xA0\\t,-]*";
  /** @type {string} */

  var optionalExtnSuffix = "#?"; // Here the extension is called out in more explicit way, i.e mentioning it obvious
  // patterns like "ext.".

  /** @type {string} */

  var explicitExtLabels = "(?:e?xt(?:ensi(?:o\u0301?|\xF3))?n?|\uFF45?\uFF58\uFF54\uFF4E?|\u0434\u043E\u0431|anexo)"; // One-character symbols that can be used to indicate an extension, and less
  // commonly used or more ambiguous extension labels.

  /** @type {string} */

  var ambiguousExtLabels = "(?:[x\uFF58#\uFF03~\uFF5E]|int|\uFF49\uFF4E\uFF54)"; // When extension is not separated clearly.

  /** @type {string} */

  var ambiguousSeparator = "[- ]+"; // This is the same as possibleSeparatorsBetweenNumberAndExtLabel, but not matching
  // comma as extension label may have it.

  /** @type {string} */

  var possibleSeparatorsNumberExtLabelNoComma = "[ \xA0\\t]*"; // ",," is commonly used for auto dialling the extension when connected. First
  // comma is matched through possibleSeparatorsBetweenNumberAndExtLabel, so we do
  // not repeat it here. Semi-colon works in Iphone and Android also to pop up a
  // button with the extension number following.

  /** @type {string} */

  var autoDiallingAndExtLabelsFound = "(?:,{2}|;)";
  /** @type {string} */

  var rfcExtn = RFC3966_EXTN_PREFIX + getExtensionDigitsPattern(extLimitAfterExplicitLabel);
  /** @type {string} */

  var explicitExtn = possibleSeparatorsBetweenNumberAndExtLabel + explicitExtLabels + possibleCharsAfterExtLabel + getExtensionDigitsPattern(extLimitAfterExplicitLabel) + optionalExtnSuffix;
  /** @type {string} */

  var ambiguousExtn = possibleSeparatorsBetweenNumberAndExtLabel + ambiguousExtLabels + possibleCharsAfterExtLabel + getExtensionDigitsPattern(extLimitAfterAmbiguousChar) + optionalExtnSuffix;
  /** @type {string} */

  var americanStyleExtnWithSuffix = ambiguousSeparator + getExtensionDigitsPattern(extLimitWhenNotSure) + "#";
  /** @type {string} */

  var autoDiallingExtn = possibleSeparatorsNumberExtLabelNoComma + autoDiallingAndExtLabelsFound + possibleCharsAfterExtLabel + getExtensionDigitsPattern(extLimitAfterLikelyLabel) + optionalExtnSuffix;
  /** @type {string} */

  var onlyCommasExtn = possibleSeparatorsNumberExtLabelNoComma + "(?:,)+" + possibleCharsAfterExtLabel + getExtensionDigitsPattern(extLimitAfterAmbiguousChar) + optionalExtnSuffix; // The first regular expression covers RFC 3966 format, where the extension is added
  // using ";ext=". The second more generic where extension is mentioned with explicit
  // labels like "ext:". In both the above cases we allow more numbers in extension than
  // any other extension labels. The third one captures when single character extension
  // labels or less commonly used labels are used. In such cases we capture fewer
  // extension digits in order to reduce the chance of falsely interpreting two
  // numbers beside each other as a number + extension. The fourth one covers the
  // special case of American numbers where the extension is written with a hash
  // at the end, such as "- 503#". The fifth one is exclusively for extension
  // autodialling formats which are used when dialling and in this case we accept longer
  // extensions. The last one is more liberal on the number of commas that acts as
  // extension labels, so we have a strict cap on the number of digits in such extensions.

  return rfcExtn + "|" + explicitExtn + "|" + ambiguousExtn + "|" + americanStyleExtnWithSuffix + "|" + autoDiallingExtn + "|" + onlyCommasExtn;
}
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