nl_tokens: Rule for validating a regular expression pattern .
pl_tokens: function pattern ( rule , value , source , errors , options ) { if ( rule . pattern ) { if ( rule . pattern instanceof RegExp ) { // if a RegExp instance is passed, reset `lastIndex` in case its `global` // flag is accidentally set to `true`, which in a validation scenario // is not necessary and the result might be misleading rule . pattern . lastIndex = 0 ; if ( ! rule . <mask> . test ( value ) ) { errors . push ( util . format ( options . messages . pattern . mismatch , rule . fullField , value , rule . pattern ) ) ; } } else if ( typeof rule . pattern === 'string' ) { const _pattern = new RegExp ( rule . pattern ) ; if ( ! _pattern . test ( value ) ) { errors . push ( util . format ( options . messages . pattern . mismatch , rule . fullField , value , rule . pattern ) ) ; } } } }