opusdev/vector-similarity-api

1/*!2 * vary3 * Copyright(c) 2014-2017 Douglas Christopher Wilson4 * MIT Licensed5 */6 7'use strict'8 9/**10 * Module exports.11 */12 13module.exports = vary14module.exports.append = append15 16/**17 * RegExp to match field-name in RFC 7230 sec 3.218 *19 * field-name    = token20 * token         = 1*tchar21 * tchar         = "!" / "#" / "$" / "%" / "&" / "'" / "*"22 *               / "+" / "-" / "." / "^" / "_" / "`" / "|" / "~"23 *               / DIGIT / ALPHA24 *               ; any VCHAR, except delimiters25 */26 27var FIELD_NAME_REGEXP = /^[!#$%&'*+\-.^_`|~0-9A-Za-z]+$/28 29/**30 * Append a field to a vary header.31 *32 * @param {String} header33 * @param {String|Array} field34 * @return {String}35 * @public36 */37 38function append (header, field) {39  if (typeof header !== 'string') {40    throw new TypeError('header argument is required')41  }42 43  if (!field) {44    throw new TypeError('field argument is required')45  }46 47  // get fields array48  var fields = !Array.isArray(field)49    ? parse(String(field))50    : field51 52  // assert on invalid field names53  for (var j = 0; j < fields.length; j++) {54    if (!FIELD_NAME_REGEXP.test(fields[j])) {55      throw new TypeError('field argument contains an invalid header name')56    }57  }58 59  // existing, unspecified vary60  if (header === '*') {61    return header62  }63 64  // enumerate current values65  var val = header66  var vals = parse(header.toLowerCase())67 68  // unspecified vary69  if (fields.indexOf('*') !== -1 || vals.indexOf('*') !== -1) {70    return '*'71  }72 73  for (var i = 0; i < fields.length; i++) {74    var fld = fields[i].toLowerCase()75 76    // append value (case-preserving)77    if (vals.indexOf(fld) === -1) {78      vals.push(fld)79      val = val80        ? val + ', ' + fields[i]81        : fields[i]82    }83  }84 85  return val86}87 88/**89 * Parse a vary header into an array.90 *91 * @param {String} header92 * @return {Array}93 * @private94 */95 96function parse (header) {97  var end = 098  var list = []99  var start = 0100 101  // gather tokens102  for (var i = 0, len = header.length; i < len; i++) {103    switch (header.charCodeAt(i)) {104      case 0x20: /*   */105        if (start === end) {106          start = end = i + 1107        }108        break109      case 0x2c: /* , */110        list.push(header.substring(start, end))111        start = end = i + 1112        break113      default:114        end = i + 1115        break116    }117  }118 119  // final token120  list.push(header.substring(start, end))121 122  return list123}124 125/**126 * Mark that a request is varied on a header field.127 *128 * @param {Object} res129 * @param {String|Array} field130 * @public131 */132 133function vary (res, field) {134  if (!res || !res.getHeader || !res.setHeader) {135    // quack quack136    throw new TypeError('res argument is required')137  }138 139  // get existing header140  var val = res.getHeader('Vary') || ''141  var header = Array.isArray(val)142    ? val.join(', ')143    : String(val)144 145  // set new header146  if ((val = append(header, field))) {147    res.setHeader('Vary', val)148  }149}150