minErr.js

'use strict';

/**
 * @description
 *
 * This object provides a utility for producing rich Error messages within
 * Angular. It can be called as follows:
 *
 * var exampleMinErr = minErr('example');
 * throw exampleMinErr('one', 'This {0} is {1}', foo, bar);
 *
 * The above creates an instance of minErr in the example namespace. The
 * resulting error will have a namespaced error code of example.one.  The
 * resulting error will replace {0} with the value of foo, and {1} with the
 * value of bar. The object is not restricted in the number of arguments it can
 * take.
 *
 * If fewer arguments are specified than necessary for interpolation, the extra
 * interpolation markers will be preserved in the final string.
 *
 * Since data will be parsed statically during a build step, some restrictions
 * are applied with respect to how minErr instances are created and called.
 * Instances should have names of the form namespaceMinErr for a minErr created
 * using minErr('namespace') . Error codes, namespaces and template strings
 * should all be static strings, not variables or general expressions.
 *
 * @param {string} module The namespace to use for the new minErr instance.
 * @param {function} ErrorConstructor Custom error constructor to be instantiated when returning
 *   error from returned function, for cases when a particular type of error is useful.
 * @returns {function(code:string, template:string, ...templateArgs): Error} minErr instance
 */

function minErr(module, ErrorConstructor) {
  ErrorConstructor = ErrorConstructor || Error;
  return function() {
    var code = arguments[0],
      prefix = '[' + (module ? module + ':' : '') + code + '] ',
      template = arguments[1],
      templateArgs = arguments,

      message, i;

    message = prefix + template.replace(/\{\d+\}/g, function(match) {
      var index = +match.slice(1, -1), arg;

      if (index + 2 < templateArgs.length) {
        return toDebugString(templateArgs[index + 2]);
      }
      return match;
    });

    message = message + '\nhttp://errors.angularjs.org/"NG_VERSION_FULL"/' +
      (module ? module + '/' : '') + code;
    for (i = 2; i < arguments.length; i++) {
      message = message + (i == 2 ? '?' : '&') + 'p' + (i - 2) + '=' +
        encodeURIComponent(toDebugString(arguments[i]));
    }
    return new ErrorConstructor(message);
  };
}