modules/labels.js

   1 /**
   2  * (C) Copyright 2008 Jeremy Maitin-Shepard
   3  *
   4  * Use, modification, and distribution are subject to the terms specified in the
   5  * COPYING file.
   6 **/
   7
   8 require("pretty-print.js");
   9
  10 /**
  11  * @param name specifies the name of the label to be defined
  12  *
  13  * The remaining arguments should be strings, specifying the names of
  14  * required arguments. Additionally, the last additional argument can
  15  * be `null', which indicates that unlimited optional arguments can
  16  * follow. If `null' is not specified as the last argument, then it is
  17  * assumed that all optional arguments are keyword arguments. The
  18  * optional arguments are stored as an array in a member called $.
  19  */
  20 function define_label (name) {
  21     var allow_optional = false;
  22     var required_args = [];
  23     for (let i = 1, ii = arguments.length; i < ii; ++i) {
  24         if (arguments[i] === null) {
  25             allow_optional = true;
  26             if (i + 1 != ii)
  27                 throw new Error("null must be the last argument");
  28         } else {
  29             required_args.push(arguments[i]);
  30         }
  31     }
  32     function toString () {
  33         let optional = this.$;
  34         if (optional == null)
  35             optional = [];
  36         let printed_args = [];
  37         let seen_defined_yet = false;
  38         for (let i = required_args.length - 1; i >= 0; --i) {
  39             let arg = required_args[i];
  40             if (seen_defined_yet || this[arg] !== undefined) {
  41                 printed_args.unshift(arg + " = " + pretty_print_value(this[arg]));
  42                 seen_defined_yet = true;
  43             }
  44         }
  45         printed_args.push.apply(null, optional.map(pretty_print_value));
  46         for (let i in this) {
  47             if (i.length > 1 && i[0] == "$")
  48                 printed_args.push(i + " = " + this[i]);
  49         }
  50         if (printed_args.length > 0)
  51             printed_args = "(" + printed_args.join(", ") + ")";
  52         else
  53             printed_args = "";
  54         return this._name + printed_args;
  55     }
  56     var result;
  57     result = function () {
  58         var o = { _name: name, toString: toString, _id: result, __is_label: true, toSource: toString };
  59         let max_req_arg = arguments.length;
  60         if (max_req_arg > required_args.length)
  61             max_req_arg = required_args.length;
  62         for (let i = 0; i < max_req_arg; ++i)
  63             o[required_args[i]] = arguments[i];
  64         if (allow_optional)
  65             o.$ = Array.prototype.slice.call(arguments, required_args.length);
  66         else
  67             write_keywords(o, arguments, required_args.length);
  68         return o;
  69     };
  70     result._name = name;
  71     result._id = result;
  72     result.$ = [];
  73     for (let i in required_args)
  74         result[i] = undefined;
  75     result.toString = toString;
  76     result.__is_label = true;
  77     conkeror[name] = result;
  78 }
  79
  80 function label_id (value) {
  81     if (value == null)
  82         return null;
  83     return value._id;
  84 }
  85
  86 provide("labels");