datastruct.js View source

Utilities: Datastruct

Cool stuff.

datastruct = require('lidoc/datastruct');

function File(options) {
  this.set(options);
}

datastruct(File)
  .property('name', { default: null })
  .property('name', { type: ClassName })

(function() {
"use strict";

CoffeeScript usage

 
# CoffeeScript
class File
  datastruct this

  @property 'name', default: null
  @property 'name', type: ClassName
  @property 'pages', subtype: ClassName
  @property 'page', get: -> ...

  constructor: (options) ->
    @set options

Creating getters/setters

 
.property('name', {
  get: function() {
    return "Hello";
  }
});

datastruct()

Applies the mixin to the given class klass.

 
function datastruct(klass) {

properties

Key/value list of properties and their respective options.

 
  klass.properties = {};

property(name, options)

Makes a property. Creates sets/gets if needed.

  • default: The default value.
  • type: Class to coerce to.
  • subtype: Class to coerce to.
  • get: Name of get function.
  • hidden: If true, doesn't show up in JSON.

Also handles the case where you pass more than one property as property({ ... }). [1]

 
  klass.property = function(name, options) {
    if ((arguments.length === 1) && (typeof name === 'object')) { /* [1] */
      var props = name;
      for (var key in props) {
        if (props.hasOwnProperty(key)) {
          var value = props[key];
          klass.property(key, value);
        }
      }

      return this;
    }

    options || (options = {});
    klass.properties[name] = options;

    if ((options.get) || (options.set)) {
      Object.defineProperty(klass.prototype, name, {
        get: options.get,
        set: options.set
      });
    }

    return this;
  };

set()

Yeah.

 
  klass.prototype.set = function(source) {
  • If invoked with an object like set({ key: value, ... }), iterate through the object and delegate to set(key, value).
 
    if (arguments.length === 1) {
      var source = arguments[0];
      source || (source = {});

      for (var prop in klass.properties) {
        if (klass.properties.hasOwnProperty(prop)) {
          var options = klass.properties[prop];

          if (source.hasOwnProperty(prop)) {
            this.set(prop, source[prop]);
          }
  • If there's a default value, and the property hasn't been set...
 
          else if ((typeof options['default'] !== 'undefined') &&
            (typeof this[prop] === 'undefined')) {
            this.set(prop, clone(options['default']));
          }
        }
      }
    }
  • Handle set(key, value).
 
    else if (arguments.length === 2) {
      var key = arguments[0];
      var value = arguments[1];
      var propOptions = klass.properties[key];

      if (propOptions) {
  • Coerce
 
        if ((propOptions.type) && (value.constructor !== propOptions.type)) {
          value = new propOptions.type(value, this);
        }

        else if (propOptions.subtype) {
          value = coerceObjectOrArray(value, propOptions.subtype, this);
        }

        this[key] = value;
      }
    }
    return this;
  };

toJSON()

Implement this so that JSON.stringify will not catch private properties.

 
  klass.prototype.toJSON = function() {
    var object = {};

    for (var prop in klass.properties) {
      if (klass.properties.hasOwnProperty(prop)) {
        var options = klass.properties[prop];

        if (!options.hidden) {
          object[prop] = this[prop];
        }
      }
    }

    return object;
  };

  return klass;
};

Private helpers

coerceObjectOrArray()

Casts the values of object into given type type.

 
function coerceObjectOrArray(object, type, self) {
  if (object.constructor === Array) {
    var re = [];
    for (var i=0, len=object.length; i<len; ++i) {
      re[i] = new type(object[i], self);
    }
    return re;
  }

  else if (!object) {
    return object; // Probably null
  }

  else if (typeof object === 'object') {
    var re = {};

    for (var key in object) {
      if (object.hasOwnProperty(key)) {
        var value = object[key];

        re[key] = new type(value, self);
      }
    }
    return re;
  }
}

clone()

Creates a shallow clone of the object obj. Taken from underscore.js.

 
function clone(obj) {
  if ((!obj) || (typeof obj !== 'object')) return obj;
  return (obj.constructor === Array) ? obj.slice() : extend({}, obj);
}

extend()

Extenda given object obj with properties from source. Taken from underscore.js.

 
function extend(obj, source) {
  for (var prop in source) {
    if (source.hasOwnProperty(prop)) {
      obj[prop] = source[prop];
    }
  }
  return obj;
}

if (typeof module !== 'undefined') {
  module.exports = datastruct;
}

})();