dotnode/ioc/injector.js

.NET-like MVC framework for Node.js

var extend = require('xtend');

var Injector = function () {

    this._generatedModules = {};

    this._cachedModules = {};
};

// #region public methods

Injector.prototype.createConstructor = function (Constructor, args) {

    var Temp = function () {
        return Constructor.apply(this, args);
    };

    Temp.prototype = extend({}, Temp.prototype, Constructor.prototype);

    return Temp;
};

Injector.prototype.invoke = function (fn, context, params) {

    var paramNames = this._getParameterNames(fn);

    var paramValues = paramNames.map(function (name) {
        return params[name];
    });

    var result = fn.apply(context, paramValues);

    return result;
};

Injector.prototype.registerBindings = function (bindingDictionary) {

    this._bindingDictionary = bindingDictionary;

    this._bindings = bindingDictionary.getBindings();
};

Injector.prototype.create = function (targetPath) {

    if (!this._bindings) {
        throw 'Cannot call method generate before bindings were registered. Use [injector].registerBindings([bindings])';
    }

    var cwd = process.cwd();

    var bindingValues = this._bindings[targetPath];

    var rawModule = require(cwd + '/' + targetPath);

    var instantiate = bindingValues && bindingValues.toInstantiate && bindingValues.toInstantiate.indexOf(targetPath) != -1;

    if (!bindingValues || !bindingValues.dependencies) {

        if (instantiate) {
            return new rawModule();
        }

        return rawModule;
    }

    var dependencies = bindingValues.dependencies.map((function (dep) {

        var createdModule = this.create(dep);

        var instantiateDependency = bindingValues && bindingValues.toInstantiate && bindingValues.toInstantiate.indexOf(dep) != -1;

        if (instantiateDependency && typeof createdModule == 'function') {
            return new createdModule();
        }

        return createdModule;

    }).bind(this));

    var constructor = this.createConstructor(rawModule, dependencies);

    if (instantiate) {

        console.log('instantiating ' + targetPath);

        return new constructor();
    }

    console.log('not instantiating ' + targetPath);

    return constructor;
};

// #endregion

// #region private methods

Injector.prototype._getParameterNames = function (func) {

    var STRIP_COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg,
        ARGUMENT_NAMES = /([^\s,]+)/g;

    var fnStr = func.toString().replace(STRIP_COMMENTS, ''),
        result = fnStr.slice(fnStr.indexOf('(') + 1, fnStr.indexOf(')')).match(ARGUMENT_NAMES);

    if (result === null) {
        result = [];
    }

    return result;
};

// #endregion

module.exports = Injector;