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model.js
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model.js
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window.util.namespace("window.jermaine", function (ns) {
"use strict";
function Model(specification) {
var that = this,
methods = {},
attributes = {},
pattern,
modified = false,
requiredConstructorArgs = [],
optionalConstructorArgs = [],
parents = [],
Method = ns.Method,
Attr = ns.Attr,
AttrList = ns.AttrList,
property,
listProperties,
create,
isImmutable,
initializer = function () {},
constructor = function () {},
model = function () {
if (modified) {
create();
}
return constructor.apply(this, arguments);
};
//temporary fix so API stays the same
if (arguments.length > 1) {
specification = arguments[arguments.length-1];
}
//handle specification function
if (specification && typeof(specification) === "function") {
model = new Model();
specification.call(model);
return model;
} else if (specification) {
throw new Error("Model: specification parameter must be a function");
}
/********** BEGIN PRIVATE METHODS ****************/
/* private method that abstracts hasA/hasMany */
var hasAProperty = function (type, name) {
var Property = type==="Attr"?Attr:AttrList,
methodName = type==="Attr"?"hasA":"hasMany",
attribute;
modified = true;
if (typeof(name) === 'string') {
attribute = new Property(name);
attributes[name] = attribute;
return attribute;
} else {
throw new Error("Model: " + methodName + " parameter must be a string");
}
};
/* private method that abstracts attribute/method */
property = function (type, name) {
var result;
if (typeof(name) !== "string") {
throw new Error("Model: expected string argument to " + type + " method, but recieved " + name);
}
result = type==="attribute"?attributes[name]:methods[name];
if (result === undefined) {
throw new Error("Model: " + type + " " + name + " does not exist!");
}
return result;
};
/* private method that abstracts attributes/methods */
listProperties = function (type) {
var i,
list = [],
properties = type==="attributes"?attributes:methods;
for (i in properties) {
if (properties.hasOwnProperty(i)) {
list.push(i);
}
}
return list;
};
/* private function that creates the constructor */
create = function (name) {
var that = this,
i,
err;
//validate the model first
model.validate();
constructor = function () {
var i,
addProperties = function (obj, type) {
var properties = type==="attributes"?attributes:methods,
i;
for (i in properties) {
if (properties.hasOwnProperty(i)) {
//if the object is immutable, all attributes should be immutable
if(properties === attributes && isImmutable) {
properties[i].isImmutable();
}
properties[i].addTo(obj);
}
}
};
//add attributes
addProperties(this, "attributes");
addProperties(this, "methods");
this.toString = pattern;
//use constructor args to build object
if(arguments.length > 0) {
if (arguments.length < requiredConstructorArgs.length) {
//throw error
err = "Constructor requires ";
for(i = 0; i < requiredConstructorArgs.length; ++i) {
err += requiredConstructorArgs[i];
err += i===requiredConstructorArgs.length-1?"":", ";
}
err += " to be specified";
throw new Error(err);
} else {
for (i = 0; i < arguments.length; ++i) {
if (i < requiredConstructorArgs.length) {
this[requiredConstructorArgs[i]](arguments[i]);
} else {
this[optionalConstructorArgs[i-requiredConstructorArgs.length]](arguments[i]);
}
}
}
}
initializer.call(this);
};
return constructor;
};
/*********** END PRIVATE METHODS **************/
/*********** BEGIN PUBLIC API *****************/
model.hasA = function (attr) {
return hasAProperty("Attr", attr);
};
model.hasAn = model.hasA;
model.hasMany = function (attrs) {
return hasAProperty("AttrList", attrs);
};
model.isA = function (parent) {
var i,
parentAttributes,
parentMethods,
isAModel;
modified = true;
//checks to make sure a potentialModel has all attributes of a model
isAModel = function (potentialModel) {
var i,
M = new Model();
for (i in M) {
if (M.hasOwnProperty(i) && typeof(potentialModel[i]) !== typeof(M[i])) {
return false;
}
}
return true;
};
//confirm parent is a model via duck-typing
if (typeof (parent) !== "function" || !isAModel(parent)) {
throw new Error("Model: parameter sent to isA function must be a Model");
}
//only allow single inheritance for now
if (parents.length === 0) {
parents.push(parent);
} else {
throw new Error("Model: Model only supports single inheritance at this time");
}
//add attributes and methods to current model
parentAttributes = parents[0].attributes();
for (i = 0; i < parentAttributes.length; ++i) {
if (attributes[parentAttributes[i]] === undefined) {
attributes[parentAttributes[i]] = parents[0].attribute(parentAttributes[i]).clone();
//subclass attributes are mutable by default
attributes[parentAttributes[i]].isMutable();
}
}
parentMethods = parents[0].methods();
for (i = 0; i < parentMethods.length; ++i) {
if (methods[parentMethods[i]] === undefined) {
methods[parentMethods[i]] = parents[0].method(parentMethods[i]);
}
}
for (i = 0; i < parents.length; i++) {
model.prototype = new parents[i]();
}
};
model.isAn = model.isA;
model.parent = function () {
return parents[0].apply(this, arguments);
};
model.attribute = function (attr) {
return property("attribute", attr);
};
model.attributes = function () {
return listProperties("attributes");
};
model.method = function (m) {
return property("method", m);
};
model.methods = function () {
return listProperties("methods");
};
model.isBuiltWith = function () {
var optionalParamFlag = false,
i;
modified = true;
requiredConstructorArgs = [];
optionalConstructorArgs = [];
for (i = 0; i < arguments.length; ++i) {
if (typeof(arguments[i]) === "string" && arguments[i].charAt(0) !== '%') {
//in required parms
if (optionalParamFlag) {
//throw error
throw new Error("Model: isBuiltWith requires parameters preceded with a % to be the final parameters before the optional function");
} else {
//insert into required array
requiredConstructorArgs.push(arguments[i]);
}
} else if(typeof(arguments[i]) === "string" && arguments[i].charAt(0) === '%') {
//in optional parms
optionalParamFlag = true;
//insert into optional array
optionalConstructorArgs.push(arguments[i].slice(1));
} else if(typeof(arguments[i]) === "function" && i === arguments.length - 1) {
//init function
initializer = arguments[i];
} else {
throw new Error("Model: isBuiltWith parameters must be strings except for a function as the optional final parameter");
}
}
};
model.isImmutable = function () {
isImmutable = true;
};
model.looksLike = function (p) {
modified = true;
pattern = p;
};
model.respondsTo = function (methodName, methodBody) {
var m = new Method(methodName, methodBody);
modified = true;
methods[methodName] = m;
};
model.validate = function () {
var i,
attributes = this.attributes(),
methods = this.methods();
//check to make sure that isBuiltWith has actual attributes
for (i = 0; i < requiredConstructorArgs.length; ++i) {
try {
this.attribute(requiredConstructorArgs[i]);
} catch (e) {
throw new Error(requiredConstructorArgs[i] + ", specified in the isBuiltWith method, is not an attribute");
}
}
for (i = 0; i < optionalConstructorArgs.length; ++i) {
try {
this.attribute(optionalConstructorArgs[i]);
} catch (e) {
throw new Error(optionalConstructorArgs[i] + ", specified in the isBuiltWith method, is not an attribute");
}
}
//check for method/attribute collisions
for (i = 0; i < attributes.length; i++) {
if (methods.indexOf(attributes[i]) > -1) {
throw new Error("Model: invalid model specification to " + attributes[i] + " being both an attribute and method");
}
}
//check to make sure that all attributes are requiredConstructorArgs if the object is immutable
if (isImmutable) {
for (i = 0; i < attributes.length; i++) {
if (requiredConstructorArgs.indexOf(attributes[i]) < 0) {
throw new Error("immutable objects must have all attributes required in a call to isBuiltWith");
}
}
}
//set modifiedSinceLastValidation to false
modified = false;
};
/************** END PUBLIC API ****************/
//here we are returning our model object
//which is a function with a bunch of methods that
//manipulate how the function behaves
return model;
}
ns.Model = Model;
});