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chapter09.js
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chapter09.js
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function lazyChain(obj) {
var calls = [];
return {
invoke: function(methodName /* args */) {
var args = _.rest(arguments);
calls.push(function(target) {
var meth = target[methodName];
return meth.apply(target, args);
});
return this;
},
force: function() {
return _.reduce(calls, function(ret, thunk) {
return thunk(ret);
}, obj);
}
};
}
function deferredSort(ary) {
return lazyChain(ary).invoke('sort');
}
var deferredSorts = _.map([[2,1,3], [7,7,1], [0,9,5]], deferredSort);
//=> [<thunk>, <thunk>, <thunk>]
function force(thunk) {
return thunk.force();
}
var validateTriples = validator(
"Each array should have three elements",
function (arrays) {
return _.every(arrays, function(a) {
return a.length === 3;
});
});
var validateTripleStore = partial1(condition1(validateTriples), _.identity);
function postProcess(arrays) {
return _.map(arrays, second);
}
function processTriples(data) {
return pipeline(data
, JSON.parse
, validateTripleStore
, deferredSort
, force
, postProcess
, invoker('sort', Array.prototype.sort)
, str);
}
var reportDataPackets = _.compose(
function(s) { $('#result').text(s) },
processTriples);
function polyToString(obj) {
if (obj instanceof String)
return obj;
else if (obj instanceof Array)
return stringifyArray(obj);
return obj.toString();
}
function stringifyArray(ary) {
return ["[", _.map(ary, polyToString).join(","), "]"].join('');
}
var polyToString = dispatch(
function(s) { return _.isString(s) ? s : undefined },
function(s) { return _.isArray(s) ? stringifyArray(s) : undefined },
function(s) { return _.isObject(s) ? JSON.stringify(s) : undefined },
function(s) { return s.toString() });
Container.prototype.toString = function() {
return ["@<", polyToString(this._value), ">"].join('');
}
function ContainerClass() {}
function ObservedContainerClass() {}
function HoleClass() {}
function CASClass() {}
function TableBaseClass() {}
ObservedContainerClass.prototype = new ContainerClass();
HoleClass.prototype = new ObservedContainerClass();
CASClass.prototype = new HoleClass();
TableBaseClass.prototype = new HoleClass();
var ContainerClass = Class.extend({
init: function(val) {
this._value = val;
},
});
var c = new ContainerClass(42);
c;
//=> {_value: 42 ...}
c instanceof Class;
//=> true
var ObservedContainerClass = ContainerClass.extend({
observe: function(f) { note("set observer") },
notify: function() { note("notifying observers") }
});
var HoleClass = ObservedContainerClass.extend({
init: function(val) { this.setValue(val) },
setValue: function(val) {
this._value = val;
this.notify();
return val;
}
});
var CASClass = HoleClass.extend({
swap: function(oldVal, newVal) {
if (!_.isEqual(oldVal, this._value)) fail("No match");
return this.setValue(newVal);
}
});
function Container(val) {
this._value = val;
this.init(val);
}
Container.prototype.init = _.identity;
var HoleMixin = {
setValue: function(newValue) {
var oldVal = this._value;
this.validate(newValue);
this._value = newValue;
this.notify(oldVal, newValue);
return this._value;
}
};
var Hole = function(val) {
Container.call(this, val);
}
var ObserverMixin = (function() {
var _watchers = [];
return {
watch: function(fun) {
_watchers.push(fun);
return _.size(_watchers);
},
notify: function(oldVal, newVal) {
_.each(_watchers, function(watcher) {
watcher.call(this, oldVal, newVal);
});
return _.size(_watchers);
}
};
}());
var ValidateMixin = {
addValidator: function(fun) {
this._validator = fun;
},
init: function(val) {
this.validate(val);
},
validate: function(val) {
if (existy(this._validator) &&
!this._validator(val))
fail("Attempted to set invalid value " + polyToString(val));
}
};
_.extend(Hole.prototype
, HoleMixin
, ValidateMixin
, ObserverMixin);
var SwapMixin = {
swap: function(fun /* , args... */) {
var args = _.rest(arguments)
var newValue = fun.apply(this, construct(this._value, args));
return this.setValue(newValue);
}
};
var SnapshotMixin = {
snapshot: function() {
return deepClone(this._value);
}
};
_.extend(Hole.prototype
, HoleMixin
, ValidateMixin
, ObserverMixin
, SwapMixin
, SnapshotMixin);
var CAS = function(val) {
Hole.call(this, val);
}
var CASMixin = {
swap: function(oldVal, f) {
if (this._value === oldVal) {
this.setValue(f(this._value));
return this._value;
}
else {
return undefined;
}
}
};
_.extend(CAS.prototype
, HoleMixin
, ValidateMixin
, ObserverMixin
, SwapMixin
, CASMixin
, SnapshotMixin);
function contain(value) {
return new Container(value);
}
function hole(val /*, validator */) {
var h = new Hole();
var v = _.toArray(arguments)[1];
if (v) h.addValidator(v);
h.setValue(val);
return h;
}
var swap = invoker('swap', Hole.prototype.swap);
function cas(val /*, args */) {
var h = hole.apply(this, arguments);
var c = new CAS(val);
c._validator = h._validator;
return c;
}
var compareAndSwap = invoker('swap', CAS.prototype.swap);
function snapshot(o) { return o.snapshot() }
function addWatcher(o, fun) { o.watch(fun) }