179 lines
6.5 KiB
JavaScript
Executable File
179 lines
6.5 KiB
JavaScript
Executable File
"use strict";
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/**
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* @fileOverview allows you to bind a change watcher that looks for get and set operations on an arbitrary
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* property of an object at at any depth. This allows you to look for changes or intercept values asynchronously or otherwise.
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* @module documents/binder
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* @requires async
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* @requires documents/probe
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* @requires lodash
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* @requires promise
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*/
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var Promise = require( 'promise' );
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var async = require( "async" );
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var probe = require( "./probe" );
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var sys = require( "lodash" );
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/**
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* Identifies the properties that the binder expects
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* @type {{getter: null, getterAsync: boolean, setter: null, validator: null, validatorAsync: boolean, setterAsync: boolean}}
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* @private
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*/
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var dataBinderOptions = exports.dataBinderOptions = {
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getter : null,
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getterAsync : false,
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setter : null,
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validator : null,
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validatorAsync : false,
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setterAsync : false
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};
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/**
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* You can unbind previously bound objects from here.
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*
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* @param {string} path The path that was bound using {@link module:documents/binder.bind}
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* @param {*} record The object that was bound
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*/
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exports.unbind = function ( path, record ) {
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var context = record;
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var lastParent = context;
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var parts = path.split( probe.delimiter );
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var lastPartName = path;
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var lastParentName;
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sys.each( parts, function ( part ) {
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lastParentName = part;
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lastParent = context;
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context = context[part];
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lastPartName = part;
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if ( sys.isNull( context ) || sys.isUndefined( context ) ) {
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context = {};
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}
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} );
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if ( lastParent === context ) {
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deleteBindings( record, lastPartName );
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} else {
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deleteBindings( lastParent, lastPartName );
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}
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function deleteBindings( mountPoint, mountName ) {
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mountPoint[mountName] = mountPoint["__" + mountName + "__"];
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delete mountPoint["__" + mountName + "__"];
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}
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};
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/**
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* Bind to a property somewhere in an object. The property is found using dot notation and can be arbitrarily deep.
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* @param {string} path The path into the object to locate the property. For instance this could be `"_id"`, `"name.last"`.
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* or `"some.really.really.long.path.including.an.array.2.name"`
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* @param {object} record Anything you can hang a property off of
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* @param {options} options What you wanna do with the doohicky when yoyu bind it.
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* @param {function(*):Promise|*=} options.getter This is the method to run when getting the value. When it runs, you will receive
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* a single parameter which is the current value as the object understands it. You can return the value directly, just raise an event or
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* whatever your little heart demands. However, if you are asynchronous, this will turn your return value into a promise, one of the
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* few places this system will embrace promises over node-like error passing and that is mainly because this is a getter so a return value
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* is particularly important. *
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* @param {*} options.getter.value The current value of the record
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* @param {function(err, value)=} options.getter.callback When asynchronous, return you value through this method using node style
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* error passing (the promise is handled for you by this method).
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* @param {boolean=} options.getterAsync When true (not truthy) the getter is treated asynchronously and returns a promise with your value.
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* @param {function(*, *, *)=} options.setter A setter method
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* @param {*} options.setter.newVal The new value
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* @param {*} options.setter.oldVal The old value
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* @param {*} options.setter.record The record hosting the change
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* @param {function(*, *, *, function=)=} options.validator If you want a validator to run before settings values, pass this guy in
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* @param {*} options.validator.newVal The new value
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* @param {*} options.validator.oldVal The old value
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* @param {*} options.validator.record The record hosting the change
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* @param {function(err)=} options.validator.callback If the validator is asynchronous, then pass your value back here, otherwise pass it back as a return value.
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* When you use an asynchronous instance, pass the error in the first value and then the rest of the parameters are yours to play with
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* @param {boolean=} options.validatorAsync When true (not truthy) the validator is treated asynchornously and returns a promise with your value.
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* @returns {*}
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*/
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exports.bind = function ( path, record, options ) {
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options = sys.extend( {}, dataBinderOptions, options );
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var context = record;
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var lastParent = context;
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var parts = path.split( probe.delimiter );
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var lastPartName = path;
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var lastParentName;
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sys.each( parts, function ( part ) {
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lastParentName = part;
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lastParent = context;
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context = context[part];
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lastPartName = part;
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if ( sys.isNull( context ) || sys.isUndefined( context ) ) {
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context = {};
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}
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} );
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if ( lastParent === context ) {
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setUpBindings( record, lastPartName );
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} else {
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setUpBindings( lastParent, lastPartName );
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}
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function setUpBindings( mountPoint, mountName ) {
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mountPoint["__" + mountName + "__"] = mountPoint[mountName];
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Object.defineProperty( mountPoint, mountName, {
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get : function () {
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if ( sys.isFunction( options.getter ) ) {
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var promise;
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if ( options.getterAsync === true ) {
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promise = Promise.denodeify( options.getter );
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}
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if ( promise ) {
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return promise( mountPoint["__" + mountName + "__"] ).then( function ( val ) {
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mountPoint["__" + mountName + "__"] = val;
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} );
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} else {
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mountPoint["__" + mountName + "__"] = options.getter( mountPoint["__" + mountName + "__"] );
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return mountPoint["__" + mountName + "__"];
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}
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} else {
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return mountPoint["__" + mountName + "__"];
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}
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},
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set : function ( val ) {
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async.waterfall( [
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function ( done ) {
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if ( sys.isFunction( options.validator ) ) {
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if ( options.validatorAsync ) {
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options.validator( val, mountPoint["__" + mountName + "__"], record, done );
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} else {
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var res = options.validator( val, mountPoint["__" + mountName + "__"], record );
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if ( res === true ) {
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done();
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} else {
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done( res );
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}
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}
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} else {
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done();
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}
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},
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function ( done ) {
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if ( sys.isFunction( options.setter ) ) {
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if ( options.setterAsync === true ) {
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options.setter( val, mountPoint["__" + mountName + "__"], record, done );
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} else {
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done( null, options.setter( val, mountPoint["__" + mountName + "__"], record ) );
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}
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} else {
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done( null, val );
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}
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}
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], function ( err, newVal ) {
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if ( err ) { throw new Error( err ); }
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mountPoint["__" + mountName + "__"] = newVal;
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} );
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}
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} );
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}
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return context;
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};
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