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phab/externals/javelinjs/src/ext/view/ViewPlaceholder.js
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ViewPlaceholder.js
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/**
* Initialize a client-side view from the server. The main idea here is to
* give server-side views a way to integrate with client-side views.
*
* The idea is that a client-side view will have an accompanying
* thin server-side component. The server-side component renders a placeholder
* element in the document, and then it will invoke this behavior to initialize
* the view into the placeholder.
*
* Because server-side views may be nested, we need to add complexity to
* handle nesting properly.
*
* Assuming a server-side view design that looks like hierarchical views,
* we have to handle structures like
*
* <server:component>
* <client:component id="1">
* <server:component>
* <client:component id="2">
* </client:component>
* </server:component>
* </client:component>
* </server:component>
*
* This leads to a problem: Client component 1 needs to initialize the behavior
* with its children, which includes client component 2. So client component
* 2 must be rendered first. When client component 2 is rendered, it will also
* initialize a copy of this behavior. If behaviors are run in the order they
* are initialized, the child component will run before the parent, and its
* placeholder won't exist yet.
*
* To solve this problem, placeholder behaviors are initialized with the token
* of a containing view that must be rendered first (if any) and a token
* representing it for its own children to depend on. This means the server code
* is free to call initBehavior in any order.
*
* In Phabricator, AphrontJavelinView demonstrates how to handle this correctly.
*
* config: {
* id: Node id to replace.
* view: class of view, without the 'JX.' prefix.
* params: view parameters
* children: messy and loud, cute when drunk
* trigger_id: id of containing view that must be rendered first
* }
*
* @provides javelin-behavior-view-placeholder
* @requires javelin-behavior
* javelin-dom
* javelin-view-renderer
*/
JX.behavior('view-placeholder', function(config, statics) {
JX.ViewPlaceholder.register(config.trigger_id, config.id, function() {
var replace = JX.$(config.id);
var children = config.children;
if (typeof children === "string") {
children = JX.$H(children);
}
var view = new JX[config.view](config.params, children);
var rendered = JX.ViewRenderer.render(view);
JX.DOM.replace(replace, rendered);
});
});
JX.install('ViewPlaceholder', {
statics: {
register: function(wait_on_token, token, cb) {
var ready_q = [];
if (!wait_on_token || wait_on_token in JX.ViewPlaceholder.ready) {
ready_q.push({token: token, cb: cb});
} else {
var waiting = JX.ViewPlaceholder.waiting;
waiting[wait_on_token] = waiting[wait_on_token] || [];
waiting[wait_on_token].push({token: token, cb: cb});
}
while(ready_q.length) {
var ready = ready_q.shift();
var waiting = JX.ViewPlaceholder.waiting[ready.token];
if (waiting) {
for (var ii = 0; ii < waiting.length; ii++) {
ready_q.push(waiting[ii]);
}
delete JX.ViewPlaceholder.waiting[ready.token];
}
ready.cb();
JX.ViewPlaceholder.ready[token] = true;
}
},
ready: {},
waiting: {}
}
});
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