Caret/js/command.js
2014-01-12 03:12:14 -06:00

108 lines
No EOL
3.1 KiB
JavaScript

define([
"util/text!config/commands.json",
"util/dom2"
], function(list) {
try {
list = JSON.parse(list);
} catch (e) {
console.error(e);
list = [];
}
/*
The command module is the heart of Caret's loosely-coupled modules. It
serves as an event bus for inter-module communication, but it also listens
to the DOM for click/change events and makes it easy to bind page interactions
to command callbacks.
Command is usually called as if synchronous, but it does support asynchronous
operation--it will pass a callback in to any subscribers, but will also
immediately pass back the return value (if any) from the those subscribers.
*/
var commands = {};
//commands can pass a callback, although most don't respond that way
var fire = function(command, argument, callback) {
if (!commands[command]) return;
var args = [].slice.call(arguments, 1);
//technically, a function as `argument` is a callback...
if (typeof argument == "function") {
callback = argument;
}
var registry = commands[command].slice();
registry.forEach(function(entry) {
var result = entry.callback.apply(null, args);
//immediately call back if sync-style return value was provided
if (typeof result !== "undefined" || entry.sync) {
//console.info("Immediate return from " + name, result);
if (callback) callback.call(null, result);
}
});
}
var register = function(command, listener, sync) {
if (!commands[command]) {
commands[command] = [];
}
//we allow a sync flag to be set for operations that will definitely return
commands[command].push({
callback: listener,
sync: sync
});
}
//delegate for all elements that have a command attribute
document.body.on("click", function(e) {
//cancel on inputs, selectboxes
if (["input", "select"].indexOf(e.target.tagName.toLowerCase()) >= 0) return;
if (e.button != 0) return;
//delegate all items with a command attribute
if (e.target.hasAttribute("command")) {
var command = e.target.getAttribute("command");
var arg = e.target.getAttribute("argument");
fire(command, arg);
e.preventDefault();
}
});
document.body.on("change", function(e) {
if (e.target.hasAttribute("command")) {
var command = e.target.getAttribute("command");
var arg = e.target.value;
fire(command, arg);
}
});
document.body.on("dragover", function(e) {
e.preventDefault();
});
document.body.on("drop", function(e) {
e.preventDefault();
if (e.dataTransfer.types.indexOf("Files") === -1) return;
fire("session:open-dragdrop", e.dataTransfer.items);
});
//register for startup and fire any commands that are pending
register("init:startup", function() {
if (window.launchCommands) {
window.launchCommands.forEach(function(bundle) {
fire(bundle.message.command, bundle.message.argument, bundle.sendResponse);
});
delete window.launchCommands;
}
});
var facade = {
fire: fire,
on: register,
list: list
};
return facade;
});