can
Version:
MIT-licensed, client-side, JavaScript framework that makes building rich web applications easy.
189 lines (188 loc) • 6.39 kB
JavaScript
steal('can/util', 'can/map', function (can) {
// ** - 'this' will be the deepest item changed
// * - 'this' will be any changes within *, but * will be the
// this returned
// tells if the parts part of a delegate matches the broken up props of the event
// gives the prop to use as 'this'
// - parts - the attribute name of the delegate split in parts ['foo','*']
// - props - the split props of the event that happened ['foo','bar','0']
// - returns - the attribute to delegate too ('foo.bar'), or null if not a match
var delegateMatches = function (parts, props) {
//check props parts are the same or
var len = parts.length,
i = 0,
// keeps the matched props we will use
matchedProps = [],
prop;
// if the event matches
for (i; i < len; i++) {
prop = props[i];
// if no more props (but we should be matching them)
// return null
if (typeof prop !== 'string') {
return null;
} else // if we have a "**", match everything
if (parts[i] === '**') {
return props.join('.');
} else // a match, but we want to delegate to "*"
if (parts[i] === '*') {
// only do this if there is nothing after ...
matchedProps.push(prop);
} else if (prop === parts[i]) {
matchedProps.push(prop);
} else {
return null;
}
}
return matchedProps.join('.');
},
// gets a change event and tries to figure out which
// delegates to call
delegateHandler = function (event, prop, how, newVal, oldVal) {
// pre-split properties to save some regexp time
var props = prop.split('.'),
delegates = (this._observe_delegates || [])
.slice(0),
delegate, attr, matchedAttr, hasMatch, valuesEqual;
event.attr = prop;
event.lastAttr = props[props.length - 1];
// for each delegate
for (var i = 0; delegate = delegates[i++];) {
// if there is a batchNum, this means that this
// event is part of a series of events caused by a single
// attrs call. We don't want to issue the same event
// multiple times
// setting the batchNum happens later
if (event.batchNum && delegate.batchNum === event.batchNum || delegate.undelegated) {
continue;
}
// reset match and values tests
hasMatch = undefined;
valuesEqual = true;
// yeah, all this under here has to be redone v
// for each attr in a delegate
for (var a = 0; a < delegate.attrs.length; a++) {
attr = delegate.attrs[a];
matchedAttr = delegateMatches(attr.parts, props);
// check if it is a match
if (matchedAttr) {
hasMatch = matchedAttr;
}
// if it has a value, make sure it's the right value
// if it's set, we should probably check that it has a
// value no matter what
if (attr.value && valuesEqual) {
valuesEqual = attr.value === '' + this.attr(attr.attr);
} else if (valuesEqual && delegate.attrs.length > 1) {
// if there are multiple attributes, each has to at
// least have some value
valuesEqual = this.attr(attr.attr) !== undefined;
}
}
// if there is a match and valuesEqual ... call back
if (hasMatch && valuesEqual) {
// how to get to the changed property from the delegate
var from = prop.replace(hasMatch + '.', '');
// if this event is part of a batch, set it on the delegate
// to only send one event
if (event.batchNum) {
delegate.batchNum = event.batchNum;
}
// if we listen to change, fire those with the same attrs
// TODO: the attrs should probably be using from
if (delegate.event === 'change') {
prop = from;
event.curAttr = hasMatch;
delegate.callback.apply(this.attr(hasMatch), can.makeArray(arguments));
} else if (delegate.event === how) {
// if it's a match, callback with the location of the match
delegate.callback.apply(this.attr(hasMatch), [
event,
newVal,
oldVal,
from
]);
} else if (delegate.event === 'set' && how === 'add') {
// if we are listening to set, we should also listen to add
delegate.callback.apply(this.attr(hasMatch), [
event,
newVal,
oldVal,
from
]);
}
}
}
};
can.extend(can.Map.prototype, {
delegate: function (selector, event, handler) {
selector = can.trim(selector);
var delegates = this._observe_delegates || (this._observe_delegates = []),
attrs = [],
selectorRegex = /([^\s=,]+)(?:=("[^",]*"|'[^',]*'|[^\s"',]*))?(,?)\s*/g,
matches;
// parse each property in the selector
while ((matches = selectorRegex.exec(selector)) !== null) {
// we need to do a little doctoring to make up for the quotes.
if (matches[2] && can.inArray(matches[2].substr(0, 1), [
'"',
'\''
]) >= 0) {
matches[2] = matches[2].substr(1, -1);
}
attrs.push({
// the attribute name
attr: matches[1],
// the attribute name, pre-split for speed
parts: matches[1].split('.'),
// the value associated with this property (if there was one given)
value: matches[2],
// whether this selector combines with the one after it with AND or OR
or: matches[3] === ','
});
}
// delegates has pre-processed info about the event
delegates.push({
// the attrs name for unbinding
selector: selector,
// an object of attribute names and values {type: 'recipe',id: undefined}
// undefined means a value was not defined
attrs: attrs,
callback: handler,
event: event
});
if (delegates.length === 1) {
this.bind('change', delegateHandler);
}
return this;
},
undelegate: function (selector, event, handler) {
selector = selector && can.trim(selector);
var i = 0,
delegates = this._observe_delegates || [],
delegateOb;
if (selector) {
while (i < delegates.length) {
delegateOb = delegates[i];
if (delegateOb.callback === handler || !handler && delegateOb.selector === selector) {
delegateOb.undelegated = true;
delegates.splice(i, 1);
} else {
i++;
}
}
} else {
// remove all delegates
delegates = [];
}
if (!delegates.length) {
//can.removeData(this, "_observe_delegates");
this.unbind('change', delegateHandler);
}
return this;
}
});
// add helpers for testing ..
can.Map.prototype.delegate.matches = delegateMatches;
return can.Map;
});