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various simplifications to _computeChanges

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Jeremy Ashkenas
2012-12-12 17:03:12 -05:00
parent 69b3c1382d
commit f8753b8fea
1 changed files with 26 additions and 27 deletions
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53
backbone.js
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@@ -249,7 +249,7 @@
attrs = _.extend({}, defaults, attrs);
}
this.set(attrs, {silent: true});
this._hasChanged = false;
this._hasComputed = true;
this._changes = [];
this._currentState = _.clone(this.attributes);
this._previousAttributes = _.clone(this.attributes);
@@ -270,7 +270,7 @@
// Whether there has been a `set` call since the last
// calculation of the changed hash, for efficiency.
_hasChanged: false,
_hasComputed: true,
// The model state used for comparison in determining if a
// change should be fired.
@@ -349,11 +349,12 @@
// Update or delete the current value, and track the change.
unset ? delete now[attr] : now[attr] = val;
this._changes.push(attr, val, unset);
this._changes.push(attr, val);
}
// Signal that the model's state has potentially changed.
this._hasChanged = true;
// Signal that the model's state has potentially changed, and we need
// to recompute the actual changes.
this._hasComputed = false;
// Fire the `"change"` events.
if (!silent) this.change(options);
@@ -529,7 +530,7 @@
// Determine if the model has changed since the last `"change"` event.
// If you specify an attribute name, determine if that attribute has changed.
hasChanged: function(attr) {
if (this._hasChanged) this._computeChanges();
if (!this._hasComputed) this._computeChanges();
if (attr == null) return !_.isEmpty(this.changed);
return _.has(this.changed, attr);
},
@@ -550,39 +551,37 @@
return changed;
},
// Calculates and handles any changes in `this._changes`,
// checking against `this._currentState` to determine current changes.
_computeChanges: function (changing) {
// Looking at the built up list of `set` attribute changes, compute how
// many of the attributes have actually changed. If `loud`, return a
// boiled-down list of only the real changes.
_computeChanges: function(loud) {
this.changed = {};
var local = {};
var already = {};
var triggers = [];
var currentState = this._currentState;
var changes = this._changes;
// Loop through the current queue of potential model changes.
for (var i = changes.length - 3; i >= 0; i -= 3) {
var key = changes[i], val = changes[i + 1], unset = changes[i + 2];
for (var i = changes.length - 2; i >= 0; i -= 2) {
var key = changes[i], val = changes[i + 1];
if (already[key]) continue;
already[key] = true;
// If the item hasn't been set locally this round, proceed.
if (!local[key]) {
local[key] = true;
// Check if the attribute has been modified since the last change,
// and update `this.changed` accordingly.
if (currentState[key] !== val) {
this.changed[key] = val;
// Check if the attribute has been modified since the last change,
// and update `this.changed` accordingly.
if (currentState[key] !== val) {
this.changed[key] = val;
// Triggers & modifications are only created inside a `change` call.
if (!changing) continue;
triggers.push(key, val);
(!unset) ? currentState[key] = val : delete currentState[key];
}
// Triggers & modifications are only created inside a `change` call.
if (!loud) continue;
triggers.push(key, val);
currentState[key] = val;
}
}
if (changing) this._changes = [];
if (loud) this._changes = [];
// Signals `this.changed` is current to prevent duplicate calls from `this.hasChanged`.
this._hasChanged = false;
this._hasComputed = true;
return triggers;
},