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phab/webroot/rsrc/externals/javelin/ext/view/View.js
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View.js
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/**
* A View is a composable wrapper on JX.$N, allowing abstraction of higher-order
* views and a consistent pattern of parameterization. It is intended
* to be used either directly or as a building block for a syntactic sugar layer
* for concise expression of markup patterns.
*
* @provides javelin-view
* @requires javelin-install
* javelin-util
*/
JX.install('View', {
construct : function(attrs, children) {
this._attributes = JX.copy({}, this.getDefaultAttributeValues());
JX.copy(this._attributes, attrs);
this._rawChildren = {};
this._childKeys = [];
if (children) {
this.addChildren(JX.$AX(children));
}
this.setName(this.__class__.__readable__);
},
events: [
'change'
],
properties: {
'name': null
},
members : {
_attributes : null,
_rawChildren : null,
_childKeys: null, // keys of rawChildren, kept ordered.
_nextChildKey: 0, // next key to use for a new child
/*
* Don't override.
* TODO: Strongly typed attribute access (getIntAttr, getStringAttr...)?
*/
getAttr : function(attrName) {
return this._attributes[attrName];
},
/*
* Don't override.
*/
multisetAttr : function(attrs) {
JX.copy(this._attributes, attrs);
this.invoke('change');
return this;
},
/*
* Don't override.
*/
setAttr : function(attrName, value) {
this._attributes[attrName] = value;
this.invoke('change');
return this;
},
/*
* Child views can override to specify default values for attributes.
*/
getDefaultAttributeValues : function() {
return {};
},
/**
* Don't override.
*/
getAllAttributes: function() {
return JX.copy({}, this._attributes);
},
/**
* Get the children. Don't override.
*/
getChildren : function() {
var result = [];
var should_repack = false;
var ii;
var key;
for (ii = 0; ii < this._childKeys.length; ii++) {
key = this._childKeys[ii];
if (this._rawChildren[key] === undefined) {
should_repack = true;
} else {
result.push(this._rawChildren[key]);
}
}
if (should_repack) {
var new_child_keys = [];
for (ii = 0; ii < this._childKeys.length; ii++) {
key = this._childKeys[ii];
if (this._rawChildren[key] !== undefined) {
new_child_keys.push(key);
}
}
this._childKeys = new_child_keys;
}
return result;
},
/**
* Add children to the view. Returns array of removal handles.
* Don't override.
*/
addChildren : function(children) {
var result = [];
for (var ii = 0; ii < children.length; ii++) {
result.push(this._addChild(children[ii]));
}
this.invoke('change');
return result;
},
/**
* Add a single child view to the view.
* Returns a removal handle, i.e. an object that has a method remove(),
* that removes the added child from the view.
*
* Don't override.
*/
addChild: function(child) {
var result = this._addChild(child);
this.invoke('change');
return result;
},
_addChild: function(child) {
var key = this._nextChildKey++;
this._rawChildren[key] = child;
this._childKeys.push(key);
return {
remove: JX.bind(this, this._removeChild, key)
};
},
_removeChild: function(child_key) {
delete this._rawChildren[child_key];
this.invoke('change');
},
/**
* Accept visitors. This allows adding new behaviors to Views without
* having to change View classes themselves.
*
* This implements a post-order traversal over the tree of views. Children
* are processed before parents, and for convenience the results of the
* visitor on the children are passed to it when processing the parent.
*
* The visitor parameter is a callable which receives two parameters.
* The first parameter is the view to visit. The second parameter is an
* array of the results of visiting the view's children.
*
* Don't override.
*/
accept: function(visitor) {
var results = [];
var children = this.getChildren();
for(var ii = 0; ii < children.length; ii++) {
var result;
if (children[ii].accept) {
result = children[ii].accept(visitor);
} else {
result = children[ii];
}
results.push(result);
}
return visitor(this, results);
},
/**
* Given the already-rendered children, return the rendered result of
* this view.
* By default, just pass the children through.
*/
render: function(rendered_children) {
return rendered_children;
}
}
});
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