carto/lib/mess/tree/import.js
2011-01-21 18:28:54 -05:00

78 lines
2.2 KiB
JavaScript

(function(tree) {
//
// CSS @import node
//
// The general strategy here is that we don't want to wait
// for the parsing to be completed, before we start importing
// the file. That's because in the context of a browser,
// most of the time will be spent waiting for the server to respond.
//
// On creation, we push the import path to our import queue, though
// `import,push`, we also pass it a callback, which it'll call once
// the file has been fetched, and parsed.
//
tree.Import = function(path, imports) {
var that = this;
this._path = path;
// The '.mess' extension is optional
if (path instanceof tree.Quoted) {
this.path = /\.(le?|c)ss$/.test(path.value) ? path.value : path.value + '.mess';
} else {
this.path = path.value.value || path.value;
}
this.css = /css$/.test(this.path);
// Only pre-compile .mess files
if (! this.css) {
imports.push(this.path, function(root) {
if (! root) {
throw new Error('Error parsing ' + that.path);
}
that.root = root;
});
}
};
//
// The actual import node doesn't return anything, when converted to CSS.
// The reason is that it's used at the evaluation stage, so that the rules
// it imports can be treated like any other rules.
//
// In `eval`, we make sure all Import nodes get evaluated, recursively, so
// we end up with a flat structure, which can easily be imported in the parent
// ruleset.
//
tree.Import.prototype = {
toString: function() {
if (this.css) {
return '@import ' + this._path.toString() + ';\n';
} else {
return '';
}
},
eval: function(env) {
var ruleset;
if (this.css) {
return this;
} else {
ruleset = new tree.Ruleset(null, this.root.rules.slice(0));
for (var i = 0; i < ruleset.rules.length; i++) {
if (ruleset.rules[i] instanceof tree.Import) {
Array.prototype
.splice
.apply(ruleset.rules,
[i, 1].concat(ruleset.rules[i].eval(env)));
}
}
return ruleset.rules;
}
}
};
})(require('mess/tree'));