/
extend.js
48 lines (40 loc) · 1.01 KB
/
extend.js
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/**
* Module dependencies.
*/
var debug = require('debug')('rework:extend');
/**
* Add extension support.
*/
module.exports = function() {
debug('use extend');
return function(style, rework){
var map = {};
style.rules.forEach(function(rule){
if (!rule.declarations) return;
rule.selectors.forEach(function(selector){
map[selector] = rule;
});
visit(rule, map);
});
}
};
/**
* Visit declarations and extensions.
*
* @param {Object} rule
* @param {Object} map
* @api private
*/
function visit(rule, map) {
for (var i = 0; i < rule.declarations.length; ++i) {
var decl = rule.declarations[i];
var key = decl.property;
var val = decl.value;
if (!/^extends?$/.test(key)) continue;
var extend = map[val];
if (!extend) throw new Error('failed to extend "' + val + '"');
debug('extend %j with %j', rule.selectors, extend.selectors);
extend.selectors = extend.selectors.concat(rule.selectors);
rule.declarations.splice(i--, 1);
}
}