47 lines
1.3 KiB
JavaScript
47 lines
1.3 KiB
JavaScript
import postcss from 'postcss';
|
|
|
|
const OVERRIDABLE_RULES = ['keyframes', 'counter-style'];
|
|
const SCOPE_RULES = ['media', 'supports'];
|
|
|
|
function isOverridable(name) {
|
|
return OVERRIDABLE_RULES.indexOf(postcss.vendor.unprefixed(name)) !== -1;
|
|
}
|
|
|
|
function isScope(name) {
|
|
return SCOPE_RULES.indexOf(postcss.vendor.unprefixed(name)) !== -1;
|
|
}
|
|
|
|
function getScope(node) {
|
|
let current = node.parent;
|
|
let chain = [node.name, node.params];
|
|
do {
|
|
if (current.type === 'atrule' && isScope(current.name)) {
|
|
chain.unshift(current.name + ' ' + current.params);
|
|
}
|
|
current = current.parent;
|
|
} while (current);
|
|
return chain.join('|');
|
|
}
|
|
|
|
export default postcss.plugin('postcss-discard-overridden', () => {
|
|
return css => {
|
|
let cache = {};
|
|
let rules = [];
|
|
css.walkAtRules(rule => {
|
|
if (rule.type === 'atrule' && isOverridable(rule.name)) {
|
|
let scope = getScope(rule);
|
|
cache[scope] = rule;
|
|
rules.push({
|
|
node: rule,
|
|
scope
|
|
});
|
|
}
|
|
});
|
|
rules.forEach(rule => {
|
|
if (cache[rule.scope] !== rule.node) {
|
|
rule.node.remove();
|
|
}
|
|
});
|
|
};
|
|
});
|