| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193 |
- /**
- * Copyright 2018 Google LLC
- *
- * Licensed under the Apache License, Version 2.0 (the "License"); you may not
- * use this file except in compliance with the License. You may obtain a copy of
- * the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations under
- * the License.
- */
- import { parse, stringify } from 'postcss';
- /**
- * Parse a textual CSS Stylesheet into a Stylesheet instance.
- * Stylesheet is a mutable postcss AST with format similar to CSSOM.
- * @see https://github.com/postcss/postcss/
- * @private
- * @param {String} stylesheet
- * @returns {css.Stylesheet} ast
- */
- export function parseStylesheet(stylesheet) {
- return parse(stylesheet);
- }
- /**
- * Serialize a postcss Stylesheet to a String of CSS.
- * @private
- * @param {css.Stylesheet} ast A Stylesheet to serialize, such as one returned from `parseStylesheet()`
- * @param {Object} options Options used by the stringify logic
- * @param {Boolean} [options.compress] Compress CSS output (removes comments, whitespace, etc)
- */
- export function serializeStylesheet(ast, options) {
- let cssStr = '';
- stringify(ast, (result, node, type) => {
- if (!options.compress) {
- cssStr += result;
- return;
- }
- // Simple minification logic
- if (node?.type === 'comment') return;
- if (node?.type === 'decl') {
- const prefix = node.prop + node.raws.between;
- cssStr += result.replace(prefix, prefix.trim());
- return;
- }
- if (type === 'start') {
- if (node.type === 'rule' && node.selectors) {
- cssStr += node.selectors.join(',') + '{';
- } else {
- cssStr += result.replace(/\s\{$/, '{');
- }
- return;
- }
- if (type === 'end' && result === '}' && node?.raws?.semicolon) {
- cssStr = cssStr.slice(0, -1);
- }
- cssStr += result.trim();
- });
- return cssStr;
- }
- /**
- * Converts a walkStyleRules() iterator to mark nodes with `.$$remove=true` instead of actually removing them.
- * This means they can be removed in a second pass, allowing the first pass to be nondestructive (eg: to preserve mirrored sheets).
- * @private
- * @param {Function} iterator Invoked on each node in the tree. Return `false` to remove that node.
- * @returns {(rule) => void} nonDestructiveIterator
- */
- export function markOnly(predicate) {
- return (rule) => {
- const sel = rule.selectors;
- if (predicate(rule) === false) {
- rule.$$remove = true;
- }
- rule.$$markedSelectors = rule.selectors;
- if (rule._other) {
- rule._other.$$markedSelectors = rule._other.selectors;
- }
- rule.selectors = sel;
- };
- }
- /**
- * Apply filtered selectors to a rule from a previous markOnly run.
- * @private
- * @param {css.Rule} rule The Rule to apply marked selectors to (if they exist).
- */
- export function applyMarkedSelectors(rule) {
- if (rule.$$markedSelectors) {
- rule.selectors = rule.$$markedSelectors;
- }
- if (rule._other) {
- applyMarkedSelectors(rule._other);
- }
- }
- /**
- * Recursively walk all rules in a stylesheet.
- * @private
- * @param {css.Rule} node A Stylesheet or Rule to descend into.
- * @param {Function} iterator Invoked on each node in the tree. Return `false` to remove that node.
- */
- export function walkStyleRules(node, iterator) {
- node.nodes = node.nodes.filter((rule) => {
- if (hasNestedRules(rule)) {
- walkStyleRules(rule, iterator);
- }
- rule._other = undefined;
- rule.filterSelectors = filterSelectors;
- return iterator(rule) !== false;
- });
- }
- /**
- * Recursively walk all rules in two identical stylesheets, filtering nodes into one or the other based on a predicate.
- * @private
- * @param {css.Rule} node A Stylesheet or Rule to descend into.
- * @param {css.Rule} node2 A second tree identical to `node`
- * @param {Function} iterator Invoked on each node in the tree. Return `false` to remove that node from the first tree, true to remove it from the second.
- */
- export function walkStyleRulesWithReverseMirror(node, node2, iterator) {
- if (node2 === null) return walkStyleRules(node, iterator);
- [node.nodes, node2.nodes] = splitFilter(
- node.nodes,
- node2.nodes,
- (rule, index, rules, rules2) => {
- const rule2 = rules2[index];
- if (hasNestedRules(rule)) {
- walkStyleRulesWithReverseMirror(rule, rule2, iterator);
- }
- rule._other = rule2;
- rule.filterSelectors = filterSelectors;
- return iterator(rule) !== false;
- }
- );
- }
- // Checks if a node has nested rules, like @media
- // @keyframes are an exception since they are evaluated as a whole
- function hasNestedRules(rule) {
- return (
- rule.nodes &&
- rule.nodes.length &&
- rule.nodes.some((n) => n.type === 'rule' || n.type === 'atrule') &&
- rule.name !== 'keyframes' &&
- rule.name !== '-webkit-keyframes'
- );
- }
- // Like [].filter(), but applies the opposite filtering result to a second copy of the Array without a second pass.
- // This is just a quicker version of generating the compliment of the set returned from a filter operation.
- function splitFilter(a, b, predicate) {
- const aOut = [];
- const bOut = [];
- for (let index = 0; index < a.length; index++) {
- if (predicate(a[index], index, a, b)) {
- aOut.push(a[index]);
- } else {
- bOut.push(a[index]);
- }
- }
- return [aOut, bOut];
- }
- // can be invoked on a style rule to subset its selectors (with reverse mirroring)
- function filterSelectors(predicate) {
- if (this._other) {
- const [a, b] = splitFilter(
- this.selectors,
- this._other.selectors,
- predicate
- );
- this.selectors = a;
- this._other.selectors = b;
- } else {
- this.selectors = this.selectors.filter(predicate);
- }
- }
|