yomichan/dev/css-to-json-util.js

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/*
* Copyright (C) 2021-2022 Yomichan Authors
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
const fs = require('fs');
const css = require('css');
function indexOfRule(rules, selectors) {
const jj = selectors.length;
for (let i = 0, ii = rules.length; i < ii; ++i) {
const ruleSelectors = rules[i].selectors;
if (ruleSelectors.length !== jj) { continue; }
let okay = true;
for (let j = 0; j < jj; ++j) {
if (selectors[j] !== ruleSelectors[j]) {
okay = false;
break;
}
}
if (okay) { return i; }
}
return -1;
}
function removeProperty(styles, property, removedProperties) {
let removeCount = removedProperties.get(property);
if (typeof removeCount !== 'undefined') { return removeCount; }
removeCount = 0;
for (let i = 0, ii = styles.length; i < ii; ++i) {
const key = styles[i][0];
if (key !== property) { continue; }
styles.splice(i, 1);
--i;
--ii;
++removeCount;
}
removedProperties.set(property, removeCount);
return removeCount;
}
function formatRulesJson(rules) {
// Manually format JSON, for improved compactness
// return JSON.stringify(rules, null, 4);
const indent1 = ' ';
const indent2 = indent1.repeat(2);
const indent3 = indent1.repeat(3);
let result = '';
result += '[';
let index1 = 0;
for (const {selectors, styles} of rules) {
if (index1 > 0) { result += ','; }
result += `\n${indent1}{\n${indent2}"selectors": `;
if (selectors.length === 1) {
result += `[${JSON.stringify(selectors[0], null, 4)}]`;
} else {
result += JSON.stringify(selectors, null, 4).replace(/\n/g, '\n' + indent2);
}
result += `,\n${indent2}"styles": [`;
let index2 = 0;
for (const [key, value] of styles) {
if (index2 > 0) { result += ','; }
result += `\n${indent3}[${JSON.stringify(key)}, ${JSON.stringify(value)}]`;
++index2;
}
if (index2 > 0) { result += `\n${indent2}`; }
result += `]\n${indent1}}`;
++index1;
}
if (index1 > 0) { result += '\n'; }
result += ']';
return result;
}
function generateRules(cssFile, overridesCssFile) {
const content1 = fs.readFileSync(cssFile, {encoding: 'utf8'});
const content2 = fs.readFileSync(overridesCssFile, {encoding: 'utf8'});
const stylesheet1 = css.parse(content1, {}).stylesheet;
const stylesheet2 = css.parse(content2, {}).stylesheet;
const removePropertyPattern = /^remove-property\s+([a-zA-Z0-9-]+)$/;
const removeRulePattern = /^remove-rule$/;
const rules = [];
// Default stylesheet
for (const rule of stylesheet1.rules) {
if (rule.type !== 'rule') { continue; }
const {selectors, declarations} = rule;
const styles = [];
for (const declaration of declarations) {
if (declaration.type !== 'declaration') { console.log(declaration); continue; }
const {property, value} = declaration;
styles.push([property, value]);
}
if (styles.length > 0) {
rules.push({selectors, styles});
}
}
// Overrides
for (const rule of stylesheet2.rules) {
if (rule.type !== 'rule') { continue; }
const {selectors, declarations} = rule;
const removedProperties = new Map();
for (const declaration of declarations) {
switch (declaration.type) {
case 'declaration':
{
const index = indexOfRule(rules, selectors);
let entry;
if (index >= 0) {
entry = rules[index];
} else {
entry = {selectors, styles: []};
rules.push(entry);
}
const {property, value} = declaration;
removeProperty(entry.styles, property, removedProperties);
entry.styles.push([property, value]);
}
break;
case 'comment':
{
const index = indexOfRule(rules, selectors);
if (index < 0) { throw new Error('Could not find rule with matching selectors'); }
const comment = declaration.comment.trim();
let m;
if ((m = removePropertyPattern.exec(comment)) !== null) {
const property = m[1];
const removeCount = removeProperty(rules[index].styles, property, removedProperties);
if (removeCount === 0) { throw new Error(`Property removal is unnecessary; ${property} does not exist`); }
} else if ((m = removeRulePattern.exec(comment)) !== null) {
rules.splice(index, 1);
}
}
break;
}
}
}
// Remove empty
for (let i = 0, ii = rules.length; i < ii; ++i) {
if (rules[i].styles.length > 0) { continue; }
rules.splice(i, 1);
--i;
--ii;
}
return rules;
}
module.exports = {
formatRulesJson,
generateRules
};