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'use strict';
const { dirname } = require('path');
const browserslist = require('browserslist');
const valueParser = require('postcss-value-parser');
const regexLowerCaseUPrefix = /^u(?=\+)/;
/**
* @param {string} range
* @return {string}
*/
function unicode(range) {
const values = range.slice(2).split('-');
if (values.length < 2) {
return range;
}
const left = values[0].split('');
const right = values[1].split('');
if (left.length !== right.length) {
return range;
}
const merged = mergeRangeBounds(left, right);
if (merged) {
return merged;
}
return range;
}
/**
* @param {string[]} left
* @param {string[]} right
* @return {false|string}
*/
function mergeRangeBounds(left, right) {
let questionCounter = 0;
let group = 'u+';
for (const [index, value] of left.entries()) {
if (value === right[index] && questionCounter === 0) {
group = group + value;
} else if (value === '0' && right[index] === 'f') {
questionCounter++;
group = group + '?';
} else {
return false;
}
}
// The maximum number of wildcard characters (?) for ranges is 5.
if (questionCounter < 6) {
return group;
} else {
return false;
}
}
/**
* IE and Edge before 16 version ignore the unicode-range if the 'U' is lowercase
*
* https://caniuse.com/#search=unicode-range
*
* @param {string} browser
* @return {boolean}
*/
function hasLowerCaseUPrefixBug(browser) {
return browserslist('ie <=11, edge <= 15').includes(browser);
}
/**
* @param {string} value
* @return {string}
*/
function transform(value, isLegacy = false) {
return valueParser(value)
.walk((child) => {
if (child.type === 'unicode-range') {
const transformed = unicode(child.value.toLowerCase());
child.value = isLegacy
? transformed.replace(regexLowerCaseUPrefix, 'U')
: transformed;
}
return false;
})
.toString();
}
/**
* @typedef {{ overrideBrowserslist?: string | string[] }} AutoprefixerOptions
* @typedef {Pick<browserslist.Options, 'stats' | 'path' | 'env'>} BrowserslistOptions
* @typedef {AutoprefixerOptions & BrowserslistOptions} Options
*/
/**
* @type {import('postcss').PluginCreator<Options>}
* @param {Options} opts
* @return {import('postcss').Plugin}
*/
function pluginCreator(opts = {}) {
return {
postcssPlugin: 'postcss-normalize-unicode',
/**
* @param {import('postcss').Result & {opts: BrowserslistOptions & {file?: string}}} result
*/
prepare(result) {
const { stats, env, from, file } = result.opts || {};
const browsers = browserslist(opts.overrideBrowserslist, {
stats: opts.stats || stats,
path: opts.path || dirname(from || file || __filename),
env: opts.env || env,
});
const cache = new Map();
const isLegacy = browsers.some(hasLowerCaseUPrefixBug);
return {
OnceExit(css) {
css.walkDecls(/^unicode-range$/i, (decl) => {
const value = decl.value;
if (cache.has(value)) {
decl.value = cache.get(value);
return;
}
const newValue = transform(value, isLegacy);
decl.value = newValue;
cache.set(value, newValue);
});
},
};
},
};
}
pluginCreator.postcss = true;
module.exports = pluginCreator;
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