63 lines
1.7 KiB
Plaintext
63 lines
1.7 KiB
Plaintext
const isPlainObject = require('lodash.isplainobject')
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const parser = require('postcss-selector-parser')
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const parseSelector = parser()
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module.exports = {
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isUsableColor(color, values) {
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return isPlainObject(values) && color !== 'gray' && values[600]
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},
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/**
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* @param {string} selector
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*/
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commonTrailingPseudos(selector) {
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let ast = parseSelector.astSync(selector)
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/** @type {import('postcss-selector-parser').Pseudo[][]} */
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let matrix = []
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// Put the pseudo elements in reverse order in a sparse, column-major 2D array
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for (let [i, sel] of ast.nodes.entries()) {
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for (const [j, child] of [...sel.nodes].reverse().entries()) {
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// We only care about pseudo elements
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if (child.type !== 'pseudo' || !child.value.startsWith('::')) {
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break
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}
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matrix[j] = matrix[j] || []
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matrix[j][i] = child
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}
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}
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let trailingPseudos = parser.selector()
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// At this point the pseudo elements are in a column-major 2D array
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// This means each row contains one "column" of pseudo elements from each selector
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// We can compare all the pseudo elements in a row to see if they are the same
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for (const pseudos of matrix) {
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// It's a sparse 2D array so there are going to be holes in the rows
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// We skip those
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if (!pseudos) {
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continue
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}
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let values = new Set([...pseudos.map((p) => p.value)])
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// The pseudo elements are not the same
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if (values.size > 1) {
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break
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}
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pseudos.forEach((pseudo) => pseudo.remove())
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trailingPseudos.prepend(pseudos[0])
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}
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if (trailingPseudos.nodes.length) {
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return [trailingPseudos.toString(), ast.toString()]
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}
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return [null, selector]
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},
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}
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