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109 lines
3.2 KiB
Text
109 lines
3.2 KiB
Text
'use strict';
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const selectorParser = require('postcss-selector-parser');
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const valueParser = require('postcss-value-parser');
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const { parser } = require('../parser.js');
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const reducer = require('./reducer.js');
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const stringifier = require('./stringifier.js');
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const MATCH_CALC = /((?:-(moz|webkit)-)?calc)/i;
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/**
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* @param {string} value
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* @param {{precision: number, warnWhenCannotResolve: boolean}} options
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* @param {import("postcss").Result} result
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* @param {import("postcss").ChildNode} item
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*/
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function transformValue(value, options, result, item) {
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return valueParser(value)
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.walk((node) => {
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// skip anything which isn't a calc() function
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if (node.type !== 'function' || !MATCH_CALC.test(node.value)) {
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return;
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}
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// stringify calc expression and produce an AST
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const contents = valueParser.stringify(node.nodes);
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const ast = parser.parse(contents);
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// reduce AST to its simplest form, that is, either to a single value
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// or a simplified calc expression
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const reducedAst = reducer(ast, options.precision);
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// stringify AST and write it back
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/** @type {valueParser.Node} */ (node).type = 'word';
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node.value = stringifier(
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node.value,
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reducedAst,
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value,
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options,
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result,
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item
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);
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return false;
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})
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.toString();
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}
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/**
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* @param {import("postcss-selector-parser").Selectors} value
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* @param {{precision: number, warnWhenCannotResolve: boolean}} options
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* @param {import("postcss").Result} result
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* @param {import("postcss").ChildNode} item
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*/
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function transformSelector(value, options, result, item) {
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return selectorParser((selectors) => {
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selectors.walk((node) => {
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// attribute value
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// e.g. the "calc(3*3)" part of "div[data-size="calc(3*3)"]"
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if (node.type === 'attribute' && node.value) {
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node.setValue(transformValue(node.value, options, result, item));
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}
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// tag value
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// e.g. the "calc(3*3)" part of "div:nth-child(2n + calc(3*3))"
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if (node.type === 'tag') {
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node.value = transformValue(node.value, options, result, item);
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}
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return;
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});
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}).processSync(value);
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}
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/**
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* @param {any} node
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* @param {{precision: number, preserve: boolean, warnWhenCannotResolve: boolean}} options
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* @param {'value'|'params'|'selector'} property
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* @param {import("postcss").Result} result
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*/
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module.exports = (node, property, options, result) => {
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let value = node[property];
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try {
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value =
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property === 'selector'
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? transformSelector(node[property], options, result, node)
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: transformValue(node[property], options, result, node);
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} catch (error) {
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if (error instanceof Error) {
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result.warn(error.message, { node });
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} else {
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result.warn('Error', { node });
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}
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return;
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}
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// if the preserve option is enabled and the value has changed, write the
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// transformed value into a cloned node which is inserted before the current
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// node, preserving the original value. Otherwise, overwrite the original
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// value.
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if (options.preserve && node[property] !== value) {
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const clone = node.clone();
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clone[property] = value;
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node.parent.insertBefore(node, clone);
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} else {
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node[property] = value;
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}
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};
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