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importer.js
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importer.js
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const fs = require('fs');
const csstree = require('css-tree');
const config = require('./css-sniper.conf');
function sniperImporter() {
return function(url, prev, done) {
if (url.startsWith('@')) {
const [definitions, fileBase, fileUrl] = parseImportString(url);
const baseUrl = getCachedOrigin(fileBase);
if (!baseUrl || baseUrl === fileBase) return new Error('Couldn\'t resolve path');
const file = `${baseUrl}/${fileUrl}`;
let contents;
if (definitions.length === 0) {
// Importing .css files has been deprecated in libsass:
// https://github.com/sass/libsass/pull/2613
// (rationale in https://github.com/sass/libsass/issues/2611)
contents = fs.readFileSync(file, 'utf-8');
}
else {
contents = parseFile(file, definitions);
}
return { contents: contents };
}
return { file: url };
};
}
function getCachedOrigin(base) {
getCachedOrigin.cache = getCachedOrigin.cache || [];
if (getCachedOrigin.cache[base]) return getCachedOrigin.cache[base];
const origin = getOrigin(base);
getCachedOrigin.cache[base] = origin;
return origin;
}
function getOrigin(base) {
return config.resolver(base);
}
/**
* Parse an import string.
*
* Syntax: @import "@seven/css/base/elements.css remove { body,
* .thunder-details, .apple { color; font-size } }";
*
*/
function parseImportString(string) {
let [file, definitionString] = string.replace(/\n/g, ' ' ).split(' remove ').map(val => val.trim());
const [, fileBase, filePath] = file.split(/@(.+?)\//);
if (definitionString) {
let selectorMatches = definitionString.match(/{([\s\S]+)}/);
if (selectorMatches) {
// Parse import string into ast.
let definition = csstree.parse(selectorMatches[1]);
return [ definition, fileBase, filePath ];
}
}
return [ [], fileBase, filePath];
}
/**
*
*/
function parseFile(file, definition){
let contents = fs.readFileSync(file, 'utf-8');
// Parse css into ast, see https://astexplorer.net
let ast = csstree.parse(contents, {
filename: file,
tolerant: true,
onParseError: function (error) {
console.log(error.message);
}
});
removeSelectors(ast, definition);
return csstree.generate(ast);
}
function removeSelectors(ast, definition) {
csstree.walk(ast, function (rule, item, list) {
// Handle removal of @-rules.
if (rule.type === 'Atrule') {
let atRule = rule;
csstree.walk(definition, function (defRule) {
if ( defRule.type !== 'Atrule' && defRule.type !== 'Rule') {
return;
}
// Remove the whole rule when there are no selectors.
if (defRule.block.children.getSize() === 0) {
if (checkAtruleIsSame(atRule, defRule)) {
list.remove(item);
}
}
});
}
// Ignore all other types.
if (rule.type !== 'Rule') {
return;
}
// Render selector from ast for comparison.
let selector = csstree.generate(rule.prelude);
// this.atrule corresponds to the stylesheet context.
let atRule = this.atrule;
// Context changes to the definition tree here.
csstree.walk(definition, function (defRule) {
if ( defRule.type !== 'Atrule' && defRule.type !== 'Rule') {
return;
}
let defSelector = csstree.generate(defRule.prelude);
if (selector === defSelector) {
if (checkAtruleIsSame(atRule, this.atrule)) {
// Remove declarations or the whole rule.
if (defRule.block.children.getSize()) {
removeDeclarations(rule, item, list, defRule.block.children);
}
else {
list.remove(item);
}
}
}
});
// Remove rule if there are no declarations.
if (rule.block.children.isEmpty()) {
list.remove(item);
}
});
}
function removeDeclarations(rule, ruleitem, rulelist, declarations) {
let warn = false;
// Traverse csstree Lists
rule.block.children.each(function(node, item, list) {
if (node.type === 'Declaration') {
declarations.each(function(currentNode) {
if (node.property === currentNode.value.replace(/;/g , '')) {
list.remove(item);
}
else if (currentNode.type === 'Raw') {
// Handle comma separated declarations.
currentNode.value.split(',').forEach(function (value) {
if (node.property === value.trim()) {
list.remove(item);
warn = true;
}
});
}
});
}
});
if (warn) console.log('WARNING: Use of commas in remove definition is deprecated and will be removed, use semi-colon instead.');
}
function checkAtruleIsSame(atRule, defAtRule) {
if (!atRule && !defAtRule) {
// no @-rule
return true;
// Check if css rule is also in @-rule and compare type. e.g. @media
} else if (atRule && defAtRule && atRule.name === defAtRule.name) {
let prelude = csstree.generate(atRule.prelude);
let defPrelude = csstree.generate(defAtRule.prelude);
// Compare selector, e.g. screen and width()
if (prelude === defPrelude) {
return true;
}
}
return false;
}
module.exports = {
sniperImporter,
};