114 lines
3.0 KiB
JavaScript
114 lines
3.0 KiB
JavaScript
'use strict';
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const keywords = new Map();
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const properties = new Map();
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const HYPHENMINUS = 45; // '-'.charCodeAt()
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const keyword = getKeywordDescriptor;
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const property = getPropertyDescriptor;
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const vendorPrefix = getVendorPrefix;
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function isCustomProperty(str, offset) {
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offset = offset || 0;
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return str.length - offset >= 2 &&
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str.charCodeAt(offset) === HYPHENMINUS &&
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str.charCodeAt(offset + 1) === HYPHENMINUS;
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}
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function getVendorPrefix(str, offset) {
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offset = offset || 0;
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// verdor prefix should be at least 3 chars length
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if (str.length - offset >= 3) {
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// vendor prefix starts with hyper minus following non-hyper minus
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if (str.charCodeAt(offset) === HYPHENMINUS &&
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str.charCodeAt(offset + 1) !== HYPHENMINUS) {
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// vendor prefix should contain a hyper minus at the ending
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const secondDashIndex = str.indexOf('-', offset + 2);
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if (secondDashIndex !== -1) {
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return str.substring(offset, secondDashIndex + 1);
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}
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}
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}
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return '';
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}
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function getKeywordDescriptor(keyword) {
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if (keywords.has(keyword)) {
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return keywords.get(keyword);
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}
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const name = keyword.toLowerCase();
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let descriptor = keywords.get(name);
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if (descriptor === undefined) {
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const custom = isCustomProperty(name, 0);
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const vendor = !custom ? getVendorPrefix(name, 0) : '';
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descriptor = Object.freeze({
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basename: name.substr(vendor.length),
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name,
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prefix: vendor,
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vendor,
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custom
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});
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}
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keywords.set(keyword, descriptor);
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return descriptor;
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}
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function getPropertyDescriptor(property) {
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if (properties.has(property)) {
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return properties.get(property);
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}
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let name = property;
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let hack = property[0];
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if (hack === '/') {
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hack = property[1] === '/' ? '//' : '/';
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} else if (hack !== '_' &&
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hack !== '*' &&
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hack !== '$' &&
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hack !== '#' &&
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hack !== '+' &&
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hack !== '&') {
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hack = '';
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}
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const custom = isCustomProperty(name, hack.length);
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// re-use result when possible (the same as for lower case)
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if (!custom) {
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name = name.toLowerCase();
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if (properties.has(name)) {
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const descriptor = properties.get(name);
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properties.set(property, descriptor);
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return descriptor;
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}
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}
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const vendor = !custom ? getVendorPrefix(name, hack.length) : '';
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const prefix = name.substr(0, hack.length + vendor.length);
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const descriptor = Object.freeze({
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basename: name.substr(prefix.length),
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name: name.substr(hack.length),
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hack,
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vendor,
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prefix,
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custom
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});
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properties.set(property, descriptor);
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return descriptor;
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}
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exports.isCustomProperty = isCustomProperty;
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exports.keyword = keyword;
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exports.property = property;
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exports.vendorPrefix = vendorPrefix;
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