names.js•2.94 kB
const keywords = new Map();
const properties = new Map();
const HYPHENMINUS = 45; // '-'.charCodeAt()
export const keyword = getKeywordDescriptor;
export const property = getPropertyDescriptor;
export const vendorPrefix = getVendorPrefix;
export function isCustomProperty(str, offset) {
offset = offset || 0;
return str.length - offset >= 2 &&
str.charCodeAt(offset) === HYPHENMINUS &&
str.charCodeAt(offset + 1) === HYPHENMINUS;
}
function getVendorPrefix(str, offset) {
offset = offset || 0;
// verdor prefix should be at least 3 chars length
if (str.length - offset >= 3) {
// vendor prefix starts with hyper minus following non-hyper minus
if (str.charCodeAt(offset) === HYPHENMINUS &&
str.charCodeAt(offset + 1) !== HYPHENMINUS) {
// vendor prefix should contain a hyper minus at the ending
const secondDashIndex = str.indexOf('-', offset + 2);
if (secondDashIndex !== -1) {
return str.substring(offset, secondDashIndex + 1);
}
}
}
return '';
}
function getKeywordDescriptor(keyword) {
if (keywords.has(keyword)) {
return keywords.get(keyword);
}
const name = keyword.toLowerCase();
let descriptor = keywords.get(name);
if (descriptor === undefined) {
const custom = isCustomProperty(name, 0);
const vendor = !custom ? getVendorPrefix(name, 0) : '';
descriptor = Object.freeze({
basename: name.substr(vendor.length),
name,
prefix: vendor,
vendor,
custom
});
}
keywords.set(keyword, descriptor);
return descriptor;
}
function getPropertyDescriptor(property) {
if (properties.has(property)) {
return properties.get(property);
}
let name = property;
let hack = property[0];
if (hack === '/') {
hack = property[1] === '/' ? '//' : '/';
} else if (hack !== '_' &&
hack !== '*' &&
hack !== '$' &&
hack !== '#' &&
hack !== '+' &&
hack !== '&') {
hack = '';
}
const custom = isCustomProperty(name, hack.length);
// re-use result when possible (the same as for lower case)
if (!custom) {
name = name.toLowerCase();
if (properties.has(name)) {
const descriptor = properties.get(name);
properties.set(property, descriptor);
return descriptor;
}
}
const vendor = !custom ? getVendorPrefix(name, hack.length) : '';
const prefix = name.substr(0, hack.length + vendor.length);
const descriptor = Object.freeze({
basename: name.substr(prefix.length),
name: name.substr(hack.length),
hack,
vendor,
prefix,
custom
});
properties.set(property, descriptor);
return descriptor;
}