const { hasOwnProperty } = Object.prototype; function buildMap(list, caseInsensitive) { const map = Object.create(null); if (!Array.isArray(list)) { return null; } for (let name of list) { if (caseInsensitive) { name = name.toLowerCase(); } map[name] = true; } return map; } function buildList(data) { if (!data) { return null; } const tags = buildMap(data.tags, true); const ids = buildMap(data.ids); const classes = buildMap(data.classes); if (tags === null && ids === null && classes === null) { return null; } return { tags, ids, classes }; } export function buildIndex(data) { let scopes = false; if (data.scopes && Array.isArray(data.scopes)) { scopes = Object.create(null); for (let i = 0; i < data.scopes.length; i++) { const list = data.scopes[i]; if (!list || !Array.isArray(list)) { throw new Error('Wrong usage format'); } for (const name of list) { if (hasOwnProperty.call(scopes, name)) { throw new Error(`Class can't be used for several scopes: ${name}`); } scopes[name] = i + 1; } } } return { whitelist: buildList(data), blacklist: buildList(data.blacklist), scopes }; }