src/vs/base/common/uri.ts/_asFormatted
function _asFormatted(uri: URI, skipEncoding: boolean): string {

	const encoder = !skipEncoding
		? encodeURIComponentFast
		: encodeURIComponentMinimal;

	let res = '';
	let { scheme, authority, path, query, fragment } = uri;
	if (scheme) {
		res += scheme;
		res += ':';
	}
	if (authority || scheme === 'file') {
		res += _slash;
		res += _slash;
	}
	if (authority) {
		let idx = authority.indexOf('@');
		if (idx !== -1) {
			// <user>@<auth>
			const userinfo = authority.substr(0, idx);
			authority = authority.substr(idx + 1);
			idx = userinfo.indexOf(':');
			if (idx === -1) {
				res += encoder(userinfo, false);
			} else {
				// <user>:<pass>@<auth>
				res += encoder(userinfo.substr(0, idx), false);
				res += ':';
				res += encoder(userinfo.substr(idx + 1), false);
			}
			res += '@';
		}
		authority = authority.toLowerCase();
		idx = authority.indexOf(':');
		if (idx === -1) {
			res += encoder(authority, false);
		} else {
			// <auth>:<port>
			res += encoder(authority.substr(0, idx), false);
			res += authority.substr(idx);
		}
	}
	if (path) {
		// lower-case windows drive letters in /C:/fff or C:/fff
		if (path.length >= 3 && path.charCodeAt(0) === CharCode.Slash && path.charCodeAt(2) === CharCode.Colon) {
			const code = path.charCodeAt(1);
			if (code >= CharCode.A && code <= CharCode.Z) {
				path = `/${String.fromCharCode(code + 32)}:${path.substr(3)}`; // "/c:".length === 3
			}
		} else if (path.length >= 2 && path.charCodeAt(1) === CharCode.Colon) {
			const code = path.charCodeAt(0);
			if (code >= CharCode.A && code <= CharCode.Z) {
				path = `${String.fromCharCode(code + 32)}:${path.substr(2)}`; // "/c:".length === 3
			}
		}
		// encode the rest of the path
		res += encoder(path, true);
	}
	if (query) {
		res += '?';
		res += encoder(query, false);
	}
	if (fragment) {
		res += '#';
		res += !skipEncoding ? encodeURIComponentFast(fragment, false) : fragment;
	}
	return res;
}