isAsyncOperation.js•1.27 kB
import {ContextualKeyword} from "../parser/tokenizer/keywords";
/**
* Determine whether this optional chain or nullish coalescing operation has any await statements in
* it. If so, we'll need to transpile to an async operation.
*
* We compute this by walking the length of the operation and returning true if we see an await
* keyword used as a real await (rather than an object key or property access). Nested optional
* chain/nullish operations need to be tracked but don't silence await, but a nested async function
* (or any other nested scope) will make the await not count.
*/
export default function isAsyncOperation(tokens) {
let index = tokens.currentIndex();
let depth = 0;
const startToken = tokens.currentToken();
do {
const token = tokens.tokens[index];
if (token.isOptionalChainStart) {
depth++;
}
if (token.isOptionalChainEnd) {
depth--;
}
depth += token.numNullishCoalesceStarts;
depth -= token.numNullishCoalesceEnds;
if (
token.contextualKeyword === ContextualKeyword._await &&
token.identifierRole == null &&
token.scopeDepth === startToken.scopeDepth
) {
return true;
}
index += 1;
} while (depth > 0 && index < tokens.tokens.length);
return false;
}