Allow await expressions in optional chaining and nullish coalescing #497
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Progress toward #461 Tech plan: https://github.com/alangpierce/sucrase/wiki/Sucrase-Optional-Chaining-and-Nullish-Coalescing-Technical-Plan We now scan for an await keyword to indicate that the nullish coalescing or optional chaining operation is an async one, and in that case, call a different helper and emit async arrow functions instead of regular ones. This needed a few extra pieces of information in the token structure: * We now keep track of the scope depth to distinguish awaits inside inner async functions. * We use a token field to mark that the start token is an async operation. * We now track the start token for each nullish coalescing operation so that we can reference it to determine whether to emit an async arrow function. The extra token state and the duplicated helpers are all a bit ugly, but hopefully there won't be much more complexity beyond this, and I may investigate ways to store the token state in a more concise way. And, of course, this transform will go away eventually when optional chaining is available in node.
Codecov Report
@@ Coverage Diff @@
## master #497 +/- ##
==========================================
+ Coverage 82.59% 82.63% +0.03%
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Files 54 55 +1
Lines 5545 5355 -190
Branches 1238 1253 +15
==========================================
- Hits 4580 4425 -155
+ Misses 678 646 -32
+ Partials 287 284 -3
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Progress toward #461
Tech plan:
https://github.com/alangpierce/sucrase/wiki/Sucrase-Optional-Chaining-and-Nullish-Coalescing-Technical-Plan
We now scan for an await keyword to indicate that the nullish coalescing or
optional chaining operation is an async one, and in that case, call a different
helper and emit async arrow functions instead of regular ones.
This needed a few extra pieces of information in the token structure:
functions.
can reference it to determine whether to emit an async arrow function.
The extra token state and the duplicated helpers are all a bit ugly, but
hopefully there won't be much more complexity beyond this, and I may investigate
ways to store the token state in a more concise way. And, of course, this
transform will go away eventually when optional chaining is available in node.