Add support for TS type-only imports and exports #532
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Fixes #520 The PR #523 already added parsing support for type-only import and export syntax, and there was already support for removing `import type` from Flow, so the only new logic was to fully support `export type`. The implementation here is a little ugly; Flow's version sets the tokens as type tokens, whereas the TS version sets the types as regular tokens and removes them at transform type. This seems to be necessary to follow the behavior that `export type` statements do not result in the imported value being elided. Ideally, Sucrase would support the `importsNotUsedAsValues` TS preference in some way, but for now, it keeps the old behavior of eliding type-only imports. The setting `importsNotUsedAsValues=error` should make the distinction irrelevant anyway, so it seems low priority to support.
Codecov Report
@@ Coverage Diff @@
## master #532 +/- ##
==========================================
+ Coverage 81.34% 81.43% +0.08%
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Files 55 55
Lines 5479 5493 +14
Branches 1289 1293 +4
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+ Hits 4457 4473 +16
+ Misses 735 734 -1
+ Partials 287 286 -1
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Fixes #520
The PR #523 already added parsing support for type-only import and export
syntax, and there was already support for removing
import typefrom Flow, sothe only new logic was to fully support
export type. The implementation hereis a little ugly; Flow's version sets the tokens as type tokens, whereas the TS
version sets the types as regular tokens and removes them at transform type.
This seems to be necessary to follow the behavior that
export typestatementsdo not result in the imported value being elided.
Ideally, Sucrase would support the
importsNotUsedAsValuesTS preference insome way, but for now, it keeps the old behavior of eliding type-only imports.
The setting
importsNotUsedAsValues=errorshould make the distinctionirrelevant anyway, so it seems low priority to support.