Alex Rickabaugh dee95994b8 refactor(compiler-cli): support ts.SourceFile versioning (#41475)
Generally, the compiler assumes that `ts.SourceFile`s are immutable objects.
If a new `ts.Program` is compared to an old one, and a `ts.SourceFile`
within that program has not changed its object identity, the compiler will
assume that its prior analysis and understanding of that source file is
still valid.

However, not all TypeScript workflows uphold this assumption. For
`ts.Program`s that originate from the `ts.LanguageService`, some source
files may be re-parsed or otherwise undergo mutations without changing their
object identity. This breaks the compiler's incremental workflow.

Within such environments, it's necessary to track source file changes
differently. In addition to object identity, it's necessary to compare a
"version" string associated with each source file, between when that file is
analyzed originally and when a new program is presented that still contains
it. It's possible for the object identity of the source file to be the same,
but the version string to have changed, indicating that the source file
should be treated as changed.

This commit adds an optional method `getSourceFileVersion` to the
`ProgramDriver`, to provide access to version information if available. When
this method is present, the compiler will build a map of source file version
strings, and use this map to augment identity comparison during incremental
compilation.

PR Close #41475
2021-04-13 13:05:36 -07:00
..
2021-02-22 12:37:40 -08:00

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License: MIT