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
Angular
The sources for this package are in the main Angular repo. Please file issues and pull requests against that repo.
Usage information and reference details can be found in Angular documentation.
License: MIT