This reverts commit a67a0436f7, reversing
changes made to 9965df76d0.
This commit or the earlier commit this commit is based on (#40531) broke the
incremental bot.
- Checkout apple/swift-experimental-string-processing using a tag.
- Build `_MatchingEngine` as part of libswift (`ExperimentalRegex`) using sources from the package.
- Parse regex literals using the parser from `_MatchingEngine`.
- Build both `_MatchingEngine` and `_StringProcessing` as part of core libs using sources from the package.
- Use `Regex<DynamicCaptures>` as the default regex type until we finalize apple/swift-experimental-string-processing#68.
- Frontend: Implicitly import `_StringProcessing` when frontend flag `-enable-experimental-string-processing` is set.
- Type checker: Set a regex literal expression's type as `_StringProcessing.Regex<(Substring, DynamicCaptures)>`. `(Substring, DynamicCaptures)` is a temporary `Match` type that will help get us to an end-to-end working system. This will be replaced by actual type inference based a regex's pattern in a follow-up patch (soon).
- SILGen: Lower a regex literal expression to a call to `_StringProcessing.Regex.init(_regexString:)`.
- String processing runtime: Add `Regex`, `DynamicCaptures` (matching actual APIs in apple/swift-experimental-string-processing), and `Regex(_regexString:)`.
Upcoming:
- Build `_MatchingEngine` and `_StringProcessing` modules with sources from apple/swift-experimental-string-processing.
- Replace `DynamicCaptures` with inferred capture types.
These modules are part of the experimental declarative string processing feature. If accepted to the Standard Library, _StringProcessing will be available via implicit import just like _Concurrency, though _MatchingEngine will still be hidden as an implementation detail.
`_MatchingEngine` will contain the general-purpose pattern matching engine ISA, bytecode, and executor. `_StringProcessing` will contain regular expression and pattern matching APIs whose implementation depends on the matching engine..
Also consolidates frontend flag `-enable-experimental-regex` as `-enable-experimental-string-processing`.
Resolves rdar://85478647.
