Merge branch 'main' of github.com:apple/swift-experimental-string-processing into main-integration-d2ff78f6

Author: rxwei

Package.swift

@@ -14,8 +14,8 @@ let package = Package(
             name: "Prototypes",
             targets: ["Prototypes"]),
         .library(
-            name: "_MatchingEngine",
-            targets: ["_MatchingEngine"]),
+            name: "_RegexParser",
+            targets: ["_RegexParser"]),
         .executable(
             name: "VariadicsGenerator",
             targets: ["VariadicsGenerator"])
@@ -27,27 +27,27 @@ let package = Package(
         // Targets are the basic building blocks of a package. A target can define a module or a test suite.
         // Targets can depend on other targets in this package, and on products in packages which this package depends on.
         .target(
-            name: "_MatchingEngine",
+            name: "_RegexParser",
             dependencies: [],
             swiftSettings: [
                 .unsafeFlags(["-enable-library-evolution"])
             ]),
         .testTarget(
             name: "MatchingEngineTests",
             dependencies: [
-              "_MatchingEngine", "_StringProcessing"]),
+              "_RegexParser", "_StringProcessing"]),
         .target(
             name: "_CUnicode",
             dependencies: []),
         .target(
             name: "_StringProcessing",
-            dependencies: ["_MatchingEngine", "_CUnicode"],
+            dependencies: ["_RegexParser", "_CUnicode"],
             swiftSettings: [
                 .unsafeFlags(["-enable-library-evolution"]),
             ]),
         .target(
             name: "RegexBuilder",
-            dependencies: ["_StringProcessing", "_MatchingEngine"],
+            dependencies: ["_StringProcessing", "_RegexParser"],
             swiftSettings: [
                 .unsafeFlags(["-enable-library-evolution"]),
                 .unsafeFlags(["-Xfrontend", "-enable-experimental-pairwise-build-block"])
@@ -63,7 +63,7 @@ let package = Package(
             ]),
         .target(
             name: "Prototypes",
-            dependencies: ["_MatchingEngine", "_StringProcessing"]),
+            dependencies: ["_RegexParser", "_StringProcessing"]),
 
         // MARK: Scripts
         .executableTarget(
@@ -75,14 +75,14 @@ let package = Package(
             name: "PatternConverter",
             dependencies: [
               .product(name: "ArgumentParser", package: "swift-argument-parser"),
-              "_MatchingEngine",
+              "_RegexParser",
               "_StringProcessing"
             ]),
 
         // MARK: Exercises
         .target(
           name: "Exercises",
-          dependencies: ["_MatchingEngine", "Prototypes", "_StringProcessing", "RegexBuilder"],
+          dependencies: ["_RegexParser", "Prototypes", "_StringProcessing", "RegexBuilder"],
           swiftSettings: [
               .unsafeFlags(["-Xfrontend", "-enable-experimental-pairwise-build-block"])
           ]),

README.md

@@ -12,13 +12,13 @@ See [Declarative String Processing Overview][decl-string]
 
 ## Integration with Swift
 
-`_MatchingEngine`, `_CUnicode` and `_StringProcessing` are specially integrated modules that are built as part of apple/swift.
+`_RegexParser` and `_StringProcessing` are specially integrated modules that are built as part of apple/swift.
 
-Specifically, `_MatchingEngine` contains the parser for regular expression literals and is built both as part of the compiler and as a core library. `_CUnicode` and `_StringProcessing` are built together as a core library named `_StringProcessing`.
+Specifically, `_RegexParser` contains the parser for regular expression literals and is built both as part of the compiler and as a core library. `_CUnicode` and `_StringProcessing` are built together as a core library named `_StringProcessing`.
 
 | Module              | Swift toolchain component                                                            |
 | ------------------- | ------------------------------------------------------------------------------------ |
-| `_MatchingEngine`   | `SwiftCompilerSources/Sources/ExperimentalRegex` and `stdlib/public/_MatchingEngine` |
+| `_RegexParser`      | `SwiftCompilerSources/Sources/_RegexParser` and `stdlib/public/_RegexParser` |
 | `_CUnicode`         | `stdlib/public/_StringProcessing`                                                    |
 | `_StringProcessing` | `stdlib/public/_StringProcessing`                                                    |
 
@@ -65,10 +65,9 @@ To integrate the latest changes in apple/swift-experimental-string-processing to
 
 ### Development notes
 
-Compiler integration can be tricky. Use special caution when developing `_MatchingEngine`, `_CUnicode` and `_StringProcessing` modules.
+Compiler integration can be tricky. Use special caution when developing `_RegexParser` and `_StringProcessing` modules.
 
 - Do not change the names of these modules without due approval from compiler and infrastructure teams.
 - Do not modify the existing ABI (e.g. C API, serialization format) between the regular expression parser and the Swift compiler unless absolutely necessary. 
 - Always minimize the number of lockstep integrations, i.e. when apple/swift-experimental-string-processing and apple/swift have to change together. Whenever possible, introduce new API first, migrate Swift compiler onto it, and then deprecate old API. Use versioning if helpful.
 - In `_StringProcessing`, do not write fully qualified references to symbols in `_CUnicode`, and always wrap `import _CUnicode` in a `#if canImport(_CUnicode)`. This is because `_CUnicode` is built as part of `_StringProcessing` with CMake.
-- In `_MatchingEngine`, do not write fully qualified references to `_MatchingEngine` itself. This is because `_MatchingEngine` is built as `ExperimentalRegex` in `SwiftCompilerSources/` with CMake. 

Sources/CMakeLists.txt

@@ -1,6 +1,6 @@
 
-add_subdirectory(_Unicode)
-add_subdirectory(_MatchingEngine)
+add_subdirectory(RegexBuilder)
+add_subdirectory(_RegexParser)
 add_subdirectory(_StringProcessing)
 add_subdirectory(Prototypes)
 add_subdirectory(VariadicsGenerator)

Sources/Exercises/Participant.swift

@@ -29,22 +29,25 @@ public protocol Participant {
   // ...
 }
 
+// Errors that may be thrown from default implementations
+private enum ParticipantError: Error {
+  case unsupported
+}
+
 // Default impls
 extension Participant {
-  static var unsupported: Error { "Unsupported" }
-
   // Produce a function that will parse a grapheme break entry from a line
   public static func graphemeBreakProperty() throws -> (String) -> GraphemeBreakEntry? {
-    throw unsupported
+    throw ParticipantError.unsupported
   }
 
   // Produce a function that will extract the bodies of C-style comments from its input
   public static func cComments() throws -> (String) -> [Substring] {
-    throw unsupported
+    throw ParticipantError.unsupported
   }
 
   // Produce a function that will extract the bodies of Swift-style comments from its input
   public static func swiftComments() throws -> (String) -> [Substring] {
-    throw unsupported
+    throw ParticipantError.unsupported
   }
 }

Sources/PatternConverter/PatternConverter.swift

@@ -12,7 +12,7 @@
 // swift run PatternConverter <regex>
 
 import ArgumentParser
-import _MatchingEngine
+import _RegexParser
 import _StringProcessing
 
 @main
@@ -52,7 +52,7 @@ struct PatternConverter: ParsableCommand {
     let delim = experimentalSyntax ? "|" : "/"
     print("Converting '\(delim)\(regex)\(delim)'")
 
-    let ast = try _MatchingEngine.parse(
+    let ast = try _RegexParser.parse(
       regex,
       experimentalSyntax ? .experimental : .traditional)
 

Sources/Prototypes/CMakeLists.txt

@@ -15,4 +15,4 @@ add_library(Prototypes
   TourOfTypes/CharacterClass.swift
   TourOfTypes/Literal.swift)
 target_link_libraries(Prototypes PUBLIC
-  _MatchingEngine)
+  _RegexParser)

Sources/Prototypes/Combinators/Combinators.swift

@@ -9,7 +9,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import _MatchingEngine
+import _RegexParser
 
 /*
 

Sources/RegexBuilder/Anchor.swift

@@ -9,7 +9,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import _MatchingEngine
+import _RegexParser
 @_spi(RegexBuilder) import _StringProcessing
 
 public struct Anchor {
@@ -107,16 +107,26 @@ extension Anchor {
   }
 }
 
-public func lookahead<R: RegexComponent>(
-  negative: Bool = false,
-  @RegexComponentBuilder _ content: () -> R
-) -> Regex<R.Output> {
-  Regex(node: .nonCapturingGroup(negative ? .negativeLookahead : .lookahead, content().regex.root))
-}
-  
-public func lookahead<R: RegexComponent>(
-  _ component: R,
-  negative: Bool = false
-) -> Regex<R.Output> {
-  Regex(node: .nonCapturingGroup(negative ? .negativeLookahead : .lookahead, component.regex.root))
+public struct Lookahead<Output>: _BuiltinRegexComponent {
+  public var regex: Regex<Output>
+
+  init(_ regex: Regex<Output>) {
+    self.regex = regex
+  }
+
+  public init<R: RegexComponent>(
+    _ component: R,
+    negative: Bool = false
+  ) where R.Output == Output {
+    self.init(node: .nonCapturingGroup(
+      negative ? .negativeLookahead : .lookahead, component.regex.root))
+  }
+
+  public init<R: RegexComponent>(
+    negative: Bool = false,
+    @RegexComponentBuilder _ component: () -> R
+  ) where R.Output == Output {
+    self.init(node: .nonCapturingGroup(
+      negative ? .negativeLookahead : .lookahead, component().regex.root))
+  }
 }

Sources/RegexBuilder/CMakeLists.txt

@@ -0,0 +1,10 @@
+
+add_library(RegexBuilder
+  Anchor.swift
+  Builder.swift
+  DSL.swift
+  Match.swift
+  Variadics.swift)
+target_compile_options(RegexBuilder PRIVATE
+  -enable-library-evolution
+  -Xfrontend -enable-experimental-pairwise-build-block)

Sources/RegexBuilder/DSL.swift

@@ -9,14 +9,14 @@
 //
 //===----------------------------------------------------------------------===//
 
-import _MatchingEngine
+import _RegexParser
 @_spi(RegexBuilder) import _StringProcessing
 
 extension Regex {
   public init<Content: RegexComponent>(
     @RegexComponentBuilder _ content: () -> Content
   ) where Content.Output == Output {
-    self.init(content())
+    self = content().regex
   }
 }
 
@@ -165,10 +165,6 @@ public struct Repeat<Output>: _BuiltinRegexComponent {
   // Variadics.swift.
 }
 
-postfix operator .?
-postfix operator .*
-postfix operator .+
-
 // MARK: Alternation
 
 // TODO: Variadic generics