[gardening] Cleanup/simplify Executor codepaths

Sources/_StringProcessing/Capture.swift

@@ -71,6 +71,11 @@ extension StructuredCapture {
       value: storedCapture?.value,
       optionalCount: optionalCount)
   }
+
+  func slice(from input: String) -> Substring? {
+    guard let r = storedCapture?.range else { return nil }
+    return input[r]
+  }
 }
 
 extension Sequence where Element == StructuredCapture {
@@ -86,5 +91,10 @@ extension Sequence where Element == StructuredCapture {
     })
     return TypeConstruction.tuple(of: caps)
   }
+
+  func slices(from input: String) -> [Substring?] {
+    self.map { $0.slice(from: input) }
+  }
 }
 
+

Sources/_StringProcessing/Engine/Consume.swift

@@ -25,16 +25,10 @@ extension Engine {
 }
 
 extension Engine where Input == String {
-  func consume(
-    _ input: Input
-  ) -> (Input.Index, CaptureList)? {
-    consume(input, in: input.startIndex ..< input.endIndex)
-  }
-
   func consume(
     _ input: Input,
     in range: Range<Input.Index>,
-    matchMode: MatchMode = .partialFromFront
+    matchMode: MatchMode
   ) -> (Input.Index, CaptureList)? {
     if enableTracing {
       print("Consume: \(input)")

Sources/_StringProcessing/Executor.swift

@@ -19,69 +19,33 @@ struct Executor {
     self.engine = Engine(program, enableTracing: enablesTracing)
   }
 
-  struct Result {
-    var range: Range<String.Index>
-    var captures: [StructuredCapture]
-    var referencedCaptureOffsets: [ReferenceID: Int]
-
-    var destructure: (
-      matched: Range<String.Index>,
-      captures: [StructuredCapture],
-      referencedCaptureOffsets: [ReferenceID: Int]
-    ) {
-      (range, captures, referencedCaptureOffsets)
-    }
-
-    init(
-      _ matched: Range<String.Index>, _ captures: [StructuredCapture],
-      _ referencedCaptureOffsets: [ReferenceID: Int]
-    ) {
-      self.range = matched
-      self.captures = captures
-      self.referencedCaptureOffsets = referencedCaptureOffsets
-    }
-  }
-
-  func execute(
-    input: String,
-    in range: Range<String.Index>,
-    mode: MatchMode = .wholeString
-  ) -> Result? {
+  func match<Match>(
+    _ input: String,
+    in inputRange: Range<String.Index>,
+    _ mode: MatchMode
+  ) throws -> RegexMatch<Match>? {
     guard let (endIdx, capList) = engine.consume(
-      input, in: range, matchMode: mode
+      input, in: inputRange, matchMode: mode
     ) else {
       return nil
     }
     let capStruct = engine.program.captureStructure
-    do {
-      let range = range.lowerBound..<endIdx
-
-      let caps = try capStruct.structuralize(
+    let range = inputRange.lowerBound..<endIdx
+    let caps = try capStruct.structuralize(
         capList, input)
-      return Result(range, caps, capList.referencedCaptureOffsets)
-    } catch {
-      fatalError(String(describing: error))
-    }
-  }
-  func execute(
-    input: Substring,
-    mode: MatchMode = .wholeString
-  ) -> Result? {
-    self.execute(
-      input: input.base,
-      in: input.startIndex..<input.endIndex,
-      mode: mode)
+
+    return RegexMatch(
+      input: input,
+      range: range,
+      rawCaptures: caps,
+      referencedCaptureOffsets: capList.referencedCaptureOffsets)
   }
 
-  func executeFlat(
-    input: String,
-    in range: Range<String.Index>,
-    mode: MatchMode = .wholeString
-  ) -> (Range<String.Index>, CaptureList)? {
-    engine.consume(
-      input, in: range, matchMode: mode
-    ).map { endIndex, capture in
-      (range.lowerBound..<endIndex, capture)
-    }
+  func dynamicMatch(
+    _ input: String,
+    in inputRange: Range<String.Index>,
+    _ mode: MatchMode
+  ) throws -> RegexMatch<(Substring, DynamicCaptures)>? {
+    try match(input, in: inputRange, mode)
   }
 }

Sources/_StringProcessing/RegexDSL/Match.swift

@@ -69,16 +69,11 @@ extension RegexProtocol {
     mode: MatchMode = .wholeString
   ) -> RegexMatch<Match>? {
     let executor = Executor(program: regex.program.loweredProgram)
-    guard let (range, captures, captureOffsets) = executor.execute(
-      input: input, in: inputRange, mode: mode
-    )?.destructure else {
-      return nil
+    do {
+      return try executor.match(input, in: inputRange, mode)
+    } catch {
+      fatalError(String(describing: error))
     }
-    return RegexMatch(
-      input: input,
-      range: range,
-      rawCaptures: captures,
-      referencedCaptureOffsets: captureOffsets)
   }
 }