Quick bug fix / workaround for whole-match values (#191)

Author: milseman

Sources/_StringProcessing/Capture.swift

@@ -96,5 +96,3 @@ extension Sequence where Element == StructuredCapture {
     self.map { $0.slice(from: input) }
   }
 }
-
-

Sources/_StringProcessing/Engine/Consume.swift

@@ -24,41 +24,17 @@ extension Engine {
   }
 }
 
-extension Engine where Input == String {
-  func consume(
-    _ input: Input,
-    in range: Range<Input.Index>,
-    matchMode: MatchMode
-  ) -> (Input.Index, CaptureList)? {
-    if enableTracing {
-      print("Consume: \(input)")
-    }
-
-    var cpu = makeProcessor(input: input, bounds: range, matchMode: matchMode)
-    let result: Input.Index? = {
-      while true {
-        switch cpu.state {
-        case .accept:
-          return cpu.currentPosition
-        case .fail:
-          return nil
-        case .inProgress: cpu.cycle()
-        }
-      }
-    }()
-
-    if enableTracing {
-      if let idx = result {
-        print("Result: \(input[..<idx]) | \(input[idx...])")
-      } else {
-        print("Result: nil")
+extension Processor where Input == String {
+  mutating func consume() -> Input.Index? {
+    while true {
+      switch self.state {
+      case .accept:
+        return self.currentPosition
+      case .fail:
+        return nil
+      case .inProgress: self.cycle()
       }
     }
-    guard let result = result else { return nil }
-
-    let capList = cpu.storedCaptures
-    return (result, CaptureList(
-      values: capList, referencedCaptureOffsets: program.referencedCaptureOffsets))
   }
 }
 

Sources/_StringProcessing/Executor.swift

@@ -24,21 +24,41 @@ struct Executor {
     in inputRange: Range<String.Index>,
     _ mode: MatchMode
   ) throws -> RegexMatch<Match>? {
-    guard let (endIdx, capList) = engine.consume(
-      input, in: inputRange, matchMode: mode
-    ) else {
+    var cpu = engine.makeProcessor(
+      input: input, bounds: inputRange, matchMode: mode)
+
+    guard let endIdx = cpu.consume() else {
       return nil
     }
+
+    let capList = CaptureList(
+      values: cpu.storedCaptures,
+      referencedCaptureOffsets: engine.program.referencedCaptureOffsets)
+
     let capStruct = engine.program.captureStructure
     let range = inputRange.lowerBound..<endIdx
     let caps = try capStruct.structuralize(
         capList, input)
 
+    // FIXME: This is a workaround for not tracking (or
+    // specially compiling) whole-match values.
+    let value: Any?
+    if Match.self != Substring.self,
+       Match.self != (Substring, DynamicCaptures).self,
+       caps.isEmpty
+    {
+      value = cpu.registers.values.first
+      assert(value != nil, "hmm, what would this mean?")
+    } else {
+      value = nil
+    }
+
     return RegexMatch(
       input: input,
       range: range,
       rawCaptures: caps,
-      referencedCaptureOffsets: capList.referencedCaptureOffsets)
+      referencedCaptureOffsets: capList.referencedCaptureOffsets,
+      value: value)
   }
 
   func dynamicMatch(

Sources/_StringProcessing/RegexDSL/Match.swift

@@ -16,6 +16,8 @@ public struct RegexMatch<Match> {
   let rawCaptures: [StructuredCapture]
   let referencedCaptureOffsets: [ReferenceID: Int]
 
+  let value: Any?
+
   public var match: Match {
     if Match.self == (Substring, DynamicCaptures).self {
       // FIXME(rdar://89449323): Compiler assertion
@@ -25,7 +27,15 @@ public struct RegexMatch<Match> {
     } else if Match.self == Substring.self {
       // FIXME: Plumb whole match (`.0`) through the matching engine.
       return input[range] as! Match
+    } else if rawCaptures.isEmpty, value != nil {
+      // FIXME: This is a workaround for whole-match values not
+      // being modeled as part of captures. We might want to
+      // switch to a model where results are alongside captures
+      return value! as! Match
     } else {
+      guard value == nil else {
+        fatalError("FIXME: what would this mean?")
+      }
       let typeErasedMatch = rawCaptures.existentialMatch(from: input[range])
       return typeErasedMatch as! Match
     }

Tests/RegexTests/CustomTests.swift

@@ -83,15 +83,14 @@ extension RegexTests {
       ("55z", .match, nil),
       ("55z", .firstMatch, "55"))
 
-    // FIXME: Requires we return a value instead of a range
-//    customTest(
-//      Regex {
-//        Numbler()
-//      },
-//      ("ab123c", .firstMatch, 1),
-//      ("abc", .firstMatch, nil),
-//      ("55z", .match, nil),
-//      ("55z", .firstMatch, 5))
+    customTest(
+      Regex {
+        Numbler()
+      },
+      ("ab123c", .firstMatch, 1),
+      ("abc", .firstMatch, nil),
+      ("55z", .match, nil),
+      ("55z", .firstMatch, 5))
 
     // TODO: Convert below tests to better infra. Right now
     // it's hard because `Match` is constrained to be