Working? Solution

Sloppy reverse quant

Fix reverse quant?

Author: JacobHearst

Sources/RegexBuilder/Anchor.swift

@@ -226,3 +226,52 @@ public struct NegativeLookahead<Output>: _BuiltinRegexComponent {
     self.init(_RegexFactory().negativeLookaheadNonCapturing(component()))
   }
 }
+
+// TODO: Write header doc
+@available(SwiftStdlib 5.10, *)
+public struct Lookbehind<Output>: _BuiltinRegexComponent {
+  public var regex: Regex<Output>
+
+  init(_ regex: Regex<Output>) {
+    self.regex = regex
+  }
+
+  /// Creates a lookbehind from the given regex component.
+  public init<R: RegexComponent>(
+    _ component: R
+  ) where R.RegexOutput == Output {
+    self.init(_RegexFactory().lookbehindNonCapturing(component))
+  }
+
+  /// Creates a lookbehind from the regex generated by the given builder closure.
+  public init<R: RegexComponent>(
+    @RegexComponentBuilder _ component: () -> R
+  ) where R.RegexOutput == Output {
+    self.init(_RegexFactory().lookbehindNonCapturing(component()))
+  }
+}
+
+// TODO: Write header doc
+@available(SwiftStdlib 5.10, *)
+public struct NegativeLookbehind<Output>: _BuiltinRegexComponent {
+  public var regex: Regex<Output>
+
+  init(_ regex: Regex<Output>) {
+    self.regex = regex
+  }
+
+  /// Creates a negative lookbehind from the given regex component.
+  public init<R: RegexComponent>(
+    _ component: R
+  ) where R.RegexOutput == Output {
+    self.init(_RegexFactory().negativeLookbehindNonCapturing(component))
+  }
+
+  /// Creates a negative lookbehind from the regex generated by the given builder
+  /// closure.
+  public init<R: RegexComponent>(
+    @RegexComponentBuilder _ component: () -> R
+  ) where R.RegexOutput == Output {
+    self.init(_RegexFactory().negativeLookbehindNonCapturing(component()))
+  }
+}

Sources/_RegexParser/Regex/Parse/Sema.swift

@@ -370,7 +370,7 @@ extension RegexValidator {
     }
     switch kind.value {
     case .capture, .namedCapture, .nonCapture, .lookahead, .negativeLookahead,
-        .atomicNonCapturing:
+        .atomicNonCapturing, .lookbehind:
       break
 
     case .balancedCapture:
@@ -384,7 +384,7 @@ extension RegexValidator {
     case .nonAtomicLookahead:
       error(.unsupported("non-atomic lookahead"), at: kind.location)
 
-    case .lookbehind, .negativeLookbehind, .nonAtomicLookbehind:
+    case .negativeLookbehind, .nonAtomicLookbehind:
       error(.unsupported("lookbehind"), at: kind.location)
 
     case .scriptRun, .atomicScriptRun: