Generic ~= operator

Make `~=` generic over `RegexComponent` so that one can use builder components, e.g. `OneOrMore(...)`, or custom-consuming regex components as patterns.

Author: rxwei

Sources/_StringProcessing/Regex/Core.swift

@@ -61,6 +61,13 @@ public struct Regex<Output>: RegexComponent {
   }
 }
 
+@available(SwiftStdlib 5.7, *)
+extension Regex {
+  public init(quoting string: String) {
+    self.init(node: .quotedLiteral(string))
+  }
+}
+
 @available(SwiftStdlib 5.7, *)
 extension Regex {
   /// A program representation that caches any lowered representation for

Sources/_StringProcessing/Regex/Match.swift

@@ -180,20 +180,13 @@ extension BidirectionalCollection where SubSequence == Substring {
 }
 
 @available(SwiftStdlib 5.7, *)
-extension Regex {
-  public init(quoting string: String) {
-    self.init(node: .quotedLiteral(string))
-  }
-}
-
-@available(SwiftStdlib 5.7, *)
-public func ~=<Output>(regex: Regex<Output>, input: String) -> Bool {
-  guard let _ = try? regex.wholeMatch(in: input) else { return false }
-  return true
+@_disfavoredOverload // disambiguate from equatable patterns
+public func ~=<R: RegexComponent>(regex: R, input: String) -> Bool {
+  input.wholeMatch(of: regex) != nil
 }
 
 @available(SwiftStdlib 5.7, *)
-public func ~=<Output>(regex: Regex<Output>, input: Substring) -> Bool {
-  guard let _ = try? regex.wholeMatch(in: input) else { return false }
-  return true
+@_disfavoredOverload // disambiguate from equatable patterns
+public func ~=<R: RegexComponent>(regex: R, input: Substring) -> Bool {
+  input.wholeMatch(of: regex) != nil
 }

Tests/RegexBuilderTests/AlgorithmsTests.swift

@@ -104,4 +104,38 @@ class RegexConsumerTests: XCTestCase {
        result: "9+16, 3, 10, 99+1")
     )
   }
+
+  func testSwitches() {
+    switch "abcde" {
+    case Regex {
+      "a"
+      ZeroOrMore(.any)
+      "f"
+    }:
+      XCTFail()
+
+    case "abc":
+      XCTFail()
+
+    case Regex {
+      "a"
+      "b"
+      "c"
+    }:
+      XCTFail()
+
+    case Regex {
+      "a"
+      ZeroOrMore(.any)
+      "e"
+    }:
+      break // success
+
+    case OneOrMore(.word):
+      break // success
+
+    default:
+      XCTFail()
+    }
+  }
 }