Add in static lookup for character classes in result builders (#115)

Author: milseman

Sources/Exercises/Participants/RegexParticipant.swift

@@ -67,16 +67,16 @@ private func graphemeBreakPropertyData(
   forLine line: String
 ) -> GraphemeBreakEntry? {
   graphemeBreakPropertyData(forLine: line, using: Regex {
-    OneOrMore(CharacterClass.hexDigit).capture()
+    OneOrMore(.hexDigit).capture()
     Optionally {
       ".."
-      OneOrMore(CharacterClass.hexDigit).capture()
+      OneOrMore(.hexDigit).capture()
     }
-    OneOrMore(CharacterClass.whitespace)
+    OneOrMore(.whitespace)
     ";"
-    OneOrMore(CharacterClass.whitespace)
-    OneOrMore(CharacterClass.word).capture()
-    Repeat(CharacterClass.any)
+    OneOrMore(.whitespace)
+    OneOrMore(.word).capture()
+    Repeat(.any)
   })
 }
 

Sources/_StringProcessing/RegexDSL/Core.swift

@@ -27,6 +27,28 @@ public protocol RegexProtocol {
   var regex: Regex<Match> { get }
 }
 
+/// A `RegexProtocol` that has a single component child.
+///
+/// This protocol adds an init supporting static lookup for character classes
+public protocol RegexProtocolWithComponent: RegexProtocol {
+  associatedtype Component: RegexProtocol
+
+  // Label needed for disambiguation
+  init(component: Component)
+}
+extension RegexProtocolWithComponent
+where Component == CharacterClass {
+  // This gives us static member lookup
+  public init(_ component: Component) {
+    self.init(component: component)
+  }
+}
+extension RegexProtocolWithComponent {
+  public init(_ component: Component) {
+    self.init(component: component)
+  }
+}
+
 /// A regular expression.
 public struct Regex<Match: MatchProtocol>: RegexProtocol {
   /// A program representation that caches any lowered representation for

Sources/_StringProcessing/RegexDSL/DSL.swift

@@ -60,12 +60,12 @@ extension CharacterClass: RegexProtocol {
 // MARK: Repetition
 
 /// A regular expression.
-public struct OneOrMore<Component: RegexProtocol>: RegexProtocol {
+public struct OneOrMore<Component: RegexProtocol>: RegexProtocolWithComponent {
   public typealias Match = Tuple2<Substring, [Component.Match.Capture]>
 
   public let regex: Regex<Match>
 
-  public init(_ component: Component) {
+  public init(component: Component) {
     self.regex = .init(ast:
       oneOrMore(.eager, component.regex.ast)
     )
@@ -86,12 +86,12 @@ public postfix func .+ <R: RegexProtocol>(
 
 public struct Repeat<
   Component: RegexProtocol
->: RegexProtocol {
+>: RegexProtocolWithComponent {
   public typealias Match = Tuple2<Substring, [Component.Match.Capture]>
 
   public let regex: Regex<Match>
 
-  public init(_ component: Component) {
+  public init(component: Component) {
     self.regex = .init(ast:
       zeroOrMore(.eager, component.regex.ast))
   }
@@ -109,12 +109,12 @@ public postfix func .* <R: RegexProtocol>(
   .init(lhs)
 }
 
-public struct Optionally<Component: RegexProtocol>: RegexProtocol {
+public struct Optionally<Component: RegexProtocol>: RegexProtocolWithComponent {
   public typealias Match = Tuple2<Substring, Component.Match.Capture?>
 
   public let regex: Regex<Match>
 
-  public init(_ component: Component) {
+  public init(component: Component) {
     self.regex = .init(ast:
       zeroOrOne(.eager, component.regex.ast))
   }