Hook up char class models

Author: milseman

Sources/_StringProcessing/CharacterClass.swift

@@ -330,7 +330,7 @@ extension DSLTree.Node {
       return ccc.modelCharacterClass
     case let .atom(a):
       return a.characterClass
-    case let .characterPredicate(p):
+    case .characterPredicate:
       // FIXME: Do we make one from this?
       return nil
     default:
@@ -417,8 +417,8 @@ extension AST.Atom.EscapedBuiltin {
 }
 
 extension DSLTree.CustomCharacterClass {
+  // TODO: Refactor a bit, and... can we drop this type?
   var modelCharacterClass: CharacterClass? {
-
     var result =
       Array<CharacterClass.CharacterSetComponent>()
     for m in members {
@@ -445,8 +445,38 @@ extension DSLTree.CustomCharacterClass {
         }
         result.append(.characterClass(cc))
 
-      case .intersection, .subtraction, .symmetricDifference:
-        fatalError("TODO")
+      case let .intersection(lhs, rhs):
+        guard let lhs = lhs.modelCharacterClass,
+              let rhs = rhs.modelCharacterClass
+        else {
+          return nil
+        }
+        result.append(.setOperation(
+          lhs: .characterClass(lhs),
+          op: .intersection,
+          rhs: .characterClass(rhs)))
+
+      case let .subtraction(lhs, rhs):
+        guard let lhs = lhs.modelCharacterClass,
+              let rhs = rhs.modelCharacterClass
+        else {
+          return nil
+        }
+        result.append(.setOperation(
+          lhs: .characterClass(lhs),
+          op: .subtraction,
+          rhs: .characterClass(rhs)))
+
+      case let .symmetricDifference(lhs, rhs):
+        guard let lhs = lhs.modelCharacterClass,
+              let rhs = rhs.modelCharacterClass
+        else {
+          return nil
+        }
+        result.append(.setOperation(
+          lhs: .characterClass(lhs),
+          op: .symmetricDifference,
+          rhs: .characterClass(rhs)))
       }
     }
     let cc = CharacterClass.custom(result)