Support Unicode scalar names in \p{name=...}

Sources/_RegexParser/Regex/AST/Atom.swift

@@ -396,6 +396,9 @@ extension AST.Atom.CharacterProperty {
     case script(Unicode.Script)
     case scriptExtension(Unicode.Script)
 
+    /// Character name in the form `\p{name=...}`
+    case named(String)
+
     case posix(Unicode.POSIXProperty)
 
     /// Some special properties implemented by PCRE and Oniguruma.

Sources/_RegexParser/Regex/Parse/CharacterPropertyClassification.swift

@@ -428,6 +428,8 @@ extension Source {
         if let cat = classifyGeneralCategory(value) {
           return .generalCategory(cat)
         }
+      case "name", "na":
+        return .named(value)
       default:
         break
       }

Sources/_StringProcessing/ConsumerInterface.swift

@@ -144,6 +144,19 @@ extension String {
   }
 }
 
+func consumeName(_ name: String, opts: MatchingOptions) -> MEProgram<String>.ConsumeFunction {
+  let consume = opts.semanticLevel == .graphemeCluster
+    ? consumeCharacterWithSingleScalar
+    : consumeScalar
+
+  return consume(propertyScalarPredicate {
+    // FIXME: name aliases not covered by $0.nameAlias are missed
+    // e.g. U+FEFF has both 'BYTE ORDER MARK' and 'BOM' as aliases
+    $0.name?.isEqualByUAX44LM2(to: name) == true
+      || $0.nameAlias?.isEqualByUAX44LM2(to: name) == true
+  })
+}
+
 // TODO: This is basically an AST interpreter, which would
 // be good or interesting to build regardless, and serves
 // as a compiler fall-back path
@@ -206,12 +219,7 @@ extension AST.Atom {
       return try p.generateConsumer(opts)
 
     case let .namedCharacter(name):
-      return consumeScalar(propertyScalarPredicate {
-        // FIXME: name aliases not covered by $0.nameAlias are missed
-        // e.g. U+FEFF is also 'FORM FEED', 'BYTE ORDER MARK', and 'BOM'
-        $0.name?.isEqualByUAX44LM2(to: name) == true
-          || $0.nameAlias?.isEqualByUAX44LM2(to: name) == true
-      })
+      return consumeName(name, opts: opts)
 
     case .any:
       assertionFailure(
@@ -479,6 +487,9 @@ extension AST.Atom.CharacterProperty {
 
       case .scriptExtension(let s):
         return consume(scriptExtensionScalarPredicate(s))
+
+      case .named(let n):
+        return consumeName(n, opts: opts)
 
       case .posix(let p):
         return p.generateConsumer(opts)

Tests/RegexTests/ParseTests.swift

@@ -1219,6 +1219,13 @@ extension RegexTests {
     parseTest(#"\p{word}"#,  prop(.posix(.word)))
     parseTest(#"\p{xdigit}"#, prop(.posix(.xdigit)))
 
+    parseTest(#"\p{name=A}"#, prop(.named("A")))
+    parseTest(#"\p{Name=B}"#, prop(.named("B")))
+    parseTest(#"\p{isName=C}"#, prop(.named("C")))
+    parseTest(#"\p{na=D}"#, prop(.named("D")))
+    parseTest(#"\p{NA=E}"#, prop(.named("E")))
+    parseTest(#"\p{na=isI}"#, prop(.named("isI")))
+
     // MARK: Conditionals
 
     parseTest(#"(?(1))"#, conditional(

Tests/RegexTests/UTS18Tests.swift

@@ -389,25 +389,34 @@ extension UTS18Tests {
   //
   // To meet this requirement, an implementation shall support individually
   // named characters.
-  func testNameProperty_XFail() {
-    XCTExpectFailure("Need \\p{name=...} support") {
-      XCTFail(#"\(#/\p{name=BOM}/#)"#)
-      // Name property
-      // XCTAssertTrue("\u{FEFF}".contains(#/\p{name=ZERO WIDTH NO-BREAK SPACE}/#))
-      // Name property and Matching Rules
-      // XCTAssertTrue("\u{FEFF}".contains(#/\p{name=zerowidthno breakspace}/#))
+  func testNameProperty() throws {
+    // Name property
+    XCTAssertTrue("\u{FEFF}".contains(regex(#"\p{name=ZERO WIDTH NO-BREAK SPACE}"#)))
+    // Name property and Matching Rules
+    XCTAssertTrue("\u{FEFF}".contains(regex(#"\p{name=zerowidthno breakspace}"#)))
+
+    // Computed name
+    XCTAssertTrue("강".contains(regex(#"\p{name=HANGUL SYLLABLE GANG}"#)))
+
+    // Graphic symbol
+    XCTAssertTrue("\u{1F514}".contains(regex(#"\p{name=BELL}"#)))
+
+    // Name match failures
+    XCTAssertFalse("\u{FEFF}".contains(regex(#"\p{name=ZERO WIDTH NO-BRAKE SPACE}"#)))
+    XCTAssertFalse("\u{FEFF}".contains(regex(#"\p{name=ZERO WIDTH NO-BREAK SPACE ZZZZ}"#)))
+    XCTAssertFalse("\u{FEFF}".contains(regex(#"\p{name=ZERO WIDTH NO-BREAK}"#)))
+    XCTAssertFalse("\u{FEFF}".contains(regex(#"\p{name=z}"#)))
+  }
+
+  func testNameProperty_XFail() throws {
+    XCTExpectFailure("Need more expansive name alias matching") {
       // Name_Alias property
-      // XCTAssertTrue("\u{FEFF}".contains(#/\p{name=BYTE ORDER MARK}/#))
+      XCTAssertTrue("\u{FEFF}".contains(regex(#"\p{name=BYTE ORDER MARK}"#)))
       // Name_Alias property (again)
-      // XCTAssertTrue("\u{FEFF}".contains(#/\p{name=BOM}/#))
-
-      // Computed name
-      // XCTAssertTrue("강".contains(#/\p{name=HANGUL SYLLABLE GANG}/#))
-
+      XCTAssertTrue("\u{FEFF}".contains(regex(#"\p{name=BOM}"#)))
+
       // Control character
-      // XCTAssertTrue("\u{7}".contains(#/\p{name=BEL}/#))
-      // Graphic symbol
-      // XCTAssertTrue("\u{1F514}".contains(#/\p{name=BELL}/#))
+      XCTAssertTrue("\u{7}".contains(regex(#"\p{name=BEL}"#)))
     }
   }