Start work on HTMLEntityDecoder port.

Modules/Parser/Sources/SAX/HTMLEntityDecoder.swift

@@ -0,0 +1,51 @@
+//
+//  HTMLEntityDecoder.swift
+//
+//
+//  Created by Brent Simmons on 9/14/24.
+//
+
+import Foundation
+
+public final class HTMLEntityDecoder {
+
+	static func decodedString(withEncodedString encodedString: String) -> String {
+
+		let scanner = Scanner(string: encodedString)
+		scanner.charactersToBeSkipped = nil
+		var result = ""
+		var didDecodeAtLeastOneEntity = false
+
+		while true {
+
+			var scannedString = nil
+			if scanner.scanUpToString("&" intoString: &scannedString) {
+				result.append(scannedString)
+			}
+			if scanner.isAtEnd {
+				break
+			}
+
+			let savedScanLocation = scanner.scanLocation
+
+			var decodedEntity: String? = nil
+			if scanner.scanEntityValue(&decodedEntity) {
+				result.append(decodedEntity)
+				didDecodeAtLeastOneEntity = true
+			}
+			else {
+				result.append("&")
+				scanner.scanLocation = savedScanLocation + 1
+			}
+			
+			if scanner.isAtEnd {
+				break
+			}
+		}
+
+		if !didDecodeAtLeastOneEntity { // No changes made?
+			return encodedString
+		}
+		return result
+	}
+}