Deduplicate known asset tags

Author: tomlokhorst

Sources/RswiftGenerators/XcodeProject+Generator.swift

@@ -10,17 +10,23 @@ import Foundation
 public struct XcodeProjectGenerator {
     public static func generateProject(developmentRegion: String?, knownAssetTags: [String]?) -> Struct {
         Struct(name: SwiftIdentifier(name: "project")) {
+            let warning: (String) -> Void = { print("warning: [R.swift]", $0) }
+
             if let developmentRegion {
                 LetBinding(name: SwiftIdentifier(name: "developmentRegion"), valueCodeString: #""\#(developmentRegion)""#)
             }
 
             if let knownAssetTags {
-                Struct(name: SwiftIdentifier(name: "knownAssetTags"), protocols: [.sequence]) {
-                    knownAssetTags.map { tag in
-                        LetBinding(name: SwiftIdentifier(name: tag), valueCodeString: #""\#(tag)""#)
-                    }
+                let grouped = knownAssetTags.grouped(bySwiftIdentifier: { $0 })
+                grouped.reportWarningsForDuplicatesAndEmpties(source: "known asset tag", result: "known asset tag", warning: warning)
+                if grouped.uniques.count > 0 {
+                    Struct(name: SwiftIdentifier(name: "knownAssetTags"), protocols: [.sequence]) {
+                        grouped.uniques.map { tag in
+                            LetBinding(name: SwiftIdentifier(name: tag), valueCodeString: #""\#(tag)""#)
+                        }
 
-                    generateMakeIterator(names: knownAssetTags.map { SwiftIdentifier(name: $0) })
+                        generateMakeIterator(names: grouped.uniques.map { SwiftIdentifier(name: $0) })
+                    }
                 }
             }
         }