More readable logs for PIRProcessDatabase duplicate keywords (#125)

Sources/PrivateInformationRetrieval/Error.swift

@@ -75,8 +75,8 @@ extension PirError: LocalizedError {
             """
         case let .invalidDatabaseDuplicateKeyword(keyword, oldValue, newValue):
             """
-            Invalid database: Duplicate values \(oldValue), \(newValue) \
-            for keyword \(keyword)
+            Invalid database: Duplicate values '\(oldValue.utf8OrBase64())', '\(newValue.utf8OrBase64())' \
+            for keyword '\(keyword.utf8OrBase64())'
             """
         case let .invalidDatabasePlaintextCount(plaintextCount, expected):
             "Invalid database: Database has \(plaintextCount) plaintexts, expected \(expected)"

Sources/PrivateInformationRetrieval/Util.swift

@@ -0,0 +1,25 @@
+// Copyright 2024 Apple Inc. and the Swift Homomorphic Encryption project authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import Foundation
+
+extension [UInt8] {
+    func utf8OrBase64() -> String {
+        if let utf8 = String(validating: self, as: UTF8.self) {
+            "\(utf8) (utf8)"
+        } else {
+            "\(Data(self).base64EncodedString()) (base64)"
+        }
+    }
+}

Tests/PrivateInformationRetrievalTests/UtilTests.swift

@@ -0,0 +1,26 @@
+// Copyright 2024 Apple Inc. and the Swift Homomorphic Encryption project authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+@testable import PrivateInformationRetrieval
+import XCTest
+
+class UtilTests: XCTestCase {
+    func testUTF8OrBase64() throws {
+        let utf8 = Array(Data("abc123".utf8))
+        XCTAssertEqual(utf8.utf8OrBase64(), "abc123 (utf8)")
+
+        let nonUtf8: [UInt8] = [128]
+        XCTAssertEqual(nonUtf8.utf8OrBase64(), Data(nonUtf8).base64EncodedString() + " (base64)")
+    }
+}