DataProtocol.withDataReader { }: Can now return a value from the cl…

…osure
orchetect · Aug 18, 2022 · 72660f5 · 72660f5
1 parent bf0eed0
commit 72660f5
Show file tree

Hide file tree

Showing 2 changed files with 23 additions and 5 deletions.
diff --git a/Sources/OTCore/Abstractions/PassiveDataReader.swift b/Sources/OTCore/Abstractions/PassiveDataReader.swift
@@ -132,12 +132,12 @@ extension PassiveDataReader {
 extension DataProtocol {
     /// **OTCore:**
     /// Accesses the data by providing a `PassiveDataReader` instance to a closure.
-    @_disfavoredOverload
-    public func withDataReader(
-        _ block: (_ dataReader: inout PassiveDataReader<Self>) throws -> Void
-    ) rethrows {
+    @_disfavoredOverload @discardableResult
+    public func withDataReader<Result>(
+        _ block: (_ dataReader: inout PassiveDataReader<Self>) throws -> Result
+    ) rethrows -> Result {
         var mutableSelf = self
         var reader = PassiveDataReader { $0(&mutableSelf) }
-        try block(&reader)
+        return try block(&reader)
     }
 }
diff --git a/Tests/OTCoreTests/Abstractions/PassiveDataReader Tests.swift b/Tests/OTCoreTests/Abstractions/PassiveDataReader Tests.swift
@@ -305,6 +305,24 @@ class Abstractions_PassiveDataReader_Tests: XCTestCase {
             }
         )
     }
+
+    func testWithDataReader_ReturnsValue() throws {
+        let data = Data([0x01, 0x02, 0x03, 0x04])
+
+        #if swift(>=5.7)
+        let getByte = try data.withDataReader { dr in
+            _ = try dr.readByte()
+            return try dr.readByte()
+        }
+        #else
+        let getByte: UInt8 = try data.withDataReader { dr in
+            _ = try dr.readByte()
+            return try dr.readByte()
+        }
+        #endif
+
+        XCTAssertEqual(getByte, 0x02)
+    }
 }
 
 #endif