Allow decoding integer values to floating point types for better inte…

…roperability with applications written in languages like JavaScript. Resolves #1.
fumoboy007 · Dec 22, 2023 · 0913fae · 0913fae
1 parent f3f382f
commit 0913fae
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Showing 2 changed files with 55 additions and 2 deletions.
diff --git a/.../MessagePack/Decoder Implementation/BinaryFloatingPoint+FromDecodedMessagePackValue.swift b/.../MessagePack/Decoder Implementation/BinaryFloatingPoint+FromDecodedMessagePackValue.swift
@@ -23,6 +23,26 @@
 extension BinaryFloatingPoint {
    init?(exactly messagePackValue: DecodedMessagePackValue) {
       switch messagePackValue {
+      case .signedInteger(let value):
+         // Some languages like JavaScript do not allow the developer to specify whether a number is a floating point
+         // or integer value. A MessagePack encoder for such a language may choose to encode the number as an integer
+         // when possible--even if the developer knows that the intended type of the value should be a floating point
+         // type.
+         //
+         // Therefore, we should allow decoding integer values to floating point types for better interoperability
+         // with applications written in such languages.
+         guard let value = Self(exactly: value) else {
+            return nil
+         }
+         self = value
+
+      case .unsignedInteger(let value):
+         // See above comment for the `signedInteger` case.
+         guard let value = Self(exactly: value) else {
+            return nil
+         }
+         self = value
+
       case .float32(let value):
          if let value = Self(exactly: value) {
             self = value
@@ -44,8 +64,6 @@ extension BinaryFloatingPoint {
       case .invalid,
             .nil,
             .boolean,
-            .signedInteger,
-            .unsignedInteger,
             .string,
             .binary,
             .array,

diff --git a/Tests/MessagePackTests/MessagePackDecoderTests.swift b/Tests/MessagePackTests/MessagePackDecoderTests.swift
@@ -167,6 +167,8 @@ class MessagePackDecoderTests: XCTestCase {
       for value in valuesToTest {
          try test(value)
       }
+
+      try testIntegerValues(decodeAs: Float32.self)
    }
 
    func testFloat32_nan() throws {
@@ -197,6 +199,8 @@ class MessagePackDecoderTests: XCTestCase {
       for value in valuesToTest {
          try test(value)
       }
+
+      try testIntegerValues(decodeAs: Float64.self)
    }
 
    func testFloat64_nan() throws {
@@ -212,6 +216,37 @@ class MessagePackDecoderTests: XCTestCase {
       XCTAssertEqual(decodedValue.significandBitPattern, value.significandBitPattern)
    }
 
+   private func testIntegerValues<FloatingPointType>(
+      decodeAs floatingPointType: FloatingPointType.Type
+   ) throws where FloatingPointType: BinaryFloatingPoint & Decodable {
+      try testValues(of: Int.self, decodeAs: floatingPointType)
+      try testValues(of: Int8.self, decodeAs: floatingPointType)
+      try testValues(of: Int16.self, decodeAs: floatingPointType)
+      try testValues(of: Int32.self, decodeAs: floatingPointType)
+      try testValues(of: Int64.self, decodeAs: floatingPointType)
+      try testValues(of: UInt.self, decodeAs: floatingPointType)
+      try testValues(of: UInt8.self, decodeAs: floatingPointType)
+      try testValues(of: UInt16.self, decodeAs: floatingPointType)
+      try testValues(of: UInt32.self, decodeAs: floatingPointType)
+      try testValues(of: UInt64.self, decodeAs: floatingPointType)
+   }
+
+   private func testValues<IntegerType, FloatingPointType>(
+      of integerType: IntegerType.Type,
+      decodeAs floatingPointType: FloatingPointType.Type
+   ) throws where IntegerType: BinaryInteger, FloatingPointType: BinaryFloatingPoint & Decodable {
+      // Only test integers up to 16 bits so that the test does not take forever.
+      let valuesToTest = (Int16.min...Int16.max).compactMap { IntegerType(exactly: $0) }
+
+      for value in valuesToTest {
+         guard let floatingPointValue = FloatingPointType(exactly: value) else {
+            continue
+         }
+
+         try test(value, encodesAndThenDecodesTo: floatingPointValue)
+      }
+   }
+
    func testString() throws {
       let valuesToTest: [String] = [
          "",