Merge pull request #1192 from bubski/codable-measurement-2

Codable conformance for Measurement

Author: itaiferber

Foundation.xcodeproj/project.pbxproj

@@ -14,6 +14,7 @@
 		231503DB1D8AEE5D0061694D /* TestDecimal.swift in Sources */ = {isa = PBXBuildFile; fileRef = 231503DA1D8AEE5D0061694D /* TestDecimal.swift */; };
 		294E3C1D1CC5E19300E4F44C /* TestNSAttributedString.swift in Sources */ = {isa = PBXBuildFile; fileRef = 294E3C1C1CC5E19300E4F44C /* TestNSAttributedString.swift */; };
 		2EBE67A51C77BF0E006583D5 /* TestDateFormatter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2EBE67A31C77BF05006583D5 /* TestDateFormatter.swift */; };
+		3E55A2331F52463B00082000 /* TestUnit.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3E55A2321F52463B00082000 /* TestUnit.swift */; };
 		3EA9D6701EF0532D00B362D6 /* TestJSONEncoder.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3EA9D66F1EF0532D00B362D6 /* TestJSONEncoder.swift */; };
 		3EDCE50C1EF04D8100C2EC04 /* Codable.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3EDCE5051EF04D8100C2EC04 /* Codable.swift */; };
 		3EDCE5101EF04D8100C2EC04 /* JSONEncoder.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3EDCE5091EF04D8100C2EC04 /* JSONEncoder.swift */; };
@@ -490,6 +491,7 @@
 		231503DA1D8AEE5D0061694D /* TestDecimal.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TestDecimal.swift; sourceTree = "<group>"; };
 		294E3C1C1CC5E19300E4F44C /* TestNSAttributedString.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TestNSAttributedString.swift; sourceTree = "<group>"; };
 		2EBE67A31C77BF05006583D5 /* TestDateFormatter.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TestDateFormatter.swift; sourceTree = "<group>"; };
+		3E55A2321F52463B00082000 /* TestUnit.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TestUnit.swift; sourceTree = "<group>"; };
 		3EA9D66F1EF0532D00B362D6 /* TestJSONEncoder.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TestJSONEncoder.swift; sourceTree = "<group>"; };
 		3EDCE5051EF04D8100C2EC04 /* Codable.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Codable.swift; sourceTree = "<group>"; };
 		3EDCE5091EF04D8100C2EC04 /* JSONEncoder.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = JSONEncoder.swift; sourceTree = "<group>"; };
@@ -1494,6 +1496,7 @@
 				D4FE895A1D703D1100DA7986 /* TestURLRequest.swift */,
 				5B6F17961C48631C00935030 /* TestUtils.swift */,
 				03B6F5831F15F339004F25AF /* TestURLProtocol.swift */,
+				3E55A2321F52463B00082000 /* TestUnit.swift */,
 			);
 			name = Tests;
 			sourceTree = "<group>";
@@ -2419,6 +2422,7 @@
 				F9E0BB371CA70B8000F7FF3C /* TestURLCredential.swift in Sources */,
 				5B13B3341C582D4C00651CE2 /* TestNSKeyedArchiver.swift in Sources */,
 				5B13B3441C582D4C00651CE2 /* TestNSSet.swift in Sources */,
+				3E55A2331F52463B00082000 /* TestUnit.swift in Sources */,
 				5B13B3321C582D4C00651CE2 /* TestIndexSet.swift in Sources */,
 				5B13B3511C582D4C00651CE2 /* TestByteCountFormatter.swift in Sources */,
 				BDFDF0A71DFF5B3E00C04CC5 /* TestPersonNameComponents.swift in Sources */,

Foundation/Measurement.swift

@@ -275,3 +275,60 @@ extension Measurement : _ObjectTypeBridgeable {
         return Measurement(value: source!.doubleValue, unit: u)
     }
 }
+
+extension Measurement : Codable {
+    private enum CodingKeys : Int, CodingKey {
+        case value
+        case unit
+    }
+
+    private enum UnitCodingKeys : Int, CodingKey {
+        case symbol
+        case converter
+    }
+
+    private enum LinearConverterCodingKeys : Int, CodingKey {
+        case coefficient
+        case constant
+    }
+
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        let value = try container.decode(Double.self, forKey: .value)
+
+        let unitContainer = try container.nestedContainer(keyedBy: UnitCodingKeys.self, forKey: .unit)
+        let symbol = try unitContainer.decode(String.self, forKey: .symbol)
+
+        let unit: UnitType
+        if UnitType.self is Dimension.Type {
+            let converterContainer = try unitContainer.nestedContainer(keyedBy: LinearConverterCodingKeys.self, forKey: .converter)
+            let coefficient = try converterContainer.decode(Double.self, forKey: .coefficient)
+            let constant = try converterContainer.decode(Double.self, forKey: .constant)
+            let unitMetaType = (UnitType.self as! Dimension.Type)
+            unit = (unitMetaType.init(symbol: symbol, converter: UnitConverterLinear(coefficient: coefficient, constant: constant)) as! UnitType)
+        } else {
+            unit = UnitType(symbol: symbol)
+        }
+
+        self.init(value: value, unit: unit)
+    }
+
+    public func encode(to encoder: Encoder) throws {
+        var container = encoder.container(keyedBy: CodingKeys.self)
+        try container.encode(self.value, forKey: .value)
+
+        var unitContainer = container.nestedContainer(keyedBy: UnitCodingKeys.self, forKey: .unit)
+        try unitContainer.encode(self.unit.symbol, forKey: .symbol)
+
+        if UnitType.self is Dimension.Type {
+            guard type(of: (self.unit as! Dimension).converter) is UnitConverterLinear.Type else {
+                preconditionFailure("Cannot encode a Measurement whose UnitType has a non-linear unit converter.")
+            }
+
+            let converter = (self.unit as! Dimension).converter as! UnitConverterLinear
+            var converterContainer = unitContainer.nestedContainer(keyedBy: LinearConverterCodingKeys.self, forKey: .converter)
+            try converterContainer.encode(converter.coefficient, forKey: .coefficient)
+            try converterContainer.encode(converter.constant, forKey: .constant)
+        }
+    }
+}