Allow JSON extension points. (#46)

Author: fabianfett

.github/workflows/ci.yaml

@@ -99,10 +99,6 @@ jobs:
       run: sudo xcode-select -s /Applications/Xcode_11.4.app/Contents/Developer
     - name: Swift version
       run: swift --version
-    # - name: SPM Build
-    #   run: swift build
-    # - name: SPM Tests
-    #   run: swift test --parallel -Xswiftc -DDEBUG
     - name: Xcode Tests
       run: |
         swift package generate-xcodeproj --skip-extra-files --enable-code-coverage

Sources/PureSwiftJSON/Decoding/JSONDecoder.swift

@@ -8,12 +8,16 @@ public struct JSONDecoder {
         throws -> T where Bytes.Element == UInt8 {
         do {
             let json = try JSONParser().parse(bytes: bytes)
-            let decoder = JSONDecoderImpl(userInfo: userInfo, from: json, codingPath: [])
-            return try decoder.decode(T.self)
+            return try decode(T.self, from: json)
         } catch let error as JSONError {
             throw error.decodingError
         }
     }
+
+    @inlinable public func decode<T: Decodable>(_: T.Type, from json: JSONValue) throws -> T {
+        let decoder = JSONDecoderImpl(userInfo: userInfo, from: json, codingPath: [])
+        return try decoder.decode(T.self)
+    }
 }
 
 @usableFromInline struct JSONDecoderImpl {

Sources/PureSwiftJSON/Encoding/JSONEncoder.swift

@@ -101,21 +101,23 @@ public class JSONEncoder {
     public init() {}
 
     public func encode<T: Encodable>(_ value: T) throws -> [UInt8] {
+        let value: JSONValue = try encodeAsJSONValue(value)
+        var bytes = [UInt8]()
+        value.appendBytes(to: &bytes)
+        return bytes
+    }
+
+    public func encodeAsJSONValue<T: Encodable>(_ value: T) throws -> JSONValue {
         let encoder = JSONEncoderImpl(userInfo: userInfo, codingPath: [])
 
         try value.encode(to: encoder)
 
         // if the top level encoder does not have a value
         // we don't have a value at all and we should return `null`
-        let value = encoder.value ?? .null
-
-        var bytes = [UInt8]()
-        value.appendBytes(to: &bytes)
-        return bytes
+        return encoder.value ?? .null
     }
 }
 
-/// TBD: This could be done with a struct on the stack, by using inout references.
 class JSONEncoderImpl {
     let userInfo: [CodingUserInfoKey: Any]
     let codingPath: [CodingKey]

Tests/PureSwiftJSONTests/Decoding/JSONDecoderTests.swift

@@ -52,16 +52,15 @@ class JSONDecoderTests: XCTestCase {
             }
         }
 
-        do {
-            let json = #"{"hello":"world"}"#
-            let result = try PureSwiftJSON.JSONDecoder().decode(HelloWorld.self, from: json.data(using: .utf8)!)
-            XCTFail("Did not expect to get a result: \(result)")
-        } catch let Swift.DecodingError.typeMismatch(type, context) {
-            // expected
+        let json = #"{"hello":"world"}"#
+        XCTAssertThrowsError(_ = try PureSwiftJSON.JSONDecoder().decode(HelloWorld.self, from: json.data(using: .utf8)!)) {
+            error in
+            guard case let Swift.DecodingError.typeMismatch(type, context) = error else {
+                XCTFail("Unexpected error: \(error)"); return
+            }
+
             XCTAssertTrue(type == [JSONValue].self)
             XCTAssertEqual(context.debugDescription, "Expected to decode Array<JSONValue> but found a dictionary instead.")
-        } catch {
-            XCTFail("Unexpected error: \(error)")
         }
     }
 
@@ -77,16 +76,15 @@ class JSONDecoderTests: XCTestCase {
             }
         }
 
-        do {
-            let json = #"["haha", "hihi"]"#
-            let result = try PureSwiftJSON.JSONDecoder().decode(HelloWorld.self, from: json.data(using: .utf8)!)
-            XCTFail("Did not expect to get a result: \(result)")
-        } catch let Swift.DecodingError.typeMismatch(type, context) {
-            // expected
+        let json = #"["haha", "hihi"]"#
+        XCTAssertThrowsError(_ = try PureSwiftJSON.JSONDecoder().decode(HelloWorld.self, from: json.data(using: .utf8)!)) {
+            error in
+            guard case let Swift.DecodingError.typeMismatch(type, context) = error else {
+                XCTFail("Unexpected error: \(error)"); return
+            }
+
             XCTAssertTrue(type == [String: JSONValue].self)
             XCTAssertEqual(context.debugDescription, "Expected to decode Dictionary<String, JSONValue> but found an array instead.")
-        } catch {
-            XCTFail("Unexpected error: \(error)")
         }
     }
 
@@ -101,17 +99,16 @@ class JSONDecoderTests: XCTestCase {
             }
         }
 
-        do {
-            let json = #"{"hello👩‍👩‍👧‍👧" 123 }"#
-            let result = try PureSwiftJSON.JSONDecoder().decode(HelloWorld.self, from: json.data(using: .utf8)!)
-            XCTFail("Did not expect to get a result: \(result)")
-        } catch let Swift.DecodingError.dataCorrupted(context) {
-            // expected
+        let json = #"{"hello👩‍👩‍👧‍👧" 123 }"#
+        XCTAssertThrowsError(_ = try PureSwiftJSON.JSONDecoder().decode(HelloWorld.self, from: json.data(using: .utf8)!)) {
+            error in
+            guard case let Swift.DecodingError.dataCorrupted(context) = error else {
+                XCTFail("Unexpected error: \(error)"); return
+            }
+
             XCTAssertEqual(context.codingPath.count, 0)
             XCTAssertEqual(context.debugDescription, "Unexpected character `1` at character index: 34")
             XCTAssertNotNil(context.underlyingError)
-        } catch {
-            XCTFail("Unexpected error: \(error)")
         }
     }
 }