Add convenience method/properties for stream decoding

Add a method `values()` on `JSONStreamDecoder` that eagerly parses all values and returns it as a `[JSON]`. Also add properties `.json` and `.error` to `JSONStreamValue`.
postmates · Oct 20, 2016 · f8ce5d0 · f8ce5d0
1 parent bd1765d
commit f8ce5d0
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Showing 2 changed files with 60 additions and 14 deletions.
diff --git a/Sources/Decoder.swift b/Sources/Decoder.swift
@@ -222,6 +222,17 @@ public struct JSONStreamDecoder<Seq: Sequence>: Sequence, IteratorProtocol where
         decoder.streaming = true
     }
 
+    /// Returns an array of all decoded values, or throws an error if one occurs.
+    ///
+    /// This eagerly decodes the rest of the JSON stream and returns all values. If a parse error occurs at any point,
+    /// the error is thrown and all values are discarded.
+    ///
+    /// - Returns: An array of `JSON` values.
+    /// - Throws: `JSONParserError`.
+    public func values() throws -> [JSON] {
+        return try map({ try $0.unwrap() })
+    }
+
     public func makeIterator() -> JSONStreamDecoder<Seq> {
         return self
     }
@@ -247,6 +258,22 @@ public enum JSONStreamValue: Equatable {
     case json(JSON)
     case error(JSONParserError)
 
+    /// Returns the contained `JSON` value, otherwise `nil`.
+    public var json: JSON? {
+        switch self {
+        case .json(let json): return json
+        case .error: return nil
+        }
+    }
+
+    /// Returns the contained error, otherwise `nil`.
+    public var error: JSONParserError? {
+        switch self {
+        case .json: return nil
+        case .error(let error): return error
+        }
+    }
+
     /// Unwraps the contained `JSON` value or throws the contained error.
     ///
     /// - Throws: `JSONParserError`.

diff --git a/Tests/JSONDecoderTests.swift b/Tests/JSONDecoderTests.swift
@@ -339,23 +339,42 @@ class JSONStreamDecoderTests: XCTestCase {
 
     func testStreamingDecoder() {
         func assertMatchesValues(_ input: String, _ expected: [JSONStreamValue], file: StaticString = #file, line: UInt = #line) {
+            for (i, (value, expected)) in zip(JSON.decodeStream(input), expected).enumerated() {
+                switch (value, expected) {
+                case let (.json(value), .json(expected)):
+                    if !matchesJSON(value, expected) {
+                        XCTFail("value \(i+1) - (\(value)) does not equal \(expected)", file: file, line: line)
+                    }
+                case let (.error(error), .error(expected)):
+                    if error != expected {
+                        XCTFail("error \(i+1) - (\(error)) does not equal \(expected)", file: file, line: line)
+                    }
+                case let (.json(value), .error(expected)):
+                    XCTFail("value \(i+1) - expected error \(expected), found value \(value)", file: file, line: line)
+                case let (.error(error), .json(expected)):
+                    XCTFail("value \(i+1) - expected value \(expected), found error \(error)", file: file, line: line)
+                }
+            }
+            // Also check the behavior of values()
             do {
-                for (i, (value, expected)) in zip(JSON.decodeStream(input), expected).enumerated() {
-                    switch (value, expected) {
-                    case let (.json(value), .json(expected)):
-                        if !matchesJSON(value, expected) {
-                            XCTFail("value \(i+1) - (\(value)) does not equal \(expected)", file: file, line: line)
-                        }
-                    case let (.error(error), .error(expected)):
-                        if error != expected {
-                            XCTFail("error \(i+1) - (\(error)) does not equal \(expected)", file: file, line: line)
-                        }
-                    case let (.json(value), .error(expected)):
-                        XCTFail("value \(i+1) - expected error \(expected), found value \(value)")
-                    case let (.error(error), .json(expected)):
-                        XCTFail("value \(i+1) - expected value \(expected), found error \(error)", file: file, line: line)
+                let expectedValues = try expected.map({ try $0.unwrap() })
+                do {
+                    let values = try JSON.decodeStream(input).values()
+                    XCTAssertEqual(values, expectedValues, file: file, line: line)
+                } catch {
+                    XCTFail("unexpected error found decoding JSON stream - \(error)", file: file, line: line)
+                }
+            } catch let expectedError as JSONParserError {
+                XCTAssertThrowsError(try JSON.decodeStream(input).values()) { (error) in
+                    switch error {
+                    case let error as JSONParserError:
+                        XCTAssertEqual(error, expectedError, file: file, line: line)
+                    default:
+                        XCTFail("expected \(expectedError), found \(error)", file: file, line: line)
                     }
                 }
+            } catch {
+                XCTFail(file: file, line: line) // unreachable
             }
         }
         func assertMatchesEvents(_ input: String, _ expected: [JSON], file: StaticString = #file, line: UInt = #line) {