Move checking condition & add expect fail test

Author: jevonmao

Sources/FoundationEssentials/JSON/JSONScanner.swift

@@ -265,6 +265,7 @@ internal struct JSONScanner {
     var reader: DocumentReader
     var depth: Int = 0
     var partialMap = JSONPartialMapData()
+    private static let maximumRecursionDepth = 512
 
     internal struct Options {
         var assumesTopLevelDictionary = false
@@ -412,7 +413,7 @@ internal struct JSONScanner {
     mutating func scanArray() throws {
         let firstChar = reader.read()
         precondition(firstChar == ._openbracket)
-        guard self.depth < 512 else {
+        guard self.depth < Self.maximumRecursionDepth else {
             throw JSONError.tooManyNestedArraysOrDictionaries(location: reader.sourceLocation(atOffset: 1))
         }
         self.depth &+= 1
@@ -470,7 +471,7 @@ internal struct JSONScanner {
     mutating func scanObject() throws {
         let firstChar = self.reader.read()
         precondition(firstChar == ._openbrace)
-        guard self.depth < 512 else {
+        guard self.depth < Self.maximumRecursionDepth else {
             throw JSONError.tooManyNestedArraysOrDictionaries(location: reader.sourceLocation(atOffset: -1))
         }
         try scanObject(withoutBraces: false)

Sources/FoundationEssentials/JSON/JSONWriter.swift

@@ -13,7 +13,7 @@
 internal struct JSONWriter {
 
     // Structures with container nesting deeper than this limit are not valid.
-    private static let maximumRecursionDepth = 513
+    private static let maximumRecursionDepth = 512
 
     private var indent = 0
     private let pretty: Bool
@@ -29,6 +29,9 @@ internal struct JSONWriter {
     }
 
     mutating func serializeJSON(_ value: JSONEncoderValue, depth: Int = 0) throws {
+        guard depth < Self.maximumRecursionDepth else {
+            throw JSONError.tooManyNestedArraysOrDictionaries()
+        }
         switch value {
         case .string(let str):
             serializeString(str)
@@ -172,10 +175,6 @@ internal struct JSONWriter {
     }
 
     mutating func serializeArray(_ array: [JSONEncoderValue], depth: Int) throws {
-        guard depth < Self.maximumRecursionDepth else {
-            throw JSONError.tooManyNestedArraysOrDictionaries()
-        }
-
         writer(ascii: ._openbracket)
         if pretty {
             writer(ascii: ._newline)
@@ -204,10 +203,6 @@ internal struct JSONWriter {
     }
 
     mutating func serializePreformattedByteArray(_ bytes: [UInt8], _ lengths: [Int], depth: Int) throws {
-        guard depth < Self.maximumRecursionDepth else {
-            throw JSONError.tooManyNestedArraysOrDictionaries()
-        }
-
         writer(ascii: ._openbracket)
         if pretty {
             writer(ascii: ._newline)
@@ -242,10 +237,6 @@ internal struct JSONWriter {
     }
 
     mutating func serializeObject(_ dict: [String:JSONEncoderValue], depth: Int) throws {
-        guard depth < Self.maximumRecursionDepth else {
-            throw JSONError.tooManyNestedArraysOrDictionaries()
-        }
-
         writer(ascii: ._openbrace)
         if pretty {
             writer(ascii: ._newline)

Tests/FoundationEssentialsTests/JSONEncoderTests.swift

@@ -2594,6 +2594,7 @@ extension JSONEncoderTests {
         _run_failTest(name: "fail39", type: JSONFail.Test39.self)
         _run_failTest(name: "fail40", type: JSONFail.Test40.self)
         _run_failTest(name: "fail41", type: JSONFail.Test41.self)
+        _run_failTest(name: "fail42", type: JSONFail.Test42.self)
 
     }
 
@@ -4422,6 +4423,7 @@ enum JSONFail {
     typealias Test39 = [String:String]
     typealias Test40 = [String:String]
     typealias Test41 = [String:String]
+    typealias Test42 = JSONPass.Test16
 }
 
 enum JSON5Pass { }