JSONEncoder and PropertyListEncoder both use NSNumber to box Bool values. An encoded Bool can be coerced to any numerical type during decoding because (false as NSNumber).intValue == 0. As a remedy, all of the unbox(_:as:) methods of _JSONDecoder and _PlistDecoder for numerical types include a check that the value is not identical to either kCFBooleanTrue or kCFBooleanFalse, and throw a DecodingError._typeMismatch(at:expectation:) if this check fails.
One of the limitations of not having conditional conformance at the
moment is that the implementation of `init(from:)` and `encode(to:)` on
types which require it is that failure to cast dependent types to
`Encodable` or `Decodable` is a runtime failure. There is no way to
statically guarantee that the wrapped type is `Encodable` or
`Decodable`.
As such, in those implementations, at best we can directly call
`(element as! Encodable).encode(to: encoder)`, or similar. However, this
encodes the element directly into an encoder, without giving the encoder
a chance to intercept the type. This is problematic for `JSONEncoder`
because it cannot apply a strategy if it doesn't get to intercept the
type.
This gives a temporary workaround for JSON strategies because of
internal Foundation knowledge.
For the benefit of unkeyed containers, coding paths currently contain optional `CodingKey`s — unkeyed containers are allowed to report a `nil` key in a path. However, this is unhelpful for debugging purposes, or inspecting the coding path for context, since any unkeyed container simply reports `nil`, whether it’s at index 1 or 1000.
Now all containers are required to report a non-optional CodingKey for their segment of the coding path, and coding paths are now exposed as `[CodingKey]`.
* Add deferredToData strategy on encode and decode
* Rename base64{Encode,Decode} to base64 (missed this in previous fixes)
* Add unit test to confirm behavior
Allow JSONEncoder/JSONDecoder to intercept Decimal values so they get
a numeric representation in JSON (instead of their default keyed
implementation).
On encode, we previously treated every container request as a push;
instead, we should allow the same container type to be requested
multiple times so a class can pass its Encoder directly to its
superclass if it needs to.
SingleValueDecondingContainers in JSON and Plist previously held the
assertion that attempting to decode an array or dictionary from them
was a type mismatch (since those represented unkeyed and keyed
containers, respectively). This assertion is no longer true, though,
since encode<T : Encodable>(_:) and decode<T : Decodable>(_:) allow
you to do just that.
This lifts the assertion and adds unit tests to both implementations to
ensure this works. (Addresses https://bugs.swift.org/browse/SR-5089)
Optional properties now get synthesized encodeIfPresent(...) and
decodeIfPresent(...) calls (to avoid encoding needless information, and
to be more accepting on input).
codingPath more often than not actually needs to be copied, not just
referenced. This makes a big difference for nested containers and
subobjects, which were getting the wrong codingPath values when asking
for them.
This also adds unit tests for JSONEncoder and PropertyListEncoder to
confirm expected behavior.
