Add some enhancements to jsonutils.nim (nim-lang#15133)

* Add some enhancements to `jsonutils.nim`

* Use `jsonutils.nim` hookable API to add a possibility to deserialize
  JSON arrays directly to `HashSet` and `OrderedSet` types and
  respectively to serialize those types to JSON arrays.

* Also add a possibility to deserialize JSON `null` objects to Nim
  option objects and respectively to serialize Nim option object to JSON
  object if some or to JSON `null` object if none.

* Move serialization/deserialization functionality for `Table` and
  `OrderedTable` types from `jsonutils.nim` to `tables.nim` via the
  hookable API.

* Add object `jsonutils.Joptions` and parameter from its type to
  `jsonutils.fromJson` procedure to control whether to allow
  deserializing JSON objects to Nim objects when the JSON has some
  extra or missing keys.

* Add unit tests for the added functionalities to `tjsonutils.nim`.

* improve fromJsonFields

* Add changelog entry for the jsonutils enhancements

* Add TODO in `jsonutils.nim`

* Added an entry to "Future directions" section in `jsonutils.nim` as
  suggestion for future support of serialization and de-serialization of
  nested variant objects.

* Added currently disabled test case in `tjsonutils.nim` for testing
  serialization and de-serialization of nested variant objects.

* Move JSON hooks to `jsonutils.nim`

Move `fromJsonHook` and `toJsonHook` procedures for different types to
`jsonutils.nim` module to avoid a dependency of collections modules to
the `json.nim` module.

The hooks are removed from the following modules:

  * `tables.nim`

  * `sets.nim`

  * `options.nim`

  * `strtabs.nim`

* Add some tests about `StringTableRef`

Add tests for `StringTableRef`'s `fromJsonHook` and `toJsonHook` to
`tjsonutils.nim`.

* Disable a warning in `jsonutils.nim`

Mark `fun` template in `jsonutils` module with `{.used.}` pragma in
order to disable `[XDeclaredButNotUsed]` hint. The template is actually
used by the `initCaseObject` macro in the same module.

Co-authored-by: Timothee Cour <timothee.cour2@gmail.com>

changelog.md

@@ -4,6 +4,20 @@
 
 ## Standard library additions and changes
 
+- Added some enhancements to `std/jsonutils` module.
+  * Added a possibility to deserialize JSON arrays directly to `HashSet` and
+    `OrderedSet` types and respectively to serialize those types to JSON arrays
+    via `jsonutils.fromJson` and `jsonutils.toJson` procedures.
+  * Added a possibility to deserialize JSON `null` objects to Nim option objects
+    and respectively to serialize Nim option object to JSON object if `isSome`
+    or to JSON null object if `isNone` via `jsonutils.fromJson` and
+    `jsonutils.toJson` procedures.
+  * Added `Joptions` parameter to `jsonutils.fromJson` procedure currently
+    containing two boolean options `allowExtraKeys` and `allowMissingKeys`.
+    - If `allowExtraKeys` is `true` Nim's object to which the JSON is parsed is
+      not required to have a field for every JSON key.
+    - If `allowMissingKeys` is `true` Nim's object to which JSON is parsed is
+      allowed to have fields without corresponding JSON keys.
 - Added `bindParams`, `bindParam` to `db_sqlite` for binding parameters into a `SqlPrepared` statement.
 - Add `tryInsert`,`insert` procs to `db_*` libs accept primary key column name.
 - Added `xmltree.newVerbatimText` support create `style`'s,`script`'s text.

lib/pure/collections/sets.nim

@@ -80,6 +80,8 @@ type
     ## <#initOrderedSet,int>`_ before calling other procs on it.
     data: OrderedKeyValuePairSeq[A]
     counter, first, last: int
+  SomeSet*[A] = HashSet[A] | OrderedSet[A]
+    ## Type union representing `HashSet` or `OrderedSet`.
 
 const
   defaultInitialSize* = 64
@@ -907,8 +909,6 @@ iterator pairs*[A](s: OrderedSet[A]): tuple[a: int, b: A] =
   forAllOrderedPairs:
     yield (idx, s.data[h].key)
 
-
-
 # -----------------------------------------------------------------------
 
 

lib/pure/collections/tables.nim

@@ -1750,10 +1750,6 @@ iterator mvalues*[A, B](t: var OrderedTable[A, B]): var B =
     yield t.data[h].val
     assert(len(t) == L, "the length of the table changed while iterating over it")
 
-
-
-
-
 # ---------------------------------------------------------------------------
 # --------------------------- OrderedTableRef -------------------------------
 # ---------------------------------------------------------------------------

lib/pure/options.nim

@@ -372,7 +372,6 @@ proc unsafeGet*[T](self: Option[T]): lent T {.inline.}=
   assert self.isSome
   result = self.val
 
-
 when isMainModule:
   import unittest, sequtils
 

lib/pure/strtabs.nim

@@ -89,6 +89,7 @@ const
   growthFactor = 2
   startSize = 64
 
+proc mode*(t: StringTableRef): StringTableMode {.inline.} = t.mode
 
 iterator pairs*(t: StringTableRef): tuple[key, value: string] =
   ## Iterates over every `(key, value)` pair in the table `t`.
@@ -422,25 +423,6 @@ proc `%`*(f: string, t: StringTableRef, flags: set[FormatFlag] = {}): string {.
       add(result, f[i])
       inc(i)
 
-since (1,3,5):
-  proc fromJsonHook*[T](a: var StringTableRef, b: T) =
-    ## for json.fromJson
-    mixin jsonTo
-    var mode = jsonTo(b["mode"], StringTableMode)
-    a = newStringTable(mode)
-    let b2 = b["table"]
-    for k,v in b2: a[k] = jsonTo(v, string)
-
-  proc toJsonHook*[](a: StringTableRef): auto =
-    ## for json.toJson
-    mixin newJObject
-    mixin toJson
-    result = newJObject()
-    result["mode"] = toJson($a.mode)
-    let t = newJObject()
-    for k,v in a: t[k] = toJson(v)
-    result["table"] = t
-
 when isMainModule:
   var x = {"k": "v", "11": "22", "565": "67"}.newStringTable
   assert x["k"] == "v"