From 86d477136f105f04bfd0dd7c0e939593d81fc581 Mon Sep 17 00:00:00 2001
From: Zahary Karadjov <zahary@status.im>
Date: Tue, 14 Mar 2023 15:31:45 +0200
Subject: [PATCH] Add support for optional sequences and arrays

---
 toml_serialization/private/array_reader.nim | 11 ++++++-----
 toml_serialization/reader.nim               |  4 ++++
 toml_serialization/types.nim                | 15 +++++++++++++++
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/toml_serialization/private/array_reader.nim b/toml_serialization/private/array_reader.nim
index 4969200..c49c549 100644
--- a/toml_serialization/private/array_reader.nim
+++ b/toml_serialization/private/array_reader.nim
@@ -25,8 +25,9 @@ const
 
 proc totalArrayFieldsImpl(T: type): int =
   mixin enumAllSerializedFields
+
   enumAllSerializedFields(T):
-    when FieldType is (seq or array):
+    when isArrayLike(FieldType):
       inc result
 
 template totalArrayFields*(T: type): int =
@@ -36,9 +37,9 @@ proc makeArrayReadersTable(RecordType, Reader: distinct type, L: static[int]):
                            array[L, ArrayReader[RecordType, Reader]] =
   var fieldPos = 0
   enumAllSerializedFields(RecordType):
-    when FieldType is (seq or array):
-      proc readArray(obj: var RecordType, reader: var Reader, idx: int)
-                    {.gcsafe, nimcall, raises: [SerializationError, Defect].} =
+    when isArrayLike(FieldType):
+      proc readArrayFieldImpl(obj: var RecordType, reader: var Reader, idx: int)
+                             {.gcsafe, nimcall, raises: [SerializationError, Defect].} =
         mixin readValue
 
         when RecordType is tuple:
@@ -59,7 +60,7 @@ proc makeArrayReadersTable(RecordType, Reader: distinct type, L: static[int]):
             when RecordType is tuple: obj[i] else: field(obj, realFieldName),
             err)
 
-      result[fieldPos] = (0, fieldName, readArray)
+      result[fieldPos] = (0, fieldName, readArrayFieldImpl)
       inc fieldPos
 
 template arrayReadersTable*(RecordType, Reader: distinct type): auto =
diff --git a/toml_serialization/reader.nim b/toml_serialization/reader.nim
index 319655a..d096144 100644
--- a/toml_serialization/reader.nim
+++ b/toml_serialization/reader.nim
@@ -242,6 +242,10 @@ proc readValue*[T](r: var TomlReader, value: var T, numRead: int)
     readValue(r, value[numRead])
   elif T is array:
     readValue(r, value[numRead])
+  elif isOptionalInToml(T):
+    if value.isNone:
+      value = some default(typeof(value.get))
+    readValue(r, value.get, numRead)
   else:
     const typeName = typetraits.name(T)
     {.error: "Failed to convert from TOML an unsupported type: " & typeName.}
diff --git a/toml_serialization/types.nim b/toml_serialization/types.nim
index c24c2ca..c615e68 100644
--- a/toml_serialization/types.nim
+++ b/toml_serialization/types.nim
@@ -116,6 +116,21 @@ type
     of TomlKind.Table, TomlKind.InlineTable:
       tableVal*: TomlTableRef
 
+template isOptionalInToml*(T: type): bool = false
+template isOptionalInToml*[X](T: type Option[X]): bool = true
+
+template BaseType*[X](T: type Option[X]): type = X
+
+template isArrayLike*(T: type): bool =
+  mixin isOptionalInToml, BaseType
+
+  when T is seq|array:
+    true
+  elif isOptionalInToml(T):
+    BaseType(T) is seq|array
+  else:
+    false
+
 when tomlOrderedTable:
   template withValue*(x: TomlTable, key: string,
                       value, body1, body2: untyped) =