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Merged
merged 3 commits into from
Jul 30, 2025
Merged

Flavor automatic serialization rework #124

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a21b34f
Flavor automatic serialization rework
jangko Jul 29, 2025
22b547e
fix
jangko Jul 29, 2025
8ac4cc4
Fix for nim 1.6
jangko Jul 30, 2025
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6 changes: 3 additions & 3 deletions json_serialization/format.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -106,7 +106,8 @@ template createJsonFlavor*(FlavorName: untyped,
requireAllFields = true,
omitOptionalFields = true,
allowUnknownFields = true,
skipNullFields = false) {.dirty.} =
skipNullFields = false,
automaticPrimitivesSerialization = true) {.dirty.} =
when declared(SerializationFormat): # Earlier versions lack mimeTypeValue
createFlavor(Json, FlavorName, mimeTypeValue)
else:
Expand Down Expand Up @@ -137,5 +138,4 @@ template createJsonFlavor*(FlavorName: untyped,
# Set default to true for backward compatibility
# but user can call it again later with different value.
# Or fine tuning use `Flavor.automaticSerialization(type, true/false)`
FlavorName.automaticBuiltinSerialization(true)

FlavorName.automaticBuiltinSerialization(automaticPrimitivesSerialization)
223 changes: 124 additions & 99 deletions json_serialization/reader_impl.nim
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Expand Up @@ -225,22 +225,66 @@ proc readRecordValue*[T](r: var JsonReader, value: var T)
else:
r.raiseUnexpectedField(key, cstring typeName)

template autoSerializeCheck(F: distinct type, T: distinct type) =
template autoSerializeCheck(F: distinct type, T: distinct type, body) =
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@arnetheduck arnetheduck Aug 11, 2025

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why is this helper in n-j-s and not in nim-serialization?

when declared(macrocache.hasKey): # Nim 1.6 have no macrocache.hasKey
mixin typeAutoSerialize
when not F.typeAutoSerialize(T):
const typeName = typetraits.name(T)
{.error: "automatic serialization is not enabled or readValue not implemented for `" &
const
typeName = typetraits.name(T)
flavorName = typetraits.name(F)
{.error: flavorName &
": automatic serialization is not enabled or readValue not implemented for `" &
typeName & "`".}
else:
body
else:
body

template autoSerializeCheck(F: distinct type, TC: distinct type, M: distinct type) =
template autoSerializeCheck(F: distinct type, TC: distinct type, M: distinct type, body) =
when declared(macrocache.hasKey): # Nim 1.6 have no macrocache.hasKey
mixin typeClassOrMemberAutoSerialize
when not F.typeClassOrMemberAutoSerialize(TC, M):
const typeName = typetraits.name(M)
const typeClassName = typetraits.name(TC)
{.error: "automatic serialization is not enabled or readValue not implemented for `" &
const
typeName = typetraits.name(M)
typeClassName = typetraits.name(TC)
flavorName = typetraits.name(F)
{.error: flavorName &
": automatic serialization is not enabled or readValue not implemented for `" &
typeName & "` of typeclass `" & typeClassName & "`".}
else:
body
else:
body

template readValueRefOrPtr(r, value) =
mixin readValue
when compiles(isNotNilCheck(value)):
allocPtr value
value[] = readValue(r, type(value[]))
else:
if r.tokKind == JsonValueKind.Null:
value = nil
r.parseNull()
else:
allocPtr value
value[] = readValue(r, type(value[]))

template readValueObjectOrTuple(Flavor, r, value) =
mixin flavorUsesAutomaticObjectSerialization

const isAutomatic =
flavorUsesAutomaticObjectSerialization(Flavor)

when not isAutomatic:
const
flavor =
"JsonReader[" & typetraits.name(typeof(r).Flavor) & "], " &
typetraits.name(T)
{.error:
"Missing Json serialization import or implementation for readValue(" &
flavor & ")".}

readRecordValue(r, value)

proc readValue*[T](r: var JsonReader, value: var T)
{.raises: [SerializationError, IOError].} =
Expand All @@ -261,129 +305,110 @@ proc readValue*[T](r: var JsonReader, value: var T)
type Flavor = JsonReader.Flavor

when value is JsonString:
autoSerializeCheck(Flavor, JsonString)
value = r.parseAsString()
autoSerializeCheck(Flavor, JsonString):
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@arnetheduck arnetheduck Aug 11, 2025

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it feels like this check could be spelled as when autoSerializeCheck(...)

value = r.parseAsString()

elif value is JsonNode:
autoSerializeCheck(Flavor, JsonNode)
value = r.parseJsonNode()
autoSerializeCheck(Flavor, JsonNode):
value = r.parseJsonNode()

elif value is JsonNumber:
autoSerializeCheck(Flavor, JsonNumber)
r.parseNumber(value)
autoSerializeCheck(Flavor, JsonNumber):
r.parseNumber(value)

elif value is JsonVoid:
autoSerializeCheck(Flavor, JsonVoid)
r.skipSingleJsValue()
autoSerializeCheck(Flavor, JsonVoid):
r.skipSingleJsValue()

elif value is JsonValueRef:
autoSerializeCheck(Flavor, JsonValueRef)
r.parseValue(value)
autoSerializeCheck(Flavor, JsonValueRef):
r.parseValue(value)

elif value is string:
autoSerializeCheck(Flavor, string)
value = r.parseString()
autoSerializeCheck(Flavor, string):
value = r.parseString()

elif value is seq[char]:
autoSerializeCheck(Flavor, seq[char])
let val = r.parseString()
value.setLen(val.len)
for i in 0..<val.len:
value[i] = val[i]
autoSerializeCheck(Flavor, seq[char]):
let val = r.parseString()
value.setLen(val.len)
for i in 0..<val.len:
value[i] = val[i]

elif isCharArray(value):
autoSerializeCheck(Flavor, array, typeof(value))
let val = r.parseString()
if val.len != value.len:
# Raise tkString because we expected a `"` earlier
r.raiseUnexpectedToken(etString)
for i in 0..<value.len:
value[i] = val[i]
autoSerializeCheck(Flavor, array, typeof(value)):
let val = r.parseString()
if val.len != value.len:
# Raise tkString because we expected a `"` earlier
r.raiseUnexpectedToken(etString)
for i in 0..<value.len:
value[i] = val[i]

elif value is bool:
autoSerializeCheck(Flavor, bool)
value = r.parseBool()
autoSerializeCheck(Flavor, bool):
value = r.parseBool()

elif value is ref|ptr:
when value is ref:
autoSerializeCheck(Flavor, ref, typeof(value))
elif value is ref:
autoSerializeCheck(Flavor, ref, typeof(value)):
readValueRefOrPtr(r, value)

when value is ptr:
autoSerializeCheck(Flavor, ptr, typeof(value))

when compiles(isNotNilCheck(value)):
allocPtr value
value[] = readValue(r, type(value[]))
else:
if r.tokKind == JsonValueKind.Null:
value = nil
r.parseNull()
else:
allocPtr value
value[] = readValue(r, type(value[]))
elif value is ptr:
autoSerializeCheck(Flavor, ptr, typeof(value)):
readValueRefOrPtr(r, value)

elif value is enum:
autoSerializeCheck(Flavor, enum, typeof(value))
r.parseEnum(value)
autoSerializeCheck(Flavor, enum, typeof(value)):
r.parseEnum(value)

elif value is SomeInteger:
autoSerializeCheck(Flavor, SomeInteger, typeof(value))
value = r.parseInt(typeof value,
JsonReaderFlag.portableInt in r.lex.flags)
autoSerializeCheck(Flavor, SomeInteger, typeof(value)):
value = r.parseInt(typeof value,
JsonReaderFlag.portableInt in r.lex.flags)

elif value is SomeFloat:
autoSerializeCheck(Flavor, SomeFloat, typeof(value))
let val = r.parseNumber(uint64)
if val.isFloat:
value = r.toFloat(val, typeof value)
else:
value = T(val.integer)
autoSerializeCheck(Flavor, SomeFloat, typeof(value)):
let val = r.parseNumber(uint64)
if val.isFloat:
value = r.toFloat(val, typeof value)
else:
value = T(val.integer)

elif value is seq:
autoSerializeCheck(Flavor, seq, typeof(value))
r.parseArray:
let lastPos = value.len
value.setLen(lastPos + 1)
readValue(r, value[lastPos])
autoSerializeCheck(Flavor, seq, typeof(value)):
r.parseArray:
let lastPos = value.len
value.setLen(lastPos + 1)
readValue(r, value[lastPos])

elif value is array:
autoSerializeCheck(Flavor, array, typeof(value))
type IDX = typeof low(value)
r.parseArray(idx):
if idx < value.len:
let i = IDX(idx + low(value).int)
readValue(r, value[i])
else:
r.raiseUnexpectedValue("Too many items for " & $(typeof(value)))

elif value is (object or tuple):
when declared(macrocache.hasKey): # Nim 1.6 have no macrocache.hasKey
when value is object:
autoSerializeCheck(Flavor, object, typeof(value))

when value is tuple:
autoSerializeCheck(Flavor, tuple, typeof(value))

# Keep existing object/tuple auto serialization
# But make it deprecated.
mixin flavorUsesAutomaticObjectSerialization
autoSerializeCheck(Flavor, array, typeof(value)):
type IDX = typeof low(value)
r.parseArray(idx):
if idx < value.len:
let i = IDX(idx + low(value).int)
readValue(r, value[i])
else:
r.raiseUnexpectedValue("Too many items for " & $(typeof(value)))

elif value is object:
when declared(macrocache.hasKey): # Nim 1.6 have no macrocache.hasKey and cannot accept `object` param
autoSerializeCheck(Flavor, object, typeof(value)):
readValueObjectOrTuple(Flavor, r, value)
else:
readValueObjectOrTuple(Flavor, r, value)

const isAutomatic =
flavorUsesAutomaticObjectSerialization(Flavor)
elif value is tuple:
when declared(macrocache.hasKey): # Nim 1.6 have no macrocache.hasKey and cannot accept `tuple` param
autoSerializeCheck(Flavor, tuple, typeof(value)):
readValueObjectOrTuple(Flavor, r, value)
else:
readValueObjectOrTuple(Flavor, r, value)

when not isAutomatic:
const
flavor =
"JsonReader[" & typetraits.name(typeof(r).Flavor) & "], " &
typetraits.name(T)
{.error:
"Missing Json serialization import or implementation for readValue(" &
flavor & ")".}

readRecordValue(r, value)
else:
const typeName = typetraits.name(T)
{.error: "Failed to convert to JSON an unsupported type: " &
const
typeName = typetraits.name(T)
flavorName = typetraits.name(Flavor)
{.error: flavorName & ": Failed to convert from JSON an unsupported type: " &
typeName.}

iterator readObjectFields*(r: var JsonReader): string {.
Expand Down
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