127 lines
4.5 KiB
Nim
127 lines
4.5 KiB
Nim
import
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parseutils,
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faststreams/output_stream, json_serialization/writer,
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types, bytes_reader, navigator
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type
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ObjKind = enum
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Record
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Indexable
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LeafValue
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FieldInfo = ref object
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name: string
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fieldType: TypeInfo
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navigator: proc (m: MemRange): MemRange {. gcsafe
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noSideEffect
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raises: [Defect,
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MalformedSszError] }
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TypeInfo = ref object
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case kind: ObjKind
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of Record:
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fields: seq[FieldInfo]
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of Indexable:
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elemType: TypeInfo
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navigator: proc (m: MemRange, idx: int): MemRange {. gcsafe
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noSideEffect
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raises: [Defect,
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MalformedSszError] }
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else:
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discard
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jsonPrinter: proc (m: MemRange,
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outStream: OutputStreamVar,
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pretty: bool) {.gcsafe, noSideEffect.}
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DynamicSszNavigator* = object
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m: MemRange
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typ: TypeInfo
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func jsonPrinterImpl[T](m: MemRange, outStream: OutputStreamVar, pretty: bool) =
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var typedNavigator = sszMount(m, T)
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var jsonWriter = init(JsonWriter, outStream, pretty)
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# TODO: it should be possible to serialize the navigator object
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# without dereferencing it (to avoid the intermediate value).
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writeValue(jsonWriter, typedNavigator[])
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func findField(fields: seq[FieldInfo], name: string): FieldInfo =
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# TODO: Replace this with a binary search?
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# Will it buy us anything when there are only few fields?
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for field in fields:
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if field.name == name:
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return field
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func indexableNavigatorImpl[T](m: MemRange, idx: int): MemRange =
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var typedNavigator = sszMount(m, T)
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getMemRange(typedNavigator[idx])
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func fieldNavigatorImpl[RecordType; FieldType;
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fieldName: static string](m: MemRange): MemRange {.raises: [Defect, MalformedSszError].} =
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# TODO: Make sure this doesn't fail with a Defect when
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# navigating to an inactive field in a case object.
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var typedNavigator = sszMount(m, RecordType)
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getMemRange navigateToField(typedNavigator, fieldName, FieldType)
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func genTypeInfo(T: type): TypeInfo {.gcsafe.}
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proc typeInfo*(T: type): TypeInfo =
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let res {.global.} = genTypeInfo(T)
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# TODO This will be safer if the RTTI object use only manually
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# managed memory, but the `fields` sequence right now make
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# things harder. We'll need to switch to a different seq type.
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{.gcsafe, noSideEffect.}: res
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func genTypeInfo(T: type): TypeInfo =
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mixin enumAllSerializedFields
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result = when T is object:
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var fields: seq[FieldInfo]
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enumAllSerializedFields(T):
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fields.add FieldInfo(name: fieldName,
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fieldType: typeInfo(FieldType),
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navigator: fieldNavigatorImpl[T, FieldType, fieldName])
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TypeInfo(kind: Record, fields: fields)
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elif T is seq|array:
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TypeInfo(kind: Indexable,
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elemType: typeInfo(ElemType(T)),
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navigator: indexableNavigatorImpl[T])
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else:
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TypeInfo(kind: LeafValue)
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result.jsonPrinter = jsonPrinterImpl[T]
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func `[]`*(n: DynamicSszNavigator, idx: int): DynamicSszNavigator =
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doAssert n.typ.kind == Indexable
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DynamicSszNavigator(m: n.typ.navigator(n.m, idx), typ: n.typ.elemType)
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func navigate*(n: DynamicSszNavigator, path: string): DynamicSszNavigator {.
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raises: [Defect, ValueError, MalformedSszError] .} =
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case n.typ.kind
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of Record:
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let fieldInfo = n.typ.fields.findField(path)
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if fieldInfo == nil:
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raise newException(KeyError, "Unrecogned field name: " & path)
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return DynamicSszNavigator(m: fieldInfo.navigator(n.m),
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typ: fieldInfo.fieldType)
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of Indexable:
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var idx: int
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let consumed = parseInt(path, idx)
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if consumed == 0 or idx < 0:
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raise newException(ValueError, "Indexing should be done with natural numbers")
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return n[idx]
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else:
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doAssert false, "Navigation should be terminated once you reach a leaf value"
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func init*(T: type DynamicSszNavigator, bytes: openarray[byte], typ: TypeInfo): T =
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T(m: MemRange(startAddr: unsafeAddr bytes[0], length: bytes.len), typ: typ)
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func writeJson*(n: DynamicSszNavigator, outStream: OutputStreamVar, pretty = true) =
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n.typ.jsonPrinter(n.m, outStream, pretty)
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func toJson*(n: DynamicSszNavigator, pretty = true): string =
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var outStream = init OutputStream
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writeJson(n, outStream, pretty)
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outStream.getOutput(string)
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