Record utilities
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@ -4,11 +4,13 @@ import base64, endians, json, hashes, tables, streams
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import bigints
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type
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PreserveKind = enum
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PreserveKind* = enum
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pkBoolean, pkFloat, pkDouble, pkSignedInteger, pkBigInteger, pkString, pkByteString,
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pkSymbol, pkRecord, pkSequence, pkSet, pkDictionary, pkEmbedded
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Preserve*[T] = object
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Preserve*[T] {.acyclic.} = object
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## Type that stores a Preserves value.
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## ``T`` is the domain-specific type of "embedded" values, otherwise ``void``.
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case kind*: PreserveKind
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of pkBoolean:
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bool*: bool
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@ -37,17 +39,111 @@ type
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of pkEmbedded:
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embedded*: T
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proc `$`*[T](prs: Preserve[T]): string =
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case prs.kind:
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of pkBoolean:
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case prs.bool
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of false: result = "#f"
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of true: result = "#t"
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of pkFloat:
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result = $prs.float & "f"
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of pkDouble:
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result = $prs.double
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of pkSignedInteger:
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result = $prs.int
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of pkBigInteger:
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result = $prs.bigint
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of pkString:
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result = escapeJson(prs.string)
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of pkByteString:
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result.add("#[")
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result.add(base64.encode(prs.bytes))
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result.add(']')
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of pkSymbol:
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result.add(escapeJsonUnquoted(prs.symbol))
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of pkRecord:
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result.add('<')
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for val in prs.record:
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result.add(' ')
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result.add($val)
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result.add('>')
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of pkSequence:
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result.add('[')
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for i, val in prs.seq:
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if i > 0:
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result.add(' ')
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result.add($val)
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result.add(']')
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of pkSet:
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result.add("#{")
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for val in prs.set.keys:
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result.add($val)
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result.add(' ')
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if result.len > 1:
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result.setLen(result.high)
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result.add('}')
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of pkDictionary:
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result.add('{')
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for (key, value) in prs.dict.pairs:
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result.add($key)
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result.add(" :")
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result.add($value)
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result.add(' ')
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if result.len > 1:
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result.setLen(result.high)
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result.add('}')
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of pkEmbedded:
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when not T is void:
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$prs.embedded
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proc toPreserve*(b: bool): Preserve[void] =
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Preserve[void](kind: pkBoolean, bool: b)
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proc toPreserve*(n: SomeInteger): Preserve[void] =
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Preserve[void](kind: pkSignedInteger, int: n.BiggestInt)
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proc toPreserve*(n: BigInt): Preserve[void] =
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if initBigInt(low(BiggestInt)) < n and n < initBigInt(high(BiggestInt)):
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var tmp: BiggestUint
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for limb in n.limbs:
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tmp = (tmp shl 32) or limb
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if Negative in n.flags:
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tmp = (not tmp) + 1
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result = Preserve[void](kind: pkSignedInteger, int: cast[BiggestInt](tmp))
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else:
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result = Preserve[void](kind: pkBigInteger, bigint: n)
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proc toPreserve*(s: string): Preserve[void] =
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Preserve[void](kind: pkString, string: s)
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proc symbol*[T](s: string): Preserve[void] {.inline.} =
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## Symbol constructor.
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Preserve[T](kind: pkSymbol, symbol: s)
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proc record*[T](label: Preserve[T], args: varargs[Preserve[T]]): Preserve[T] =
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## Record constructor.
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result = Preserve[T](kind: pkRecord, record: newSeqOfCap(1+args.len))
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result.record.add(label)
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for arg in args: result.record.add(arg)
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proc record*[T](label: string, args: varargs[Preserve[T]]): Preserve[T] {.inline.} =
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## Record constructor that converts ``label`` to a symbol.
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record(symbol[T](label), args)
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proc label*[T](prs: Preserve[T]): Preserve[T] {.inline.} =
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## Return the label of a record value.
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prs.record[0]
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proc arity*[T](prs: Preserve[T]): int {.inline.} =
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## Return the number of fields in a record value.
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pred(prs.record.len)
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proc fields*[T](prs: Preserve[T]): seq[Preserve[T]] {.inline.} =
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## Return the fields of a record value.
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prs.record[1..prs.record.high]
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iterator fields*[T](prs: Preserve[T]): seq[Preserve[T]] =
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iterator fields*[T](prs: Preserve[T]): Preserve[T] =
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## Iterate the fields of a record value.
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for i in 1..prs.record.high:
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yield prs.record[i]
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@ -160,66 +256,6 @@ proc hash*[T](prs: Preserve[T]): Hash =
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h = h !& hash(prs.embedded)
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!$h
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proc `$`*[T](prs: Preserve[T]): string =
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case prs.kind:
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of pkBoolean:
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case prs.bool
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of false: result = "#f"
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of true: result = "#t"
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of pkFloat:
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result = $prs.float & "f"
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of pkDouble:
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result = $prs.double
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of pkSignedInteger:
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result = $prs.int
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of pkBigInteger:
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result = $prs.bigint
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of pkString:
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result = escapeJson(prs.string)
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of pkByteString:
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result.add("#[")
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result.add(base64.encode(prs.bytes))
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result.add(']')
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of pkSymbol:
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result.add('|')
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result.add(escapeJsonUnquoted(prs.symbol))
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result.add('|')
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of pkRecord:
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result.add('<')
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result.add(prs.label)
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for val in prs.fields:
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result.add(' ')
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result.add($val)
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result.add('>')
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of pkSequence:
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result.add('[')
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for i, val in prs.seq:
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if i > 0:
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result.add(' ')
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result.add($val)
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result.add(']')
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of pkSet:
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result.add("#{")
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for val in prs.set.keys:
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result.add($val)
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result.add(' ')
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if result.len > 1:
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result.setLen(result.high)
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result.add('}')
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of pkDictionary:
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result.add('{')
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for (key, value) in prs.dict.pairs:
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result.add($key)
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result.add(" :")
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result.add($value)
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result.add(' ')
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if result.len > 1:
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result.setLen(result.high)
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result.add('}')
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of pkEmbedded:
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when not T is void:
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$prs.embedded
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proc writeVarint(s: Stream; n: int) =
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var n = n
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while true:
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@ -420,26 +456,6 @@ proc parsePreserve*(s: Stream): Preserve[void] =
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else:
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assertStream(false)
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proc toPreserve*(b: bool): Preserve[void] =
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Preserve[void](kind: pkBoolean, bool: b)
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proc toPreserve*(n: SomeInteger): Preserve[void] =
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Preserve[void](kind: pkSignedInteger, int: n.BiggestInt)
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proc toPreserve*(n: BigInt): Preserve[void] =
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if initBigInt(low(BiggestInt)) < n and n < initBigInt(high(BiggestInt)):
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var tmp: BiggestUint
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for limb in n.limbs:
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tmp = (tmp shl 32) or limb
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if Negative in n.flags:
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tmp = (not tmp) + 1
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result = Preserve[void](kind: pkSignedInteger, int: cast[BiggestInt](tmp))
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else:
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result = Preserve[void](kind: pkBigInteger, bigint: n)
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proc toPreserve*(s: string): Preserve[void] =
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Preserve[void](kind: pkString, string: s)
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proc toPreserve*(js: JsonNode): Preserve[void] =
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case js.kind
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of JString:
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@ -506,3 +522,26 @@ proc toJson*[T](prs: Preserve[T]): JsonNode =
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result[key.string] = val.toJson
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of pkEmbedded:
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raise newException(ValueError, "cannot convert embedded value to JSON")
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type Record* = object
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## Type of a preserves record type.
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label*: string
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arity*: Natural
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proc init*[T](rec: Record, fields: varargs[Preserve[T]]): Preserve[T] =
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## Initialize a new record value.
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assert(fields.len == rec.arity)
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record(rec.label, fields)
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proc isClassOf*[T](rec: Record, val: Preserve[T]): bool =
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## Compare the label and arity of ``val`` to the record type ``rec``.
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if val.kind == pkRecord:
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let label = val.label
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if label.kind == pkSymbol:
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result = label.symbol == rec.label and rec.arity == val.arity
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proc classOf*[T](val: Preserve[T]): Record =
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## Derive the ``Record`` type of ``val``.
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if val.kind != pkRecord or val.label.kind == pkSymbol:
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raise newException(ValueError, "cannot derive class of non-record value")
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Record(label: val.label.symbol, arity: val.arity)
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