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add enumutils.items for sparse enums, typetraits.SomeSparseEnum (#17080)

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* add enumutils.items for enum with holes
* changelog
* ref in lib.rst
* use `type SomeSparseEnum* = (not Ordinal) and enum` instead of concept
* address comment: rename back to enum with holes
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Timothee Cour 2021-02-23 11:25:35 -08:00 • committed by GitHub
commit c274e67198
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6 changed files with 58 additions and 6 deletions
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19
lib/std/enumutils.nim
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@ -7,7 +7,9 @@
# distribution, for details about the copyright.
#
import macros
import std/macros
# xxx `genEnumCaseStmt` needs tests and runnableExamples
macro genEnumCaseStmt*(typ: typedesc, argSym: typed, default: typed,
userMin, userMax: static[int], normalizer: static[proc(s :string): string]): untyped =
@ -61,4 +63,17 @@ macro genEnumCaseStmt*(typ: typedesc, argSym: typed, default: typed,
result.add nnkElse.newTree(raiseStmt)
else:
expectKind(default, nnkSym)
result.add nnkElse.newTree(default)
result.add nnkElse.newTree(default)
macro enumWithHolesFullRange(a: typed): untyped =
newNimNode(nnkCurly).add(a.getType[1][1..^1])
iterator items*[T: enum and not Ordinal](E: typedesc[T]): T =
## Iterates over an enum with holes.
runnableExamples:
type A = enum a0 = 2, a1 = 4, a2
type B[T] = enum b0 = 2, b1 = 4
from std/sequtils import toSeq
assert A.toSeq == [a0, a1, a2]
assert B[float].toSeq == [B[float].b0, B[float].b1]
for a in enumWithHolesFullRange(E): yield a