nim-stew/stew/objects.nim

112 lines
3.2 KiB
Nim

import
macros,
sequtils
template init*(lvalue: var auto) =
mixin init
lvalue = init(type(lvalue))
template init*(lvalue: var auto, a1: auto)=
mixin init
lvalue = init(type(lvalue), a1)
template init*(lvalue: var auto, a1, a2: auto) =
mixin init
lvalue = init(type(lvalue), a1, a2)
template init*(lvalue: var auto, a1, a2, a3: auto) =
mixin init
lvalue = init(type(lvalue), a1, a2, a3)
when not declared(default):
proc default*(T: type): T = discard
proc toArray*[T](N: static int, data: openArray[T]): array[N, T] =
doAssert data.len == N
copyMem(addr result[0], unsafeAddr data[0], N)
template anonConst*(val: untyped): untyped =
const c = val
c
func declval*(T: type): T {.compileTime.} =
## `declval` denotes an anonymous expression of a particular
## type. It can be used in situations where you want to determine
## the type of an overloaded call in `typeof` expressions.
##
## Example:
## ```
## type T = typeof foo(declval(string), declval(var int))
## ```
##
## Please note that `declval` has two advantages over `default`:
##
## 1. It can return expressions with proper `var` or `lent` types.
##
## 2. It will work for types that lack a valid default value due
## to `not nil` or `requiresInit` requirements.
##
doAssert false,
"declval should be used only in `typeof` expressions and concepts"
default(ptr T)[]
when not compiles(len((1, 2))):
import typetraits
func len*(x: tuple): int =
arity(type(x))
# Get an object's base type, as a cstring. Ref objects will have an ":ObjectType"
# suffix.
# From: https://gist.github.com/stefantalpalaru/82dc71bb547d6f9178b916e3ed5b527d
proc baseType*(obj: RootObj): cstring =
when not defined(nimTypeNames):
raiseAssert("you need to compile this with '-d:nimTypeNames'")
else:
{.emit: "result = `obj`->m_type->name;".}
proc baseType*(obj: ref RootObj): cstring =
obj[].baseType
macro enumRangeInt64*(a: type[enum]): untyped =
## This macro returns an array with all the ordinal values of an enum
let
values = a.getType[1][1..^1]
valuesOrded = values.mapIt(newCall("int64", it))
newNimNode(nnkBracket).add(valuesOrded)
macro hasHoles*(T: type[enum]): bool =
# As an enum is always sorted, just substract the first and the last ordinal value
# and compare the result to the number of element in it will do the trick.
let len = T.getType[1].len - 2
quote: `T`.high.ord - `T`.low.ord != `len`
proc contains*[I: SomeInteger](e: type[enum], v: I): bool =
when I is uint64:
if v > int.high.uint64:
return false
when e.hasHoles():
v.int64 in enumRangeInt64(e)
else:
v.int64 in e.low.int64 .. e.high.int64
func checkedEnumAssign*[E: enum, I: SomeInteger](res: var E, value: I): bool =
## This function can be used to safely assign a tainted integer value (coming
## from untrusted source) to an enum variable. The function will return `true`
## if the integer value is within the acceped values of the enum and `false`
## otherwise.
if value notin E:
return false
res = E value
return true
func isZeroMemory*[T](x: T): bool =
# TODO: iterate over words here
for b in cast[ptr array[sizeof(T), byte]](unsafeAddr x)[]:
if b != 0:
return false
return true