diff options
| -rw-r--r-- | lib/pure/random.nim | 46 |
1 files changed, 32 insertions, 14 deletions
diff --git a/lib/pure/random.nim b/lib/pure/random.nim index e2a7ff5bd..8ce23b948 100644 --- a/lib/pure/random.nim +++ b/lib/pure/random.nim @@ -362,6 +362,30 @@ proc rand*[T: Ordinal or SomeFloat](x: HSlice[T, T]): T = result = rand(state, x) +proc rand*[T: Ordinal](r: var Rand; t: typedesc[T]): T {.since: (1, 7, 1).} = + ## Returns a random Ordinal in the range `low(T)..high(T)`. + ## + ## If `randomize <#randomize>`_ has not been called, the sequence of random + ## numbers returned from this proc will always be the same. + ## + ## **See also:** + ## * `rand proc<#rand,int>`_ that returns an integer + ## * `rand proc<#rand,float>`_ that returns a floating point number + ## * `rand proc<#rand,HSlice[T: Ordinal or float or float32 or float64,T: Ordinal or float or float32 or float64]>`_ + ## that accepts a slice + when T is range or T is enum: + result = rand(r, low(T)..high(T)) + elif T is bool: + when defined(js): + result = (r.next or 0) < 0 + else: + result = cast[int64](r.next) < 0 + else: + when defined(js): + result = cast[T](r.next shr (sizeof(uint)*8 - sizeof(T)*8)) + else: + result = cast[T](r.next shr (sizeof(uint64)*8 - sizeof(T)*8)) + proc rand*[T: Ordinal](t: typedesc[T]): T = ## Returns a random Ordinal in the range `low(T)..high(T)`. ## @@ -378,20 +402,14 @@ proc rand*[T: Ordinal](t: typedesc[T]): T = runnableExamples: randomize(567) type E = enum a, b, c, d - if false: # implementation defined - assert rand(E) in a..d - assert rand(char) in low(char)..high(char) - assert rand(int8) in low(int8)..high(int8) - assert rand(uint32) in low(uint32)..high(uint32) - assert rand(range[1..16]) in 1..16 - # pending csources >= 1.4.0 or fixing https://github.com/timotheecour/Nim/issues/251#issuecomment-831599772, - # use `runnableExamples("-r:off")` instead of `if false` - when T is range or T is enum: - result = rand(state, low(T)..high(T)) - elif T is bool: - result = state.next shr 63 == 1 # sign test, works on js - else: - result = cast[T](state.next shr (64 - sizeof(T)*8)) + + assert rand(E) in a..d + assert rand(char) in low(char)..high(char) + assert rand(int8) in low(int8)..high(int8) + assert rand(uint32) in low(uint32)..high(uint32) + assert rand(range[1..16]) in 1..16 + + result = rand(state, t) proc sample*[T](r: var Rand; s: set[T]): T = ## Returns a random element from the set `s` using the given state. |