diff options
Diffstat (limited to 'lib/pure/collections/hashcommon.nim')
-rw-r--r-- | lib/pure/collections/hashcommon.nim | 29 |
1 files changed, 14 insertions, 15 deletions
diff --git a/lib/pure/collections/hashcommon.nim b/lib/pure/collections/hashcommon.nim index e998145e7..17785c8c7 100644 --- a/lib/pure/collections/hashcommon.nim +++ b/lib/pure/collections/hashcommon.nim @@ -7,17 +7,17 @@ # distribution, for details about the copyright. # -# An ``include`` file which contains common code for +# An `include` file which contains common code for # hash sets and tables. +when defined(nimPreviewSlimSystem): + import std/assertions + +import std / outparams + const growthFactor = 2 -when not defined(nimHasDefault): - template default[T](t: typedesc[T]): T = - var v: T - v - # hcode for real keys cannot be zero. hcode==0 signifies an empty slot. These # two procs retain clarity of that encoding without the space cost of an enum. proc isEmpty(hcode: Hash): bool {.inline.} = @@ -30,16 +30,12 @@ proc nextTry(h, maxHash: Hash): Hash {.inline.} = result = (h + 1) and maxHash proc mustRehash[T](t: T): bool {.inline.} = + # If this is changed, make sure to synchronize it with `slotsNeeded` below assert(t.dataLen > t.counter) result = (t.dataLen * 2 < t.counter * 3) or (t.dataLen - t.counter < 4) -proc rightSize*(count: Natural): int {.inline.} = - ## Return the value of ``initialSize`` to support ``count`` items. - ## - ## If more items are expected to be added, simply add that - ## expected extra amount to the parameter before calling this. - # - # Make sure to synchronize with `mustRehash` +proc slotsNeeded(count: Natural): int {.inline.} = + # Make sure to synchronize with `mustRehash` above result = nextPowerOfTwo(count * 3 div 2 + 4) template rawGetKnownHCImpl() {.dirty.} = @@ -62,7 +58,10 @@ proc rawGetKnownHC[X, A](t: X, key: A, hc: Hash): int {.inline.} = template genHashImpl(key, hc: typed) = hc = hash(key) if hc == 0: # This almost never taken branch should be very predictable. - hc = 314159265 # Value doesn't matter; Any non-zero favorite is fine. + when sizeof(int) < 4: + hc = 31415 # Value doesn't matter; Any non-zero favorite is fine <= 16-bit. + else: + hc = 314159265 # Value doesn't matter; Any non-zero favorite is fine. template genHash(key: typed): Hash = var res: Hash @@ -73,5 +72,5 @@ template rawGetImpl() {.dirty.} = genHashImpl(key, hc) rawGetKnownHCImpl() -proc rawGet[X, A](t: X, key: A, hc: var Hash): int {.inline.} = +proc rawGet[X, A](t: X, key: A, hc: var Hash): int {.inline, outParamsAt: [3].} = rawGetImpl() |