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|
{ depot, lib, ... }:
let
# TODO(sterni): implement nix.float and figure out which of these
# functions can be split out into a common nix.num
# library.
inherit (depot.users.sterni.nix)
string
;
inherit (builtins)
bitOr
bitAnd
bitXor
mul
div
add
sub
;
abs = i: if i < 0 then -i else i;
exp = base: pow:
if pow > 0
then base * (exp base (pow - 1))
else if pow < 0
then 1.0 / exp base (abs pow)
else 1;
bitShiftR = bit: count:
if count == 0
then bit
else div (bitShiftR bit (count - 1)) 2;
bitShiftL = bit: count:
if count == 0
then bit
else 2 * (bitShiftL bit (count - 1));
hexdigits = "0123456789ABCDEF";
toHex = int:
let
go = i:
if i == 0
then ""
else go (bitShiftR i 4)
+ string.charAt (bitAnd i 15) hexdigits;
sign = lib.optionalString (int < 0) "-";
in
if int == 0
then "0"
else "${sign}${go (abs int)}";
fromHexMap = builtins.listToAttrs
(lib.imap0 (i: c: { name = c; value = i; })
(lib.stringToCharacters hexdigits));
fromHex = literal:
let
negative = string.charAt 0 literal == "-";
start = if negative then 1 else 0;
len = builtins.stringLength literal;
# reversed list of all digits
digits = builtins.genList
(i: string.charAt (len - 1 - i) literal)
(len - start);
parsed = builtins.foldl'
(v: d: {
val = v.val + (fromHexMap."${d}" * v.mul);
mul = v.mul * 16;
})
{ val = 0; mul = 1; }
digits;
in
if negative
then -parsed.val
else parsed.val;
# A nix integer is a 64bit signed integer
maxBound = 9223372036854775807;
# fun fact: -9223372036854775808 is the lower bound
# for a nix integer (as you would expect), but you can't
# use it as an integer literal or you'll be greeted with:
# error: invalid integer '9223372036854775808'
# This is because all int literals when parsing are
# positive, negative "literals" are positive literals
# which are preceded by the arithmetric negation operator.
minBound = -9223372036854775807 - 1;
odd = x: bitAnd x 1 == 1;
even = x: bitAnd x 1 == 0;
# div and mod behave like quot and rem in Haskell,
# i. e. they truncate towards 0
mod = a: b: let res = a / b; in a - (res * b);
inRange = a: b: x: x >= a && x <= b;
in
{
inherit
maxBound
minBound
abs
exp
odd
even
add
sub
mul
div
mod
bitShiftR
bitShiftL
bitOr
bitAnd
bitXor
toHex
fromHex
inRange
;
}
|
