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Implement builtins.floor and builtins.ceil using the C library functions internally

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Closes #4782

Note: even though the type is internally called `NixFloat`, it's
actually a `double`.
This commit is contained in:
Maximilian Bosch 2021-05-10 11:47:00 +02:00
parent db6ab75cae
commit 7f7f99f350
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3 changed files with 50 additions and 0 deletions
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40
src/libexpr/primops.cc
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@ -21,6 +21,8 @@
#include <regex>
#include <dlfcn.h>
#include <math.h>
namespace nix {
@ -714,6 +716,44 @@ static RegisterPrimOp primop_addErrorContext(RegisterPrimOp::Info {
.fun = prim_addErrorContext,
});
static void prim_ceil(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
auto value = state.forceFloat(*args[0], args[0]->determinePos(pos));
mkInt(v, ceil(value));
}
static RegisterPrimOp primop_ceil({
.name = "__ceil",
.args = {"double"},
.doc = R"(
Converts an IEEE-754 double-precision floating-point number (*double*) to
the next higher integer.
If the datatype is neither an integer nor a "float", an evaluation error will be
thrown.
)",
.fun = prim_ceil,
});
static void prim_floor(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
auto value = state.forceFloat(*args[0], args[0]->determinePos(pos));
mkInt(v, floor(value));
}
static RegisterPrimOp primop_floor({
.name = "__floor",
.args = {"double"},
.doc = R"(
Converts an IEEE-754 double-precision floating-point number (*double*) to
the next lower integer.
If the datatype is neither an integer nor a "float", an evaluation error will be
thrown.
)",
.fun = prim_floor,
});
/* Try evaluating the argument. Success => {success=true; value=something;},
* else => {success=false; value=false;} */
static void prim_tryEval(EvalState & state, const Pos & pos, Value * * args, Value & v)

1
tests/lang/eval-okay-floor-ceil.exp Normal file
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@ -0,0 +1 @@
"23;24;23;23"

9
tests/lang/eval-okay-floor-ceil.nix Normal file
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@ -0,0 +1,9 @@
with import ./lib.nix;
let
n1 = builtins.floor 23.5;
n2 = builtins.ceil 23.5;
n3 = builtins.floor 23;
n4 = builtins.ceil 23;
in
builtins.concatStringsSep ";" (map toString [ n1 n2 n3 n4 ])