fish-shell/share/functions/math.fish
Kurtis Rader 98449fec51 fix math regression
The previous change to use `argparse` for parity with every other
builtin and function introduced a regression. Invocations that start
with a negative number can fail because the negative value looks like an
invalid flag.
2017-07-14 16:03:31 -07:00

56 lines
2 KiB
Fish

function math --description "Perform math calculations in bc"
if not set -q argv[2]
# Make sure an invocation like `math "-1 + 1"` doesn't treat the string as an option.
set argv -- $argv
end
set -l options 'h/help' 's/scale=' '#-val'
argparse -n math --stop-nonopt --min-args=1 $options -- $argv
or return
if set -q _flag_help
__fish_print_help math
return 0
end
set -l scale 0 # default is integer arithmetic
if set -q _flag_scale
set scale $_flag_scale
if not string match -q -r '^\d+$' "$scale"
printf (_ "%s: Expected an integer to follow --scale") math >&2
return 2 # missing argument is an error
end
end
if set -q _flag_val
# The expression began with a negative number. Put it back in the expression.
# The correct thing is for the person calling us to insert a `--` separator before the
# expression to stop parsing flags. But we'll work around that missing token here.
set argv -$_flag_val $argv
end
# Set BC_LINE_LENGTH to a ridiculously high number so it only uses one line for most results.
# We can't use 0 since some systems (including macOS) use an ancient bc that doesn't support it.
# We also can't count on this being recognized since some BSD systems don't recognize this env
# var at all and limit the line length to 70.
set -lx BC_LINE_LENGTH 500
set -l out (echo "scale=$scale; $argv" | bc)
if set -q out[2]
set out (string join '' (string replace \\ '' $out))
end
switch "$out"
case ''
# No output indicates an error occurred.
return 3
case 0
# For historical reasons a zero result translates to a failure status.
echo 0
return 1
case '*'
# For historical reasons a non-zero result translates to a success status.
echo $out
return 0
end
end