High memory usage

[mingodad]

While testing https://github.com/WheretIB/nullc/files/9668225/exprtk_functional_test.nc.zip from this issue #33 I noticed a high memory usage 212 MB:

/usr/bin/time  ../bin/nullc_exec exprtk_functional_test.nc 
-10.123456789107372 == -10.123456789107 == -10.1234567891073723
7366	7285
0.61user 0.05system 0:00.67elapsed 99%CPU (0avgtext+0avgdata 212124maxresident)k
0inputs+0outputs (0major+52238minor)pagefaults 0swaps

Lua uses only 5 MB:

/usr/bin/time lua exprtk_functional_test.txt.lua 
7437	7321
0.03user 0.00system 0:00.04elapsed 100%CPU (0avgtext+0avgdata 4484maxresident)k
0inputs+0outputs (0major+571minor)pagefaults 0swaps

Nodejs uses 58 MB:

/usr/bin/time node exprtk_functional_test.txt.js  7445 7299
0.08user 0.02system 0:00.14elapsed 80%CPU (0avgtext+0avgdata 57880maxresident)k
8696inputs+0outputs (36major+7445minor)pagefaults 0swaps

[mingodad]

GCC uses 186 MB:

/usr/bin/time gcc -O2 -o exprtk_functional_test exprtk_functional_test.c 
1.74user 0.08system 0:01.82elapsed 99%CPU (0avgtext+0avgdata 186080maxresident)k
1424inputs+200outputs (0major+53145minor)pagefaults 0swaps