Arithmetic evaluation: Difference between revisions

=={{header|Ursala}}==

with no error checking other than removal of spaces

<lang Ursala>

#import std

#import nat

#import flo

lex = ~=' '*~F+ rlc both -=digits # separate into tokens

parse = # build a tree

--<';'>; @iNX ~&l->rh ^/~&lt cases~&lhh\~&lhPNVrC {

'*/': ^|C/~&hNV associate '*/',

'+-': ^|C/~&hNV associate '*/+-',

');': @r ~&htitBPC+ associate '*/+-'}

associate "ops" = ~&tihdh2B-="ops"-> ~&thd2tth2hNCCVttt2C

traverse = *^ ~&v?\%ep ^H\~&vhthPX '+-*/'-$<plus,minus,times,div>@dh

evaluate = traverse+ parse+ lex</lang>

test program:

<lang Ursala>

#cast %eL

test = evaluate*t

-[

1+1

4/5

2-1

3*7

3+4+5

9-2-4

7/3/2

4+2*3

5*2-1

5-3*2

(1+1)*(2+3)

(2-4)/(3+5*(8-1))]-</lang>

output:

<pre>

<

2.000000e+00,

8.000000e-01,

1.000000e+00,

2.100000e+01,

1.200000e+01,

3.000000e+00,

1.166667e+00,

1.000000e+01,

9.000000e+00,

-1.000000e+00,

1.000000e+01,

-5.263158e-02></pre>