File: calculator.lgt

package info (click to toggle)
yap 5.1.1-3
  • links: PTS
  • area: main
  • in suites: lenny
  • size: 16,124 kB
  • ctags: 14,650
  • sloc: ansic: 122,796; perl: 22,545; sh: 3,768; java: 1,277; makefile: 1,191; xml: 739; tcl: 624; lisp: 142; awk: 9
file content (23 lines) | stat: -rw-r--r-- 511 bytes parent folder | download 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
 

:- object(calculator,
	implements(parsep)).


	parse(Expression, Value) :-
		phrase(expr(Value), Expression).


	expr(Z) --> term(X), "+", expr(Y), {Z is X + Y}.
	expr(Z) --> term(X), "-", expr(Y), {Z is X - Y}.
	expr(X) --> term(X).

	term(Z) --> number(X), "*", term(Y), {Z is X * Y}.
	term(Z) --> number(X), "/", term(Y), {Z is X / Y}.
	term(Z) --> number(Z).

	number(C) --> "+", number(C).
	number(C) --> "-", number(X), {C is -X}.
	number(X) --> [C], {0'0 =< C, C =< 0'9, X is C - 0'0}.


:- end_object.