1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
|
(* camlp5r *)
(* streams.ml,v *)
open Genlex ;
value lexer = make_lexer ["+";"-";"*";"/"; "("; ")"] ;
value list_of_stream strm =
let rec listrec acc = parser [
[: `t ; strm :] -> listrec [ t::acc ] strm
| [: :] -> List.rev acc
]
in listrec [] strm
;
value pleft f sep =
let rec paux v1 = parser [
[: op = sep ; v2 = f ; rv = paux (op v1 v2) :] -> rv
| [: :] -> v1
]
in parser [
[: v = f ; rv = paux v :] -> rv
]
;
value additives = parser [
[: `Kwd"+" :] -> (fun x y -> x + y)
| [: `Kwd"-" :] -> (fun x y -> x - y)
]
;
value multiplicatives = parser [
[: `Kwd"*" :] -> (fun x y -> x * y)
| [: `Kwd"/" :] -> (fun x y -> x / y)
]
;
value rec expr strm = expr1 strm
and expr1 = parser [
[: rv = pleft expr2 additives :] -> rv
]
and expr2 = parser [
[: rv = pleft expr3 multiplicatives :] -> rv
]
and expr3 = parser [
[: `Int n :] -> n
| [: `Kwd"(" ; e = expr1 ; `Kwd")" :] -> e
]
;
open Printf;
try
for i = 1 to Array.length Sys.argv - 1 do {
let r = Sys.argv.(i) |> Stream.of_string |> lexer |> expr in
printf "%s = %d\n" Sys.argv.(i) r;
flush stdout;
}
with [ exc -> Fmt.(pf stderr "%a@.%!" exn exc) ]
;
|
