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1 | (* HCoop Domtool (http://hcoop.sourceforge.net/) |
2 | * Copyright (c) 2006, Adam Chlipala |
3 | * |
4 | * This program is free software; you can redistribute it and/or |
5 | * modify it under the terms of the GNU General Public License |
6 | * as published by the Free Software Foundation; either version 2 |
7 | * of the License, or (at your option) any later version. |
8 | * |
9 | * This program is distributed in the hope that it will be useful, |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
12 | * GNU General Public License for more details. |
13 | * |
14 | * You should have received a copy of the GNU General Public License |
15 | * along with this program; if not, write to the Free Software |
16 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
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17 | *) |
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18 | |
19 | (* Execution of Domtool programs reduced to primitive actions *) |
20 | |
21 | structure Eval :> EVAL = struct |
22 | |
23 | open Ast |
24 | |
25 | structure SM = StringMap |
26 | |
27 | fun lookup (evs, ev) = |
28 | case SM.find (evs, ev) of |
29 | NONE => raise Fail ("Couldn't find an environment variable " |
30 | ^ ev ^ " that type-checking has guaranteed") |
31 | | SOME v => v |
32 | |
33 | val conjoin : Env.env_vars * Env.env_vars -> Env.env_vars = |
34 | SM.unionWith #2 |
35 | |
36 | fun findPrimitive e = |
37 | let |
38 | fun findPrim (e, _) = |
39 | case e of |
40 | EVar name => (name, []) |
41 | | EApp (e1, e2) => |
42 | let |
43 | val (name, args) = findPrim e1 |
44 | in |
45 | (name, e2 :: args) |
46 | end |
47 | | _ => raise Fail "Non-primitive action left after reduction" |
48 | |
49 | val (name, args) = findPrim e |
50 | in |
51 | (name, rev args) |
52 | end |
53 | |
54 | fun exec evs e = |
55 | let |
56 | fun exec' evs (eAll as (e, _)) = |
57 | case e of |
58 | ESkip => SM.empty |
59 | | ESet (ev, e) => SM.insert (SM.empty, ev, e) |
60 | | EGet (x, ev, e) => exec' evs (Reduce.subst x (lookup (evs, ev)) e) |
61 | | ESeq es => |
62 | let |
63 | val (new, _) = |
64 | foldl (fn (e, (new, keep)) => |
65 | let |
66 | val new' = exec' keep e |
67 | in |
68 | (conjoin (new, new'), |
69 | conjoin (keep, new')) |
70 | end) (SM.empty, evs) es |
71 | in |
72 | new |
73 | end |
74 | | ELocal (e1, e2) => |
75 | let |
76 | val evs' = exec' evs e1 |
77 | val evs'' = exec' (conjoin (evs, evs')) e2 |
78 | in |
79 | conjoin (evs, evs'') |
80 | end |
81 | | EWith (e1, e2) => |
82 | let |
83 | val (prim, args) = findPrimitive e1 |
84 | in |
85 | case Env.container prim of |
86 | NONE => raise Fail "Unbound primitive container" |
87 | | SOME (action, cleanup) => |
88 | let |
89 | val evs' = action (evs, args) |
90 | val evs'' = exec' evs e2 |
91 | in |
92 | cleanup (); |
93 | conjoin (conjoin (evs, evs'), evs'') |
94 | end |
95 | end |
96 | |
97 | | _ => |
98 | let |
99 | val (prim, args) = findPrimitive eAll |
100 | in |
101 | case Env.action prim of |
102 | NONE => raise Fail "Unbound primitive action" |
103 | | SOME action => action (evs, args) |
104 | end |
105 | |
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106 | val _ = Env.pre () |
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107 | val evs' = exec' evs e |
108 | in |
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109 | Env.post () |
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110 | end |
111 | |
112 | end |