apache: enable php 8.0 support
[hcoop/domtool2.git] / src / ast.sml
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42198578 1(* HCoop Domtool (http://hcoop.sourceforge.net/)
b21491de 2 * Copyright (c) 2006-2007, Adam Chlipala
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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.
dac62e84 17 *)
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18
19(* Configuration language abstract syntax *)
20
21structure Ast = struct
22
23open DataStructures
24
25(* A description of a predicate on configuration block stacks *)
63920aa5 26datatype pred' =
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27 CRoot
28 (* The stack is empty. *)
29 | CConst of string
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30 (* The given pred name is on top of the stack. *)
31 | CPrefix of pred
32 (* Some prefix of the stack matches the pred. *)
33 | CNot of pred
34 (* The pred does not match. *)
35 | CAnd of pred * pred
36 (* Both preds match. *)
37withtype pred = pred' * position
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38
39datatype typ' =
40 TBase of string
41 (* Base type *)
42 | TList of typ
43 (* SML 'a list *)
44 | TArrow of typ * typ
45 (* SML -> *)
63920aa5 46 | TAction of pred * record * record
42198578 47 (* An action that:
63920aa5 48 * - Is valid in the given pred
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49 * - Expects an environment compatible with the first record
50 * - Modifies it according to the second record *)
1a4e5a6c 51 | TNested of pred * typ
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52 (* Allow nested configuration, in the form of a function from an action
53 * satisfying the first predicate to an action satisfying the second and
54 * with the same environment variable IO behavior. *)
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55
56 | TError
57 (* Marker that something already went wrong, so don't generate further
58 * error messages. *)
59 | TUnif of string * typ option ref
60 (* Unification variable to be determined during type-checking *)
42198578 61withtype typ = typ' * position
a49a9bfb 62 and record = (typ' * position) StringMap.map
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63
64datatype exp' =
65 EInt of int
66 (* Constant integer *)
67 | EString of string
68 (* Constant string *)
69 | EList of exp list
70 (* Basic list constructor *)
71
27d9de59 72 | ELam of string * typ option * exp
42198578 73 (* Function abstraction *)
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74 | EVar of string
75 (* Variable bound by a function *)
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76 | EApp of exp * exp
77 (* Function application *)
78
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79 | ESkip
80 (* Do-nothing action *)
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81 | ESet of string * exp
82 (* Set an environment variable *)
8cbb9632 83 | EGet of string * typ option * string * exp
a22c187b 84 (* Get an environment variable *)
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85 | ESeq of exp list
86 (* Monad sequencer; execute a number of commands in order *)
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87 | ELocal of exp * exp
88 (* Local execution; like ESeq, but the writes of the first
89 * action are abandoned *)
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90 | EWith of exp * exp
91 (* Apply a TNested to an action *)
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92 | EALam of string * pred * exp
93 (* Abstraction for building TNested values *)
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94 | EIf of exp * exp * exp
95 (* If..then..else *)
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96withtype exp = exp' * position
97
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98datatype decl' =
99 DExternType of string
100 | DExternVal of string * typ
492c1cff 101 | DVal of string * typ option * exp
8230d010 102 | DEnv of string * typ option * exp
095de39e 103 | DContext of string
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104type decl = decl' * string option * position
105
095de39e 106type file = string option * decl list * exp option
42198578 107
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108fun multiApp (f, loc, args) =
109 foldl (fn (arg, e) => (EApp (e, arg), loc)) f args
110
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111datatype unification_error =
112 UnifyPred of pred * pred
113 | UnifyTyp of typ * typ
114 | UnifyOccurs of string * typ
115
116exception Unify of unification_error
117
118datatype type_error =
119 WrongType of string * exp * typ * typ * unification_error option
120 | WrongForm of string * string * exp * typ * unification_error option
121 | UnboundVariable of string
122 | WrongPred of string * pred * pred
123
42198578 124end