blob: 272cc893161b4377c2b6ef8576b9663af902ad3f (
plain)
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
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
(************************************************************************)
(* v * The Coq Proof Assistant / The Coq Development Team *)
(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
(* \VV/ **************************************************************)
(* // * This file is distributed under the terms of the *)
(* * GNU Lesser General Public License Version 2.1 *)
(************************************************************************)
(* *)
(* A persistent hashtable *)
(* *)
(* Frédéric Besson (Inria Rennes) 2009 *)
(* *)
(************************************************************************)
module type PHashtable =
sig
type 'a t
type key
val create : int -> string -> 'a t
(** [create i f] creates an empty persistent table
with initial size i
associated with file [f] *)
val open_in : string -> 'a t
(** [open_in f] rebuilds a table from the records stored in file [f] *)
val find : 'a t -> key -> 'a
(** find has the specification of Hashtable.find *)
val add : 'a t -> key -> 'a -> unit
(** [add tbl key elem] adds the binding [key] [elem] to the table [tbl].
(and writes the binding to the file associated with [tbl].)
If [key] is already bound, raises KeyAlreadyBound *)
val close : 'a t -> unit
(** [close tbl] is closing the table.
Once closed, a table cannot be used.
i.e, copy, find,add will raise UnboundTable *)
end
open Hashtbl
module PHashtable(Key:HashedType) : PHashtable with type key = Key.t =
struct
type key = Key.t
module Table = Hashtbl.Make(Key)
exception InvalidTableFormat
exception UnboundTable
type mode = Closed | Open
type 'a t =
{
outch : out_channel ;
mutable status : mode ;
htbl : 'a Table.t
}
let create i f =
{
outch = open_out_bin f ;
status = Open ;
htbl = Table.create i
}
let finally f rst =
try
let res = f () in
rst () ; res
with x ->
(try rst ()
with _ -> raise x
); raise x
(** [from_file f] returns a hashtable by parsing records from file [f].
The structure of the file is
(KEY NL ELEM NL)*
where
NL is the character '\n'
KEY and ELEM are strings (without NL) parsed
by the functions Key.parse and Elem.parse
Raises Sys_error if the file cannot be open
Raises InvalidTableFormat if the file does not conform to the format,
*)
let read_key_elem inch =
try
Some (Marshal.from_channel inch)
with
| End_of_file -> None
| _ -> raise InvalidTableFormat
let open_in f =
let flags = [Open_rdonly;Open_binary;Open_creat] in
let inch = open_in_gen flags 0o666 f in
let htbl = Table.create 10 in
let rec xload () =
match read_key_elem inch with
| None -> ()
| Some (key,elem) ->
Table.add htbl key elem ;
xload () in
try
finally (fun () -> xload () ) (fun () -> close_in inch) ;
{
outch = begin
let flags = [Open_append;Open_binary;Open_creat] in
open_out_gen flags 0o666 f
end ;
status = Open ;
htbl = htbl
}
with InvalidTableFormat ->
(* Try to keep as many entries as possible *)
begin
let flags = [Open_wronly; Open_trunc;Open_binary;Open_creat] in
let outch = open_out_gen flags 0o666 f in
Table.iter (fun k e -> Marshal.to_channel outch (k,e) [Marshal.No_sharing]) htbl;
{ outch = outch ;
status = Open ;
htbl = htbl
}
end
let close t =
let {outch = outch ; status = status ; htbl = tbl} = t in
match t.status with
| Closed -> () (* don't do it twice *)
| Open ->
close_out outch ;
Table.clear tbl ;
t.status <- Closed
let add t k e =
let {outch = outch ; status = status ; htbl = tbl} = t in
if status = Closed
then raise UnboundTable
else
begin
Table.add tbl k e ;
Marshal.to_channel outch (k,e) [Marshal.No_sharing]
end
let find t k =
let {outch = outch ; status = status ; htbl = tbl} = t in
if status = Closed
then raise UnboundTable
else
let res = Table.find tbl k in
res
end
(* Local Variables: *)
(* coding: utf-8 *)
(* End: *)
|
