Annotation of gforth/except.fs, revision 1.4
1.1 anton 1: \ catch, throw, etc.
2:
1.2 anton 3: \ Copyright (C) 1999,2000 Free Software Foundation, Inc.
1.1 anton 4:
5: \ This file is part of Gforth.
6:
7: \ Gforth is free software; you can redistribute it and/or
8: \ modify it under the terms of the GNU General Public License
9: \ as published by the Free Software Foundation; either version 2
10: \ of the License, or (at your option) any later version.
11:
12: \ This program is distributed in the hope that it will be useful,
13: \ but WITHOUT ANY WARRANTY; without even the implied warranty of
14: \ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15: \ GNU General Public License for more details.
16:
17: \ You should have received a copy of the GNU General Public License
18: \ along with this program; if not, write to the Free Software
1.3 anton 19: \ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
1.1 anton 20:
21: \ !! use a separate exception stack? anton
22:
23: \ user-definable rollback actions
24:
25: Defer 'catch
26: Defer 'throw
27:
28: ' noop IS 'catch
29: ' noop IS 'throw
30:
31: \ has? backtrace [IF]
32: Defer store-backtrace
33: ' noop IS store-backtrace
34: \ [THEN]
35:
36: : (try) ( -- )
37: \ inline argument: address of the handler
38: r>
1.4 ! anton 39: dup @ >r \ recovery address
1.1 anton 40: rp@ 'catch >r
41: sp@ >r
42: fp@ >r
43: lp@ >r
44: handler @ >r
45: rp@ handler !
46: backtrace-empty on
47: cell+ >r ;
48:
49: : try ( compilation -- orig ; run-time -- ) \ gforth
50: POSTPONE (try) >mark ; immediate compile-only
51:
52: : (recover) ( -- )
53: \ normal end of try block: restore handler, forget rest
54: r>
55: r> handler !
56: rdrop \ lp
57: rdrop \ fp
58: rdrop \ sp
59: r> rp!
60: rdrop \ recovery address
61: >r ;
62:
63: : recover ( compilation orig1 -- orig2 ; run-time -- ) \ gforth
64: \ !! check using a special tag
65: POSTPONE (recover)
66: POSTPONE else ; immediate compile-only
67:
68: : endtry ( compilation orig -- ; run-time -- ) \ gforth
69: POSTPONE then ; immediate compile-only
70:
71: :noname ( x1 .. xn xt -- y1 .. ym 0 / z1 .. zn error ) \ exception
72: try
73: execute 0
74: recover
75: nip
76: endtry ;
77: is catch
78:
79: :noname ( y1 .. ym error/0 -- y1 .. ym / z1 .. zn error ) \ exception
80: ?DUP IF
81: [ here forthstart 9 cells + ! ]
82: store-backtrace
83: handler @ ?dup-0=-IF
84: cr ." uncaught exception: " .error cr
85: 2 (bye)
86: quit
87: THEN
88: rp!
89: r> handler !
90: r> lp!
91: r> fp!
92: r> swap >r sp! drop r>
93: rdrop 'throw
94: THEN ;
95: is throw
96:
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