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Annotation of gforth/exceptions.fs, revision 1.1

1.1     ! anton       1: \ catch, throw, etc.
        !             2: 
        !             3: \ Copyright (C) 1999 Free Software Foundation, Inc.
        !             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
        !            19: \ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
        !            20: 
        !            21: Defer 'catch
        !            22: Defer 'throw
        !            23: 
        !            24: ' noop IS 'catch
        !            25: ' noop IS 'throw
        !            26: 
        !            27: \ has? backtrace [IF]
        !            28: Defer store-backtrace
        !            29: ' noop IS store-backtrace
        !            30: \ [THEN]
        !            31: 
        !            32: : (protect) ( -- )
        !            33:     \ inline argument: address of the handler
        !            34:     r>
        !            35:     'catch
        !            36:     dup dup @ + >r \ recovery address
        !            37:     lp@ >r
        !            38:     handler @ >r
        !            39:     rp@ handler !
        !            40:     backtrace-empty on
        !            41:     cell+ >r ;
        !            42: 
        !            43: : protect ( compilation  -- orig ; run-time  -- ) \ gforth
        !            44:     POSTPONE (protect) >mark ; immediate compile-only
        !            45: 
        !            46: : (endprotect) ( -- )
        !            47:     \ end of protect block: restore handler, forget rest
        !            48:     r>
        !            49:     r> handler !
        !            50:     rdrop \ lp
        !            51:     rdrop \ recovery address
        !            52:     >r ;
        !            53: 
        !            54: : endprotect ( compilation  orig -- ; run-time  -- x ) \ gforth
        !            55:     0 POSTPONE literal
        !            56:     POSTPONE (endprotect)
        !            57:     POSTPONE then ; immediate compile-only
        !            58: 
        !            59: : catch-protect ( ... xt -- ... x )
        !            60:     protect execute endprotect ;
        !            61: 
        !            62: : (try) ( -- )
        !            63:     \ inline argument: address of the handler
        !            64:     r>
        !            65:     sp@ >r
        !            66:     fp@ >r
        !            67:     >r ;
        !            68: 
        !            69: : try ( compilation  -- orig ; run-time  -- ) \ gforth
        !            70:     POSTPONE (try) POSTPONE (protect) >mark ; immediate compile-only
        !            71: 
        !            72: : (recover) ( -- )
        !            73:     \ normal end of try block: restore handler, forget rest
        !            74:     r>
        !            75:     r> handler !
        !            76:     rdrop \ lp
        !            77:     rdrop \ recovery address
        !            78:     rdrop \ fp
        !            79:     rdrop \ sp
        !            80:     >r ;
        !            81: 
        !            82: : (recover2) ( ... x -- ... x )
        !            83:     \ restore sp and fp
        !            84:     r>
        !            85:     r> fp!
        !            86:     r> -rot >r >r sp! drop r> ;
        !            87: 
        !            88: : recover ( compilation  orig -- ; run-time  -- ) \ gforth
        !            89:     \ !! check using a special tag
        !            90:     POSTPONE (endprotect) POSTPONE rdrop POSTPONE rdrop
        !            91:     POSTPONE else
        !            92:     POSTPONE (recover2) ; immediate compile-only
        !            93: 
        !            94: : endtry ( compilation  orig -- ; run-time  -- ) \ gforth
        !            95:     POSTPONE then ; immediate compile-only
        !            96: 
        !            97: :noname ( x1 .. xn xt -- y1 .. ym 0 / z1 .. zn error ) \ exception
        !            98:     try
        !            99:        execute 0
        !           100:     recover
        !           101:         nip
        !           102:     endtry ;
        !           103: is catch
        !           104: 
        !           105: \ :noname ( x1 .. xn xt -- y1 .. ym 0 / z1 .. zn error ) \ exception
        !           106: \     'catch
        !           107: \     sp@ >r
        !           108: \ \ [ has? floating [IF] ]
        !           109: \     fp@ >r
        !           110: \ \ [ [THEN] ]
        !           111: \ \ [ has? glocals [IF] ]
        !           112: \     lp@ >r
        !           113: \ \ [ [THEN] ]
        !           114: \     handler @ >r
        !           115: \     rp@ handler !
        !           116: \ \ [ has? backtrace [IF] ]
        !           117: \     backtrace-empty on
        !           118: \ \ [ [THEN] ]
        !           119: \     execute
        !           120: \     r> handler ! rdrop 
        !           121: \ \ [ has? floating [IF] ]
        !           122: \     rdrop
        !           123: \ \ [ [THEN] ]
        !           124: \ \ [ has? glocals [IF] ]
        !           125: \     rdrop
        !           126: \ \ [ [THEN] ]
        !           127: \     0 ;
        !           128: \ is catch
        !           129: 
        !           130: :noname ( y1 .. ym error/0 -- y1 .. ym / z1 .. zn error ) \ exception
        !           131:     ?DUP IF
        !           132:        [ here forthstart 9 cells + ! ]
        !           133: \      [ has? header [IF] here 9 cells ! [THEN] ] \ entry point for signal handler
        !           134: \ [ has? backtrace [IF] ]
        !           135:        store-backtrace
        !           136: \ [ [THEN] ]
        !           137: \ [ has? interpreter [IF] ]
        !           138:        handler @ dup 0= IF
        !           139: \ [ has? os [IF] ]
        !           140:            cr ." error " .
        !           141:            2 (bye)
        !           142: \ [ [ELSE] ]
        !           143:            quit
        !           144: \ [ [THEN] ]
        !           145:        THEN
        !           146: \ [ [THEN] ]
        !           147:        rp!
        !           148:        r> handler !
        !           149: \ [ has? glocals [IF] ]
        !           150:         r> lp!
        !           151: \ [ [THEN] ]
        !           152:        'throw
        !           153:     THEN ;
        !           154: is throw
        !           155: