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Annotation of gforth/look.fs, revision 1.22

1.1       anton       1: \ LOOK.FS      xt -> lfa                               22may93jaw
                      2: 
1.14      anton       3: \ Copyright (C) 1995,1996,1997,2000 Free Software Foundation, Inc.
1.3       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
1.15      anton      19: \ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
1.3       anton      20: 
1.1       anton      21: \ Look checks first if the word is a primitive. If yes then the
                     22: \ vocabulary in the primitive area is beeing searched, meaning
                     23: \ creating for each word a xt and comparing it...
                     24: 
                     25: \ If a word is no primitive look searches backwards to find the nfa.
                     26: \ Problems: A compiled xt via compile, might be created with noname:
                     27: \           a noname: leaves now a empty name field
                     28: 
1.16      jwilke     29: require stuff.fs
                     30: require environ.fs
                     31: 
1.1       anton      32: decimal
                     33: 
1.8       jwilke     34: \ look                                                  17may93jaw
1.1       anton      35: 
1.8       jwilke     36: \ rename to discover!!!
1.1       anton      37: 
1.18      anton      38: : xt>threaded ( xt -- x )
                     39: \G produces the threaded-code cell for the primitive xt
                     40:     threading-method 0= if
                     41:        @
                     42:     then ;
                     43: 
1.1       anton      44: : (look)  ( xt startlfa -- lfa flag )
1.22    ! anton      45:     \ look up name of primitive with code at xt
1.20      pazsan     46:     swap
1.21      pazsan     47:     >r false swap
1.17      anton      48:     BEGIN
                     49:        @ dup
                     50:     WHILE
1.22    ! anton      51:            dup name>int
1.21      pazsan     52:            r@ = IF
1.17      anton      53:                nip dup
                     54:            THEN
                     55:     REPEAT
1.21      pazsan     56:     drop rdrop
1.17      anton      57:     dup 0<> ;
1.1       anton      58: 
1.22    ! anton      59: : threaded>xt ( ca -- xt|0 )
        !            60: \G For the code address ca of a primitive, find the xt (or 0).
        !            61:     [IFDEF] decompile-prim
        !            62:        decompile-prim
        !            63:     [THEN]
        !            64:      \ walk through the array of primitive CAs
        !            65:     >r ['] noop begin
        !            66:        dup @ while
        !            67:            dup xt>threaded r@ = if
        !            68:                rdrop exit
        !            69:            endif
        !            70:            cell+
        !            71:     repeat
        !            72:     drop rdrop 0 ;
1.8       jwilke     73: 
                     74: \ !!! nicht optimal!
                     75: [IFUNDEF] look
1.9       jwilke     76: has? ec [IF]
                     77: 
1.10      jwilke     78: has? rom 
1.8       jwilke     79: [IF]
1.22    ! anton      80: : prim>name ( xt -- nt flag )
        !            81:     forth-wordlist @ (look) ;
        !            82: 
1.9       jwilke     83: : look
                     84:     dup [ unlock rom-dictionary area lock ] 
                     85:     literal literal within
                     86:     IF
1.13      anton      87:        >head-noprim dup ?? <>
1.9       jwilke     88:     ELSE
1.22    ! anton      89:        xt>threaded threaded>name
1.9       jwilke     90:     THEN ;
                     91: [ELSE]
1.8       jwilke     92: : look ( cfa -- lfa flag )
1.13      anton      93:     >head-noprim dup ??? <> ;
1.9       jwilke     94: [THEN]
1.8       jwilke     95: 
                     96: [ELSE]
                     97: 
1.13      anton      98: : PrimStart ['] true >head-noprim ;
1.8       jwilke     99: 
1.22    ! anton     100: : prim>name ( xt -- lfa flag )
        !           101:     PrimStart (look) ;
        !           102: 
1.1       anton     103: : look ( cfa -- lfa flag )
1.12      anton     104:     dup in-dictionary?
1.9       jwilke    105:     IF
1.13      anton     106:        >head-noprim dup ??? <>
1.12      anton     107:     ELSE
1.22    ! anton     108:        prim>name
1.9       jwilke    109:     THEN ;
1.1       anton     110: 
1.8       jwilke    111: [THEN]
                    112: [THEN]
1.22    ! anton     113: 
        !           114: : threaded>name ( ca -- lfa flag )
        !           115:     threaded>xt prim>name ;
1.13      anton     116: 
                    117: : >head ( cfa -- nt|0 ) \ gforth to-head
                    118:     \G tries to find the name token nt of the word represented by cfa;
                    119:     \G returns 0 if it fails.  This word is not absolutely reliable,
                    120:     \G it may give false positives and produce wrong nts.
                    121:     look and ;
                    122: 
                    123: ' >head ALIAS >name \ gforth to-name
                    124: \G old name of @code{>head}