File:  [gforth] / gforth / look.fs
Revision 1.16: download - view: text, annotated - select for diffs
Sun Sep 16 10:20:39 2001 UTC (19 years, 9 months ago) by jwilke
Branches: MAIN
CVS tags: HEAD
added requires

    1: \ LOOK.FS      xt -> lfa                               22may93jaw
    2: 
    3: \ Copyright (C) 1995,1996,1997,2000 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., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
   20: 
   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: 
   29: require stuff.fs
   30: require environ.fs
   31: 
   32: decimal
   33: 
   34: \ look                                                  17may93jaw
   35: 
   36: \ rename to discover!!!
   37: 
   38: : (look)  ( xt startlfa -- lfa flag )
   39:         false swap
   40:         BEGIN @ dup
   41:         WHILE dup name>int
   42:               3 pick = IF nip dup THEN
   43:         REPEAT
   44:         drop nip
   45:         dup 0<> ;
   46: 
   47: 
   48: \ !!! nicht optimal!
   49: [IFUNDEF] look
   50: has? ec [IF]
   51: 
   52: has? rom 
   53: [IF]
   54: : look
   55:     dup [ unlock rom-dictionary area lock ] 
   56:     literal literal within
   57:     IF
   58: 	>head-noprim dup ?? <>
   59:     ELSE
   60: 	forth-wordlist @ (look)
   61:     THEN ;
   62: [ELSE]
   63: : look ( cfa -- lfa flag )
   64:     >head-noprim dup ??? <> ;
   65: [THEN]
   66: 
   67: [ELSE]
   68: 
   69: : PrimStart ['] true >head-noprim ;
   70: 
   71: : look ( cfa -- lfa flag )
   72:     dup in-dictionary?
   73:     IF
   74: 	>head-noprim dup ??? <>
   75:     ELSE
   76: 	PrimStart (look)
   77:     THEN ;
   78: 
   79: [THEN]
   80: [THEN]
   81: 
   82: : >head ( cfa -- nt|0 ) \ gforth to-head
   83:     \G tries to find the name token nt of the word represented by cfa;
   84:     \G returns 0 if it fails.  This word is not absolutely reliable,
   85:     \G it may give false positives and produce wrong nts.
   86:     look and ;
   87: 
   88: ' >head ALIAS >name \ gforth to-name
   89: \G old name of @code{>head}

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