File:  [gforth] / gforth / look.fs
Revision 1.17: download - view: text, annotated - select for diffs
Sat Sep 14 10:59:31 2002 UTC (17 years, 5 months ago) by anton
Branches: MAIN
CVS tags: HEAD
bugfix: simple decompilation of static hybrid threaded code

    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
   41: 	@ dup
   42:     WHILE
   43: 	    dup name>int
   44: 	    threading-method 0= if
   45: 		@
   46: 	    then
   47: 	    3 pick = IF
   48: 		nip dup
   49: 	    THEN
   50:     REPEAT
   51:     drop nip
   52:     dup 0<> ;
   53: 
   54: 
   55: \ !!! nicht optimal!
   56: [IFUNDEF] look
   57: has? ec [IF]
   58: 
   59: has? rom 
   60: [IF]
   61: : look
   62:     dup [ unlock rom-dictionary area lock ] 
   63:     literal literal within
   64:     IF
   65: 	>head-noprim dup ?? <>
   66:     ELSE
   67: 	forth-wordlist @ (look)
   68:     THEN ;
   69: [ELSE]
   70: : look ( cfa -- lfa flag )
   71:     >head-noprim dup ??? <> ;
   72: [THEN]
   73: 
   74: [ELSE]
   75: 
   76: : PrimStart ['] true >head-noprim ;
   77: 
   78: : look ( cfa -- lfa flag )
   79:     dup in-dictionary?
   80:     IF
   81: 	>head-noprim dup ??? <>
   82:     ELSE
   83: 	PrimStart (look)
   84:     THEN ;
   85: 
   86: [THEN]
   87: [THEN]
   88: 
   89: : >head ( cfa -- nt|0 ) \ gforth to-head
   90:     \G tries to find the name token nt of the word represented by cfa;
   91:     \G returns 0 if it fails.  This word is not absolutely reliable,
   92:     \G it may give false positives and produce wrong nts.
   93:     look and ;
   94: 
   95: ' >head ALIAS >name \ gforth to-name
   96: \G old name of @code{>head}

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