File:  [gforth] / gforth / look.fs
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Sat Dec 21 17:27:13 2002 UTC (17 years, 3 months ago) by pazsan
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CVS tags: HEAD
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rest: made compilable with gforth 0.5.0

    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: : xt>threaded ( xt -- x )
   39: \G produces the threaded-code cell for the primitive xt
   40:     threading-method 0= if
   41: 	@
   42:     then ;
   43: 
   44: : (look)  ( xt startlfa -- lfa flag )
   45:     swap
   46:     [IFDEF] decompile-prim
   47:     decompile-prim
   48:     [THEN]
   49:     false rot
   50:     BEGIN
   51: 	@ dup
   52:     WHILE
   53: 	    dup name>int xt>threaded
   54: 	    3 pick = IF
   55: 		nip dup
   56: 	    THEN
   57:     REPEAT
   58:     drop nip
   59:     dup 0<> ;
   60: 
   61: 
   62: \ !!! nicht optimal!
   63: [IFUNDEF] look
   64: has? ec [IF]
   65: 
   66: has? rom 
   67: [IF]
   68: : look
   69:     dup [ unlock rom-dictionary area lock ] 
   70:     literal literal within
   71:     IF
   72: 	>head-noprim dup ?? <>
   73:     ELSE
   74: 	forth-wordlist @ (look)
   75:     THEN ;
   76: [ELSE]
   77: : look ( cfa -- lfa flag )
   78:     >head-noprim dup ??? <> ;
   79: [THEN]
   80: 
   81: [ELSE]
   82: 
   83: : PrimStart ['] true >head-noprim ;
   84: 
   85: : look ( cfa -- lfa flag )
   86:     dup in-dictionary?
   87:     IF
   88: 	>head-noprim dup ??? <>
   89:     ELSE
   90: 	PrimStart (look)
   91:     THEN ;
   92: 
   93: [THEN]
   94: [THEN]
   95: 
   96: : >head ( cfa -- nt|0 ) \ gforth to-head
   97:     \G tries to find the name token nt of the word represented by cfa;
   98:     \G returns 0 if it fails.  This word is not absolutely reliable,
   99:     \G it may give false positives and produce wrong nts.
  100:     look and ;
  101: 
  102: ' >head ALIAS >name \ gforth to-name
  103: \G old name of @code{>head}

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