File:  [gforth] / gforth / look.fs
Revision 1.18: download - view: text, annotated - select for diffs
Sat Sep 14 11:18:57 2002 UTC (17 years, 6 months ago) by anton
Branches: MAIN
CVS tags: HEAD
bugfix: (complex) SEE now works (output quality could be improved, though).

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

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