File:  [gforth] / gforth / look.fs
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Sat Dec 31 15:29:25 2011 UTC (7 years, 7 months ago) by anton
Branches: MAIN
CVS tags: HEAD
updated copyright years

    1: \ LOOK.FS      xt -> lfa                               22may93jaw
    2: 
    3: \ Copyright (C) 1995,1996,1997,2000,2003,2007,2011 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 3
   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, see http://www.gnu.org/licenses/.
   19: 
   20: \ Look checks first if the word is a primitive. If yes then the
   21: \ vocabulary in the primitive area is beeing searched, meaning
   22: \ creating for each word a xt and comparing it...
   23: 
   24: \ If a word is no primitive look searches backwards to find the nfa.
   25: \ Problems: A compiled xt via compile, might be created with noname:
   26: \           a noname: leaves now a empty name field
   27: 
   28: require stuff.fs
   29: require environ.fs
   30: 
   31: decimal
   32: 
   33: \ look                                                  17may93jaw
   34: 
   35: \ rename to discover!!!
   36: 
   37: : xt>threaded ( xt -- x )
   38: \G produces the threaded-code cell for the primitive xt
   39:     threading-method 0= if
   40: 	@
   41:     then ;
   42: 
   43: : search-name  ( xt startlfa -- nt|0 )
   44:     \ look up name of primitive with code at xt
   45:     swap
   46:     >r false swap
   47:     BEGIN
   48: 	@ dup
   49:     WHILE
   50: 	    dup name>int
   51: 	    r@ = IF
   52: 		nip dup
   53: 	    THEN
   54:     REPEAT
   55:     drop rdrop ;
   56: 
   57: : threaded>xt ( ca -- xt|0 )
   58: \G For the code address ca of a primitive, find the xt (or 0).
   59:     [IFDEF] decompile-prim
   60: 	decompile-prim
   61:     [THEN]
   62:      \ walk through the array of primitive CAs
   63:     >r ['] noop begin
   64: 	dup @ while
   65: 	    dup xt>threaded r@ = if
   66: 		rdrop exit
   67: 	    endif
   68: 	    cell+
   69:     repeat
   70:     drop rdrop 0 ;
   71: 
   72: \ !!! nicht optimal!
   73: [IFUNDEF] look
   74: has? ec [IF]
   75: 
   76: has? rom 
   77: [IF]
   78: : prim>name ( xt -- nt|0 )
   79:     forth-wordlist @ search-name ;
   80: 
   81: : look ( xt -- lfa flag )
   82:     dup [ unlock rom-dictionary area lock ] 
   83:     literal literal within
   84:     IF
   85: 	>head-noprim dup ?? <>
   86:     ELSE
   87: 	prim>name dup 0<>
   88:     THEN ;
   89: [ELSE]
   90: : look ( cfa -- lfa flag )
   91:     >head-noprim dup ??? <> ;
   92: [THEN]
   93: 
   94: [ELSE]
   95: 
   96: : PrimStart ['] true >head-noprim ;
   97: 
   98: : prim>name ( xt -- nt|0 )
   99:     PrimStart search-name ;
  100: 
  101: : look ( xt -- lfa flag )
  102:     dup in-dictionary?
  103:     IF
  104: 	>head-noprim dup ??? <>
  105:     ELSE
  106: 	prim>name dup 0<>
  107:     THEN ;
  108: 
  109: [THEN]
  110: [THEN]
  111: 
  112: : threaded>name ( ca -- nt|0 )
  113:     threaded>xt prim>name ;
  114: 
  115: : >name ( xt -- nt|0 ) \ gforth to-name
  116:     \G tries to find the name token @var{nt} of the word represented
  117:     \G by @var{xt}; returns 0 if it fails.  This word is not
  118:     \G absolutely reliable, it may give false positives and produce
  119:     \G wrong nts.
  120:     look and ;
  121: 
  122: ' >name ALIAS >head \ gforth to-head
  123: \G another name of @code{>name}
  124: 
  125: \ print recognizer stack
  126: 
  127: [IFDEF] forth-recognizer
  128:     : .recs ( -- )
  129: 	forth-recognizer get-recognizers 0 ?DO
  130: 	    >name .name
  131: 	LOOP ;
  132: [THEN]

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