Annotation of gforth/look.fs, revision 1.13

1.1       anton       1: \ LOOK.FS      xt -> lfa                               22may93jaw
                      2: 
1.11      anton       3: \ Copyright (C) 1995,1996,1997 Free Software Foundation, Inc.
1.3       anton       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., 675 Mass Ave, Cambridge, MA 02139, USA.
                     20: 
1.1       anton      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: decimal
                     30: 
1.8       jwilke     31: \ look                                                  17may93jaw
1.1       anton      32: 
1.8       jwilke     33: \ rename to discover!!!
1.1       anton      34: 
                     35: : (look)  ( xt startlfa -- lfa flag )
                     36:         false swap
                     37:         BEGIN @ dup
1.5       anton      38:         WHILE dup name>int
1.1       anton      39:               3 pick = IF nip dup THEN
                     40:         REPEAT
                     41:         drop nip
                     42:         dup 0<> ;
                     43: 
1.8       jwilke     44: 
                     45: \ !!! nicht optimal!
                     46: [IFUNDEF] look
1.9       jwilke     47: has? ec [IF]
                     48: 
1.10      jwilke     49: has? rom 
1.8       jwilke     50: [IF]
1.9       jwilke     51: : look
                     52:     dup [ unlock rom-dictionary area lock ] 
                     53:     literal literal within
                     54:     IF
1.13    ! anton      55:        >head-noprim dup ?? <>
1.9       jwilke     56:     ELSE
                     57:        forth-wordlist @ (look)
                     58:     THEN ;
                     59: [ELSE]
1.8       jwilke     60: : look ( cfa -- lfa flag )
1.13    ! anton      61:     >head-noprim dup ??? <> ;
1.9       jwilke     62: [THEN]
1.8       jwilke     63: 
                     64: [ELSE]
                     65: 
1.13    ! anton      66: : PrimStart ['] true >head-noprim ;
1.8       jwilke     67: 
1.1       anton      68: : look ( cfa -- lfa flag )
1.12      anton      69:     dup in-dictionary?
1.9       jwilke     70:     IF
1.13    ! anton      71:        >head-noprim dup ??? <>
1.12      anton      72:     ELSE
1.9       jwilke     73:        PrimStart (look)
                     74:     THEN ;
1.1       anton      75: 
1.8       jwilke     76: [THEN]
                     77: [THEN]
1.13    ! anton      78: 
        !            79: : >head ( cfa -- nt|0 ) \ gforth to-head
        !            80:     \G tries to find the name token nt of the word represented by cfa;
        !            81:     \G returns 0 if it fails.  This word is not absolutely reliable,
        !            82:     \G it may give false positives and produce wrong nts.
        !            83:     look and ;
        !            84: 
        !            85: ' >head ALIAS >name \ gforth to-name
        !            86: \G old name of @code{>head}

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