Annotation of gforth/look.fs, revision 1.19

1.1       anton       1: \ LOOK.FS      xt -> lfa                               22may93jaw
                      2: 
1.14      anton       3: \ Copyright (C) 1995,1996,1997,2000 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
1.15      anton      19: \ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
1.3       anton      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: 
1.16      jwilke     29: require stuff.fs
                     30: require environ.fs
                     31: 
1.1       anton      32: decimal
                     33: 
1.8       jwilke     34: \ look                                                  17may93jaw
1.1       anton      35: 
1.8       jwilke     36: \ rename to discover!!!
1.1       anton      37: 
1.18      anton      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: 
1.1       anton      44: : (look)  ( xt startlfa -- lfa flag )
1.19    ! anton      45:     swap decompile-prim false rot
1.17      anton      46:     BEGIN
                     47:        @ dup
                     48:     WHILE
1.18      anton      49:            dup name>int xt>threaded
1.17      anton      50:            3 pick = IF
                     51:                nip dup
                     52:            THEN
                     53:     REPEAT
                     54:     drop nip
                     55:     dup 0<> ;
1.1       anton      56: 
1.8       jwilke     57: 
                     58: \ !!! nicht optimal!
                     59: [IFUNDEF] look
1.9       jwilke     60: has? ec [IF]
                     61: 
1.10      jwilke     62: has? rom 
1.8       jwilke     63: [IF]
1.9       jwilke     64: : look
                     65:     dup [ unlock rom-dictionary area lock ] 
                     66:     literal literal within
                     67:     IF
1.13      anton      68:        >head-noprim dup ?? <>
1.9       jwilke     69:     ELSE
                     70:        forth-wordlist @ (look)
                     71:     THEN ;
                     72: [ELSE]
1.8       jwilke     73: : look ( cfa -- lfa flag )
1.13      anton      74:     >head-noprim dup ??? <> ;
1.9       jwilke     75: [THEN]
1.8       jwilke     76: 
                     77: [ELSE]
                     78: 
1.13      anton      79: : PrimStart ['] true >head-noprim ;
1.8       jwilke     80: 
1.1       anton      81: : look ( cfa -- lfa flag )
1.12      anton      82:     dup in-dictionary?
1.9       jwilke     83:     IF
1.13      anton      84:        >head-noprim dup ??? <>
1.12      anton      85:     ELSE
1.9       jwilke     86:        PrimStart (look)
                     87:     THEN ;
1.1       anton      88: 
1.8       jwilke     89: [THEN]
                     90: [THEN]
1.13      anton      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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