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en:pfw:string_handling [2024-04-17 15:54] – [The idea] willemen:pfw:string_handling [2024-06-05 22:53] (current) – [Generic Forth] willem
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 (We define) A few words that make string manipulation in forth a little smoother.\\ (We define) A few words that make string manipulation in forth a little smoother.\\
-Original idea Albert Nijhof en [[https://home.hccnet.nl/a.w.m.van.der.horst/index.html|Albert van der Horst]]. Examples are:+Original idea Albert Nijhof & [[https://home.hccnet.nl/a.w.m.van.der.horst/index.html|Albert van der Horst]]. Examples are:
  
   * Manipulate files   * Manipulate files
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 {{https://user-images.githubusercontent.com/11397265/142727480-4cb13037-c118-4d05-9eec-529aeaf23cad.jpg| string usage example}} {{https://user-images.githubusercontent.com/11397265/142727480-4cb13037-c118-4d05-9eec-529aeaf23cad.jpg| string usage example}}
  
-However it more useful to use a construct of a cell containing a byte count followed by that many bytes. +
-You should not store a count in a character unless there is a dire need to conserve space. +
-Also a string in Chinese is some of the UTF representation is a sequence,  +
-where an interpretation of a byte is dependant on previous bytes.  +
-The abstraction presented here work equally well on this kind of data structure.+
    
 ===== Pseudo code ===== ===== Pseudo code =====
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 : C+!   ( n a -- )      >r  r@ c@ +  r> c! ;    \ Incr. byte with n at a : C+!   ( n a -- )      >r  r@ c@ +  r> c! ;    \ Incr. byte with n at a
 : $@    ( s -- c )      count ;                 \ Fetch string : $@    ( s -- c )      count ;                 \ Fetch string
-: $+!   ( c s -- )      >r  tuck  r@ $@ +  swap cmove  r> c+! ; \ Extend string +: $+!   ( c s -- )      >r  tuck  r@ $@ +  swap move  r> c+! ; \ Extend string 
 : $!    ( c s -- )      0 over c!  $+! ;        \ Store string : $!    ( c s -- )      0 over c!  $+! ;        \ Store string
 : $.    ( c -- )        type ;                  \ Print string : $.    ( c -- )        type ;                  \ Print string
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 </code> </code>
  
-The version where the count is stored in a cell is hardly different, but simpler.+Here is a version where the count is stored in a cell, it is hardly different.
 Note that it uses the non Generic Forth word ''%%@+%%'' you can find an implementation example in Note that it uses the non Generic Forth word ''%%@+%%'' you can find an implementation example in
 the [[https://project-forth-works.github.io/well-known-words.txt|well known words]] list. the [[https://project-forth-works.github.io/well-known-words.txt|well known words]] list.
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 : $@    ( s -- c )      @+  ;                  \ Fetch string : $@    ( s -- c )      @+  ;                  \ Fetch string
-: $+!   ( c s -- )      >r  tuck  r@ $@ +  swap cmove  r> +! ; \ Extend string +: $+!   ( c s -- )      >r  tuck  r@ $@ +  swap move  r> +! ; \ Extend string 
 : $!    ( c s -- )      0 over !  $+! ;        \ Store string : $!    ( c s -- )      0 over !  $+! ;        \ Store string
 : $.    ( c -- )        type ;                 \ Print string : $.    ( c -- )        type ;                 \ Print string
en/pfw/string_handling.1713362040.txt.gz · Last modified: 2024-04-17 15:54 by willem