retroforth/example/edit.forth

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#!/usr/bin/env rre
# Hua: a text editor written in RETRO
Hua is a small, functional text editor written in RETRO, using the
*RRE* interface. It is line oriented, visual, and tries to be very
simple to use.
First up, several variables and constants that are used through
the rest of the code.
~~~
'SourceFile var
'CurrentLine var
'FID var
~~~
The configuration here is for two items. The number of lines from the
file to show on screen, and the name of the temporary file to use
when editing.
~~~
#80 'COLS const
#12 'MAX-LINES const
'/tmp/rre.edit 'TEMP-FILE s:const
~~~
Get the name of the file to edit. If no file is provided, exit.
~~~
sys:argc n:zero? [ #0 unix:exit ] if
#0 sys:argv s:keep !SourceFile
~~~
This is just a shortcut to make writing strings to the current file
easier.
~~~
:file:puts (s-) [ @FID file:write ] s:for-each ASCII:LF @FID file:write ;
~~~
I now turn my attention to displaying the file. I am aiming for
an interface like:
<filename> : <line-count>
---------------------------------------------------------------
* 99:
100: :n:square dup * ;
101:
102: This is the current line
103:
---------------------------------------------------------------
j: down | k: up | ... other helpful text ...
The * denotes the currently selected line.
I start with words to count the number of lines in the file and
advance to the currently selected line.
~~~
:count-lines (-)
#0 @SourceFile [ drop n:inc ] file:for-each-line ;
:skip-to
@CurrentLine #0 n:max [ @FID file:read-line drop ] times ;
~~~
Now for words to format the output. This should all be pretty clear in
intent.
`clear-display` uses an ANSI/VT100 escape sequence. This might need to
be adjusted for your chosen terminal.
~~~
:clear-display (-)
ASCII:ESC '%c[2J s:with-format puts nl ;
~~~
This just displays the separator bars.
~~~
:---- (-)
COLS [ $- putc ] times nl ;
~~~
Next, a word to display the header. Currently just the name of the file
being edited and the line count.
~~~
:header (-)
count-lines @SourceFile '%s_:_%n_lines\n s:with-format puts ;
~~~
The `pad` word is used to make sure line numbers are all the same width.
~~~
:pad (n-n)
dup #0 #9 n:between? [ '____ puts ] if
dup #10 #99 n:between? [ '___ puts ] if
dup #100 #999 n:between? [ '__ puts ] if
dup #1000 #9999 n:between? [ '_ puts ] if ;
~~~
A line has a form:
<indicator><number>: <text>
The indicator is an asterisk, and visually marks the current line.
~~~
:mark-if-current (n-n)
dup @CurrentLine eq? [ $* putc ] [ sp ] choose ;
:line# (n-)
putn ':_ puts ;
:display-line (n-n)
dup mark-if-current pad line# n:inc @FID file:read-line puts nl ;
~~~
~~~
:display (-)
@SourceFile file:R file:open !FID
clear-display header ---- skip-to
@CurrentLine count-lines MAX-LINES n:min [ display-line ] times drop
---- dump-stack
@FID file:close ;
~~~
With the code to display the file done, I can proceed on to words for
handling editing. First, is a word to delete contents of the current
line.
The process here is to just write all but the current line to a dummy
file, replacing the current line text with a newline. Then replace the
original file with the dummy one.
I add a custom combinator, `process-lines` to iterate over the lines in
the file. This takes a quote, and runs it once for each line in the file.
The quote gets passed two values: a counter and a pointer to the current
line in the file. The quote should consume the pointer an increment the
counter. This also sets up `FID` as a pointer to the temporary file where
changes can be written. The combinator will replace the original file
after execution completes.
~~~
:process-lines (q-)
TEMP-FILE file:W file:open !FID
[ #0 @SourceFile ] dip file:for-each-line drop
@FID file:close
@SourceFile TEMP-FILE 'mv_%s_%s s:with-format unix:system ;
~~~
~~~
:current? (n-nf)
over @CurrentLine eq? ;
:delete-line (-)
[ current? [ drop '_ ] if file:puts n:inc ] process-lines ;
~~~
~~~
:kill-line (-)
[ current? [ drop ] [ file:puts ] choose n:inc ] process-lines ;
~~~
~~~
:add-line (-)
[ current? [ ASCII:LF @FID file:write ] if file:puts n:inc ] process-lines ;
~~~
Replacing a line is next. Much like the `delete-line`, this writes all
but the current line to a dummy file. It uses a `gets` word to read in
the text to write instead of the original current line. When done, it
replaces the original file with the dummy one.
~~~
{{
:save (c-)
ASCII:BS [ buffer:get drop ] case
ASCII:DEL [ buffer:get drop ] case
buffer:add ;
---reveal---
:gets (-s)
s:empty [ buffer:set
[ repeat getc dup ASCII:LF -eq? 0; drop save again ] call drop ] sip ;
}}
:replace-line (-)
[ current? [ drop gets ] if file:puts n:inc ] process-lines ;
~~~
~~~
'CopiedLine d:create #1025 allot
:copy-line (-)
[ current? [ dup &CopiedLine s:copy ] if file:puts n:inc ] process-lines ;
:paste-line (-)
[ current? [ drop &CopiedLine ] if file:puts n:inc ] process-lines ;
~~~
~~~
:goto (-)
gets s:to-number !CurrentLine ;
~~~
And now tie everything together. There's a key handler and a top level loop.
~~~
:| '_|_ puts ;
:describe (cs-)
swap putc $: putc puts ;
:help
$1 'insert_line describe | $2 'replace_text describe | $3 '____________ describe |
$4 'erase_text_ describe | $5 'delete_line_ describe nl
$j 'down_______ describe | $k 'up__________ describe | $g 'goto_line___ describe |
$c 'copy_______ describe | $v 'paste_______ describe nl ;
:handler
getc
$1 [ add-line ] case
$2 [ replace-line ] case
$4 [ delete-line ] case
$5 [ kill-line ] case
$c [ copy-line ] case
$v [ paste-line ] case
$j [ &CurrentLine v:inc &CurrentLine #0 #10000 v:limit ] case
$k [ &CurrentLine v:dec &CurrentLine #0 #10000 v:limit ] case
$g [ goto &CurrentLine #0 #10000 v:limit ] case
$q [ 'stty_-cbreak unix:system #0 unix:exit ] case
drop ;
:edit
'stty_cbreak unix:system
repeat
display help handler
again ;
~~~
Run the editor.
~~~
edit
~~~