365 lines
9 KiB
Text
Executable file
365 lines
9 KiB
Text
Executable file
#!/usr/bin/env retro
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line oriented editor
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# Hua: a text editor written in RETRO
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Hua is a small, functional text editor written in RETRO for
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Unix systems. It is line oriented, visual, and easy to learn.
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## Starting
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Hua is intended to run as a standalone tool. Use a line like:
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edit.forth filename
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To create a new file:
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edit.forth new filename
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## A Word of Warning
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Hua saves changes as you edit the file. I advise using it along
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with a version control system so you can revert changes when
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needed.
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## The Code
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Since this runs as a standalone application I use a quick check
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to exit if no arguments were passed.
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~~~
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sys:argc n:zero? [ 'No_file_specified! s:put nl #0 unix:exit ] if
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~~~
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If I get here, a filename was provided. So I start by creating
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a few variables and constants.
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Get the name of the file to edit.
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~~~
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#0 sys:argv s:keep 'SourceFile var<n>
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~~~
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The configuration here is for two items. The number of lines
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from the file to show on screen, and the name of the temporary
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file to use when editing.
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~~~
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#70 'COLS const
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#16 'MAX-LINES const
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'/tmp/hua.editor.scratch 'TEMP-FILE s:const
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~~~
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Next are the variables that I use to track various bits of
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state.
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~~~
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'CurrentLine var
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'LineCount var
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'ShowEOL var
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'FID var
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'CopiedLine d:create #1025 allot
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~~~
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To create a new file, Hua allows for the use of `new` followed
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by the filename. I handle the file creation here.
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~~~
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@SourceFile 'new s:eq?
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[ #1 sys:argv s:keep !SourceFile
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@SourceFile file:A file:open file:close ] if
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~~~
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This is just a shortcut to make writing strings to the current file
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easier.
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~~~
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:file:s:put (s-) [ @FID file:write ] s:for-each ASCII:LF @FID file:write ;
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~~~
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I now turn my attention to displaying the file. I am aiming for
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an interface like:
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<filename> : <line-count>
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---------------------------------------------------------------
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* 99:
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100: :n:square dup * ;
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101:
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102: This is the current line
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103:
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---------------------------------------------------------------
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j: down | k: up | ... other helpful text ...
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The * denotes the currently selected line.
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I start with words to count the number of lines in the file and
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advance to the currently selected line.
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~~~
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:count-lines (-)
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#0 @SourceFile [ drop n:inc ] file:for-each-line dup !LineCount ;
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:skip-to
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@CurrentLine MAX-LINES #2 / - #0 n:max [ @FID file:read-line drop ] times ;
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~~~
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Now for words to format the output. This should all be pretty
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clear in intent.
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`clear-display` uses an ANSI/VT100 escape sequence. This might
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need to be adjusted for your chosen terminal.
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~~~
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:clear-display (-)
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ASCII:ESC dup '%c[2J%c[0;0H s:format s:put nl ;
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~~~
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This just displays the separator bars.
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~~~
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:---- (-)
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#7 [ $- c:put ] times
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#0 COLS #10 / [ dup n:put #9 [ $- c:put ] times n:inc ] times n:put nl ;
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~~~
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Next, a word to display the header. Currently just the name of
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the file being edited and the line count.
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~~~
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:header (-)
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count-lines @SourceFile '%s_:_%n_lines\n s:format s:put ;
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~~~
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The `pad` word is used to make sure line numbers are all the
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same width.
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~~~
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:pad (n-n)
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dup #0 #9 n:between? [ '____ s:put ] if
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dup #10 #99 n:between? [ '___ s:put ] if
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dup #100 #999 n:between? [ '__ s:put ] if
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dup #1000 #9999 n:between? [ '_ s:put ] if ;
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~~~
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A line has a form:
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<indicator><number>: <text><eol>
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The indicator is an asterisk, and visually marks the current
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line.
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EOL is optional. If `ShowEOL` is `TRUE`, it'll display a ~ at
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the end of each line. This is useful when looking for trailing
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whitespace. The indicator can be toggled via the ~ key.
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~~~
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:mark-if-current (n-n)
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dup @CurrentLine eq? [ $* c:put ] [ sp ] choose ;
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:line# (n-)
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n:put ':_ s:put ;
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:eol (-)
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@ShowEOL [ $~ c:put ] if nl ;
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:display-line (n-n)
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dup @LineCount lt?
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[ dup mark-if-current pad line# n:inc @FID file:read-line s:put eol ] if ;
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:display (-)
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@SourceFile file:R file:open !FID
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clear-display header ---- skip-to
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@CurrentLine MAX-LINES #2 / - #0 n:max count-lines MAX-LINES n:min
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[ display-line ] times drop
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---- @FID file:close ;
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~~~
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With the code to display the file done, I can proceed to the
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words for handling editing.
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I add a custom combinator, `process-lines` to iterate over the
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lines in the file. This takes a quote, and runs it once for
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each line in the file. The quote gets passed two values: a
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counter and a pointer to the current line in the file. The
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quote should consume the pointer an increment the counter. This
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also sets up `FID` as a pointer to the temporary file where
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changes can be written. The combinator will replace the
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original file after execution completes.
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Additionally, I define a word named `current?` which returns
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`TRUE` if the specified line is the current one. This is just
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to aid in later readability.
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~~~
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:process-lines (q-)
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TEMP-FILE file:W file:open !FID
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[ #0 @SourceFile ] dip file:for-each-line drop
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@FID file:close
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here TEMP-FILE file:slurp here @SourceFile file:spew ;
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:current? (ns-nsf)
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over @CurrentLine eq? ;
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~~~
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So first up, a word to delete all text in the current line.
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~~~
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:delete-line (-)
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[ current? [ drop '_ ] if file:s:put n:inc ] process-lines ;
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~~~
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Then a word to discard the current line, removing it from the file.
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~~~
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:kill-line (-)
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[ current? [ drop ] [ file:s:put ] choose n:inc ] process-lines ;
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~~~
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And the inverse, a word to inject a new line into the file.
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~~~
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:add-line (-)
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[ current? [ file:s:put ASCII:LF @FID file:write ]
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[ file:s:put ] choose n:inc ] process-lines CurrentLine v:inc ;
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~~~
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Replacing a line is next. Much like the `delete-line`, this
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writes all but the current line to a dummy file. It uses an
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`s:get` word to read in the text to write instead of the
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original current line. When done, it replaces the original
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file with the dummy one.
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~~~
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{{
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:save (c-)
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ASCII:BS [ buffer:get drop ] case
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ASCII:DEL [ buffer:get drop ] case
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buffer:add ;
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---reveal---
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:s:get (-s)
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s:empty [ buffer:set
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[ repeat c:get dup ASCII:LF -eq? 0; drop save again ] call drop ] sip ;
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}}
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:replace-line (-)
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[ current? [ drop #7 [ ASCII:SPACE c:put ] times s:get ] if
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file:s:put n:inc ] process-lines ;
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~~~
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The next four are just things I find useful. They allow me to
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indent, remove indention, trim trailing whitespace, and insert
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a code block delimiter at a single keystroke.
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~~~
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:indent-line (-)
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[ current? [ ASCII:SPACE dup @FID file:write @FID file:write ] if file:s:put n:inc ] process-lines ;
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:dedent-line (-)
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[ current? [ n:inc n:inc ] if file:s:put n:inc ] process-lines ;
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:trim-trailing (-)
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[ current? [ s:trim-right ] if file:s:put n:inc ] process-lines ;
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:code-block (-)
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[ current? [ drop '~~~ ] if file:s:put n:inc ] process-lines ;
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~~~
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And then a very limited form of copy/paste, which moves a copy
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of the current line into a `CopiedLine` buffer and back again.
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The line buffer is 1024 characters long, use of a longer line
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will cause problems.
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~~~
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:copy-line (-)
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[ current? [ dup &CopiedLine s:copy ] if file:s:put n:inc ] process-lines ;
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:paste-line (-)
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[ current? [ drop &CopiedLine ] if file:s:put n:inc ] process-lines ;
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~~~
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One more set of commands: jump to a particular line in the
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file, jump to the start or end of the file.
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~~~
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:goto (-)
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s:get s:to-number !CurrentLine ;
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:goto-start (-)
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#0 !CurrentLine ;
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:goto-end (-)
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@LineCount n:dec !CurrentLine ;
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~~~
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And now tie everything together. There's a key handler and a
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top level loop.
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~~~
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:describe (cs-)
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swap c:put $: c:put s:put ;
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:| describe '_|_ s:put ;
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:help
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$1 'replace_ |
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$2 'insert__ |
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$3 'trim____ |
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$4 'erase___ |
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$5 'delete__ |
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$j 'down____ | nl
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$k 'up______ |
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$g 'goto____ |
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$[ 'start___ |
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$] 'end_____ |
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$c 'copy____ |
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$v 'paste___ | nl
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$< 'dedent__ |
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$> 'indent__ |
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$~ 'mark_eol |
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$| '~~~_____ |
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'___________|_ s:put
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$q 'quit____ | nl ;
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~~~
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~~~
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:constrain (-) &CurrentLine #0 @LineCount n:dec v:limit ;
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:handler
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c:get
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$1 [ replace-line ] case
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$2 [ add-line ] case
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$3 [ trim-trailing ] case
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$4 [ delete-line ] case
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$5 [ kill-line ] case
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$~ [ @ShowEOL not !ShowEOL ] case
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$c [ copy-line ] case
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$v [ paste-line ] case
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$< [ dedent-line ] case
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$> [ indent-line ] case
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$| [ code-block ] case
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$[ [ goto-start ] case
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$] [ goto-end ] case
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$j [ &CurrentLine v:inc constrain ] case
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$k [ &CurrentLine v:dec constrain ] case
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$h [ &CurrentLine v:inc constrain ] case
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$t [ &CurrentLine v:dec constrain ] case
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$g [ goto constrain ] case
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$q [ 'stty_-cbreak unix:system bye ] case
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drop ;
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:edit
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'stty_cbreak unix:system
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repeat
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display help handler
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again ;
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~~~
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Run the editor.
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~~~
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edit
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~~~
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