402 lines
9.9 KiB
Forth
Executable file
402 lines
9.9 KiB
Forth
Executable file
#!/usr/bin/env retro
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# retro-edit
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Copyright (c) 2021, Charles Childers
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As part of my personal goal of using my own tools as much as possible,
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I've written this little line editor. It's vaguely similar to ed or
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edlin, but I've not attempted to replicate these. Mine is much simpler.
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On startup, it reads each line from a file into memory. The maximum line
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length and number of lines can be configured in the source, but must fit
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into Retro's memory space.
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Commands are entered as a single character, which may be followed by
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optional or mandatory parameters.
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An editing session (sans output) might look like:
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,n
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a5
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i5,enter some text on line 5
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p0,10
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x8
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p15,30
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x20,22
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,n
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w
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q
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Look further in the source for a table of commands.
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# The Code
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## Configuration
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On startup, this loads a working file specified here. Use the
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commands later to load a specific file if needed.
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~~~
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'scratch 'SCRATCH s:const
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~~~
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The editor needs a max line length and max number of lines per
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file.
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~~~
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#141 'cfg:MAX-LINE-LENGTH const
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#2001 'cfg:MAX-LINES const
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~~~
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## The File Contents
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The file gets read into an array of lines. This is in the `File`
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structure. `Lines` holds the number of lines in the file.
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A word, `ed:to-line` takes a line number and returns the address
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of the actual line contents.
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Of note here: these account for adding in a NULL terminator for
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each line.
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~~~
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'File d:create
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cfg:MAX-LINES cfg:MAX-LINE-LENGTH *
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cfg:MAX-LINES + allot
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'Lines var
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'Filename d:create
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#1025 allot
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:ed:constrain (n-m) #0 @Lines n:limit ;
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:ed:to-line (n-a) cfg:MAX-LINE-LENGTH over * + &File + ;
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~~~
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## Display A Line
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Line display is trivial in this. I optionally support line numbers,
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controlled by setting `ShowLineNumbers` to `TRUE`.
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~~~
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TRUE 'ShowLineNumbers var-n
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:ed:show-line-number (-)
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@ShowLineNumbers [ dup n:put ': s:put tab ] if ;
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:ed:display-line (n)
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ed:constrain ed:show-line-number ed:to-line s:put nl ;
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~~~
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## Command Processor
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Commands are single characters. I reserve an array of pointers
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(`Commands`), with the ASCII value of the character being an
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index into this. If the final pointer is non-zero, this will
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call the command handler.
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`ed:register-command` is used to add a handler to the table,
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and `ed:deregister-command` is used to remove one.
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~~~
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'Commands d:create #255 allot
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:ed:register-command (ac) &Commands + store ;
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:ed:deregister-command (c) &Commands + v:off ;
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:ed:process-command (c) fetch &Commands + fetch 0; call ;
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~~~
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## Some Editing Functions
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~~~
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:ed:blank-line (n) ed:to-line s:empty swap s:copy ;
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:ed:delete-line (n)
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&Lines v:dec
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@Lines over - [ [ ed:blank-line ]
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[ dup n:inc swap [ ed:to-line ] bi@ s:copy ]
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[ n:inc ] tri ] times drop ;
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:ed:copy-line (mn) [ ed:to-line ] bi@ s:copy ;
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{{
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:shift-line dup n:dec swap ed:copy-line ;
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---reveal---
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:ed:insert-line (n)
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[ @Lines [ [ shift-line ] sip n:dec dup-pair eq? ] until drop
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&Lines v:inc ] sip ed:blank-line ;
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}}
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~~~
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## Input
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Input is read by `ed:get-input`. This returns the first character as
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a value and stores the rest, with the pointer being kept in `Input`.
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~~~
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'Input var
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:ed:get-input (-c) s:get dup n:inc s:keep !Input ;
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~~~
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## Editor Loop
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The editor loop is thus simple. Get input, process the command, and
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repeat. I run this in a simple `Heap` preserving loop, so command
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handlers can allocate space at `here` without worrying about cleanup
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afterwards. I also reset the stack.
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~~~
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'Done var
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'Context var
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:edit
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[ &Heap [
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@Context [ @Context call ] if
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reset ed:get-input ed:process-command
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] v:preserve @Done ] until ;
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~~~
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## The Commands
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In general, each command is intended to do a single task.
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### Display
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`re` displays the file contents on command. I provide a few commands for
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this.
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| , | | display all lines in the file |
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| , | n | display all lines in the file with line numbers |
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| p | line | display a single line |
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| p | first,last | display a range of lines |
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| / | | search for text; display matching lines |
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| # | | toggle display of line numbers |
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The `,` command displays all lines in the file. It will optionally
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display line numbers if a `n` is included after the `,`.
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~~~
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:cmd:,
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&ShowLineNumbers [
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@Input 'n s:eq? [ &ShowLineNumbers v:on ] if
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#0 @Lines [ dup ed:display-line n:inc ] times drop
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] v:preserve ;
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~~~
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It's sometimes useful to have all outputs using line numbers. I
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define a `#` command to toggle the line number display. This will
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affect all outputs.
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~~~
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:cmd:# @ShowLineNumbers not !ShowLineNumbers ;
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~~~
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To display a single line, use `p` followed by the line number or to
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display a range of lines, use `p`, followed by a `first,last` line
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number pair.
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~~~
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:pair? @Input $, s:contains-char? ;
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:get-limits @Input $, s:tokenize [ s:to-number ed:constrain ] a:for-each ;
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:display-range over - n:inc [ dup ed:display-line n:inc ] times drop ;
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:cmd:p
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pair? [ get-limits display-range ]
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[ @Input s:to-number ed:display-line ] choose ;
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~~~
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The final display related command is `/`, which displays lines that contain
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the text following the `/`.
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~~~
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:match? I ed:to-line @Input s:contains-string? ;
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:cmd:/ @Lines [ match? [ I ed:display-line ] if ] indexed-times ;
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~~~
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### Editing
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| a | line | add a line at line number, shifting lines down |
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| a | line,count | add lines at line number, shifting lines down |
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Adding lines is done with `a`. Provide either a line number or a
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`first,count` pair and lines will be inserted starting at the specified
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line.
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~~~
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:cmd:a
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pair? [ get-limits [ dup ed:insert-line ] times drop ]
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[ @Input s:to-number ed:insert-line ] choose ;
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~~~
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| x | line | remove line |
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| x | first,last | remove lines first through last, inclusive |
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Use `x` to delete one or more lines. Pass either a single line number or
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a `first,last` pair.
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~~~
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:delete-lines [ dup ed:delete-line n:dec dup-pair lteq? ] while drop-pair ;
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:cmd:x
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pair? [ get-limits delete-lines ]
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[ @Input s:to-number ed:delete-line ] choose ;
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~~~
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| d | line | erase contents of a line |
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To erase the contents of a line, use `d` followed by the line number.
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~~~
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:cmd:d @Input s:to-number ed:blank-line ;
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~~~
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| i | line,text | replace contents of line with text |
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| e | line | insert text beginning at line, shifting down |
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I provide two words for editing the text of the file. `i` replaces the
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text on a line with the provided text, and `e` insterts text, shifting
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existing lines down. When entering text with `e`, use a period on an
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otherwise blank line to return to the command processing mode.
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~~~
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:cmd:i @Input $, s:split/char s:to-number ed:to-line [ n:inc ] dip s:copy ;
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{{
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:add-space dup ed:insert-line ;
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:store-line over ed:to-line s:copy n:inc ;
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:cleanup n:dec ed:delete-line ;
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:ruler #6 [ '---------+ s:put ] times '---- s:put nl ;
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---reveal---
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'Prompt var
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:cmd:e
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ruler
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@Input s:to-number
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[ @Prompt [ @Prompt call ] if
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add-space s:get [ store-line ] sip '. s:eq? ] until cleanup ;
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}}
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~~~
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Copy/paste
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~~~
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'LineBuffer d:create
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cfg:MAX-LINE-LENGTH allot #0 ,
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:cmd:c @Input s:to-number ed:to-line &LineBuffer s:copy ;
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:cmd:u cmd:a &LineBuffer @Input s:to-number ed:to-line s:copy ;
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~~~
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### Setting the Filename
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| f | filename | set the filename for saves, loads |
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~~~
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:cmd:f @Input &Filename s:copy ;
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~~~
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### Saving
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| w | | save file |
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Files are saved with `w`. The number of lines written will be displayed
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upon completion.
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~~~
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{{
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:with-file &Filename file:open-for-writing [ swap call ] sip file:close ;
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:file:nl ASCII:LF over file:write ;
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:write-line I ed:to-line [ over file:write ] s:for-each file:nl ;
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:write-file [ @Lines [ write-line ] indexed-times ] with-file ;
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:select @Input s:length n:-zero? [ cmd:f ] if ;
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---reveal---
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:cmd:w select write-file @Lines n:put nl ;
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}}
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~~~
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~~~
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:create-if-not-present
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@Input s:length n:-zero? [ cmd:f ] if
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&Filename file:exists? [ &Filename file:W file:open file:close ] -if ;
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:erase-all
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#0 cfg:MAX-LINES [ #0 over ed:to-line store n:inc ] times drop ;
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:load-file
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create-if-not-present
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#0 &Filename [ over ed:to-line s:copy n:inc ] file:for-each-line
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!Lines ;
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:cmd:l erase-all load-file @Lines n:put nl ;
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~~~
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### New
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~~~
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:cmd:* SCRATCH &Filename s:copy erase-all #1 !Lines ;
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~~~
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### Quit
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| q | | quit retro-edit |
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Use `q` to quit the editor.
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~~~
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:cmd:q nl &Done v:on ;
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~~~
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### Others
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| n | line | indent line |
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| N | line | unindent line |
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| ; | | save, then run file via retro |
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| ; | text | save, then run text as a shell command |
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~~~
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:cmd:n @Input s:to-number ed:to-line dup '__ s:prepend swap s:copy ;
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:cmd:N @Input s:to-number ed:to-line dup #2 + swap s:copy ;
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:cmd::
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@Input dup s:length n:zero?
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[ drop &Filename ] if 'retro_%s s:format unix:system ;
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~~~
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## Register The Commands
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~~~
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{ ',p#/axdiefwlqnN:*cu [ ] s:for-each }
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[ [ 'cmd:%c s:format d:lookup d:xt fetch ] sip ed:register-command ]
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a:for-each
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~~~
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The final startup process is:
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- copy the file name to Filename
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- create it if the file does not exist
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- load the file into memory
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- run the editor command loop
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~~~
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:cmd:?
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here n:put nl ;
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&cmd:? $? ed:register-command
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~~~
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~~~
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s:empty !Input erase-all
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script:arguments n:-zero? [ #0 script:get-argument ] [ SCRATCH ] choose
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&Filename s:copy
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load-file
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edit bye
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~~~
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{ '|\_|V|_/|\_|\_/\__Charles_Childers'_Personal_Computing_System
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'|/_|_|__|__|/_\/__a_Unix_Kernel,_Retro_Forth,_and_a_non-POSIX
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'|\_|_|__|__|\_/\__environment_written_in_Forth }
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