155 lines
3.5 KiB
Forth
155 lines
3.5 KiB
Forth
This is a tiny Gopher client written in RETRO. It's only for the iOS implementation, but could be adapted for others with a little reworking of the file I/O code.
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It's intentionally kept minimal, handling only text files and directories. The interface is line oriented.
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# General Configuration
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`GOPHER-DATA` is the name of the file to store the last downloaded content into.
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`WrapPoint` holds the number of characters to display before wrapping output.
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There is also a `Results` variable which will point to the data set being displayed.
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~~~
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'GopherData.txt 'GOPHER-DATA s:const
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#34 'WrapPoint var<n>
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'Results var
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~~~
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# Download Data
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Specify a server, a port number, and the initial seletor to fetch.
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~~~
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:grab (sns-)
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s:empty 'abcd 'ddabc reorder gopher:get
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drop GOPHER-DATA file:spew ;
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~~~
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# Indexes
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An output line will have a format like this:
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1234: TXT About this server
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1235: DIR Archive
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1236: This is an information line or
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unknown type
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I define a variable `Displayed` to track how
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many characters have been displayed so far.
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~~~
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{{
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'Displayed var
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~~~
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A `wrap` word handles wrapping and indenting lines based on the `Displayed` characters and the global `WrapPoint`.
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~~~
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:wrap
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@Displayed @WrapPoint gt?
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[ #0 !Displayed nl '__________ puts ]
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[ &Displayed v:inc ] choose ;
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~~~
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Next is a word to display the directory type. This uses a simple case structure to handle things.
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~~~
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:type (c-)
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$0 [ 'TXT_ puts ] case
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$1 [ 'DIR_ puts ] case
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drop '____ puts ;
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~~~
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I define a `line` word to display the line number. This lets me pad the number with a leading number of spaces and have a colon and space following it.
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~~~
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:line (n-)
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n:to-string dup
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s:length #4 swap - [ sp ] times
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puts ':_ puts ;
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~~~
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I now define a custom version of `puts` that will call the `wrap` word defined earlier. I've not used `s:for-each` here as this will be called frequently, so it's a little faster to have a manually constructed loop here.
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~~~
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:puts<w/wrap> (s-)
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[ repeat fetch-next 0; putc wrap again ]
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call drop ;
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~~~
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The next word is `display`. This will tokenize a line and display the `type` and then the rest of the description using `puts<w/wrap>`.
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~~~
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:display (s-)
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#0 !Displayed
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ASCII:HT s:tokenize #0 set:nth fetch
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fetch-next type puts<w/wrap> ;
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~~~
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~~~
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---reveal---
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~~~
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And finally, tie everything together. This will display an index.
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~~~
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:display:index (-)
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#0 here GOPHER-DATA file:slurp drop
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ASCII:LF s:tokenize !Results
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@Results fetch #2 - @Results store
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@Results
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[ over line display nl n:inc ]
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set:for-each drop ;
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}}
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~~~
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# Text Viewer
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Text files are really easy. We just read the downloaded file into a buffer and display it.
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~~~
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:display:text (-)
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GOPHER-DATA file:slurp puts nl ;
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~~~
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# Final Bits
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`display-by-type` takes a type identifer and then calls the proper viewer.
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~~~
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:display-by-type (c-)
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$0 [ display:text ] case
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$1 [ display:index ] case
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dup putc nl drop ;
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~~~
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`home` just fetches a starting index and displays it. I have this hardcoded to my personal Gopher server.
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~~~
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:home (-)
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'forthworks.com #70 '/ grab
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$1 display-by-type ;
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~~~
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The last bit is `g`, which is used to navigate a directory. Pass it the line number to load.
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~~~
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:g (n-)
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@Results swap set:nth fetch
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ASCII:HT s:tokenize
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dup #0 set:nth fetch fetch [
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[ #2 set:nth fetch ]
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[ #3 set:nth fetch s:chop s:to-number ]
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[ #1 set:nth fetch ] tri grab
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] dip display-by-type ;
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~~~
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The final thing to do is just call `home` to get started.
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~~~
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home
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~~~
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