tree-sitter-pikchr

About

This repository contains Tree Sitter grammar for Pikchr and (possibly) minor extension.

It's naïve implementation based on the language spec, with some minor precedence guesses.

About Pikchr

More can be read at Pikchr's website, but in the nutshell it's diagramming language:

# Basic definitions
color=0x111111
fill=white

# Color palette
define $C1 { 0x8ecae6 }
define $C2 { 0x219ebc }
define $C3 { 0x023047 }
define $C4 { 0xffb703 }
define $C5 { 0xfb8500 }
define $text { text }
define $white { 0xdfdfdf }
define $box { box rad 3pt }
define $area { [
  box width 150% height 400% color None $2;
  text $1 above at last box.n
];}

# Position helper
define $yPos { $1<$2.nw,$2.sw> }

# Areas
PAST: $area("Past", fill $C1 ); move 10px;
PRESENT: $area("Present", fill $C2 );
BLANK: move 50px
FUTURE: $area("Future", fill $C4)

# Boxes
PL: $box() "Pikchr" "Language" at (PAST.c,$yPos(1/4,PAST))
TSG: $box() "Tree Sitter" "Grammar" at (PRESENT.c,$yPos(3/4,PRESENT))
PLUS: $text() "+" big big bold bold at BLANK.c
QM: $box "???" at FUTURE.c

thickness=1.5pt
linecolor=red

color=$C3
# "Arrows"
line from PL.e then right until even with PRESENT.c then down until even with $yPos(1/3,QM) then right until even with PLUS.w
line from TSG.n then up until even with $yPos(2/3,QM) then right until even with PLUS.w

# Arrowhead
line from (PLUS.e,$yPos(1/3,QM)) then right 6pt \
  then up 7pt then to QM.w
line from (PLUS.e,$yPos(2/3,QM)) then right 6pt \
  then down 7pt then to QM.w

Extra features

Since macro per se isn't part of the language spec there is 1 extra macroCall expression definition, allowing for macro calls.

Issues / Caveats

Issues

• [!] Missing corpus/tests
• Macro technically isn't part of the language but it should be checked for partial correctness
• Currently only downcase tokens are being recognized, (potential solution) ¹

Caveats

• Parser implementation has constraints that aren't present in language (e.g. 5 labels per object, unique attributes etc.)

Extension

I'm missing some QOL features that aren't present in original language. As it doesn't make sense to keep 2 repositories (especially given current state). Extension will be kept on separate branch (until eventual breakoff) yet main development branch will be aligned with official specs.

Planned extension features:

• Page break token
• Import statement
• Explicit diagram narrowing
• Standard hex color codes (#aa00ee, etc.)
• Config header support

Footnotes

¹ it has to be verified with implementation, though