Initial vim syntax for just

including:
- operators
- quotes/strings
- raw quotes/strings
- backtick sub-shells
- curly substitutions
- "set shell" handling

vim-just/syntax/just.vim

@@ -0,0 +1,118 @@
+" Vim syntax file
+" Language: Just Command Runner
+" Maintainer: Dan Buch
+" Latest Revision: 22 May 2021
+
+if exists("b:current_syntax")
+  finish
+endif
+
+let b:shell_name = "sh"
+let b:load_time_cursor = getpos('.')
+let b:debug = $JUST_VIM_DEBUG == 'enabled'
+
+function JustGetShellName()
+  let lineno = 0
+
+  while lineno < line("$")
+    let lineno += 1
+    let line = getline(lineno)
+
+    let set_shell_match = "^ *set  *shell  *:"
+    if matchstr(line, set_shell_match) == ""
+      if b:debug
+        echom "line number " . lineno . " does not match '" . set_shell_match . "': '" . line . "'"
+      endif
+
+      continue
+    endif
+
+    if b:debug
+      echom "found matching line number " . lineno . ": " . line
+    endif
+
+    :normal /"<CR>lv/"<CR>hy:nohl
+    let shell_name = @"
+
+    if shell_name != ""
+      return shell_name
+    fi
+  endwhile 
+
+  return "sh"
+endfunc
+
+try
+  let shell_name = JustGetShellName()
+
+  if b:debug
+    echom "found shell name: '" . shell_name . "'"
+  endif
+
+  exe "syn include @setshellsyntax syntax/" . shell_name . ".vim"
+
+  let b:shell_name = shell_name
+catch
+  if b:debug
+    echom "oh no: " v:exception
+    echom "just.vim: falling back to sh syntax"
+  endif
+
+  syn include @setshellsyntax syntax/sh.vim
+endtry
+
+syn keyword justKeyword alias export if else set
+
+syn keyword justFunction arch os os_family
+syn keyword justFunction env_var env_var_or_default invocation_directory
+syn keyword justFunction justfile justfile_directory just_executable
+
+syn keyword justSetting shell export dotenv-load positional-arguments
+
+syn match justOperator /\v:/
+syn match justOperator /\v\)/
+syn match justOperator /\v\(/
+syn match justOperator /\v\=/
+syn match justOperator /\v:\=/
+
+syn match justQuote /\v"/
+syn match justQuote /\v'/
+syn match justQuote /\v"""/
+syn match justQuote /\v'''/
+
+syn match justBacktick /\v\`/
+syn match justBacktick /\v\`\`\`/
+
+syn match justCurlyBrace /\v\{\{/
+syn match justCurlyBrace /\v\}\}/
+
+syn region justCurlyBraced matchgroup=justCurlyBrace start=/\v\{\{/ skip=/\v\\\{/ end=/\v\}\}/ contains=justKeyword,justFunction,justOperator,justQuote,justString,justRawString
+
+syn region justString matchgroup=justQuote start=/\v"/ skip=/\v\\"/ end=/\v"/ contains=justCurlyBraced
+syn region justString matchgroup=justQuote start=/\v"""/ skip=/\v\\"/ end=/\v"""/ contains=justCurlyBraced
+
+syn region justRawString matchgroup=justQuote start=/\v'/ end=/\v'/
+syn region justRawString matchgroup=justQuote start=/\v'''/ end=/\v'''/
+
+syn region justSubshell matchgroup=justBacktick start=/\v\`/ skip=/\v\\\`/ end=/\v\`/ contains=@setshellsyntax
+syn region justSubshell matchgroup=justBacktick start=/\v\`\`\`/ skip=/\v\\\`/ end=/\v\`\`\`/ contains=@setshellsyntax
+
+syn match justComment /\v#.*$/
+
+syn match justShebang /\v^ *#!.*$/
+
+hi def link justKeyword Keyword
+hi def link justSetting Keyword
+hi def link justOperator Operator
+hi def link justComment Comment
+hi def link justShebang PreProc
+hi def link justFunction Function
+hi def link justQuote String
+hi def link justString String
+hi def link justRawString String
+hi def link justCurlyBrace Keyword
+hi def link justBacktick Special
+
+let b:current_syntax = "just"
+
+" vim:expandtab:ts=2:sts=2