runtime(typst): Add typst runtime files

closes: #15234

Signed-off-by: Gregory Anders <greg@gpanders.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/autoload/typst.vim

@@ -0,0 +1,50 @@
+" Language:    Typst
+" Maintainer:  Gregory Anders
+" Last Change: 2024-07-14
+" Based on:    https://github.com/kaarmu/typst.vim
+
+function! typst#indentexpr() abort
+    let l:lnum = v:lnum
+    let s:sw = shiftwidth()
+
+    let [l:plnum, l:pline] = s:get_prev_nonblank(l:lnum - 1)
+    if l:plnum == 0 | return 0 | endif
+
+    let l:line = getline(l:lnum)
+    let l:ind = indent(l:plnum)
+
+    let l:synname = synIDattr(synID(l:lnum, 1, 1), 'name')
+
+    " Use last indent for block comments
+    if l:synname == 'typstCommentBlock'
+        return l:ind
+    endif
+
+    if l:pline =~ '\v[{[(]\s*$'
+        let l:ind += s:sw
+    endif
+
+    if l:line =~ '\v^\s*[}\])]'
+        let l:ind -= s:sw
+    endif
+
+    return l:ind
+endfunction
+
+" Gets the previous non-blank line that is not a comment.
+function! s:get_prev_nonblank(lnum) abort
+    let l:lnum = prevnonblank(a:lnum)
+    let l:line = getline(l:lnum)
+
+    while l:lnum > 0 && l:line =~ '^\s*//'
+        let l:lnum = prevnonblank(l:lnum - 1)
+        let l:line = getline(l:lnum)
+    endwhile
+
+    return [l:lnum, s:remove_comments(l:line)]
+endfunction
+
+" Removes comments from the given line.
+function! s:remove_comments(line) abort
+    return substitute(a:line, '\s*//.*', '', '')
+endfunction