1 files changed, 138 insertions, 0 deletions
diff --git a/runtime/indent/hare.vim b/runtime/indent/hare.vim
new file mode 100644
index 0000000..bc4fea4
--- /dev/null
+++ b/runtime/indent/hare.vim
@@ -0,0 +1,138 @@
+" Vim indent file
+" Language: Hare
+" Maintainer: Amelia Clarke <me@rsaihe.dev>
+" Last Change: 2022 Sep 22
+
+if exists("b:did_indent")
+  finish
+endif
+let b:did_indent = 1
+
+if !has("cindent") || !has("eval")
+  finish
+endif
+
+setlocal cindent
+
+" L0 -> don't deindent labels
+" (s -> use one indent after a trailing (
+" m1 -> if ) starts a line, indent it the same as its matching (
+" ks -> add an extra indent to extra lines in an if expression or for expression
+" j1 -> indent code inside {} one level when in parentheses
+" J1 -> see j1
+" *0 -> don't search for unclosed block comments
+" #1 -> don't deindent lines that begin with #
+setlocal cinoptions=L0,(s,m1,ks,j1,J1,*0,#1
+
+" Controls which keys reindent the current line.
+" 0{     -> { at beginning of line
+" 0}     -> } at beginning of line
+" 0)     -> ) at beginning of line
+" 0]     -> ] at beginning of line
+" !^F    -> <C-f> (not inserted)
+" o      -> <CR> or `o` command
+" O      -> `O` command
+" e      -> else
+" 0=case -> case
+setlocal indentkeys=0{,0},0),0],!^F,o,O,e,0=case
+
+setlocal cinwords=if,else,for,switch,match
+
+setlocal indentexpr=GetHareIndent()
+
+function! FloorCindent(lnum)
+  return cindent(a:lnum) / shiftwidth() * shiftwidth()
+endfunction
+
+function! GetHareIndent()
+  let line = getline(v:lnum)
+  let prevlnum = prevnonblank(v:lnum - 1)
+  let prevline = getline(prevlnum)
+  let prevprevline = getline(prevnonblank(prevlnum - 1))
+
+  " This is all very hacky and imperfect, but it's tough to do much better when
+  " working with regex-based indenting rules.
+
+  " If the previous line ended with =, indent by one shiftwidth.
+  if prevline =~# '\v\=\s*(//.*)?$'
+    return indent(prevlnum) + shiftwidth()
+  endif
+
+  " If the previous line ended in a semicolon and the line before that ended
+  " with =, deindent by one shiftwidth.
+  if prevline =~# '\v;\s*(//.*)?$' && prevprevline =~# '\v\=\s*(//.*)?$'
+    return indent(prevlnum) - shiftwidth()
+  endif
+
+  " TODO: The following edge-case is still indented incorrectly:
+  " case =>
+  "         if (foo) {
+  "                 bar;
+  "         };
+  " | // cursor is incorrectly deindented by one shiftwidth.
+  "
+  " This only happens if the {} block is the first statement in the case body.
+  " If `case` is typed, the case will also be incorrectly deindented by one
+  " shiftwidth. Are you having fun yet?
+
+  " Deindent cases.
+  if line =~# '\v^\s*case'
+    " If the previous line was also a case, don't do any special indenting.
+    if prevline =~# '\v^\s*case'
+      return indent(prevlnum)
+    end
+
+    " If the previous line was a multiline case, deindent by one shiftwidth.
+    if prevline =~# '\v\=\>\s*(//.*)?$'
+      return indent(prevlnum) - shiftwidth()
+    endif
+
+    " If the previous line started a block, deindent by one shiftwidth.
+    " This handles the first case in a switch/match block.
+    if prevline =~# '\v\{\s*(//.*)?$'
+      return FloorCindent(v:lnum) - shiftwidth()
+    end
+
+    " If the previous line ended in a semicolon and the line before that wasn't
+    " a case, deindent by one shiftwidth.
+    if prevline =~# '\v;\s*(//.*)?$' && prevprevline !~# '\v\=\>\s*(//.*)?$'
+      return FloorCindent(v:lnum) - shiftwidth()
+    end
+
+    let l:indent = FloorCindent(v:lnum)
+
+    " If a normal cindent would indent the same amount as the previous line,
+    " deindent by one shiftwidth. This fixes some issues with `case let` blocks.
+    if l:indent == indent(prevlnum)
+      return l:indent - shiftwidth()
+    endif
+
+    " Otherwise, do a normal cindent.
+    return l:indent
+  endif
+
+  " Don't indent an extra shiftwidth for cases which span multiple lines.
+  if prevline =~# '\v\=\>\s*(//.*)?$' && prevline !~# '\v^\s*case\W'
+    return indent(prevlnum)
+  endif
+
+  " Indent the body of a case.
+  " If the previous line ended in a semicolon and the line before that was a
+  " case, don't do any special indenting.
+  if prevline =~# '\v;\s*(//.*)?$' && prevprevline =~# '\v\=\>\s*(//.*)?$' && line !~# '\v^\s*}'
+    return indent(prevlnum)
+  endif
+
+  let l:indent = FloorCindent(v:lnum)
+
+  " If the previous line was a case and a normal cindent wouldn't indent, indent
+  " an extra shiftwidth.
+  if prevline =~# '\v\=\>\s*(//.*)?$' && l:indent == indent(prevlnum)
+    return l:indent + shiftwidth()
+  endif
+
+  " If everything above is false, do a normal cindent.
+  return l:indent
+endfunction
+
+" vim: tabstop=2 shiftwidth=2 expandtab