1 files changed, 103 insertions, 0 deletions
diff --git a/runtime/indent/tcl.vim b/runtime/indent/tcl.vim
new file mode 100644
index 0000000..c35150d
--- /dev/null
+++ b/runtime/indent/tcl.vim
@@ -0,0 +1,103 @@
+" Vim indent file
+" Language:		Tcl
+" Maintainer:		Chris Heithoff <chrisheithoff@gmail.com>
+" Previous Maintainer:	Nikolai Weibull <now@bitwi.se>
+" Last Change:		24 Sep 2021
+
+if exists("b:did_indent")
+  finish
+endif
+let b:did_indent = 1
+
+setlocal indentexpr=GetTclIndent()
+setlocal indentkeys=0{,0},!^F,o,O,0]
+setlocal nosmartindent
+
+let b:undo_indent = "setl inde< indk< si<"
+
+if exists("*GetTclIndent")
+  finish
+endif
+
+function s:prevnonblanknoncomment(lnum)
+  let lnum = prevnonblank(a:lnum)
+  while lnum > 0
+    let line = getline(lnum)
+    if line !~ '^\s*\(#\|$\)'
+      break
+    endif
+    let lnum = prevnonblank(lnum - 1)
+  endwhile
+  return lnum
+endfunction
+
+function s:ends_with_backslash(lnum)
+  let line = getline(a:lnum)
+  if line =~ '\\\s*$'
+    return 1
+  else
+    return 0
+  endif
+endfunction 
+
+function s:count_braces(lnum, count_open)
+  let n_open = 0
+  let n_close = 0
+  let line = getline(a:lnum)
+  let pattern = '[{}]'
+  let i = match(line, pattern)
+  while i != -1
+    if synIDattr(synID(a:lnum, i + 1, 0), 'name') !~ 'tcl\%(Comment\|String\)'
+      if line[i] == '{'
+        let n_open += 1
+      elseif line[i] == '}'
+        if n_open > 0
+          let n_open -= 1
+        else
+          let n_close += 1
+        endif
+      endif
+    endif
+    let i = match(line, pattern, i + 1)
+  endwhile
+  return a:count_open ? n_open : n_close
+endfunction
+
+function GetTclIndent()
+  let line = getline(v:lnum)
+
+  " Get the line number of the previous non-blank or non-comment line.
+  let pnum = s:prevnonblanknoncomment(v:lnum - 1)
+  if pnum == 0
+    return 0
+  endif
+
+  " ..and the previous line before the previous line.
+  let pnum2 = s:prevnonblanknoncomment(pnum-1)
+
+  " Default indentation is to preserve the previous indentation.
+  let ind = indent(pnum)
+ 
+  " ...but if previous line introduces an open brace, then increase current line's indentation
+  if s:count_braces(pnum, 1) > 0
+    let ind += shiftwidth()
+  else
+    " Look for backslash line continuation on the previous two lines.
+    let slash1 = s:ends_with_backslash(pnum)
+    let slash2 = s:ends_with_backslash(pnum2)
+    if slash1 && !slash2
+      " If the previous line begins a line continuation.
+      let ind += shiftwidth()
+    elseif !slash1 && slash2
+      " If two lines ago was the end of a line continuation group of lines.
+      let ind -= shiftwidth()
+    endif
+  endif
+
+  " If the current line begins with a closed brace, then decrease the indentation by one.
+  if line =~ '^\s*}'
+    let ind -= shiftwidth()
+  endif
+  
+  return ind
+endfunction