Added an improved indent function

indent/tex.vim

@@ -0,0 +1,154 @@
+if exists("b:did_indent")
+  finish
+endif
+let b:did_indent = 1
+let s:cpo_save = &cpo
+set cpo&vim
+
+" {{{1 Options and common patterns
+setlocal autoindent
+setlocal indentexpr=s:indent()
+setlocal indentkeys&
+setlocal indentkeys+=[,(,{,),},],\&,0=item
+
+" Define some common patterns
+let s:envs_lists = 'itemize\|description\|enumerate\|thebibliography'
+let s:envs_noindent = 'document\|verbatim\|lstlisting'
+let s:delimiters_open = '\(' . join([
+        \ '{',
+        \ '(',
+        \ '\[',
+        \ '\\{',
+        \ '\\(',
+        \ '\\\[',
+        \ '\\\Cbegin\s*{.\{-}}',
+        \ '\\\Cleft\s*\%([^\\]\|\\.\|\\\a*\)',
+        \ '\\\cbigg\?\((\|\[\|\\{\)',
+      \ ], '\|') . '\)'
+let s:delimiters_close = '\(' . join([
+        \ '}',
+        \ ')',
+        \ '\]',
+        \ '\\}',
+        \ '\\)',
+        \ '\\\]',
+        \ '\\\Cend\s*{.\{-}}',
+        \ '\\\Cright\s*\%([^\\]\|\\.\|\\\a*\)',
+        \ '\\\cbigg\?\()\|\]\|\\}\)',
+      \ ], '\|') . '\)'
+" }}}1
+
+" {{{1 s:indent
+function! s:indent()
+  " Find a non-blank non-comment line above the current line
+  let lnum = prevnonblank(v:lnum - 1)
+  while lnum != 0 && getline(lnum) =~ '^\s*%'
+    let lnum = prevnonblank(lnum - 1)
+  endwhile
+
+  " Zero indent for top of file
+  if lnum == 0
+    return 0
+  endif
+
+  " Get current and previous line, remove comments
+  let cline = substitute(getline(v:lnum), '\\\@<!%.*', '', '')
+  let pline = substitute(getline(lnum),   '\\\@<!%.*', '', '')
+
+  " Check for verbatim modes
+  if synIDattr(synID(v:lnum, indent(v:lnum), 1), "name") == "texZone"
+    if empty(cline)
+      return indent(lnum)
+    else
+      return indent(v:lnum)
+    end
+  endif
+
+  " Align on ampersands
+  if cline =~ '^\s*&' && pline =~ '\\\@<!&.*'
+    return indent(v:lnum) + match(pline, '\\\@<!&') - stridx(cline, "&")
+  endif
+
+  " Find previous non-empty non-comment non-ampersand line
+  while lnum != 0 && (match(pline, '\\\@<!&') != -1 || pline =~ '^\s*%')
+    let lnum = prevnonblank(lnum - 1)
+    let pline = getline(lnum)
+  endwhile
+
+  " Zero indent for top of file
+  if lnum == 0
+    return 0
+  endif
+
+  " Use previous indentation for comments
+  if cline =~ '^\s*%'
+    return indent(v:lnum)
+  endif
+
+  let ind = indent(lnum)
+
+  " Add indent on begin environment
+  if pline =~ '\\begin{.*}' && pline !~ s:envs_noindent
+    let ind = ind + &sw
+
+    " Add extra indent for list environments
+    if pline =~ s:envs_lists
+      let ind = ind + &sw
+    endif
+  endif
+
+  " Subtract indent on end environment
+  if cline =~ '\\end{.*}' && cline !~ s:envs_noindent
+    let ind = ind - &sw
+
+    " Subtract extra indent for list environments
+    if cline =~ s:envs_lists
+      let ind = ind - &sw
+    endif
+  endif
+
+  " Indent opening and closing delimiters
+  let ind += s:indent_braces(cline, pline) * &sw
+
+  " Indent list items
+  if pline =~ '^\s*\\\(bib\)\?item'
+    let ind += &sw
+  endif
+  if cline =~ '^\s*\\\(bib\)\?item'
+    let ind -= &sw
+  endif
+
+  return ind
+endfunction
+"}}}
+
+" {{{1 s:indent_braces
+function! s:indent_braces(cline, pline)
+  let sum1  = s:match_brace(a:pline, s:delimiters_open)
+  let sum1 -= s:match_brace(a:pline, s:delimiters_close)
+
+  let sum2  = s:match_brace(a:cline, s:delimiters_open)
+  let sum2 -= s:match_brace(a:cline, s:delimiters_close)
+
+  echom max([0, sum1]) + min([0, sum2])
+  return max([0, sum1]) + min([0, sum2])
+endfunction
+
+" {{{1 s:match_brace
+function! s:match_brace(line, pattern)
+  let sum = 0
+  let indx = match(a:line, a:pattern)
+  while indx >= 0
+    let sum += 1
+    let match = matchstr(a:line, a:pattern, indx)
+    let indx += len(match)
+    let indx = match(a:line, a:pattern, indx)
+  endwhile
+  return sum
+endfunction
+" }}}1
+
+let &cpo = s:cpo_save
+unlet s:cpo_save
+
+" vim:fdm=marker:ff=unix