From 0fdaee31ed673e754fe462bbe78410b830df9de4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Karl=20Yngve=20Lerv=C3=A5g?= <karl.yngve+git@gmail.com>
Date: Mon, 1 Aug 2016 22:57:43 +0200
Subject: [PATCH] Completed a fully custom formatexpr (#436)

---
 autoload/vimtex/format.vim | 108 ++++++++++++++++++++++++++++++++++---
 indent/tex.vim             |  22 ++++----
 test/vader/format.vader    |   9 ++--
 3 files changed, 115 insertions(+), 24 deletions(-)

diff --git a/autoload/vimtex/format.vim b/autoload/vimtex/format.vim
index bb55288..4e0fd1d 100644
--- a/autoload/vimtex/format.vim
+++ b/autoload/vimtex/format.vim
@@ -44,7 +44,8 @@ function! vimtex#format#formatexpr() " {{{1
 
   let l:top = v:lnum
   let l:bottom = v:lnum + v:count - 1
-  let l:mark = l:bottom
+  let l:lines_old = getline(l:top, l:bottom)
+  let l:tries = 5
 
   " This is a hack to make undo restore the correct position
   if mode() !=# 'i'
@@ -52,7 +53,43 @@ function! vimtex#format#formatexpr() " {{{1
     normal! x
   endif
 
-  for l:current in range(l:bottom, l:top, -1)
+  " Main formatting algorithm
+  while l:tries > 0
+    " Format the range of lines
+    let l:bottom = s:format(l:top, l:bottom)
+
+    " Ensure proper indentation
+    silent! execute printf('normal! %sG=%sG', l:top, l:bottom)
+
+    " Check if any lines have changed
+    let l:lines_new = getline(l:top, l:bottom)
+    let l:index = s:compare_lines(l:lines_new, l:lines_old)
+    let l:top += l:index
+    if l:top > l:bottom | break | endif
+    let l:lines_old = l:lines_new[l:index:]
+    let l:tries -= 1
+  endwhile
+
+  " Move cursor to first non-blank of the last formatted line
+  if mode() !=# 'i'
+    execute 'normal!' l:bottom . 'G^'
+  endif
+
+  " Don't change the text if the formatting algorithm failed
+  if l:tries == 0
+    silent! undo
+    call vimtex#echo#warning('Formatting of selected text failed!')
+  endif
+
+  let &l:foldenable = l:foldenable
+endfunction
+
+" }}}1
+
+function! s:format(top, bottom) " {{{1
+  let l:bottom = a:bottom
+  let l:mark = a:bottom
+  for l:current in range(a:bottom, a:top, -1)
     let l:line = getline(l:current)
 
     if vimtex#util#in_mathzone(l:current, 1)
@@ -63,24 +100,79 @@ function! vimtex#format#formatexpr() " {{{1
 
     if l:line =~# s:border_end
       if l:current < l:mark
-        execute 'normal!' (l:current+1) . 'Ggw' . l:mark . 'G'
+        let l:bottom += s:format_build_lines(l:current+1, l:mark)
       endif
       let l:mark = l:current
     endif
 
     if l:line =~# s:border_beginning
       if l:current < l:mark
-        execute 'normal!' l:current . 'Ggw' . l:mark . 'G'
+        let l:bottom += s:format_build_lines(l:current, l:mark)
       endif
       let l:mark = l:current-1
     endif
-  endwhile
 
-  if l:top <= l:mark
-    execute 'normal!' l:top . 'Ggw' . l:mark . 'G'
+    if l:line =~# '^\s*$'
+      let l:bottom += s:format_build_lines(l:current+1, l:mark)
+      let l:mark = l:current-1
+    endif
+  endfor
+
+  if a:top <= l:mark
+    let l:bottom += s:format_build_lines(a:top, l:mark)
   endif
 
-  let &l:foldenable = l:foldenable
+  return l:bottom
+endfunction
+
+" }}}1
+function! s:format_build_lines(start, end) " {{{1
+  "
+  " Get the desired text to format as a list of words
+  "
+  let l:words = split(join(map(getline(a:start, a:end),
+        \ 'substitute(v:val, ''^\s*'', '''', '''')'), ' '), ' ')
+  if empty(l:words) | return 0 | endif
+
+  "
+  " Add the words in properly indented and formatted lines
+  "
+  let l:lnum = a:start-1
+  let l:current = repeat(' ', VimtexIndent(a:start))
+  for l:word in l:words
+    if len(l:word) + len(l:current) > &tw
+      call append(l:lnum, substitute(l:current, '\s$', '', ''))
+      let l:lnum += 1
+      let l:current = repeat(' ', VimtexIndent(a:start))
+    endif
+    let l:current .= l:word . ' '
+  endfor
+  if l:current !~# '^\s*$'
+    call append(l:lnum, substitute(l:current, '\s$', '', ''))
+    let l:lnum += 1
+  endif
+
+  "
+  " Remove old text
+  "
+  silent! execute printf('%s;+%s delete', l:lnum+1, a:end-a:start)
+
+  "
+  " Return the difference between number of lines of old and new text
+  "
+  return l:lnum - a:end
+endfunction
+
+" }}}1
+
+function! s:compare_lines(new, old) " {{{1
+  let l:min_length = min([len(a:new), len(a:old)])
+  for l:i in range(l:min_length)
+    if a:new[l:i] !=# a:old[l:i]
+      return l:i
+    endif
+  endfor
+  return l:min_length
 endfunction
 
 " }}}1
diff --git a/indent/tex.vim b/indent/tex.vim
index b0a3c20..687f10d 100644
--- a/indent/tex.vim
+++ b/indent/tex.vim
@@ -17,31 +17,31 @@ let s:cpo_save = &cpo
 set cpo&vim
 
 setlocal autoindent
-setlocal indentexpr=VimtexIndent()
+setlocal indentexpr=VimtexIndent(v:lnum)
 setlocal indentkeys&
 setlocal indentkeys+=[,(,{,),},],\&,=item
 
-function! VimtexIndent() " {{{1
-  let l:nprev = s:get_prev_line(prevnonblank(v:lnum - 1))
+function! VimtexIndent(lnum) " {{{1
+  let l:nprev = s:get_prev_line(prevnonblank(a:lnum - 1))
   if l:nprev == 0 | return 0 | endif
 
   " Get current and previous line and remove comments
-  let l:cur = substitute(getline(v:lnum), '\\\@<!%.*', '', '')
+  let l:cur = substitute(getline(a:lnum), '\\\@<!%.*', '', '')
   let l:prev = substitute(getline(l:nprev),   '\\\@<!%.*', '', '')
 
   " Check for verbatim modes
-  if s:is_verbatim(l:cur, v:lnum)
-    return empty(l:cur) ? indent(l:nprev) : indent(v:lnum)
+  if s:is_verbatim(l:cur, a:lnum)
+    return empty(l:cur) ? indent(l:nprev) : indent(a:lnum)
   endif
 
   " Align on ampersands
   if l:cur =~# '^\s*&' && l:prev =~# '\\\@<!&.*'
-    return indent(v:lnum) + match(l:prev, '\\\@<!&') - stridx(l:cur, '&')
+    return indent(a:lnum) + match(l:prev, '\\\@<!&') - stridx(l:cur, '&')
   endif
 
   " Use previous indentation for comments
   if l:cur =~# '^\s*%'
-    return indent(v:lnum)
+    return indent(a:lnum)
   endif
 
   let l:nprev = s:get_prev_line(l:nprev, 'ignore-ampersands')
@@ -50,7 +50,7 @@ function! VimtexIndent() " {{{1
 
   let l:ind = indent(l:nprev)
   let l:ind += s:indent_envs(l:cur, l:prev)
-  let l:ind += s:indent_delims(l:cur, l:prev)
+  let l:ind += s:indent_delims(l:cur, l:prev, a:lnum)
   let l:ind += s:indent_tikz(l:nprev, l:prev)
   return l:ind
 endfunction
@@ -105,8 +105,8 @@ let s:envs_begitem = s:envs_item . '\|' . s:envs_beglist
 let s:envs_enditem = s:envs_item . '\|' . s:envs_endlist
 
 " }}}1
-function! s:indent_delims(cur, prev) " {{{1
-  let [l:open, l:close] = vimtex#delim#get_valid_regexps(v:lnum, col('.'))
+function! s:indent_delims(cur, prev, lnum) " {{{1
+  let [l:open, l:close] = vimtex#delim#get_valid_regexps(a:lnum, col('.'))
   return &sw*(  max([s:count(a:prev, l:open) - s:count(a:prev, l:close), 0])
         \     - max([s:count(a:cur, l:close) - s:count(a:cur, l:open),   0]))
 endfunction
diff --git a/test/vader/format.vader b/test/vader/format.vader
index 06501eb..caf0b0a 100644
--- a/test/vader/format.vader
+++ b/test/vader/format.vader
@@ -168,9 +168,8 @@ Expect tex (Verify):
   distribution over $x^u$ when sampled at label $\vec x$ some time later; another
   population started around $\vec x_1$ carries a different history when it, too,
   visits $\vec x$ later. Therefore, for instance the effective drift $\vec v(\vec
-    x)$ will be different in the two cases. We conclude that, if unobserved
-    degrees of freedom have dynamics on the time scale of the experiment
-    eq.~\ref{eq:fpe} is an approximation whose coefficients become
-    \emph{non-universal} (dependent on intial conditions) and
-    \emph{time-dependent}.
+  x)$ will be different in the two cases. We conclude that, if unobserved degrees
+  of freedom have dynamics on the time scale of the experiment eq.~\ref{eq:fpe}
+  is an approximation whose coefficients become \emph{non-universal} (dependent
+  on intial conditions) and \emph{time-dependent}.