[plugins] added Linediff

2 files changed, 173 insertions, 0 deletions

diff --git a/autoload/linediff/differ.vim b/autoload/linediff/differ.vim
new file mode 100644
index 0000000..7eb5c9d
--- /dev/null
+++ b/autoload/linediff/differ.vim
@@ -0,0 +1,169 @@
+" Constructs a Differ object that is still unbound. To initialize the object
+" with data, `Init(from, to)` needs to be invoked on that object.
+function! linediff#differ#New(sign_name, sign_number)
+  let differ = {
+        \ 'original_buffer': -1,
+        \ 'diff_buffer':     -1,
+        \ 'filetype':        '',
+        \ 'from':            -1,
+        \ 'to':              -1,
+        \ 'sign_name':       a:sign_name,
+        \ 'sign_number':     a:sign_number,
+        \ 'sign_text':       a:sign_number.'-',
+        \ 'is_blank':        1,
+        \ 'other_differ':    {},
+        \
+        \ 'Init':                      function('linediff#differ#Init'),
+        \ 'IsBlank':                   function('linediff#differ#IsBlank'),
+        \ 'Reset':                     function('linediff#differ#Reset'),
+        \ 'Lines':                     function('linediff#differ#Lines'),
+        \ 'CreateDiffBuffer':          function('linediff#differ#CreateDiffBuffer'),
+        \ 'SetupDiffBuffer':           function('linediff#differ#SetupDiffBuffer'),
+        \ 'CloseDiffBuffer':           function('linediff#differ#CloseDiffBuffer'),
+        \ 'UpdateOriginalBuffer':      function('linediff#differ#UpdateOriginalBuffer'),
+        \ 'PossiblyUpdateOtherDiffer': function('linediff#differ#PossiblyUpdateOtherDiffer'),
+        \ 'SetupSigns':                function('linediff#differ#SetupSigns')
+        \ }
+
+  exe "sign define ".differ.sign_name." text=".differ.sign_text." texthl=Search"
+
+  return differ
+endfunction
+
+" Sets up the Differ with data from the argument list and from the current
+" file.
+function! linediff#differ#Init(from, to) dict
+  let self.original_buffer = bufnr('%')
+  let self.filetype        = &filetype
+  let self.from            = a:from
+  let self.to              = a:to
+
+  call self.SetupSigns()
+
+  let self.is_blank = 0
+endfunction
+
+" Returns true if the differ is blank, which means not initialized with data.
+function! linediff#differ#IsBlank() dict
+  return self.is_blank
+endfunction
+
+" Resets the differ to the blank state. Invoke `Init(from, to)` on it later to
+" make it usable again.
+function! linediff#differ#Reset() dict
+  call self.CloseDiffBuffer()
+
+  let self.original_buffer = -1
+  let self.diff_buffer     = -1
+  let self.filetype        = ''
+  let self.from            = -1
+  let self.to              = -1
+  let self.other_differ    = {}
+
+  exe "sign unplace ".self.sign_number."1"
+  exe "sign unplace ".self.sign_number."2"
+
+  let self.is_blank = 1
+endfunction
+
+" Extracts the relevant lines from the original buffer and returns them as a
+" list.
+function! linediff#differ#Lines() dict
+  return getbufline(self.original_buffer, self.from, self.to)
+endfunction
+
+" Creates the buffer used for the diffing and connects it to this differ
+" object.
+function! linediff#differ#CreateDiffBuffer(edit_command) dict
+  let lines     = self.Lines()
+  let temp_file = tempname()
+
+  exe a:edit_command . " " . temp_file
+  call append(0, lines)
+  normal! Gdd
+  set nomodified
+
+  let self.diff_buffer = bufnr('%')
+  call self.SetupDiffBuffer()
+
+  diffthis
+endfunction
+
+" Sets up the temporary buffer's filetype and statusline.
+"
+" Attempts to leave the current statusline as it is, and simply add the
+" relevant information in the place of the current filename. If that fails,
+" replaces the whole statusline.
+function! linediff#differ#SetupDiffBuffer() dict
+  let b:differ = self
+
+  let statusline = printf('[%s:%%{b:differ.from}-%%{b:differ.to}]', bufname(self.original_buffer))
+  if &statusline =~ '%[fF]'
+    let statusline = substitute(&statusline, '%[fF]', statusline, '')
+  endif
+  exe "setlocal statusline=" . escape(statusline, ' |')
+  exe "set filetype=" . self.filetype
+  setlocal bufhidden=hide
+
+  autocmd BufWrite <buffer> silent call b:differ.UpdateOriginalBuffer()
+endfunction
+
+function! linediff#differ#CloseDiffBuffer() dict
+  if bufexists(self.diff_buffer)
+    exe "bdelete ".self.diff_buffer
+  endif
+endfunction
+
+function! linediff#differ#SetupSigns() dict
+  exe "sign unplace ".self.sign_number."1"
+  exe "sign unplace ".self.sign_number."2"
+
+  exe printf("sign place %d1 name=%s line=%d buffer=%d", self.sign_number, self.sign_name, self.from, self.original_buffer)
+  exe printf("sign place %d2 name=%s line=%d buffer=%d", self.sign_number, self.sign_name, self.to,   self.original_buffer)
+endfunction
+
+" Updates the original buffer after saving the temporary one. It might also
+" update the other differ's data, provided a few conditions are met. See
+" linediff#differ#PossiblyUpdateOtherDiffer() for details.
+function! linediff#differ#UpdateOriginalBuffer() dict
+  let new_lines = getbufline('%', 0, '$')
+
+  " Switch to the original buffer, delete the relevant lines, add the new
+  " ones, switch back to the diff buffer.
+  call linediff#util#SwitchBuffer(self.original_buffer)
+  let saved_cursor = getpos('.')
+  call cursor(self.from, 1)
+  exe "normal! ".(self.to - self.from + 1)."dd"
+  call append(self.from - 1, new_lines)
+  call setpos('.', saved_cursor)
+  call linediff#util#SwitchBuffer(self.diff_buffer)
+
+  " Keep the difference in lines to know how to update the other differ if
+  " necessary.
+  let line_count     = self.to - self.from + 1
+  let new_line_count = len(new_lines)
+
+  let self.to = self.from + len(new_lines) - 1
+  call self.SetupDiffBuffer()
+  call self.SetupSigns()
+
+  call self.PossiblyUpdateOtherDiffer(new_line_count - line_count)
+endfunction
+
+" If the other differ originates from the same buffer and it's located below
+" this one, we need to update its starting and ending lines, since any change
+" would result in a line shift.
+"
+" a:delta is the change in the number of lines.
+function! linediff#differ#PossiblyUpdateOtherDiffer(delta) dict
+  let other = self.other_differ
+
+  if self.original_buffer == other.original_buffer
+        \ && self.to <= other.from
+        \ && a:delta != 0
+    let other.from = other.from + a:delta
+    let other.to   = other.to   + a:delta
+
+    call other.SetupSigns()
+  endif
+endfunction
diff --git a/autoload/linediff/util.vim b/autoload/linediff/util.vim
new file mode 100644
index 0000000..4655b92
--- /dev/null
+++ b/autoload/linediff/util.vim
@@ -0,0 +1,4 @@
+" Helper method to change to a certain buffer.
+function! linediff#util#SwitchBuffer(bufno)
+  exe "buffer ".a:bufno
+endfunction