XML folding

.vim-after-ftplugin-xml-folding.vim

setlocal foldtext=MakeXMLFoldingLabelByConcatenatingNextLine()

function! MakeXMLFoldingLabelByConcatenatingNextLine()
    if getline(v:foldstart) !~# '^\s*<propert\(y\|ies\)\s\+name="[^"]\+"'
      return foldtext()
    endif
    let l:line = s:shorten(getline(v:foldstart) . getline(v:foldstart + 1))
    return l:line
endfunction

function! s:shorten(line)
    let l:rv = substitute(a:line, '<propert\(y\|ies\)\s\+name="\([^"]\+\)"', '<\2', 'g')
    let l:rv = substitute(l:rv, '\s*value=', '=', 'g')
    let l:rv = substitute(l:rv, '\(<[a-zA-Z0-9\-]*\)>\s*<', '\1 ', 'g')
    return l:rv
endfunction

.vim-after-ftplugin-xml.vim

setlocal foldmethod=syntax

.vimrc

let g:xml_syntax_folding = 1

sample.xml

<property name="foo">
  <property name="bar">
    <property name="id" value="aaa" />
  </property>
  <property name="bar">
    <property name="id" value="bbb" />
  </property>
  <property name="bar">
    <property name="id" value="ccc" />
  </property>
</property>