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Tag folding poses a few difficulties. Many elements, e.g.
"blockquote", are always delimited by start and end tags;
end tags for some elements, e.g. "p", can be omitted in
certain contexts; void elements, e.g. "hr", have no end tag.
Although the rules for supporting omissible end tags are
ad-hoc and involved, they apply to elements in scope.
Assuming syntactical wellformedness, an end tag can be
associated with its nearest matching start tag discoverable
in scope and towards the beginning of a file, whereas all
unbalanced tags and inlined tags can be disregarded.
For example:
------------------------------------------------------------
<!DOCTYPE html>
<html lang="en"> <!-- >1 : 1 -->
<body> <!-- >2 : 2 -->
<p>Paragraph vim/vim#1. <!-- = : 2 -->
<p> <!-- >3 : 3 -->
Paragraph vim/vim#2. <!-- = : 3 -->
</p> <!-- <3 : 3 -->
<p>Paragraph vim/vim#3.</p> <!-- = : 2 -->
</body> <!-- <2 : 2 -->
</html> <!-- <1 : 1 -->
------------------------------------------------------------
(HTML comments here, "<!-- ... -->", record two values for
each folded line that are separated by ":", a value obtained
from "&foldexpr" and a value obtained from "foldlevel()".)
Innermost foldedable tags will be flattened. For example:
------------------------------------------------------------
<!DOCTYPE html>
<html lang="en"> <!-- >1 : 1 -->
<body> <!-- >2 : 2 -->
<div class="block"> <!-- >3 : 3 -->
<pre><code> <!-- >4 : 4 -->
[CODE SNIPPET] <!-- = : 4 -->
</code></pre> <!-- <4 : 4 -->
</div> <!-- <3 : 3 -->
</body> <!-- <2 : 2 -->
</html> <!-- <1 : 1 -->
------------------------------------------------------------
No folding will be requested for the "<code>"-"</code>" tag
pair and reflected by "&foldexpr" because such a fold would
have claimed the same lines that the immediate fold of the
"<pre>"-"</pre>" tag already claims.
Run-on folded tags may confuse Vim. When a file such as:
------------------------------------------------------------
<!DOCTYPE html>
<html lang="en"> <!-- >1 : 1 -->
<body> <!-- >2 : 2 -->
<div class="block"> <!-- >3 : 3 -->
<pre> <!-- >4 : 4 -->
<code> <!-- >5 : 5 -->
[CODE SNIPPET vim/vim#1] <!-- = : 5 -->
</code> <!-- <5 : 5 -->
</pre> <!-- <4 : 4 -->
</div> <!-- <3 : 3 -->
<!-- = : 3 -->
<div class="block"> <!-- >3 : 3 -->
<pre> <!-- >4 : 4 -->
<code> <!-- >5 : 5 -->
[CODE SNIPPET vim/vim#2] <!-- = : 5 -->
</code> <!-- <5 : 5 -->
</pre> <!-- <4 : 4 -->
</div> <!-- <3 : 3 -->
</body> <!-- <2 : 2 -->
</html> <!-- <1 : 1 -->
------------------------------------------------------------
is reformatted as follows:
------------------------------------------------------------
<!DOCTYPE html>
<html lang="en"> <!-- >1 : 1 -->
<body> <!-- >2 : 2 -->
<div class="block"> <!-- >3 : 3 -->
<pre> <!-- >4 : 4 -->
<code> <!-- >5 : 5 -->
[CODE SNIPPET vim/vim#1] <!-- = : 5 -->
</code> <!-- <5 : 5 -->
</pre> <!-- <4 : 4 -->
</div><div class="block"><pre><code> <!-- <3 : 3 -->
[CODE SNIPPET vim/vim#2] <!-- = : 2 ? -->
</code> <!-- <5 : 2 ? -->
</pre> <!-- <4 : 2 ? -->
</div> <!-- <3 : 2 ? -->
</body> <!-- <2 : 2 -->
</html> <!-- <1 : 1 -->
------------------------------------------------------------
"&foldexpr" values will not be used as is for the lines
between (and including) "[CODE SNIPPET vim/vim#2]" and "</div>".
(Cf. v9.1.0002.)
Having syntax highlighting in effect, tag folding using the
"fold-expr" method can be enabled with:
------------------------------------------------------------
let g:html_expr_folding = 1
------------------------------------------------------------
By default, tag folding will be redone from scratch after
each occurrence of a TextChanged or an InsertLeave event.
Such frequency may not be desired, especially for large
files, and this recomputation can be disabled with:
------------------------------------------------------------
let g:html_expr_folding_without_recomputation = 1
doautocmd FileType
------------------------------------------------------------
To force another recomputation, do:
------------------------------------------------------------
unlet! b:foldsmap
normal zx
------------------------------------------------------------
References:
https://web.archive.org/web/20250328105626/https://html.spec.whatwg.org/multipage/syntax.html#optional-tags
https://en.wikipedia.org/wiki/Dangling_else
closes: vim/vim#17141
dc7ed8f946
Co-authored-by: Aliaksei Budavei <0x000c70@gmail.com>
109 lines
3.0 KiB
VimL
109 lines
3.0 KiB
VimL
" Vim filetype plugin file
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" Language: HTML
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" Maintainer: Doug Kearns <dougkearns@gmail.com>
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" Previous Maintainer: Dan Sharp
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" Last Change: 2024 Jan 14
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" 2024 May 24 update 'commentstring' option
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" 2025 May 10 add expression folding #17141
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if exists("b:did_ftplugin")
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finish
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endif
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let b:did_ftplugin = 1
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let s:save_cpo = &cpo
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set cpo-=C
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setlocal matchpairs+=<:>
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setlocal commentstring=<!--\ %s\ -->
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setlocal comments=s:<!--,m:\ \ \ \ ,e:-->
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let b:undo_ftplugin = "setlocal comments< commentstring< matchpairs<"
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if get(g:, "ft_html_autocomment", 0)
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setlocal formatoptions-=t formatoptions+=croql
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let b:undo_ftplugin ..= " | setlocal formatoptions<"
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endif
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if exists('&omnifunc')
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setlocal omnifunc=htmlcomplete#CompleteTags
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call htmlcomplete#DetectOmniFlavor()
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let b:undo_ftplugin ..= " | setlocal omnifunc<"
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endif
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" HTML: thanks to Johannes Zellner and Benji Fisher.
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if exists("loaded_matchit") && !exists("b:match_words")
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let b:match_ignorecase = 1
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let b:match_words = '<!--:-->,' ..
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\ '<:>,' ..
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\ '<\@<=[ou]l\>[^>]*\%(>\|$\):<\@<=li\>:<\@<=/[ou]l>,' ..
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\ '<\@<=dl\>[^>]*\%(>\|$\):<\@<=d[td]\>:<\@<=/dl>,' ..
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\ '<\@<=\([^/!][^ \t>]*\)[^>]*\%(>\|$\):<\@<=/\1>'
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let b:html_set_match_words = 1
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let b:undo_ftplugin ..= " | unlet! b:match_ignorecase b:match_words b:html_set_match_words"
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endif
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" Change the :browse e filter to primarily show HTML-related files.
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if (has("gui_win32") || has("gui_gtk")) && !exists("b:browsefilter")
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let b:browsefilter = "HTML Files (*.html, *.htm)\t*.html;*.htm\n" ..
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\ "JavaScript Files (*.js)\t*.js\n" ..
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\ "Cascading StyleSheets (*.css)\t*.css\n"
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if has("win32")
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let b:browsefilter ..= "All Files (*.*)\t*\n"
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else
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let b:browsefilter ..= "All Files (*)\t*\n"
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endif
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let b:html_set_browsefilter = 1
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let b:undo_ftplugin ..= " | unlet! b:browsefilter b:html_set_browsefilter"
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endif
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if has("folding") && get(g:, "html_expr_folding", 0)
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function! HTMLTagFold() abort
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if empty(get(b:, "foldsmap", {}))
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if empty(get(b:, "current_syntax", ''))
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return '0'
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else
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let b:foldsmap = htmlfold#MapBalancedTags()
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endif
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endif
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return get(b:foldsmap, v:lnum, '=')
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endfunction
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setlocal foldexpr=HTMLTagFold()
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setlocal foldmethod=expr
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let b:undo_ftplugin ..= " | setlocal foldexpr< foldmethod<"
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if !get(g:, "html_expr_folding_without_recomputation", 0)
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augroup htmltagfold
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autocmd! htmltagfold
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autocmd TextChanged,InsertLeave <buffer> let b:foldsmap = {}
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augroup END
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" XXX: Keep ":autocmd" last in "b:undo_ftplugin" (see ":help :bar").
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let b:undo_ftplugin ..= " | silent! autocmd! htmltagfold * <buffer>"
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endif
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endif
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let &cpo = s:save_cpo
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unlet s:save_cpo
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" See ":help vim9-mix".
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if !has("vim9script")
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finish
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endif
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if exists("*g:HTMLTagFold")
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def! g:HTMLTagFold(): string
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if empty(get(b:, "foldsmap", {}))
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if empty(get(b:, "current_syntax", ''))
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return '0'
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else
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b:foldsmap = g:htmlfold#MapBalancedTags()
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endif
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endif
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return get(b:foldsmap, v:lnum, '=')
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enddef
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endif
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