runtime/syntax/testdir/input/setup/html_fold_expr.vim

let g:html_expr_folding = 1
filetype plugin on
runtime(html): Optionally fold tags with the "expr" method 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 #1. <!-- = : 2 --> <p> <!-- >3 : 3 --> Paragraph #2. <!-- = : 3 --> </p> <!-- <3 : 3 --> <p>Paragraph #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 #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 #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 #1] <!-- = : 5 --> </code> <!-- <5 : 5 --> </pre> <!-- <4 : 4 --> </div><div class="block"><pre><code> <!-- <3 : 3 --> [CODE SNIPPET #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 #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: #17141 Signed-off-by: Aliaksei Budavei <0x000c70@gmail.com> Signed-off-by: Christian Brabandt <cb@256bit.org> 2025-05-10 21:40:41 +02:00			`let g:html_expr_folding = 1`
			`filetype plugin on`