kakoune/rc/filetype/markdown.kak
Chris Webb ca50379771 Avoid semantically significant comments in kak files
Kakoune's balanced strings require that delimiter characters nested inside
them are also paired, so for example in %{ }, each nested { must occur
before a corresponding } to balance it out.

In general this will automatically be the case for code in common scripting
languages, but sometimes regular expressions used for syntax highlighting
do end up containing an unbalanced bracket of one type or another.

This problem is easily solved because there is a free choice of balanced
delimiter characters. However, it can also be worked around by adding
a comment which itself contains an unbalanced delimiter character, to
'balance out' the unpaired one in the regular expression.

These unbalanced comments are not ideal as the semantic role they perform
is easy for a casual reader to overlook. A good example is

    catch %{
        # indent after lines with an unclosed { or (
        try %< execute-keys -draft [c[({],[)}] <ret> <a-k> \A[({][^\n]*\n[^\n]*\n?\z <ret> j<a- gt> >
        # indent after a switch's case/default statements
        try %[ execute-keys -draft kx <a-k> ^\h*(case|default).*:$ <ret> j<a-gt> ]
        # deindent closing brace(s) when after cursor
        try %[ execute-keys -draft x <a-k> ^\h*[})] <ret> gh / [})] <ret> m <a-S> 1<a-&> ]
    }

in rc/filetype/go/kak. Here, it is not instantly obvious that the comment
containing an unmatched { is required for correctness. If you change the
comment, delete it or rearrange the contents of the catch block, go.kak
will fail to load, and if you cut-and-paste this code as the basis for
a new filetype, it is a loaded gun pointing at your feet.

Luckily, a careful audit of the standard kakoune library turned up only
three such instances, in go.kak, hare.kak and markdown.kak.

The examples in go.kak and hare.kak are easily made robust by replacing
a %{ } with %< > or %[ ] respectively. The example in markdown.kak is
least-intrusively fixed by rewriting the affected regular expression
slightly so it has balanced { and } anyway.
2023-12-13 16:40:48 +00:00

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# http://daringfireball.net/projects/markdown
# ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
# Detection
# ‾‾‾‾‾‾‾‾‾
hook global BufCreate .*[.](markdown|md|mkd) %{
set-option buffer filetype markdown
}
# Initialization
# ‾‾‾‾‾‾‾‾‾‾‾‾‾‾
hook global WinSetOption filetype=markdown %{
require-module markdown
hook window ModeChange pop:insert:.* -group markdown-trim-indent markdown-trim-indent
hook window InsertChar \n -group markdown-insert markdown-insert-on-new-line
hook window InsertChar \n -group markdown-indent markdown-indent-on-new-line
hook -once -always window WinSetOption filetype=.* %{ remove-hooks window markdown-.+ }
}
hook -group markdown-load-languages global WinSetOption filetype=markdown %{
markdown-load-languages '%'
}
hook -group markdown-load-languages global WinSetOption filetype=markdown %{
hook -group markdown-load-languages window NormalIdle .* %{markdown-load-languages gtGbGl}
hook -group markdown-load-languages window InsertIdle .* %{markdown-load-languages gtGbGl}
}
hook -group markdown-highlight global WinSetOption filetype=markdown %{
add-highlighter window/markdown ref markdown
hook -once -always window WinSetOption filetype=.* %{ remove-highlighter window/markdown }
}
provide-module markdown %{
# Highlighters
# ‾‾‾‾‾‾‾‾‾‾‾‾
add-highlighter shared/markdown regions
add-highlighter shared/markdown/inline default-region regions
add-highlighter shared/markdown/inline/text default-region group
add-highlighter shared/markdown/listblock region ^\h*[-*]\s ^(?=\S) regions
add-highlighter shared/markdown/listblock/g default-region group
add-highlighter shared/markdown/listblock/g/ ref markdown/inline
add-highlighter shared/markdown/listblock/g/marker regex ^\h*([-*])\s 1:bullet
add-highlighter shared/markdown/codeblock region -match-capture \
^(\h*)```\h* \
^(\h*)```\h*$ \
regions
add-highlighter shared/markdown/codeblock/ default-region fill meta
add-highlighter shared/markdown/listblock/codeblock region -match-capture \
^(\h*)```\h* \
^(\h*)```\h*$ \
regions
add-highlighter shared/markdown/listblock/codeblock/ default-region fill meta
add-highlighter shared/markdown/codeline region "^( {4}|\t)" "$" fill meta
# https://spec.commonmark.org/0.29/#link-destination
add-highlighter shared/markdown/angle_bracket_url region (?<=<)([a-z]+://|(mailto|magnet|xmpp):) (?!\\).(?=>)|\n fill link
add-highlighter shared/markdown/inline/url region -recurse \( (\b[a-z]+://|(mailto|magnet|xmpp):) (?!\\).(?=\))|\s fill link
add-highlighter shared/markdown/listblock/angle_bracket_url region (?<=<)(\b[a-z]+://|(mailto|magnet|xmpp):) (?!\\).(?=>)|\n fill link
try %{
require-module html
add-highlighter shared/markdown/inline/tag region (?i)</?[a-z][a-z0-9-]*\s*([a-z_:]|(?=>)) > ref html/tag
}
add-highlighter shared/markdown/inline/code region -match-capture (`+) (`+) fill mono
# Setext-style header
add-highlighter shared/markdown/inline/text/ regex (\A|^\n)[^\n]+\n={2,}\h*\n\h*$ 0:title
add-highlighter shared/markdown/inline/text/ regex (\A|^\n)[^\n]+\n-{2,}\h*\n\h*$ 0:header
# Atx-style header
add-highlighter shared/markdown/inline/text/ regex ^#[^\n]* 0:header
add-highlighter shared/markdown/inline/text/ regex (?<!\*)(\*([^\s*]|([^\s*](\n?[^\n*])*[^\s*]))\*)(?!\*) 1:+i
add-highlighter shared/markdown/inline/text/ regex (?<!_)(_([^\s_]|([^\s_](\n?[^\n_])*[^\s_]))_)(?!_) 1:+i
add-highlighter shared/markdown/inline/text/ regex (?<!\*)(\*\*([^\s*]|([^\s*](\n?[^\n*])*[^\s*]))\*\*)(?!\*) 1:+b
add-highlighter shared/markdown/inline/text/ regex (?<!_)(__([^\s_]|([^\s_](\n?[^\n_])*[^\s_]))__)(?!_) 1:+b
add-highlighter shared/markdown/inline/text/ regex ^\h*(>\h*)+ 0:comment
add-highlighter shared/markdown/inline/text/ regex "\H( {2,})$" 1:+r@meta
# Commands
# ‾‾‾‾‾‾‾‾
define-command markdown-load-languages -params 1 %{
evaluate-commands -draft %{ try %{
execute-keys "%arg{1}1s```\h*\{?[.=]?(\w+)\}?<ret>"
evaluate-commands -itersel %{ try %{
require-module %val{selection}
add-highlighter "shared/markdown/codeblock/%val{selection}" region -match-capture "^(\h*)```\h*(%val{selection}\b|\{[.=]?%val{selection}\})" ^(\h*)``` regions
add-highlighter "shared/markdown/codeblock/%val{selection}/" default-region fill meta
add-highlighter "shared/markdown/codeblock/%val{selection}/inner" region \A\h*```[^\n]*\K (?=```) ref %val{selection}
add-highlighter "shared/markdown/listblock/codeblock/%val{selection}" region -match-capture "^(\h*)```\h*(%val{selection}\b|\{[.=]?%val{selection}\})" ^(\h*)``` regions
add-highlighter "shared/markdown/listblock/codeblock/%val{selection}/" default-region fill meta
add-highlighter "shared/markdown/listblock/codeblock/%val{selection}/inner" region \A\h*```[^\n]*\K (?=```) ref %val{selection}
}}
}}
}
define-command -hidden markdown-trim-indent %{
evaluate-commands -no-hooks -draft -itersel %{
execute-keys x
# remove trailing white spaces
try %{ execute-keys -draft s \h + $ <ret> d }
}
}
define-command -hidden markdown-insert-on-new-line %{
try %{ execute-keys -draft -itersel k x s ^\h*\K((>\h*)+([*+-]\h)?|(>\h*)*[*+-]\h)\h* <ret> y gh j P }
}
define-command -hidden markdown-indent-on-new-line %{
evaluate-commands -draft -itersel %{
# preserve previous line indent
try %{ execute-keys -draft <semicolon> K <a-&> }
# remove trailing white spaces
try %{ execute-keys -draft k x s \h+$ <ret> d }
}
}
}