Filters & conversion

Most of leech's expressiveness comes from template filters. All standard Nunjucks filters are available, plus the custom ones below. They work in filename, content, and commit-message templates (and in hook command strings).

Custom filters

datefmt(value, format = "YYYY-MM-DD")

Format a Unix-seconds timestamp (UTC). Supported tokens: YYYY MM DD HH mm ss.

{{ submission.timestamp | datefmt('YYYY/MM/DD') }}

slugify(value)

Lowercase, trim, collapse non-alphanumerics to -, strip leading/trailing dashes.

{{ question.title | slugify }}

pad(value, width = 4, char = "0")

Pad with char to at least width. It never truncates; a multi-character char repeats and is cut to fit.

{{ question.frontend_id | pad(4) }}
{{ question.frontend_id | pad(4, '*') }}

ext(lang)

Map a LeetCode language id to a file extension (fallback: the id itself).

{{ submission.lang | ext }}

regexReplace(value, pattern, replacement, flags?)

Replace matches of a regular expression. Nunjucks' built-in replace only handles literal strings. Pass 'g' in flags for all matches.

{{ submission.code | regexReplace('\s+$', '', 'm') }}

codeBlock(content, lang?, options?)

Wrap content in a fenced code block with an optional language id. The fence is chosen so it cannot collide with the content (longest run of fence characters plus one). Options: fence (` or ~, default `).

{{ submission.code | codeBlock(submission.lang_ext) }}

toMarkdown(html, options?) and toTypst(html, options?)

Convert the raw problem HTML. See conversion options below.

Conversion options

Each conversion filter accepts an options object as a template argument:

{{ question.content | toMarkdown({ codeBlockStyle: "indented", gfm: true, tables: false }) }}

toMarkdown(options?)

Option	Default	Notes
gfm	false	Enable GitHub-flavored tables, strikethrough, and task lists
tables	true	Only applies when gfm is enabled
strikethrough	true	Only applies when gfm is enabled
taskListItems	true	Only applies when gfm is enabled
superscript	["^", "^"]	Wrapper [prefix, suffix] around <sup>; false renders inline
subscript	["~", "~"]	Wrapper [prefix, suffix] around <sub>; false renders inline
headingStyle	atx	atx | setext
hr	* * *	Thematic break
bulletListMarker	-	- | * | +
codeBlockStyle	fenced	fenced | indented
fence	```	Fence characters
emDelimiter	_	* | _
strongDelimiter	**	** | __
linkStyle	inlined	inlined | referenced
linkReferenceStyle	full	full | collapsed | shortcut

A common LeetCode-specific choice disables the caret/underscore wrappers that collide with markdown emphasis:

{{ question.content | toMarkdown({ gfm: true, superscript: ["^", ""], subscript: ["_", ""] }) }}

toTypst(options?)

Typst markup, with custom rules for <sup>/<sub>, code blocks, and tables.

Option	Default	Notes
headingPrefixes	["", "= ", "== ", …]	Prefix per heading level 1–6
codeFence	```	Fence characters
escape	true	Escape Typst special characters, including [/], so unmatched brackets in problem strings don't break the document
hr	#line(length: 100%)	Thematic break
superscript	["#super[", "]"]	Real Typst superscript; false renders inline
subscript	["#sub[", "]"]	Real Typst subscript; false renders inline

Using the converters from code

The same converters are exported as factories for embedding:

• makeToMarkdown(options)
• makeToTypst(options)

toGfm is kept as an alias for toMarkdown({ gfm: true }).