I need to automatically deduplicate identical footnotes that appear multiple times on the same page. Instead of showing the same footnote content repeatedly, I want subsequent instances to reference the first occurrence with the same footnote number. The manual approach using labels isn’t suitable for my use case since I need this to work automatically without manually tracking which footnotes have already been used. Is there a way to implement this automatic deduplication behavior in Typst?
I’m using metadata and a global show rule for style. The style rule figures out which footnotes are unique on each page and shows them.
We want to avoid using state and toggling footnotes from visible to not visible. I guess some layout convergence problems might show up anyway, but maybe this can be a way to avoid the largest problems.
#set page(width: 5cm, height: 5cm)
#let dedupfootnotes(body) = context {
let sel = selector.and(metadata, <_dedup_footnote_item>)
// find every first unique footnote on each page
let footnotes = query(sel).dedup(key: mt => (mt.value.footnote, mt.location().page()))
show sel: mt => {
if footnotes.any(elt => elt.location() == mt.location()) {
// this is the first footnote
footnote(mt.value.footnote)
} else {
// duplicate footnote, get the previous one's number.
let previous-numbers = query(sel.before(here()))
.filter(elt => elt.location().page() == here().page())
.filter(elt => elt.value.footnote == mt.value.footnote)
for prev in previous-numbers {
super([#{counter(footnote).at(prev.location()).first() + 1}])
break
}
}
mt
}
body
}
#show: dedupfootnotes
#let ft(body) = {
[#metadata((footnote: body))<_dedup_footnote_item>]
}
One#ft[one] two#ft[one] and three#ft[one] and four#ft[two]
#pagebreak()
Again#ft[one] and again#ft[two] and again#ft[one]
