mirror of
https://github.com/typst/typst
synced 2025-07-20 19:12:53 +08:00
93 lines
2.9 KiB
Rust
93 lines
2.9 KiB
Rust
use comemo::Tracked;
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use crate::diag::HintedStrResult;
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use crate::engine::Engine;
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use crate::foundations::{func, Array, Context, IntoValue, LocatableSelector, Selector};
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/// Counts element in the document.
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///
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/// The `count` function lets you count elements in your document of a
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/// particular type or with a particular label. It also allows to count them
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/// in a hierachical way. To use it, you first need to ensure that [context]
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/// is available.
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///
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/// Always returns an array of integers, even if called with just a single
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/// target.
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/// # Counting elements - simple
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///
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/// To just count elements of a single type/label up to the current location,
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/// pass the selector you want to count:
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/// ```example
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/// = Heading
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///
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/// = Another Heading
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///
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/// #context count(heading)
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///
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/// = Third Heading
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/// ```
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///
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/// Note that it will not return an integer, but an array with a single integer
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/// entry.
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/// # Counting elements - hierarchical
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///
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/// If you pass multiple targets, then it starts by counting the first target.
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/// Then the second target is counted _starting only from the last counted
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/// element of the first target_.
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///
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/// ```example
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/// = Some Heading
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///
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/// == Some Subheading
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///
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/// = Another Heading
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///
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/// == Some Subheading
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///
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/// #context count(heading.where(level: 1), heading.where(level: 2))
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///
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/// == Another Subheading
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/// ```
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#[func(contextual)]
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pub fn count(
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/// The engine.
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engine: &mut Engine,
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/// The callsite context.
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context: Tracked<Context>,
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/// Each target can be
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/// - an element function like a `heading` or `figure`,
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/// - a `{<label>}`,
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/// - a more complex selector like `{heading.where(level: 1)}`,
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/// - or `{selector(heading).before(here())}`.
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///
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/// Only [locatable]($location/#locatable) element functions are supported.
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#[variadic]
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targets: Vec<LocatableSelector>,
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/// When passing this argument, it will count everything only from a
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/// certain location on.
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/// The selector must match exactly one element in the document. The most
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/// useful kinds of selectors for this are [labels]($label) and
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/// [locations]($location).
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// TODO remove Option as soon as there is a special `start` location
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#[named]
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after: Option<LocatableSelector>,
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) -> HintedStrResult<Array> {
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// NOTE this could be made more efficient
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// one could directly get a slice &[Selector] from Vec<LocatableSelector>
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// by using #[repr(transparent)] on LocatableSelector
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let selectors: Vec<Selector> = targets.into_iter().map(|sel| sel.0).collect();
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// TODO add argument "at" with default value "here"
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// and compute `before` accordingly
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let before = Some(context.location()?);
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let after = match after {
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Some(selector) => Some(selector.resolve_unique(engine.introspector, context)?),
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None => None,
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};
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let nums = engine.introspector.count(&selectors, after, before);
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Ok(nums.into_iter().map(IntoValue::into_value).collect())
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}
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