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|
use super::{capability, Content, NodeId, Recipe, Selector, StyleChain, Vt};
use crate::diag::SourceResult;
/// Whether the target is affected by show rules in the given style chain.
pub fn applicable(target: &Content, styles: StyleChain) -> bool {
if target.has::<dyn Prepare>() && !target.is_prepared() {
return true;
}
if target.has::<dyn Show>() && target.is_pristine() {
return true;
}
// Find out how many recipes there are.
let mut n = styles.recipes().count();
// Find out whether any recipe matches and is unguarded.
for recipe in styles.recipes() {
if recipe.applicable(target) && !target.is_guarded(Guard::Nth(n)) {
return true;
}
n -= 1;
}
false
}
/// Apply the show rules in the given style chain to a target.
pub fn realize(
vt: &mut Vt,
target: &Content,
styles: StyleChain,
) -> SourceResult<Option<Content>> {
// Find out how many recipes there are.
let mut n = styles.recipes().count();
// Find an applicable recipe.
let mut realized = None;
for recipe in styles.recipes() {
let guard = Guard::Nth(n);
if recipe.applicable(target) && !target.is_guarded(guard) {
if let Some(content) = try_apply(vt, target, recipe, guard)? {
realized = Some(content);
break;
}
}
n -= 1;
}
// Realize if there was no matching recipe.
if let Some(showable) = target.with::<dyn Show>() {
let guard = Guard::Base(target.id());
if realized.is_none() && !target.is_guarded(guard) {
realized = Some(showable.show(vt, target, styles)?);
}
}
// Finalize only if this is the first application for this node.
if let Some(node) = target.with::<dyn Finalize>() {
if target.is_pristine() {
if let Some(already) = realized {
realized = Some(node.finalize(already));
}
}
}
Ok(realized)
}
/// Try to apply a recipe to the target.
fn try_apply(
vt: &Vt,
target: &Content,
recipe: &Recipe,
guard: Guard,
) -> SourceResult<Option<Content>> {
match &recipe.selector {
Some(Selector::Node(id, _)) => {
if target.id() != *id {
return Ok(None);
}
recipe.apply(vt.world(), target.clone().guarded(guard)).map(Some)
}
Some(Selector::Label(label)) => {
if target.label() != Some(label) {
return Ok(None);
}
recipe.apply(vt.world(), target.clone().guarded(guard)).map(Some)
}
Some(Selector::Regex(regex)) => {
let Some(text) = item!(text_str)(target) else {
return Ok(None);
};
let make = |s| {
let mut content = item!(text)(s);
content.copy_modifiers(target);
content
};
let mut result = vec![];
let mut cursor = 0;
for m in regex.find_iter(text) {
let start = m.start();
if cursor < start {
result.push(make(text[cursor..start].into()));
}
let piece = make(m.as_str().into()).guarded(guard);
let transformed = recipe.apply(vt.world(), piece)?;
result.push(transformed);
cursor = m.end();
}
if result.is_empty() {
return Ok(None);
}
if cursor < text.len() {
result.push(make(text[cursor..].into()));
}
Ok(Some(Content::sequence(result)))
}
None => Ok(None),
}
}
/// Preparations before execution of any show rule.
#[capability]
pub trait Prepare {
/// Prepare the node for show rule application.
fn prepare(
&self,
vt: &mut Vt,
this: Content,
styles: StyleChain,
) -> SourceResult<Content>;
}
/// The base recipe for a node.
#[capability]
pub trait Show {
/// Execute the base recipe for this node.
fn show(
&self,
vt: &mut Vt,
this: &Content,
styles: StyleChain,
) -> SourceResult<Content>;
}
/// Post-process a node after it was realized.
#[capability]
pub trait Finalize {
/// Finalize the fully realized form of the node. Use this for effects that
/// should work even in the face of a user-defined show rule, for example
/// the linking behaviour of a link node.
fn finalize(&self, realized: Content) -> Content;
}
/// Guards content against being affected by the same show rule multiple times.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
pub enum Guard {
/// The nth recipe from the top of the chain.
Nth(usize),
/// The [base recipe](Show) for a kind of node.
Base(NodeId),
}
|
