95 lines
3.1 KiB
Rust
95 lines
3.1 KiB
Rust
use crate::renderer::breadcrumb_tree::BreadcrumbTreeElement;
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use crate::renderer::context_element::IntoContextElement;
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use crate::renderer::WalkError;
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use std::borrow::Borrow;
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enum WalkResult<'a> {
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NoWalk,
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PartialWalk,
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FullyWalked(&'a dyn IntoContextElement),
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}
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fn walk_path_from_single_level<'a, P>(
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context: &'a dyn IntoContextElement,
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path: &[P],
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) -> WalkResult<'a>
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where
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P: Borrow<str>,
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{
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if path.is_empty() {
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return WalkResult::FullyWalked(context);
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}
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let mut walk_failure = WalkResult::NoWalk;
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let mut output = context;
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for elem in path.iter() {
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match output.walk(elem.borrow()) {
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Err(WalkError::CantWalk { .. }) => {
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return walk_failure;
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}
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Ok(new_val) => {
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walk_failure = WalkResult::PartialWalk;
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output = new_val;
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}
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}
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}
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WalkResult::FullyWalked(output)
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}
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fn get_first_non_pseudo_element<'a>(
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breadcrumbs: &'a Vec<BreadcrumbTreeElement<'a>>,
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) -> Option<&'a BreadcrumbTreeElement<'a>> {
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breadcrumbs
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.iter()
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.rev()
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.filter(|b| {
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std::borrow::Borrow::<dyn IntoContextElement + 'a>::borrow(*b).is_pseudo_element()
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})
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.next()
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}
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pub fn walk_path<'a, P>(
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breadcrumbs: &'a Vec<BreadcrumbTreeElement<'a>>,
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path: &Vec<P>,
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) -> Result<&'a dyn IntoContextElement, WalkError>
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where
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P: Borrow<str>,
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{
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match (breadcrumbs.last(), path.first()) {
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(None, _) => return Err(WalkError::CantWalk),
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(Some(last_elem), None) => return Ok(last_elem.borrow()),
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(Some(_), Some(path_first)) if path_first.borrow() == "." => {
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let first_non_pseudo_element = get_first_non_pseudo_element(breadcrumbs);
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return match first_non_pseudo_element {
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None => Err(WalkError::CantWalk),
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Some(current_context) => {
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match walk_path_from_single_level(current_context.borrow(), &path[1..]) {
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// If no walking was done at all or we partially walked
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// then stop trying to find anything because '.' restricts
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// us to the current scope
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WalkResult::NoWalk | WalkResult::PartialWalk => Err(WalkError::CantWalk),
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WalkResult::FullyWalked(new_context) => Ok(new_context),
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}
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}
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};
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}
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(Some(_), Some(path_first)) => {
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for context in breadcrumbs.iter().rev() {
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match walk_path_from_single_level(context.borrow(), path) {
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// If no walking was done at all, keep looping
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WalkResult::NoWalk => {}
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// If we partially walked then stop trying to find
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// anything
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WalkResult::PartialWalk => {
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return Err(WalkError::CantWalk);
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}
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WalkResult::FullyWalked(new_context) => return Ok(new_context),
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}
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}
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}
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}
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Err(WalkError::CantWalk)
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}
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