//! Deal with content in other content.
//!
//! To deal with content in content, *you* (a `micromark-rs` contributor) add
//! information on events.
//! Events are a flat list, but they can be connected to each other by setting
//! `previous` and `next` links.
//! These links:
//!
//! * …must occur on [`Enter`][EventType::Enter] events only
//! * …must occur on void events (they are followed by their corresponding
//! [`Exit`][EventType::Exit] event)
//! * …must have `content_type` field to define the kind of subcontent
//!
//! Links will then be passed through a tokenizer for the corresponding content
//! type by `subtokenize`.
//! The subevents they result in are split up into slots for each linked token
//! and replace those links.
//!
//! Subevents are not immediately subtokenized again because markdown prevents
//! us from doing so due to definitions, which can occur after references, and
//! thus the whole document needs to be parsed up to the level of definitions,
//! before any level that can include references can be parsed.
use crate::event::{Content, Event, Kind};
use crate::parser::ParseState;
use crate::state::{Name as StateName, State};
use crate::tokenizer::Tokenizer;
use crate::util::edit_map::EditMap;
/// Create a link between two [`Event`][]s.
///
/// Arbitrary (void) events can be linked together.
/// This optimizes for the common case where the token at `index` is connected
/// to the previous void token.
pub fn link(events: &mut [Event], index: usize) {
link_to(events, index - 2, index);
}
/// Link two arbitrary [`Event`][]s together.
pub fn link_to(events: &mut [Event], pevious: usize, next: usize) {
debug_assert_eq!(events[pevious].kind, Kind::Enter);
debug_assert_eq!(events[pevious + 1].kind, Kind::Exit);
debug_assert_eq!(events[pevious + 1].name, events[pevious].name);
debug_assert_eq!(events[next].kind, Kind::Enter);
// Note: the exit of this event may not exist, so don’t check for that.
let link_previous = events[pevious]
.link
.as_mut()
.expect("expected `link` on previous");
link_previous.next = Some(next);
let link_next = events[next].link.as_mut().expect("expected `link` on next");
link_next.previous = Some(pevious);
debug_assert_eq!(
events[pevious].link.as_ref().unwrap().content_type,
events[next].link.as_ref().unwrap().content_type
);
}
/// Parse linked events.
///
/// Supposed to be called repeatedly, returns `1: true` when done.
pub fn subtokenize(events: &mut Vec<Event>, parse_state: &ParseState) -> bool {
let mut map = EditMap::new();
let mut done = true;
let mut index = 0;
while index < events.len() {
let event = &events[index];
// Find each first opening chunk.
if let Some(ref link) = event.link {
debug_assert_eq!(event.kind, Kind::Enter);
// No need to enter linked events again.
if link.previous == None {
// Index into `events` pointing to a chunk.
let mut link_index = Some(index);
// Subtokenizer.
let mut tokenizer = Tokenizer::new(event.point.clone(), parse_state);
// Substate.
let mut state = State::Next(if link.content_type == Content::String {
StateName::StringStart
} else {
StateName::TextStart
});
// Loop through links to pass them in order to the subtokenizer.
while let Some(index) = link_index {
let enter = &events[index];
let link_curr = enter.link.as_ref().expect("expected link");
debug_assert_eq!(enter.kind, Kind::Enter);
if link_curr.previous != None {
tokenizer.define_skip(enter.point.clone());
}
let end = &events[index + 1].point;
state = tokenizer.push(
(enter.point.index, enter.point.vs),
(end.index, end.vs),
state,
);
link_index = link_curr.next;
}
tokenizer.flush(state, true);
divide_events(&mut map, events, index, &mut tokenizer.events);
done = false;
}
}
index += 1;
}
map.consume(events);
done
}
/// Parse linked events.
///
/// Supposed to be called repeatedly, returns `1: true` when done.
pub fn divide_events(
map: &mut EditMap,
events: &[Event],
mut link_index: usize,
child_events: &mut Vec<Event>,
) {
// Now, loop through all subevents to figure out which parts
// belong where and fix deep links.
let mut subindex = 0;
let mut slices = vec![];
let mut slice_start = 0;
let mut old_prev: Option<usize> = None;
while subindex < child_events.len() {
let current = &child_events[subindex].point;
let end = &events[link_index + 1].point;
// Find the first event that starts after the end we’re looking
// for.
if current.index > end.index || (current.index == end.index && current.vs > end.vs) {
slices.push((link_index, slice_start));
slice_start = subindex;
link_index = events[link_index].link.as_ref().unwrap().next.unwrap();
}
// Fix sublinks.
if let Some(sublink_curr) = &child_events[subindex].link {
if sublink_curr.previous.is_some() {
let old_prev = old_prev.unwrap();
let prev_event = &mut child_events[old_prev];
// The `index` in `events` where the current link is,
// minus one to get the previous link,
// minus 2 events (the enter and exit) for each removed
// link.
let new_link = if slices.is_empty() {
old_prev + link_index + 2
} else {
old_prev + link_index - (slices.len() - 1) * 2
};
prev_event.link.as_mut().unwrap().next = Some(new_link);
}
}
// If there is a `next` link in the subevents, we have to change
// its `previous` index to account for the shifted events.
// If it points to a next event, we also change the next event’s
// reference back to *this* event.
if let Some(sublink_curr) = &child_events[subindex].link {
if let Some(next) = sublink_curr.next {
let sublink_next = child_events[next].link.as_mut().unwrap();
old_prev = sublink_next.previous;
sublink_next.previous = sublink_next
.previous
// The `index` in `events` where the current link is,
// minus 2 events (the enter and exit) for each removed
// link.
.map(|previous| previous + link_index - (slices.len() * 2));
}
}
subindex += 1;
}
if !child_events.is_empty() {
slices.push((link_index, slice_start));
}
// Finally, inject the subevents.
let mut index = slices.len();
while index > 0 {
index -= 1;
let start = slices[index].0;
map.add(
start,
if start == events.len() { 0 } else { 2 },
child_events.split_off(slices[index].1),
);
}
}
