//! The flow content type.
//!
//! **Flow** represents the sections, such as headings, code, and content, which
//! is parsed per line.
//! An example is HTML, which has a certain starting condition (such as
//! `<script>` on its own line), then continues for a while, until an end
//! condition is found (such as `</style>`).
//! If that line with an end condition is never found, that flow goes until
//! the end.
//!
//! The constructs found in flow are:
//!
//! * [Blank line][crate::construct::blank_line]
//! * [Code (fenced)][crate::construct::code_fenced]
//! * [Code (indented)][crate::construct::code_indented]
//! * [Heading (atx)][crate::construct::heading_atx]
//! * [HTML (flow)][crate::construct::html_flow]
//! * [Thematic break][crate::construct::thematic_break]
//!
//! <!-- To do: `setext` in content? Link to content. -->
use crate::constant::TAB_SIZE;
use crate::construct::{
blank_line::start as blank_line, code_fenced::start as code_fenced,
code_indented::start as code_indented, heading_atx::start as heading_atx,
html_flow::start as html_flow, partial_whitespace::start as whitespace,
thematic_break::start as thematic_break,
};
use crate::tokenizer::{Code, Event, State, StateFnResult, TokenType, Tokenizer};
use crate::util::get_span;
/// Turn `codes` as the flow content type into events.
// To do: remove this `allow` when all the content types are glued together.
#[allow(dead_code)]
pub fn flow(codes: Vec<Code>) -> Vec<Event> {
let mut tokenizer = Tokenizer::new();
let (state, remainder) = tokenizer.feed(codes, Box::new(start), true);
if let Some(ref x) = remainder {
if !x.is_empty() {
unreachable!("expected no final remainder {:?}", x);
}
}
match state {
State::Ok => {}
_ => unreachable!("expected final state to be `State::Ok`"),
}
tokenizer.events
}
/// Before flow.
///
/// First we assume a blank line.
//
/// ```markdown
/// |
/// |## alpha
/// | bravo
/// |***
/// ```
fn start(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
match code {
Code::None => (State::Ok, None),
_ => tokenizer.attempt(blank_line, |ok| {
Box::new(if ok { blank_line_after } else { initial_before })
})(tokenizer, code),
}
}
/// After a blank line.
///
/// Move to `start` afterwards.
///
/// ```markdown
/// ␠␠|
/// ```
fn blank_line_after(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
match code {
Code::None => (State::Ok, None),
Code::CarriageReturnLineFeed | Code::Char('\n' | '\r') => {
tokenizer.enter(TokenType::BlankLineEnding);
tokenizer.consume(code);
tokenizer.exit(TokenType::BlankLineEnding);
(State::Fn(Box::new(start)), None)
}
_ => unreachable!("expected eol/eof after blank line `{:?}`", code),
}
}
/// Before flow (initial).
///
/// “Initial” flow means unprefixed flow, so right at the start of a line.
/// Interestingly, the only flow (initial) construct is indented code.
/// Move to `before` afterwards.
///
/// ```markdown
/// |qwe
/// | asd
/// |~~~js
/// |<div>
/// ```
fn initial_before(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
match code {
Code::None => (State::Ok, None),
_ => tokenizer.attempt_3(code_indented, code_fenced, html_flow, |ok| {
Box::new(if ok { after } else { before })
})(tokenizer, code),
}
}
/// After a flow construct.
///
/// ```markdown
/// ## alpha|
/// |
/// ~~~js
/// asd
/// ~~~|
/// ```
fn after(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
match code {
Code::None => (State::Ok, None),
Code::CarriageReturnLineFeed | Code::Char('\n' | '\r') => {
tokenizer.enter(TokenType::LineEnding);
tokenizer.consume(code);
tokenizer.exit(TokenType::LineEnding);
(State::Fn(Box::new(start)), None)
}
_ => unreachable!("unexpected non-eol/eof after flow `{:?}`", code),
}
}
/// Before flow, but not at code (indented) or code (fenced).
///
/// Compared to flow (initial), normal flow can be arbitrarily prefixed.
///
/// ```markdown
/// |qwe
/// ```
pub fn before(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
tokenizer.attempt(
|tokenizer, code| whitespace(tokenizer, code, TokenType::Whitespace),
|_ok| Box::new(before_after_prefix),
)(tokenizer, code)
}
/// Before flow, after potential whitespace.
///
/// ```markdown
/// |# asd
/// |***
/// ```
pub fn before_after_prefix(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
tokenizer.attempt_2(heading_atx, thematic_break, |ok| {
Box::new(if ok { after } else { content_before })
})(tokenizer, code)
}
/// Before flow, but not before a heading (atx) or thematic break.
///
/// At this point, we’re at content (zero or more definitions and zero or one
/// paragraph/setext heading).
///
/// ```markdown
/// |qwe
/// ```
// To do: currently only parses a single line.
// To do:
// - Multiline
// - One or more definitions.
// - Setext heading.
fn content_before(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
match code {
Code::None | Code::CarriageReturnLineFeed | Code::Char('\n' | '\r') => {
after(tokenizer, code)
}
_ => {
tokenizer.enter(TokenType::Content);
tokenizer.enter(TokenType::ContentChunk);
content(tokenizer, code)
}
}
}
/// In content.
///
/// ```markdown
/// al|pha
/// ```
// To do: lift limitations as documented above.
fn content(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
match code {
Code::None => {
tokenizer.exit(TokenType::ContentChunk);
content_end(tokenizer, code)
}
Code::CarriageReturnLineFeed | Code::Char('\n' | '\r') => {
tokenizer.exit(TokenType::ContentChunk);
tokenizer.check(continuation_construct, |ok| {
Box::new(if ok { content_continue } else { content_end })
})(tokenizer, code)
}
_ => {
tokenizer.consume(code);
(State::Fn(Box::new(content)), None)
}
}
}
fn continuation_construct(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
match code {
Code::CarriageReturnLineFeed | Code::Char('\n' | '\r') => {
tokenizer.enter(TokenType::LineEnding);
tokenizer.consume(code);
tokenizer.exit(TokenType::LineEnding);
(
State::Fn(Box::new(continuation_construct_initial_before)),
None,
)
}
_ => unreachable!("expected eol"),
}
}
fn continuation_construct_initial_before(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
tokenizer.attempt_2(code_fenced, html_flow, |ok| {
if ok {
Box::new(|_tokenizer, _code| (State::Nok, None))
} else {
Box::new(|tokenizer, code| {
tokenizer.attempt(
|tokenizer, code| whitespace(tokenizer, code, TokenType::Whitespace),
|_ok| Box::new(continuation_construct_after_prefix),
)(tokenizer, code)
})
}
})(tokenizer, code)
}
fn continuation_construct_after_prefix(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
let tail = tokenizer.events.last();
let mut prefix = 0;
if let Some(event) = tail {
if event.token_type == TokenType::Whitespace {
let span = get_span(&tokenizer.events, tokenizer.events.len() - 1);
prefix = span.end_index - span.start_index;
}
}
match code {
// Blank lines are not allowed in content.
Code::None | Code::CarriageReturnLineFeed | Code::Char('\n' | '\r') => (State::Nok, None),
// To do: If code is disabled, indented lines are part of the content.
_ if prefix >= TAB_SIZE => (State::Ok, None),
_ => tokenizer.attempt_2(heading_atx, thematic_break, |ok| {
let result = if ok {
(State::Nok, None)
} else {
(State::Ok, None)
};
Box::new(|_t, _c| result)
})(tokenizer, code),
}
}
fn content_continue(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
// To do: should this be part of the content chunk?
// That’s what `micromark-js` does.
tokenizer.enter(TokenType::LineEnding);
tokenizer.consume(code);
tokenizer.exit(TokenType::LineEnding);
tokenizer.enter(TokenType::ContentChunk);
(State::Fn(Box::new(content)), None)
}
fn content_end(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
tokenizer.exit(TokenType::Content);
after(tokenizer, code)
}
