//! Destination occurs in [definition][] and label end.
//!
//! They’re formed with the following BNF:
//!
//! ```bnf
//! destination ::= destination_enclosed | destination_raw
//!
//! destination_enclosed ::= '<' *( destination_enclosed_text | destination_enclosed_escape ) '>'
//! destination_enclosed_text ::= code - '<' - '\\' - '>' - eol
//! destination_enclosed_escape ::= '\\' [ '<' | '\\' | '>' ]
//! destination_raw ::= 1*( destination_raw_text | destination_raw_escape )
//! ; Restriction: unbalanced `)` characters are not allowed.
//! destination_raw_text ::= code - '\\' - ascii_control - space_or_tab - eol
//! destination_raw_escape ::= '\\' [ '(' | ')' | '\\' ]
//! ```
//!
//! Balanced parens allowed in raw destinations.
//! They are counted with a counter that starts at `0`, and is incremented
//! every time `(` occurs and decremented every time `)` occurs.
//! If `)` is found when the counter is `0`, the destination closes immediately
//! after it.
//! Escaped parens do not count.
//!
//! It is recommended to use the enclosed variant of destinations, as it allows
//! arbitrary parens, and also allows for whitespace and other characters in
//! URLs.
//!
//! The destination is interpreted as the [string][] content type.
//! That means that character escapes and character reference are allowed.
//!
//! ## References
//!
//! * [`micromark-factory-destination/index.js` in `micromark`](https://github.com/micromark/micromark/blob/main/packages/micromark-factory-destination/dev/index.js)
//!
//! [definition]: crate::construct::definition
//! [string]: crate::content::string
//!
//! <!-- To do: link label end. -->
// To do: pass token types in.
use crate::tokenizer::{Code, State, StateFnResult, TokenType, Tokenizer};
/// Before a destination.
///
/// ```markdown
/// |<ab>
/// |ab
/// ```
pub fn start(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
match code {
Code::Char('<') => {
tokenizer.enter(TokenType::DefinitionDestination);
tokenizer.enter(TokenType::DefinitionDestinationLiteral);
tokenizer.enter(TokenType::DefinitionDestinationLiteralMarker);
tokenizer.consume(code);
tokenizer.exit(TokenType::DefinitionDestinationLiteralMarker);
(State::Fn(Box::new(enclosed_before)), None)
}
Code::None | Code::CarriageReturnLineFeed | Code::VirtualSpace | Code::Char(')') => {
(State::Nok, None)
}
Code::Char(char) if char.is_ascii_control() => (State::Nok, None),
Code::Char(_) => {
tokenizer.enter(TokenType::DefinitionDestination);
tokenizer.enter(TokenType::DefinitionDestinationRaw);
tokenizer.enter(TokenType::DefinitionDestinationString);
// To do: link.
tokenizer.enter(TokenType::ChunkString);
raw(tokenizer, code, 0)
}
}
}
/// After `<`, before an enclosed destination.
///
/// ```markdown
/// <|ab>
/// ```
fn enclosed_before(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
if let Code::Char('>') = code {
tokenizer.enter(TokenType::DefinitionDestinationLiteralMarker);
tokenizer.consume(code);
tokenizer.exit(TokenType::DefinitionDestinationLiteralMarker);
tokenizer.exit(TokenType::DefinitionDestinationLiteral);
tokenizer.exit(TokenType::DefinitionDestination);
(State::Ok, None)
} else {
tokenizer.enter(TokenType::DefinitionDestinationString);
// To do: link.
tokenizer.enter(TokenType::ChunkString);
enclosed(tokenizer, code)
}
}
/// In an enclosed destination.
///
/// ```markdown
/// <u|rl>
/// ```
fn enclosed(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
match code {
Code::Char('>') => {
tokenizer.exit(TokenType::ChunkString);
tokenizer.exit(TokenType::DefinitionDestinationString);
enclosed_before(tokenizer, code)
}
Code::None | Code::CarriageReturnLineFeed | Code::Char('\r' | '\n' | '<') => {
(State::Nok, None)
}
Code::Char('\\') => {
tokenizer.consume(code);
(State::Fn(Box::new(enclosed_escape)), None)
}
_ => {
tokenizer.consume(code);
(State::Fn(Box::new(enclosed)), None)
}
}
}
/// After `\`, in an enclosed destination.
///
/// ```markdown
/// <a\|>b>
/// ```
fn enclosed_escape(tokenizer: &mut Tokenizer, code: Code) -> StateFnResult {
match code {
Code::Char('<' | '>' | '\\') => {
tokenizer.consume(code);
(State::Fn(Box::new(enclosed)), None)
}
_ => enclosed(tokenizer, code),
}
}
/// In a raw destination.
///
/// ```markdown
/// a|b
/// ```
// To do: these arms can be improved?
fn raw(tokenizer: &mut Tokenizer, code: Code, balance: usize) -> StateFnResult {
// To do: configurable.
let limit = usize::MAX;
match code {
Code::Char('(') if balance >= limit => (State::Nok, None),
Code::Char('(') => {
tokenizer.consume(code);
(
State::Fn(Box::new(move |t, c| raw(t, c, balance + 1))),
None,
)
}
Code::Char(')') if balance == 0 => {
tokenizer.exit(TokenType::ChunkString);
tokenizer.exit(TokenType::DefinitionDestinationString);
tokenizer.exit(TokenType::DefinitionDestinationRaw);
tokenizer.exit(TokenType::DefinitionDestination);
(State::Ok, Some(vec![code]))
}
Code::Char(')') => {
tokenizer.consume(code);
(
State::Fn(Box::new(move |t, c| raw(t, c, balance - 1))),
None,
)
}
Code::None
| Code::CarriageReturnLineFeed
| Code::VirtualSpace
| Code::Char('\t' | '\r' | '\n' | ' ')
if balance > 0 =>
{
(State::Nok, None)
}
Code::None
| Code::CarriageReturnLineFeed
| Code::VirtualSpace
| Code::Char('\t' | '\r' | '\n' | ' ') => {
tokenizer.exit(TokenType::ChunkString);
tokenizer.exit(TokenType::DefinitionDestinationString);
tokenizer.exit(TokenType::DefinitionDestinationRaw);
tokenizer.exit(TokenType::DefinitionDestination);
(State::Ok, Some(vec![code]))
}
Code::Char(char) if char.is_ascii_control() => (State::Nok, None),
Code::Char('\\') => {
tokenizer.consume(code);
(
State::Fn(Box::new(move |t, c| raw_escape(t, c, balance))),
None,
)
}
Code::Char(_) => {
tokenizer.consume(code);
(State::Fn(Box::new(move |t, c| raw(t, c, balance))), None)
}
}
}
/// After `\`, in a raw destination.
///
/// ```markdown
/// a\|)b
/// ```
fn raw_escape(tokenizer: &mut Tokenizer, code: Code, balance: usize) -> StateFnResult {
match code {
Code::Char('(' | ')' | '\\') => {
tokenizer.consume(code);
(
State::Fn(Box::new(move |t, c| raw(t, c, balance + 1))),
None,
)
}
_ => raw(tokenizer, code, balance),
}
}
