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use std::ops::Range;
use crate::{
error::{ErrorInfo, SyntaxError},
lexer::{self, Lexer, Token},
parser::{
ast::{Element, Lines, Link},
ParseState,
},
SyntaxResult,
};
#[derive(Debug, Default)]
struct EscapeFlags {
newline: bool,
pipe: bool,
bracket: bool,
}
impl EscapeFlags {
fn has_escape_sequences(&self) -> bool {
self.newline || self.pipe || self.bracket
}
fn into_owned<'a>(&self, value: &'a str) -> String {
let mut val = value.to_string();
if self.newline {
val = val.replace("\\n", "\n");
}
if self.pipe {
val = val.replace("\\|", "|");
}
if self.bracket {
val = val.replace("\\]", "]");
}
val
}
}
enum ValueType {
Label,
Title,
}
/// Assign an owned value to the link if escape sequences
/// were detected.
fn assign_if_escaped<'source>(
source: &'source str,
link: &mut Link<'source>,
flags: &EscapeFlags,
span: &Range<usize>,
value_type: &ValueType,
) {
if flags.has_escape_sequences() {
match value_type {
ValueType::Label => {
let value = flags
.into_owned(&source[link.label_span().start..span.start]);
link.set_label(value);
}
ValueType::Title => {
let value = flags
.into_owned(&source[link.title_span().start..span.start]);
link.set_title(value);
}
}
}
}
/// Parse the label and title components.
fn value<'source>(
source: &'source str,
lexer: &mut Lexer<'source>,
state: &mut ParseState,
link: &mut Link<'source>,
value_type: ValueType,
) -> SyntaxResult<()> {
let mut flags: EscapeFlags = Default::default();
while let Some(token) = lexer.next() {
match token {
Token::Link(lex, span) => {
match &lex {
_ => *state.byte_mut() = span.end - 1,
}
match lex {
lexer::Link::Newline => {
*state.line_mut() += 1;
}
lexer::Link::Text => match value_type {
ValueType::Label => {
link.label_end(span.end);
}
ValueType::Title => {
link.title_end(span.end);
}
},
lexer::Link::Pipe => {
match value_type {
ValueType::Label => {
link.label_end(span.start);
assign_if_escaped(
source,
link,
&flags,
&span,
&value_type,
);
link.title_start(span.end);
return value(
source,
lexer,
state,
link,
ValueType::Title,
);
}
ValueType::Title => {
// Consume any additional pipes until we get till the end.
// TODO: make this an error?
link.title_end(span.end);
}
}
}
lexer::Link::EscapedNewline => {
flags.newline = true;
}
lexer::Link::EscapedPipe => {
flags.pipe = true;
}
lexer::Link::Escaped => {
flags.bracket = true;
}
lexer::Link::End => {
assign_if_escaped(
source,
link,
&flags,
&span,
&value_type,
);
link.exit(span);
return Ok(());
}
_ => {
return Err(SyntaxError::TokenLink(
ErrorInfo::from((source, state)).into(),
))
}
}
}
_ => {
return Err(SyntaxError::TokenLink(
ErrorInfo::from((source, state)).into(),
))
}
}
}
Ok(())
}
fn href<'source>(
source: &'source str,
lexer: &mut Lexer<'source>,
state: &mut ParseState,
link: &mut Link<'source>,
) -> SyntaxResult<()> {
let mut flags: EscapeFlags = Default::default();
while let Some(token) = lexer.next() {
match token {
Token::Link(lex, span) => {
match &lex {
_ => *state.byte_mut() = span.end - 1,
}
match lex {
lexer::Link::Newline => {
*state.line_mut() += 1;
// NOTE: newlines are not allowed in links
// NOTE: by returning early the link will
// NOTE: never be closed and we should generate
// NOTE: an unclosed link error.
return Ok(());
}
lexer::Link::Text => {
link.href_end(span.end);
}
lexer::Link::Pipe => {
if flags.has_escape_sequences() {
let value = flags.into_owned(
&source[link.open_span().end..span.start],
);
link.set_href(value);
}
link.label_start(span.end);
return value(
source,
lexer,
state,
link,
ValueType::Label,
);
}
lexer::Link::EscapedNewline => {
flags.newline = true;
}
lexer::Link::EscapedPipe => {
flags.pipe = true;
}
lexer::Link::Escaped => {
flags.bracket = true;
}
lexer::Link::End => {
if flags.has_escape_sequences() {
let value = flags.into_owned(
&source[link.open_span().end..span.start],
);
link.set_href(value);
}
link.exit(span);
return Ok(());
}
_ => {
return Err(SyntaxError::TokenLink(
ErrorInfo::from((source, state)).into(),
))
}
}
}
_ => {
return Err(SyntaxError::TokenLink(
ErrorInfo::from((source, state)).into(),
))
}
}
}
Ok(())
}
pub(crate) fn parse<'source>(
source: &'source str,
lexer: &mut Lexer<'source>,
state: &mut ParseState,
open: Range<usize>,
) -> SyntaxResult<Link<'source>> {
*state.byte_mut() = open.end;
let mut link = Link::new(source, open, state.line_range());
href(source, lexer, state, &mut link)?;
if !link.is_closed() {
Err(SyntaxError::LinkNotTerminated(
ErrorInfo::from((source, state)).into(),
))
} else {
link.lines_end(state.line());
Ok(link)
}
}