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use std::borrow::Cow;
use std::iter::once;
use memchr::{memchr, memchr_iter};
use nom::{
branch::alt,
bytes::complete::tag,
character::complete::{digit1, space0},
combinator::{map, recognize},
sequence::terminated,
IResult,
};
/// Plain List Element
#[cfg_attr(test, derive(PartialEq))]
#[cfg_attr(feature = "ser", derive(serde::Serialize))]
#[derive(Debug, Clone)]
pub struct List {
/// List indent, number of whitespaces
pub indent: usize,
/// List's type, determined by the first item of this list
pub ordered: bool,
/// Numbers of blank lines between last list's line and next non-blank line
/// or buffer's end
pub post_blank: usize,
}
/// List Item Element
#[cfg_attr(test, derive(PartialEq))]
#[cfg_attr(feature = "ser", derive(serde::Serialize))]
#[derive(Debug, Clone)]
pub struct ListItem<'a> {
/// List item bullet
pub bullet: Cow<'a, str>,
/// List item indent, number of whitespaces
pub indent: usize,
/// List item type
pub ordered: bool,
// TODO checkbox
// TODO counter
// TODO tag
}
impl ListItem<'_> {
#[inline]
pub(crate) fn parse(input: &str) -> Option<(&str, (ListItem, &str))> {
list_item(input).ok()
}
pub fn into_owned(self) -> ListItem<'static> {
ListItem {
bullet: self.bullet.into_owned().into(),
indent: self.indent,
ordered: self.ordered,
}
}
}
fn list_item(input: &str) -> IResult<&str, (ListItem, &str), ()> {
let (input, indent) = map(space0, |s: &str| s.len())(input)?;
let (input, bullet) = recognize(alt((
tag("+ "),
tag("* "),
tag("- "),
terminated(digit1, tag(". ")),
)))(input)?;
let (input, contents) = list_item_contents(input, indent);
Ok((
input,
(
ListItem {
bullet: bullet.into(),
indent,
ordered: bullet.starts_with(|c: char| c.is_ascii_digit()),
},
contents,
),
))
}
fn list_item_contents(input: &str, indent: usize) -> (&str, &str) {
let mut last_end = memchr(b'\n', input.as_bytes())
.map(|i| i + 1)
.unwrap_or_else(|| input.len());
for i in memchr_iter(b'\n', input.as_bytes())
.map(|i| i + 1)
.chain(once(input.len()))
.skip(1)
{
if input[last_end..i]
.as_bytes()
.iter()
.all(u8::is_ascii_whitespace)
{
let x = memchr(b'\n', &input[i..].as_bytes())
.map(|ii| i + ii + 1)
.unwrap_or_else(|| input.len());
// two consecutive empty lines
if input[i..x].as_bytes().iter().all(u8::is_ascii_whitespace) {
return (&input[x..], &input[0..x]);
}
}
// line less or equally indented than the starting line
if input[last_end..i]
.as_bytes()
.iter()
.take(indent + 1)
.any(|c| !c.is_ascii_whitespace())
{
return (&input[last_end..], &input[0..last_end]);
}
last_end = i;
}
("", input)
}
#[test]
fn parse() {
assert_eq!(
list_item(
r#"+ item1
+ item2"#
),
Ok((
"+ item2",
(
ListItem {
bullet: "+ ".into(),
indent: 0,
ordered: false,
},
r#"item1
"#
)
))
);
assert_eq!(
list_item(
r#"* item1
* item2"#
),
Ok((
"* item2",
(
ListItem {
bullet: "* ".into(),
indent: 0,
ordered: false,
},
r#"item1
"#
)
))
);
assert_eq!(
list_item(
r#"* item1
* item2"#
),
Ok((
"* item2",
(
ListItem {
bullet: "* ".into(),
indent: 0,
ordered: false,
},
r#"item1
"#
)
))
);
assert_eq!(
list_item(
r#"* item1
"#
),
Ok((
"",
(
ListItem {
bullet: "* ".into(),
indent: 0,
ordered: false,
},
r#"item1
"#
)
))
);
assert_eq!(
list_item(
r#"+ item1
+ item2
"#
),
Ok((
"",
(
ListItem {
bullet: "+ ".into(),
indent: 0,
ordered: false,
},
r#"item1
+ item2
"#
)
))
);
assert_eq!(
list_item(
r#"+ item1
+ item2
+ item 3"#
),
Ok((
"+ item 3",
(
ListItem {
bullet: "+ ".into(),
indent: 0,
ordered: false,
},
r#"item1
+ item2
"#
)
))
);
assert_eq!(
list_item(
r#" + item1
+ item2"#
),
Ok((
" + item2",
(
ListItem {
bullet: "+ ".into(),
indent: 2,
ordered: false,
},
r#"item1
"#
)
))
);
assert_eq!(
list_item(
r#" 1. item1
2. item2
3. item3"#
),
Ok((
r#"2. item2
3. item3"#,
(
ListItem {
bullet: "1. ".into(),
indent: 2,
ordered: true,
},
r#"item1
"#
)
))
);
assert_eq!(
list_item(
r#"+ 1
- 2
- 3
+ 4"#
),
Ok((
"+ 4",
(
ListItem {
bullet: "+ ".into(),
indent: 0,
ordered: false,
},
r#"1
- 2
- 3
"#
)
))
);
}