1//! Line breaks
2//!
3//! Processes EOL (`\n`, soft and hard breaks).
4//!
5//! - <https://spec.commonmark.org/0.30/#hard-line-breaks>
6//! - <https://spec.commonmark.org/0.30/#soft-line-breaks>
7use crate::parser::inline::{InlineRule, InlineState};
8use crate::{MarkdownIt, Node, NodeValue, Renderer};
9
10#[derive(Debug)]
11pub struct Hardbreak;
12
13impl NodeValue for Hardbreak {
14 fn render(&self, _: &Node, fmt: &mut dyn Renderer) {
15 fmt.self_close("br", &[]);
16 fmt.cr();
17 }
18}
19
20#[derive(Debug)]
21pub struct Softbreak;
22
23impl NodeValue for Softbreak {
24 fn render(&self, _: &Node, fmt: &mut dyn Renderer) {
25 fmt.cr();
26 }
27}
28
29pub fn add(md: &mut MarkdownIt) {
30 md.inline.add_rule::<NewlineScanner>();
31}
32
33#[doc(hidden)]
34pub struct NewlineScanner;
35impl InlineRule for NewlineScanner {
36 const MARKER: char = '\n';
37
38 fn check(state: &mut InlineState) -> Option<usize> {
39 // check rule is required because run() modifies trailing text
40 let mut chars = state.src[state.pos..state.pos_max].chars();
41 if chars.next().unwrap() != '\n' { return None; }
42 Some(1)
43 }
44
45 fn run(state: &mut InlineState) -> Option<(Node, usize)> {
46 let mut chars = state.src[state.pos..state.pos_max].chars();
47
48 if chars.next().unwrap() != '\n' { return None; }
49
50 let mut pos = state.pos;
51 pos += 1;
52
53 // skip leading whitespaces from next line
54 while let Some(' ' | '\t') = chars.next() {
55 pos += 1;
56 }
57
58 // ' \n' -> hardbreak
59 let mut tail_size = 0;
60 let trailing_text = state.trailing_text_get();
61
62 for ch in trailing_text.chars().rev() {
63 if ch == ' ' {
64 tail_size += 1;
65 } else {
66 break;
67 }
68 }
69
70 state.trailing_text_pop(tail_size);
71
72 let node = if tail_size >= 2 {
73 Node::new(Hardbreak)
74 } else {
75 Node::new(Softbreak)
76 };
77
78 state.pos -= tail_size; // backtrack to include tail in source maps
79 Some((node, pos - state.pos))
80 }
81}