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#![feature(never_type)]
mod block; pub use block::{Block, Level};
mod line; pub use line::Line;
mod token; pub use token::Token;
mod table; pub use table::{Table, Column, Alignment};
pub struct MarkdownDocument {
pub blocks: Vec<Block>,
}
impl MarkdownDocument {
pub fn from_str(raw_markdown: &str) -> Self {
let mut blocks = Vec::new();
let mut current_block = None;
// Chain a blank line to the end to ensure the final block is flushed.
for line in raw_markdown.lines().chain(std::iter::once("")) {
let line_raw = line;
let line = line.trim();
// Handle a fragment block separately, because fragment lines are not prefixed.
if let Some(BlockMultiline::Fragment { language, mut content }) = current_block {
if line == "```" {
let language = language.to_string();
let content = content.join("\n");
blocks.push(Block::Fragment { language, content });
current_block = None;
} else {
content.push(line_raw);
current_block = Some(BlockMultiline::Fragment { language, content });
}
continue;
}
// Determine line type from prefix.
let line = {
if let Some(("", tail)) = line.split_once("# ") {
BlockLine::Heading { level: Level::Heading1, line: tail.trim() }
} else if let Some(("", tail)) = line.split_once("## ") {
BlockLine::Heading { level: Level::Heading2, line: tail.trim() }
} else if let Some(("", tail)) = line.split_once("### ") {
BlockLine::Heading { level: Level::Heading3, line: tail.trim() }
} else if let Some(("", tail)) = line.split_once("- ") {
BlockLine::List(tail.trim())
} else if let Some(("", tail)) = line.split_once("> ") {
BlockLine::Note(tail.trim())
} else if line == ">" {
BlockLine::Note("")
} else if let Some(("", tail)) = line.split_once("```") {
BlockLine::FragmentHeader(tail.trim())
} else if line.starts_with("|") {
BlockLine::Table(line)
} else if line.len() >= 3 && line.chars().all(|c| c=='-') {
BlockLine::Break
} else if line.is_empty() {
BlockLine::BlankLine
} else {
BlockLine::Paragraph(line)
}
};
// If line has the same type as the current block, append and continue.
if let Some(ref mut block) = current_block {
match (&line, block) {
(BlockLine::List(line), BlockMultiline::List(ref mut lines)) => {
lines.push(line); continue; }
(BlockLine::Note(line), BlockMultiline::Note(ref mut lines)) => {
lines.push(line); continue; }
(BlockLine::Table(line), BlockMultiline::Table(ref mut lines)) => {
lines.push(line); continue; }
_ => (),
};
}
// Otherwise commit the current block before handling the new line.
if let Some(current_block) = std::mem::take(&mut current_block) {
match current_block {
BlockMultiline::List(raw_lines) => {
let lines = raw_lines.into_iter().map(Line::from_str).collect();
blocks.push(Block::List(lines)); }
BlockMultiline::Note(raw_lines) => {
let lines = raw_lines.into_iter().map(Line::from_str).collect();
blocks.push(Block::Note(lines)); }
BlockMultiline::Table(raw_lines) => {
if let Some(table) = Table::from_strs(&raw_lines) {
blocks.push(Block::Table(table)) }
else {
for raw_line in raw_lines {
blocks.push(Block::Paragraph(Line::from_str(&raw_line)))
}
}}
BlockMultiline::Fragment {..} => unreachable!(),
}
}
// Handle the new line.
match line {
BlockLine::List(line) => current_block = Some(
BlockMultiline::List(vec![line])),
BlockLine::Note(line) => current_block = Some(
BlockMultiline::Note(vec![line])),
BlockLine::Table(line) => current_block = Some(
BlockMultiline::Table(vec![line])),
BlockLine::FragmentHeader(language) => current_block = Some(
BlockMultiline::Fragment { language, content: Vec::new() }),
BlockLine::Heading {level, line} => blocks.push(
Block::Heading { level, line: Line::from_str(&line) }),
BlockLine::Break => blocks.push(Block::Break),
BlockLine::BlankLine => (),
BlockLine::Paragraph(line) => if let Some(embed) = parse_embed(&line) {
blocks.push(embed)
} else if let Some(math) = parse_math(&line) {
blocks.push(math)
} else {
blocks.push(Block::Paragraph(Line::from_str(&line)))
}
}
}
Self { blocks }
}
}
enum BlockLine<'a> {
Heading { level: Level, line: &'a str },
Paragraph(&'a str),
List(&'a str),
Note(&'a str),
Table(&'a str),
FragmentHeader(&'a str),
Break,
BlankLine,
}
enum BlockMultiline<'a> {
List(Vec<&'a str>),
Note(Vec<&'a str>),
Table(Vec<&'a str>),
Fragment { language: &'a str, content: Vec<&'a str> },
}
fn parse_embed(line: &str) -> Option<Block> {
let line = line.trim();
if let Some(stripped) = line.strip_prefix("!<") {
if let Some(stripped) = stripped.strip_suffix(">") {
if let Some((label, path)) = stripped.split_once("::") {
let label = label.trim().to_string();
let path = path.trim().to_string();
return Some(Block::Embed { label, path })
} else {
let label = String::new();
let path = stripped.trim().to_string();
return Some(Block::Embed { label, path })
}
}
}
return None;
}
fn parse_math(line: &str) -> Option<Block> {
let line = line.trim();
if let Some(stripped) = line.strip_prefix("$$") {
if let Some(stripped) = stripped.strip_suffix("$$") {
return Some(Block::Math(stripped.trim().to_string()))
}
}
return None;
}
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