Fix headline parsing leading to dropped lines.
Currently, headline parsing breaks the file into lines before parsing headlines, stripping terminal \n or \r\n. This prevents parse_headline_level from differentiating between end of line and end of file. This can lead to an edge case where a line is considered a headline for the purposes of stopping parsing the body of the previous, yet not a headline itself. This leads to parsing stopping there. If the file is immediately written, this results in truncating it. One example of this is `"* \n*\r\n* \n"`, which will be parsed identically to `"* \n"`.
This commit is contained in:
parent
5e4457e26e
commit
4fe0958843
132
src/parsers.rs
132
src/parsers.rs
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@ -4,7 +4,12 @@ use std::marker::PhantomData;
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use indextree::{Arena, NodeId};
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use jetscii::{bytes, BytesConst};
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use memchr::{memchr, memchr_iter};
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use nom::bytes::complete::take_while1;
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use nom::{
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bytes::complete::is_a,
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character::complete::one_of,
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combinator::{map, verify},
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IResult,
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};
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use crate::config::ParseConfig;
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use crate::elements::{
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@ -635,23 +640,114 @@ pub fn blank_lines_count(input: &str) -> (&str, usize) {
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crate::parse::combinators::blank_lines_count(input).unwrap_or((input, 0))
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}
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pub fn parse_headline(input: &str) -> Option<(&str, (&str, usize))> {
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let (input_, level) = parse_headline_level(input)?;
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let (input_, content) = lines_while(move |line| {
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parse_headline_level(line)
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.map(|(_, l)| l > level)
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.unwrap_or(true)
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})(input_)
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.unwrap_or((input_, ""));
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Some((input_, (&input[0..level + content.len()], level)))
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}
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pub fn parse_headline_level(input: &str) -> Option<(&str, usize)> {
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let (input, stars) = take_while1::<_, _, ()>(|c: char| c == '*')(input).ok()?;
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if input.starts_with(' ') || input.starts_with('\n') || input.is_empty() {
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Some((input, stars.len()))
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// Matches a headline of level <= max_level. This will always be exactly one
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// line, including the terminal \n if one is present. Unlike org-mode (but like
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// org-element), we accept '\n' and EOF to terminate the stars. Returns the
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// number of stars. Must only be called at the start of a line.
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fn parse_headline_level_le(input: &str, max_level: usize) -> IResult<&str, usize, ()> {
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let (input, level) = verify(
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map(is_a("*"), |s: &str| s.chars().count()),
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|level: &usize| *level <= max_level,
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)(input)?;
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if !input.is_empty() {
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one_of("\n ")(input)?;
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let (input, _) = line_length(input)?;
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Ok((input, level))
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} else {
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None
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Ok((input, level))
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}
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}
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// Recognizes until end-of-line or end-of-input and returns the length of the
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// line, including the terminal \n (or \r\n) if present.
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fn line_length(input: &str) -> IResult<&str, usize, ()> {
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match memchr(b'\n', input.as_bytes()) {
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Some(index) => Ok((&input[index + 1..], index + 1)),
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None => Ok(("", input.len())),
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}
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}
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pub fn parse_headline(input: &str) -> Option<(&str, (&str, usize))> {
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// Consume the headline.
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let (text, level) = parse_headline_level_le(input, std::usize::MAX).ok()?;
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// Collect lines until EOF or a headline.
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let mut last = 0;
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for i in memchr_iter(b'\n', text.as_bytes()) {
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if parse_headline_level_le(&text[last..], level).is_ok() {
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break;
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}
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last = i + 1;
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}
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if last < text.len() && parse_headline_level_le(&text[last..], level).is_err() {
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Some(("", (input, level)))
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} else {
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Some((
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&text[last..],
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(&input[..(input.len() - text.len()) + last], level),
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))
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_parse_headline() {
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assert_eq!(parse_headline("*"), Some(("", ("*", 1))));
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assert_eq!(parse_headline("* "), Some(("", ("* ", 1))));
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assert_eq!(parse_headline("* \r"), Some(("", ("* \r", 1))));
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assert_eq!(parse_headline("*\t"), None);
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assert_eq!(parse_headline("*\t\n"), None);
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assert_eq!(parse_headline("* \n"), Some(("", ("* \n", 1))));
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assert_eq!(parse_headline("* \n\r*"), Some(("", ("* \n\r*", 1))));
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assert_eq!(parse_headline("* \n\r**"), Some(("", ("* \n\r**", 1))));
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assert_eq!(parse_headline("*\n*"), Some(("*", ("*\n", 1))));
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assert_eq!(parse_headline("*\n\n*"), Some(("*", ("*\n\n", 1))));
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assert_eq!(parse_headline("*\r"), None);
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assert_eq!(parse_headline("* *"), Some(("", ("* *", 1))));
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assert_eq!(parse_headline("***\r** Hello\n"), None);
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assert_eq!(
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parse_headline("*** ** Hello\n"),
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Some(("", ("*** ** Hello\n", 3)))
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);
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assert_eq!(parse_headline("* Hello"), Some(("", ("* Hello", 1))));
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assert_eq!(
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parse_headline("*** Hi\nWorld"),
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Some(("", ("*** Hi\nWorld", 3)))
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);
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assert_eq!(
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parse_headline("* Hello\nText\n** Test\n ** More text\n* World\n"),
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Some(("* World\n", ("* Hello\nText\n** Test\n ** More text\n", 1)))
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);
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// We can parse a headline that contains the *\r\n. It is treated as
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// text in the section.
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assert_eq!(
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parse_headline("* \n*\r\n* \n"),
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Some(("* \n", ("* \n*\r\n", 1)))
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);
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// We can't parse a headline starting at *\r\n, thus ensuring that each
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// line either is or is not a headline.
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assert_eq!(parse_headline("*\r\n* \n"), None);
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assert_eq!(parse_headline("* \n"), Some(("", ("* \n", 1))));
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assert_eq!(
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parse_headline("* \n**\r\n* \n"),
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Some(("* \n", ("* \n**\r\n", 1)))
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);
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assert_eq!(parse_headline("* a\n*"), Some(("*", ("* a\n", 1))));
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assert_eq!(parse_headline("* a\r\n*"), Some(("*", ("* a\r\n", 1))));
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assert_eq!(parse_headline("* a\r\n* b"), Some(("* b", ("* a\r\n", 1))));
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assert_eq!(parse_headline("* a\n* "), Some(("* ", ("* a\n", 1))));
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assert_eq!(parse_headline("* a\n* \n"), Some(("* \n", ("* a\n", 1))));
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assert_eq!(parse_headline("* a\n* \n"), Some(("* \n", ("* a\n", 1))));
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}
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}
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