Implement line break parser.

src/parser/line_break.rs

@@ -1,13 +1,42 @@
+use nom::bytes::complete::tag;
+use nom::character::complete::line_ending;
+use nom::character::complete::one_of;
+use nom::combinator::recognize;
+use nom::multi::many0;
+
 use super::Context;
+use crate::error::CustomError;
+use crate::error::MyError;
 use crate::error::Res;
-use crate::parser::util::not_yet_implemented;
-use crate::parser::CitationReference;
+use crate::parser::util::get_consumed;
+use crate::parser::util::get_one_before;
+use crate::parser::LineBreak;
 
 #[tracing::instrument(ret, level = "debug")]
-pub fn citation_reference<'r, 's>(
-    context: Context<'r, 's>,
-    input: &'s str,
-) -> Res<&'s str, CitationReference<'s>> {
-    not_yet_implemented()?;
-    todo!()
+pub fn line_break<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, LineBreak<'s>> {
+    let (remaining, _) = pre(context, input)?;
+    let (remaining, _) = tag(r#"\\"#)(remaining)?;
+    let (remaining, _) = recognize(many0(one_of(" \t")))(remaining)?;
+    let (remaining, _) = line_ending(remaining)?;
+    let source = get_consumed(input, remaining);
+    Ok((remaining, LineBreak { source }))
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn pre<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, ()> {
+    let document_root = context.get_document_root().unwrap();
+    let preceding_character = get_one_before(document_root, input)
+        .map(|slice| slice.chars().next())
+        .flatten();
+    // TODO: Must be at the end of a non-empty line so instead of getting one character before, we need to grab the entire line.
+    match preceding_character {
+        // If None, we are at the start of the file
+        None | Some('\\') => {
+            return Err(nom::Err::Error(CustomError::MyError(MyError(
+                "Not a valid pre character for line break.",
+            ))));
+        }
+        _ => {}
+    };
+    Ok((input, ()))
 }

src/parser/object_parser.rs

@@ -15,6 +15,7 @@ use crate::parser::footnote_reference::footnote_reference;
 use crate::parser::inline_babel_call::inline_babel_call;
 use crate::parser::inline_source_block::inline_source_block;
 use crate::parser::latex_fragment::latex_fragment;
+use crate::parser::line_break::line_break;
 use crate::parser::object::Object;
 use crate::parser::org_macro::org_macro;
 use crate::parser::plain_link::plain_link;
@@ -31,6 +32,7 @@ pub fn standard_set_object<'r, 's>(
     not(|i| context.check_exit_matcher(i))(input)?;
 
     alt((
+        map(parser_with_context!(line_break)(context), Object::LineBreak),
         map(
             parser_with_context!(inline_source_block)(context),
             Object::InlineSourceBlock,
@@ -96,6 +98,7 @@ pub fn any_object_except_plain_text<'r, 's>(
 ) -> Res<&'s str, Object<'s>> {
     // Used for exit matchers so this does not check exit matcher condition.
     alt((
+        map(parser_with_context!(line_break)(context), Object::LineBreak),
         map(
             parser_with_context!(inline_source_block)(context),
             Object::InlineSourceBlock,