Implement key parser and begin key_suffix parser.

src/parser/citation_reference.rs

@@ -1,7 +1,22 @@
+use nom::character::complete::anychar;
+use nom::combinator::not;
+use nom::combinator::recognize;
+use nom::combinator::verify;
+use nom::multi::many1;
+use nom::multi::many_till;
+use nom::sequence::preceded;
+
 use super::Context;
 use crate::error::Res;
 use crate::parser::object::CitationReference;
+use crate::parser::object_parser::minimal_set_object;
+use crate::parser::parser_context::CitationBracket;
+use crate::parser::parser_context::ContextElement;
+use crate::parser::parser_with_context::parser_with_context;
+use crate::parser::util::exit_matcher_parser;
 use crate::parser::util::not_yet_implemented;
+use crate::parser::util::WORD_CONSTITUENT_CHARACTERS;
+use crate::parser::Object;
 
 #[tracing::instrument(ret, level = "debug")]
 pub fn citation_reference<'r, 's>(
@@ -11,3 +26,39 @@ pub fn citation_reference<'r, 's>(
     not_yet_implemented()?;
     todo!()
 }
+
+#[tracing::instrument(ret, level = "debug")]
+fn key<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
+    let (remaining, source) = recognize(many1(verify(
+        preceded(
+            not(parser_with_context!(exit_matcher_parser)(context)),
+            anychar,
+        ),
+        |c| WORD_CONSTITUENT_CHARACTERS.contains(*c) || "-.:?~`'/*@+|(){}<>&_^$#%~".contains(*c),
+    )))(input)?;
+    Ok((remaining, source))
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn key_suffix<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, Vec<Object<'s>>> {
+    // TODO: Add to context with the depth object and an exit matcher
+    let (remaining, (children, _exit_contents)) = verify(
+        many_till(
+            parser_with_context!(minimal_set_object)(context),
+            parser_with_context!(exit_matcher_parser)(context),
+        ),
+        |(children, _exit_contents)| !children.is_empty(),
+    )(input)?;
+    todo!()
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn get_bracket_depth<'r, 's>(context: Context<'r, 's>) -> Option<&'r CitationBracket<'s>> {
+    for node in context.iter() {
+        match node.get_data() {
+            ContextElement::CitationBracket(depth) => return Some(depth),
+            _ => {}
+        }
+    }
+    None
+}

src/parser/parser_context.rs

@@ -147,12 +147,27 @@ pub enum ContextElement<'r, 's> {
     /// The definition inside a footnote reference must have balanced
     /// brackets [] inside the definition, so this stores the amount
     /// of opening brackets subtracted by the amount of closing
-    /// brackets within the definition.
+    /// brackets within the definition must equal zero.
     ///
     /// A reference to the position in the string is also included so
     /// unbalanced brackets can be detected in the middle of an
     /// object.
     FootnoteReferenceDefinition(FootnoteReferenceDefinition<'s>),
+
+    /// Stores the current bracket depth inside a citation.
+    ///
+    /// The global prefix, global suffix, key prefix, and key suffix
+    /// inside a footnote reference must have balanced brackets []
+    /// inside the definition, so this stores the amount of opening
+    /// brackets subtracted by the amount of closing brackets within
+    /// the definition must equal zero. None of the prefixes or
+    /// suffixes can be nested inside each other so we can use a
+    /// single type for this without conflict.
+    ///
+    /// A reference to the position in the string is also included so
+    /// unbalanced brackets can be detected in the middle of an
+    /// object.
+    CitationBracket(CitationBracket<'s>),
 }
 
 pub struct ExitMatcherNode<'r> {
@@ -166,6 +181,12 @@ pub struct FootnoteReferenceDefinition<'s> {
     pub depth: usize,
 }
 
+#[derive(Debug)]
+pub struct CitationBracket<'s> {
+    pub position: &'s str,
+    pub depth: usize,
+}
+
 impl<'r> std::fmt::Debug for ExitMatcherNode<'r> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let mut formatter = f.debug_struct("ExitMatcherNode");