From c79b8c7833290a12d4245d2177bf2141474e295b Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Tue, 18 Jul 2023 21:50:29 -0400
Subject: [PATCH] Implement the first form of LaTeX fragment.

---
 src/parser/latex_fragment.rs | 79 +++++++++++++++++++++++++-----------
 src/parser/object.rs         |  1 -
 2 files changed, 56 insertions(+), 24 deletions(-)

diff --git a/src/parser/latex_fragment.rs b/src/parser/latex_fragment.rs
index 8b3113f..84dfae8 100644
--- a/src/parser/latex_fragment.rs
+++ b/src/parser/latex_fragment.rs
@@ -1,18 +1,21 @@
 use nom::branch::alt;
 use nom::bytes::complete::tag;
-use nom::bytes::complete::tag_no_case;
-use nom::character::complete::satisfy;
+use nom::character::complete::alpha1;
+use nom::character::complete::anychar;
+use nom::character::complete::line_ending;
+use nom::character::complete::one_of;
 use nom::character::complete::space0;
-use nom::combinator::eof;
+use nom::combinator::opt;
 use nom::combinator::peek;
 use nom::combinator::recognize;
+use nom::multi::many_till;
+use nom::sequence::tuple;
 
 use super::Context;
 use crate::error::Res;
-use crate::parser::object::Entity;
 use crate::parser::parser_with_context::parser_with_context;
+use crate::parser::util::exit_matcher_parser;
 use crate::parser::util::get_consumed;
-use crate::parser::util::not_yet_implemented;
 use crate::parser::LatexFragment;
 
 #[tracing::instrument(ret, level = "debug")]
@@ -20,22 +23,52 @@ pub fn latex_fragment<'r, 's>(
     context: Context<'r, 's>,
     input: &'s str,
 ) -> Res<&'s str, LatexFragment<'s>> {
-    not_yet_implemented()?;
-    let (remaining, _) = tag("\\")(input)?;
-    todo!()
-    // let (remaining, entity_name) = name(context, remaining)?;
-    // let (remaining, _) = alt((
-    //     tag("{}"),
-    //     peek(recognize(parser_with_context!(entity_end)(context))),
-    // ))(remaining)?;
-    // let (remaining, _) = space0(remaining)?;
-
-    // let source = get_consumed(input, remaining);
-    // Ok((
-    //     remaining,
-    //     Entity {
-    //         source,
-    //         entity_name,
-    //     },
-    // ))
+    let (remaining, _) = alt((parser_with_context!(raw_latex_fragment)(context),))(input)?;
+    let (remaining, _) = space0(remaining)?;
+    let source = get_consumed(input, remaining);
+    Ok((remaining, LatexFragment { source }))
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn raw_latex_fragment<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
+    let (remaining, _) = tag("\\")(input)?;
+    let (remaining, _) = name(context, remaining)?;
+    let (remaining, _) = opt(parser_with_context!(brackets)(context))(remaining)?;
+
+    let source = get_consumed(input, remaining);
+    Ok((remaining, source))
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn name<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
+    alpha1(input)
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn brackets<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
+    let (remaining, body) = alt((
+        recognize(tuple((
+            tag("["),
+            many_till(
+                anychar,
+                peek(alt((
+                    parser_with_context!(exit_matcher_parser)(context),
+                    alt((recognize(one_of("{}[]")), line_ending)),
+                ))),
+            ),
+            tag("]"),
+        ))),
+        recognize(tuple((
+            tag("{"),
+            many_till(
+                anychar,
+                peek(alt((
+                    parser_with_context!(exit_matcher_parser)(context),
+                    alt((recognize(one_of("{}")), line_ending)),
+                ))),
+            ),
+            tag("}"),
+        ))),
+    ))(input)?;
+    Ok((remaining, body))
 }
diff --git a/src/parser/object.rs b/src/parser/object.rs
index 5cd1bc0..7aa01f5 100644
--- a/src/parser/object.rs
+++ b/src/parser/object.rs
@@ -107,7 +107,6 @@ pub struct Entity<'s> {
 #[derive(Debug, PartialEq)]
 pub struct LatexFragment<'s> {
     pub source: &'s str,
-    pub entity_name: &'s str,
 }
 
 impl<'s> Source<'s> for Object<'s> {