From 03faa7257f34a35ba9a718222b9e9807a7449a10 Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Thu, 24 Aug 2023 20:37:58 -0400
Subject: [PATCH] Move the indent level for plain list's exit matcher to const
 fn instead of grabbing from the context.

This made a slight improvement to performance.
---
 src/parser/parser_context.rs |  3 ---
 src/parser/plain_list.rs     | 52 +++++++++++++++++++++---------------
 2 files changed, 30 insertions(+), 25 deletions(-)

diff --git a/src/parser/parser_context.rs b/src/parser/parser_context.rs
index 1369cd9..4ee2a76 100644
--- a/src/parser/parser_context.rs
+++ b/src/parser/parser_context.rs
@@ -112,9 +112,6 @@ pub enum ContextElement<'r, 's> {
     ExitMatcherNode(ExitMatcherNode<'r>),
     Context(&'r str),
 
-    /// Stores the indentation level of the current list item.
-    ListItem(usize),
-
     /// Stores the name of the greater block.
     GreaterBlock(&'s str),
 
diff --git a/src/parser/plain_list.rs b/src/parser/plain_list.rs
index 12aab97..fb65c5f 100644
--- a/src/parser/plain_list.rs
+++ b/src/parser/plain_list.rs
@@ -135,12 +135,12 @@ pub fn plain_list_item<'r, 's>(
     };
 
     let (remaining, _ws) = space1(remaining)?;
+    let exit_matcher = plain_list_item_end(indent_level);
     let parser_context = context
         .with_additional_node(ContextElement::ConsumeTrailingWhitespace(true))
-        .with_additional_node(ContextElement::ListItem(indent_level))
         .with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
             class: ExitClass::Beta,
-            exit_matcher: &plain_list_item_end,
+            exit_matcher: &exit_matcher,
         }));
 
     let (remaining, (children, _exit_contents)) = verify(
@@ -194,47 +194,55 @@ fn plain_list_end<'r, 's>(
     )))(input)
 }
 
-#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
-fn plain_list_item_end<'r, 's>(
+const fn plain_list_item_end(
+    indent_level: usize,
+) -> impl for<'r, 's> Fn(Context<'r, 's>, OrgSource<'s>) -> Res<OrgSource<'s>, OrgSource<'s>> {
+    let line_indented_lte_matcher = line_indented_lte(indent_level);
+    move |context: Context, input: OrgSource<'_>| {
+        _plain_list_item_end(context, input, &line_indented_lte_matcher)
+    }
+}
+
+#[cfg_attr(
+    feature = "tracing",
+    tracing::instrument(ret, level = "debug", skip(line_indented_lte_matcher))
+)]
+fn _plain_list_item_end<'r, 's>(
     context: Context<'r, 's>,
     input: OrgSource<'s>,
+    line_indented_lte_matcher: impl for<'rr, 'ss> Fn(
+        Context<'rr, 'ss>,
+        OrgSource<'ss>,
+    ) -> Res<OrgSource<'ss>, OrgSource<'ss>>,
 ) -> Res<OrgSource<'s>, OrgSource<'s>> {
     start_of_line(input)?;
     recognize(tuple((
         opt(blank_line),
-        parser_with_context!(line_indented_lte)(context),
+        parser_with_context!(line_indented_lte_matcher)(context),
     )))(input)
 }
 
+const fn line_indented_lte(
+    indent_level: usize,
+) -> impl for<'r, 's> Fn(Context<'r, 's>, OrgSource<'s>) -> Res<OrgSource<'s>, OrgSource<'s>> {
+    move |context: Context, input: OrgSource<'_>| _line_indented_lte(context, input, indent_level)
+}
+
 #[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
-fn line_indented_lte<'r, 's>(
+fn _line_indented_lte<'r, 's>(
     context: Context<'r, 's>,
     input: OrgSource<'s>,
+    indent_level: usize,
 ) -> Res<OrgSource<'s>, OrgSource<'s>> {
-    let current_item_indent_level: &usize =
-        get_context_item_indent(context).ok_or(nom::Err::Error(CustomError::MyError(MyError(
-            "Not inside a plain list item".into(),
-        ))))?;
-
     let matched = recognize(verify(
         tuple((space0::<OrgSource<'_>, _>, non_whitespace_character)),
         // It is fine that we get the indent level using the number of bytes rather than the number of characters because nom's space0 only matches space and tab (0x20 and 0x09)
-        |(_space0, _anychar)| _space0.len() <= *current_item_indent_level,
+        |(_space0, _anychar)| _space0.len() <= indent_level,
     ))(input)?;
 
     Ok(matched)
 }
 
-fn get_context_item_indent<'r, 's>(context: Context<'r, 's>) -> Option<&'r usize> {
-    for thing in context.iter() {
-        match thing.get_data() {
-            ContextElement::ListItem(depth) => return Some(depth),
-            _ => {}
-        };
-    }
-    None
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;