From 1952d175c021fc6dcca21729a9fc4145bb90de1b Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Sun, 27 Aug 2023 23:21:41 -0400
Subject: [PATCH] Record line number in OrgSource.

This will be used for elements who have limits on the number of lines inside of them. This includes LaTeX fragment bodies and text markup.
---
 src/parser/org_source.rs | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/src/parser/org_source.rs b/src/parser/org_source.rs
index 9789c8e..db252d4 100644
--- a/src/parser/org_source.rs
+++ b/src/parser/org_source.rs
@@ -18,6 +18,7 @@ pub struct OrgSource<'s> {
     end: usize, // exclusive
     start_of_line: usize,
     preceding_character: Option<char>,
+    line_number: usize,
 }
 
 impl<'s> OrgSource<'s> {
@@ -31,6 +32,7 @@ impl<'s> OrgSource<'s> {
             end: input.len(),
             start_of_line: 0,
             preceding_character: None,
+            line_number: 1,
         }
     }
 
@@ -56,6 +58,10 @@ impl<'s> OrgSource<'s> {
         assert!(other.end <= self.end);
         self.slice(..(other.start - self.start))
     }
+
+    pub fn get_line_number(&self) -> usize {
+        self.line_number
+    }
 }
 
 impl<'s> InputTake for OrgSource<'s> {
@@ -119,10 +125,14 @@ where
         }
 
         let skipped_text = &self.full_source[self.start..new_start];
-        let start_of_line = skipped_text
-            .rfind('\n')
-            .map(|idx| self.start + idx + 1)
-            .unwrap_or(self.start_of_line);
+        let mut start_of_line = self.start_of_line;
+        let mut line_number = self.line_number;
+        for (offset, character) in skipped_text.char_indices() {
+            if character == '\n' {
+                start_of_line = self.start + offset + 1;
+                line_number += 1;
+            }
+        }
 
         OrgSource {
             full_source: self.full_source,
@@ -130,6 +140,7 @@ where
             end: new_end,
             start_of_line,
             preceding_character: skipped_text.chars().last(),
+            line_number,
         }
     }
 }
@@ -369,4 +380,13 @@ mod tests {
         assert_eq!(input.get_preceding_character(), None);
         assert_eq!(input.slice(8..).get_preceding_character(), Some('💛'));
     }
+
+    #[test]
+    fn line_number() {
+        let input = OrgSource::new("lorem\nfoo\nbar\nbaz\nipsum");
+        assert_eq!(input.get_line_number(), 1);
+        assert_eq!(input.slice(5..).get_line_number(), 1);
+        assert_eq!(input.slice(6..).get_line_number(), 2);
+        assert_eq!(input.slice(6..).slice(10..).get_line_number(), 4);
+    }
 }