refactor(parser): clean up parse functions

src/elements/fn_def.rs

@@ -1,19 +1,23 @@
 use memchr::memchr;
 
 #[inline]
-pub fn parse(src: &str) -> Option<(&str, &str, usize)> {
-    debug_assert!(src.starts_with("[fn:"));
+pub fn parse(text: &str) -> Option<(&str, &str, usize)> {
+    debug_assert!(text.starts_with("[fn:"));
 
-    let label = memchr(b']', src.as_bytes()).filter(|&i| {
-        i != 4
-            && src.as_bytes()[4..i]
-                .iter()
-                .all(|&c| c.is_ascii_alphanumeric() || c == b'-' || c == b'_')
-    })?;
+    let (label, off) = memchr(b']', text.as_bytes())
+        .filter(|&i| {
+            i != 4
+                && text.as_bytes()[4..i]
+                    .iter()
+                    .all(|&c| c.is_ascii_alphanumeric() || c == b'-' || c == b'_')
+        })
+        .map(|i| (&text[4..i], i + 1))?;
 
-    let end = memchr(b'\n', src.as_bytes()).unwrap_or_else(|| src.len());
+    let (content, off) = memchr(b'\n', text.as_bytes())
+        .map(|i| (&text[off..i], i))
+        .unwrap_or_else(|| (&text[off..], text.len()));
 
-    Some((&src[4..label], &src[label + 1..end], end))
+    Some((label, content, off))
 }
 
 #[cfg(test)]