use memrchr

Cargo.toml

@@ -16,6 +16,7 @@ exclude = ["fuzz/**/*", ".vscode/**/*"]
 serde = ["serde_crate"]
 
 [dependencies]
+memchr = "2"
 nom = { version = "6", default_features = false, features = ["std"] }
 serde_crate = { version = "1", package = "serde", optional = true }
 

src/parser.rs

@@ -700,7 +700,7 @@ fn section_header(i: &[u8]) -> IResult<&[u8], ParsedSectionHeader> {
     if let Ok((i, _)) = char::<_, NomError<&[u8]>>(']')(i) {
         // Either section does not have a subsection or using deprecated
         // subsection syntax at this point.
-        let header = match find_legacy_subsection_separator(name) {
+        let header = match memchr::memrchr(b'.', name.as_bytes()) {
             Some(index) => ParsedSectionHeader {
                 name: Cow::Borrowed(&name[..index]),
                 separator: name.get(index..=index).map(|slice| Cow::Borrowed(slice)),
@@ -747,16 +747,6 @@ fn section_header(i: &[u8]) -> IResult<&[u8], ParsedSectionHeader> {
     ))
 }
 
-fn find_legacy_subsection_separator(input: &str) -> Option<usize> {
-    let input = input.as_bytes();
-    for i in (0..input.len()).into_iter().rev() {
-        if input[i] == b'.' {
-            return Some(i);
-        }
-    }
-    None
-}
-
 fn section_body<'a, 'b, 'c>(
     i: &'a [u8],
     node: &'b mut ParserNode,