Improve inner loop of config value parsing

I found this cut in half from the performance issue from fe997c8.

I'm assuming for less degenerate cases it will still offer performance
improvements.

Author: epage

gix-config/src/parse/nom/mod.rs

@@ -265,62 +265,67 @@ fn value_impl<'i>(i: &mut &'i [u8], dispatch: &mut impl FnMut(Event<'i>)) -> PRe
     // Used to determine if we return a Value or Value{Not,}Done
     let mut partial_value_found = false;
 
-    while let Some(c) = i.next_token() {
-        match c {
-            b'\n' => {
-                value_end = Some(i.offset_from(&value_start_checkpoint) - 1);
-                break;
-            }
-            b';' | b'#' if !is_in_quotes => {
-                value_end = Some(i.offset_from(&value_start_checkpoint) - 1);
-                break;
-            }
-            b'\\' => {
-                let escaped_index = i.offset_from(&value_start_checkpoint);
-                let escape_index = escaped_index - 1;
-                let Some(mut c) = i.next_token() else {
-                    i.reset(start_checkpoint);
-                    return Err(winnow::error::ErrMode::from_error_kind(i, ErrorKind::Token));
-                };
-                let mut consumed = 1;
-                if c == b'\r' {
-                    c = i.next_token().ok_or_else(|| {
-                        i.reset(start_checkpoint);
-                        winnow::error::ErrMode::from_error_kind(i, ErrorKind::Token)
-                    })?;
-                    if c != b'\n' {
+    loop {
+        let _ = take_while(0.., |c| !matches!(c, b'\n' | b'\\' | b'"' | b';' | b'#')).parse_next(i)?;
+        if let Some(c) = i.next_token() {
+            match c {
+                b'\n' => {
+                    value_end = Some(i.offset_from(&value_start_checkpoint) - 1);
+                    break;
+                }
+                b';' | b'#' if !is_in_quotes => {
+                    value_end = Some(i.offset_from(&value_start_checkpoint) - 1);
+                    break;
+                }
+                b'\\' => {
+                    let escaped_index = i.offset_from(&value_start_checkpoint);
+                    let escape_index = escaped_index - 1;
+                    let Some(mut c) = i.next_token() else {
                         i.reset(start_checkpoint);
-                        return Err(winnow::error::ErrMode::from_error_kind(i, ErrorKind::Slice));
+                        return Err(winnow::error::ErrMode::from_error_kind(i, ErrorKind::Token));
+                    };
+                    let mut consumed = 1;
+                    if c == b'\r' {
+                        c = i.next_token().ok_or_else(|| {
+                            i.reset(start_checkpoint);
+                            winnow::error::ErrMode::from_error_kind(i, ErrorKind::Token)
+                        })?;
+                        if c != b'\n' {
+                            i.reset(start_checkpoint);
+                            return Err(winnow::error::ErrMode::from_error_kind(i, ErrorKind::Slice));
+                        }
+                        consumed += 1;
                     }
-                    consumed += 1;
-                }
 
-                match c {
-                    b'\n' => {
-                        partial_value_found = true;
+                    match c {
+                        b'\n' => {
+                            partial_value_found = true;
 
-                        i.reset(value_start_checkpoint);
+                            i.reset(value_start_checkpoint);
 
-                        let value = i.next_slice(escape_index).as_bstr();
-                        dispatch(Event::ValueNotDone(Cow::Borrowed(value)));
+                            let value = i.next_slice(escape_index).as_bstr();
+                            dispatch(Event::ValueNotDone(Cow::Borrowed(value)));
 
-                        i.next_token();
+                            i.next_token();
 
-                        let nl = i.next_slice(consumed).as_bstr();
-                        dispatch(Event::Newline(Cow::Borrowed(nl)));
+                            let nl = i.next_slice(consumed).as_bstr();
+                            dispatch(Event::Newline(Cow::Borrowed(nl)));
 
-                        value_start_checkpoint = i.checkpoint();
-                        value_end = None;
-                    }
-                    b'n' | b't' | b'\\' | b'b' | b'"' => {}
-                    _ => {
-                        i.reset(start_checkpoint);
-                        return Err(winnow::error::ErrMode::from_error_kind(i, ErrorKind::Token));
+                            value_start_checkpoint = i.checkpoint();
+                            value_end = None;
+                        }
+                        b'n' | b't' | b'\\' | b'b' | b'"' => {}
+                        _ => {
+                            i.reset(start_checkpoint);
+                            return Err(winnow::error::ErrMode::from_error_kind(i, ErrorKind::Token));
+                        }
                     }
                 }
+                b'"' => is_in_quotes = !is_in_quotes,
+                _ => {}
             }
-            b'"' => is_in_quotes = !is_in_quotes,
-            _ => {}
+        } else {
+            break;
         }
     }
     if is_in_quotes {