From b512c670e62fb60148b40688731dc33c9796da3c Mon Sep 17 00:00:00 2001
From: Noah Hellman <noah@hllmn.net>
Date: Mon, 16 Jan 2023 17:24:27 +0100
Subject: [PATCH] attr valid: return whether attrs non-empty

---
 src/attr.rs   | 45 ++++++++++++++++++++++++++++++++++-----------
 src/block.rs  |  2 +-
 src/inline.rs |  8 ++++----
 3 files changed, 39 insertions(+), 16 deletions(-)

diff --git a/src/attr.rs b/src/attr.rs
index 1499427..41033a1 100644
--- a/src/attr.rs
+++ b/src/attr.rs
@@ -10,13 +10,18 @@ pub(crate) fn parse<'s, S: DiscontinuousString<'s>>(chars: S) -> Attributes<'s>
     a
 }
 
-pub fn valid<I: Iterator<Item = char>>(chars: I) -> usize {
+pub fn valid<I: Iterator<Item = char>>(chars: I) -> (usize, bool) {
+    let mut has_attr = false;
     let mut p = Parser::new(chars);
-    if p.any(|e| matches!(e, Element::Invalid)) {
-        0
-    } else {
-        p.pos
+    for e in &mut p {
+        match e {
+            Element::Class(..) | Element::Identifier(..) | Element::Attribute(..) => {
+                has_attr = true
+            }
+            Element::Invalid => return (0, false),
+        }
     }
+    (p.pos, has_attr)
 }
 
 // Attributes are relatively rare, we choose to pay 8 bytes always and sometimes an extra
@@ -357,7 +362,25 @@ mod test {
     #[test]
     fn valid_full() {
         let src = "{.class %comment%}";
-        assert_eq!(super::valid(src.chars()), src.len());
+        assert_eq!(super::valid(src.chars()), (src.len(), true));
+    }
+
+    #[test]
+    fn valid_empty() {
+        let src = "{}";
+        assert_eq!(super::valid(src.chars()), (src.len(), false));
+    }
+
+    #[test]
+    fn valid_whitespace() {
+        let src = "{ \n }";
+        assert_eq!(super::valid(src.chars()), (src.len(), false));
+    }
+
+    #[test]
+    fn valid_comment() {
+        let src = "{%comment%}";
+        assert_eq!(super::valid(src.chars()), (src.len(), false));
     }
 
     #[test]
@@ -365,15 +388,15 @@ mod test {
         let src = "{.class}";
         assert_eq!(
             super::valid(src.chars().chain("{.ignore}".chars())),
-            src.len()
+            (src.len(), true),
         );
     }
 
     #[test]
     fn valid_invalid() {
-        assert_eq!(super::valid(" {.valid}".chars()), 0);
-        assert_eq!(super::valid("{.class invalid}".chars()), 0);
-        assert_eq!(super::valid("abc".chars()), 0);
-        assert_eq!(super::valid("{.abc.}".chars()), 0);
+        assert_eq!(super::valid(" {.valid}".chars()), (0, false));
+        assert_eq!(super::valid("{.class invalid}".chars()), (0, false));
+        assert_eq!(super::valid("abc".chars()), (0, false));
+        assert_eq!(super::valid("{.abc.}".chars()), (0, false));
     }
 }
diff --git a/src/block.rs b/src/block.rs
index f57041d..ffa0a95 100644
--- a/src/block.rs
+++ b/src/block.rs
@@ -270,7 +270,7 @@ impl BlockParser {
                     ))
                 }
             }
-            '{' => (attr::valid(line_t.chars()) == line_t.trim_end().len())
+            '{' => (attr::valid(line_t.chars()).0 == line_t.trim_end().len())
                 .then(|| (Block::Atom(Attributes), Span::by_len(start, line_t.len()))),
             '|' => (&line_t[line_t.len() - 1..] == "|"
                 && &line_t[line_t.len() - 2..line_t.len() - 1] != "\\")
diff --git a/src/inline.rs b/src/inline.rs
index ee7056b..9bfa87b 100644
--- a/src/inline.rs
+++ b/src/inline.rs
@@ -239,12 +239,12 @@ impl<I: Iterator<Item = char> + Clone> Parser<I> {
                 .map_or(false, |e| e.kind == EventKind::Str)
         {
             let mut ahead = self.lexer.inner().clone();
-            let mut attr_len = attr::valid(std::iter::once('{').chain(&mut ahead)) - 1;
+            let mut attr_len = attr::valid(std::iter::once('{').chain(&mut ahead)).0 - 1;
             if attr_len > 0 {
                 while attr_len > 0 {
                     self.lexer = lex::Lexer::new(ahead.clone());
                     self.span = self.span.extend(attr_len);
-                    attr_len = attr::valid(&mut ahead);
+                    attr_len = attr::valid(&mut ahead).0;
                 }
 
                 let i = self
@@ -345,7 +345,7 @@ impl<I: Iterator<Item = char> + Clone> Parser<I> {
                         };
                         self.openers.drain(o..);
                         let mut ahead = self.lexer.inner().clone();
-                        let mut attr_len = attr::valid(&mut ahead);
+                        let mut attr_len = attr::valid(&mut ahead).0;
                         if attr_len > 0 {
                             let span_closer = self.span;
                             self.events[e_attr].span = Span::empty_at(self.span.end());
@@ -354,7 +354,7 @@ impl<I: Iterator<Item = char> + Clone> Parser<I> {
                                 self.lexer = lex::Lexer::new(ahead.clone());
                                 self.span = self.events[e_attr].span.extend(attr_len);
                                 self.events[e_attr].span = self.span;
-                                attr_len = attr::valid(&mut ahead);
+                                attr_len = attr::valid(&mut ahead).0;
                             }
 
                             if event.is_none() {