2 files changed, 70 insertions, 10 deletions

diff --git a/src/construct/partial_mdx_expression.rs b/src/construct/partial_mdx_expression.rs
index a949347..aeea52e 100644
--- a/src/construct/partial_mdx_expression.rs
+++ b/src/construct/partial_mdx_expression.rs
@@ -36,13 +36,22 @@ pub fn before(tokenizer: &mut Tokenizer) -> State {
             State::Next(StateName::MdxExpressionEolAfter)
         },
         Some(b'}') if tokenizer.tokenize_state.size == 0 => {
-            tokenizer.enter(Name::MdxExpressionMarker);
-            tokenizer.consume();
-            tokenizer.exit(Name::MdxExpressionMarker);
-            tokenizer.exit(tokenizer.tokenize_state.token_1.clone());
-            State::Ok
+            if tokenizer.tokenize_state.token_1 == Name::MdxJsxTagAttributeValueExpression && !tokenizer.tokenize_state.seen {
+                State::Error(format!(
+                    "{}:{}: Unexpected empty in expression, expected a value between braces",
+                    tokenizer.point.line, tokenizer.point.column
+                ))
+            } else {
+                tokenizer.tokenize_state.seen = false;
+                tokenizer.enter(Name::MdxExpressionMarker);
+                tokenizer.consume();
+                tokenizer.exit(Name::MdxExpressionMarker);
+                tokenizer.exit(tokenizer.tokenize_state.token_1.clone());
+                State::Ok
+            }
         },
         Some(_) => {
+            tokenizer.tokenize_state.seen = true;
             tokenizer.enter(Name::MdxExpressionData);
             State::Retry(StateName::MdxExpressionInside)
         }
@@ -56,9 +65,11 @@ pub fn inside(tokenizer: &mut Tokenizer) -> State {
         tokenizer.exit(Name::MdxExpressionData);
         State::Retry(StateName::MdxExpressionBefore)
     } else {
-        // To do: only count if agnostic.
+        // To do: don’t count if gnostic.
         if tokenizer.current == Some(b'{') {
             tokenizer.tokenize_state.size += 1;
+        } else if tokenizer.current == Some(b'}') {
+            tokenizer.tokenize_state.size -= 1;
         }
 
         tokenizer.consume();
@@ -67,8 +78,11 @@ pub fn inside(tokenizer: &mut Tokenizer) -> State {
 }
 
 pub fn eol_after(tokenizer: &mut Tokenizer) -> State {
-    // Lazy continuation in a flow expression is a syntax error.
-    if tokenizer.tokenize_state.token_1 == Name::MdxFlowExpression && tokenizer.lazy {
+    // Lazy continuation in a flow expression (or in a flow tag) is a syntax error.
+    if (tokenizer.tokenize_state.token_1 == Name::MdxFlowExpression
+        || tokenizer.tokenize_state.token_2 == Name::MdxJsxFlowTag)
+        && tokenizer.lazy
+    {
         State::Error(format!(
             "{}:{}: Unexpected lazy line in expression in container, expected line to be prefixed with `>` when in a block quote, whitespace when in a list, etc",
             tokenizer.point.line, tokenizer.point.column
diff --git a/src/construct/partial_mdx_jsx.rs b/src/construct/partial_mdx_jsx.rs
index 05a2c0c..9177b5b 100644
--- a/src/construct/partial_mdx_jsx.rs
+++ b/src/construct/partial_mdx_jsx.rs
@@ -610,7 +610,17 @@ pub fn attribute_before(tokenizer: &mut Tokenizer) -> State {
         // End of tag.
         Some(b'>') => State::Retry(StateName::MdxJsxTagEnd),
         // Attribute expression.
-        Some(b'{') => unreachable!("to do: attribute expression"),
+        Some(b'{') => {
+            // To do: force `spread: true` if gnostic.
+            // To do: pass `start_point` if gnostic.
+            tokenizer.tokenize_state.token_2 = tokenizer.tokenize_state.token_1.clone();
+            tokenizer.tokenize_state.token_1 = Name::MdxJsxTagAttributeExpression;
+            tokenizer.attempt(
+                State::Next(StateName::MdxJsxAttributeExpressionAfter),
+                State::Nok,
+            );
+            State::Retry(StateName::MdxExpressionStart)
+        }
         _ => {
             // Start of an attribute name.
             if id_start(char_after_index(
@@ -633,6 +643,19 @@ pub fn attribute_before(tokenizer: &mut Tokenizer) -> State {
     }
 }
 
+/// After attribute expression.
+///
+/// ```markdown
+/// > | a <b {c} d/> e
+///             ^
+/// ```
+pub fn attribute_expression_after(tokenizer: &mut Tokenizer) -> State {
+    tokenizer.tokenize_state.token_1 = tokenizer.tokenize_state.token_2.clone();
+    tokenizer.tokenize_state.token_2 = Name::Data;
+    tokenizer.attempt(State::Next(StateName::MdxJsxAttributeBefore), State::Nok);
+    State::Retry(StateName::MdxJsxEsWhitespaceStart)
+}
+
 /// In primary attribute name.
 ///
 /// ```markdown
@@ -862,7 +885,16 @@ pub fn attribute_value_before(tokenizer: &mut Tokenizer) -> State {
             State::Next(StateName::MdxJsxAttributeValueQuotedStart)
         }
         // Attribute value expression.
-        Some(b'{') => unreachable!("to do: attribute value expression"),
+        Some(b'{') => {
+            // To do: pass `start_point` if gnostic.
+            tokenizer.tokenize_state.token_2 = tokenizer.tokenize_state.token_1.clone();
+            tokenizer.tokenize_state.token_1 = Name::MdxJsxTagAttributeValueExpression;
+            tokenizer.attempt(
+                State::Next(StateName::MdxJsxAttributeValueExpressionAfter),
+                State::Nok,
+            );
+            State::Retry(StateName::MdxExpressionStart)
+        }
         _ => crash(
             tokenizer,
             "before attribute value",
@@ -878,6 +910,20 @@ pub fn attribute_value_before(tokenizer: &mut Tokenizer) -> State {
     }
 }
 
+/// After attribute value expression.
+///
+/// ```markdown
+/// > | a <b c={d} e/> f
+///               ^
+/// ```
+pub fn attribute_value_expression_after(tokenizer: &mut Tokenizer) -> State {
+    tokenizer.tokenize_state.token_1 = tokenizer.tokenize_state.token_2.clone();
+    tokenizer.tokenize_state.token_2 = Name::Data;
+    tokenizer.exit(Name::MdxJsxTagAttribute);
+    tokenizer.attempt(State::Next(StateName::MdxJsxAttributeBefore), State::Nok);
+    State::Retry(StateName::MdxJsxEsWhitespaceStart)
+}
+
 /// Before quoted literal attribute value.
 ///
 /// ```markdown