FIX lint clippy::len_without_is_empty (#451)

src/eval/array.rs

@@ -41,6 +41,11 @@ impl Array {
         Self(vec)
     }
 
+    /// Return `true` if the length is 0.
+    pub fn is_empty(&self) -> bool {
+        self.0.len() == 0
+    }
+
     /// The length of the array.
     pub fn len(&self) -> i64 {
         self.0.len() as i64

src/eval/str.rs

@@ -34,6 +34,11 @@ impl Str {
         Self(EcoString::new())
     }
 
+    /// Return `true` if the length is 0.
+    pub fn is_empty(&self) -> bool {
+        self.0.len() == 0
+    }
+
     /// The length of the string in bytes.
     pub fn len(&self) -> i64 {
         self.0.len() as i64

src/syntax/node.rs

@@ -53,6 +53,11 @@ impl SyntaxNode {
         }
     }
 
+    /// Return `true` if the length is 0.
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
     /// The byte length of the node in the source text.
     pub fn len(&self) -> usize {
         match &self.0 {

src/syntax/parser.rs

@@ -1324,7 +1324,7 @@ impl<'s> Parser<'s> {
         while self
             .nodes
             .last()
-            .map_or(false, |child| child.kind() == SyntaxKind::Error && child.len() == 0)
+            .map_or(false, |child| child.kind() == SyntaxKind::Error && child.is_empty())
         {
             self.nodes.pop();
         }