buck2/superconsole: factor out span style equality

Summary: Consecutive `Span`s with the same style are merged in a `Line`. Deciding if two spans have the same style should be a function on `Span`, instead of coded into `Line.push()`.

Reviewed By: ndmitchell

Differential Revision: D68901431

fbshipit-source-id: 0eec5dfa8353aaaf716a4424f99eabd7f66ebf1f

src/content/line.rs

@@ -192,7 +192,7 @@ impl Line {
             return;
         }
         if let Some(last) = self.0.last_mut() {
-            if last.style == span.style && last.hyperlink == span.hyperlink {
+            if last.is_mergeable_with(&span) {
                 last.content.to_mut().push_str(&span.content);
                 return;
             }

src/content/span.rs

@@ -94,6 +94,12 @@ impl Span {
         }
     }
 
+    /// Determine if this span is mergeable with another span, i.e. if they
+    /// are equal except for content.
+    pub fn is_mergeable_with(&self, other: &Span) -> bool {
+        self.style == other.style && self.hyperlink == other.hyperlink
+    }
+
     /// Attempt to create a new, unstyled span equivalent to the underlying stringlike.
     /// This will fail if the input string is not [`valid`](Span::valid).
     pub fn new_unstyled<S: std::fmt::Display>(stringlike: S) -> anyhow::Result<Self> {