LibLine: Ignore empty spans when stylizing

Previously we would erroneously apply the stylization to the whoever
called stylize next. Now we first check whether the span is non-empty
before stylizing. All non-empty spans must have at least one character
in them (end-exclusive).

2 files changed, 7 insertions, 0 deletions

diff --git a/Userland/Libraries/LibLine/Editor.cpp b/Userland/Libraries/LibLine/Editor.cpp
index 0587cf13cc..c10c2497c3 100644
--- a/Userland/Libraries/LibLine/Editor.cpp
+++ b/Userland/Libraries/LibLine/Editor.cpp
@@ -463,6 +463,8 @@ Editor::CodepointRange Editor::byte_offset_range_to_code_point_offset_range(size
 
 void Editor::stylize(Span const& span, Style const& style)
 {
+    if (!span.is_empty())
+        return;
     if (style.is_empty())
         return;
 
diff --git a/Userland/Libraries/LibLine/Span.h b/Userland/Libraries/LibLine/Span.h
index 669341b23c..c497926859 100644
--- a/Userland/Libraries/LibLine/Span.h
+++ b/Userland/Libraries/LibLine/Span.h
@@ -28,6 +28,11 @@ public:
     size_t end() const { return m_end; }
     Mode mode() const { return m_mode; }
 
+    bool is_empty() const
+    {
+        return m_beginning < m_end;
+    }
+
 private:
     size_t m_beginning { 0 };
     size_t m_end { 0 };