Add support for curly underline and separate underline color

Add support for a third color in face definition that controls
the underline and a 'c' attribute for curly underline (that takes
precedence over 'u' if both are specified)

Allow empty colors to mean default, so that `,,red+u` means the
same as `default,default,red+u`

Fixes #4138

1 files changed, 18 insertions, 14 deletions

diff --git a/src/face.hh b/src/face.hh
index 798cd3f3..ce544116 100644
--- a/src/face.hh
+++ b/src/face.hh
@@ -9,18 +9,19 @@ namespace Kakoune
 
 enum class Attribute : int
 {
-    Normal        = 0,
-    Underline     = 1 << 1,
-    Reverse       = 1 << 2,
-    Blink         = 1 << 3,
-    Bold          = 1 << 4,
-    Dim           = 1 << 5,
-    Italic        = 1 << 6,
-    Strikethrough = 1 << 7,
-    FinalFg       = 1 << 8,
-    FinalBg       = 1 << 9,
-    FinalAttr     = 1 << 10,
-    Final         = FinalFg | FinalBg | FinalAttr
+    Normal         = 0,
+    Underline      = 1 << 1,
+    CurlyUnderline = 1 << 2,
+    Reverse        = 1 << 3,
+    Blink          = 1 << 4,
+    Bold           = 1 << 5,
+    Dim            = 1 << 6,
+    Italic         = 1 << 7,
+    Strikethrough  = 1 << 8,
+    FinalFg        = 1 << 9,
+    FinalBg        = 1 << 10,
+    FinalAttr      = 1 << 11,
+    Final          = FinalFg | FinalBg | FinalAttr
 };
 
 constexpr bool with_bit_ops(Meta::Type<Attribute>) { return true; }
@@ -30,11 +31,13 @@ struct Face
     Color fg = Color::Default;
     Color bg = Color::Default;
     Attribute attributes = Attribute::Normal;
+    Color underline = Color::Default;
 
     friend constexpr bool operator==(const Face& lhs, const Face& rhs)
     {
         return lhs.fg == rhs.fg and
                lhs.bg == rhs.bg and
+               lhs.underline == rhs.underline and
                lhs.attributes == rhs.attributes;
     }
 
@@ -45,7 +48,7 @@ struct Face
 
     friend constexpr size_t hash_value(const Face& val)
     {
-        return hash_values(val.fg, val.bg, val.attributes);
+        return hash_values(val.fg, val.bg, val.underline, val.attributes);
     }
 };
 
@@ -77,7 +80,8 @@ inline Face merge_faces(const Face& base, const Face& face)
                  choose(&Face::bg, Attribute::FinalBg),
                  face.attributes & Attribute::FinalAttr ? face.attributes :
                  base.attributes & Attribute::FinalAttr ? base.attributes :
-                 face.attributes | base.attributes };
+                 face.attributes | base.attributes,
+                 choose(&Face::underline, Attribute{0}) };
 }
 
 }