use ternery instead of ifelse since ifelse force evaluation of the RHS

Author: KristofferC

src/faces.jl

@@ -128,7 +128,7 @@ struct Face
                      Tuple{<:Union{Nothing, SimpleColor}, Symbol}}
     strikethrough::Union{Nothing, Bool}
     inverse::Union{Nothing, Bool}
-    inherit::Vector{Symbol}
+    inherit::Union{Nothing ,Vector{Symbol}}
 end
 
 function Face(; font::Union{Nothing, String} = nothing,
@@ -143,7 +143,7 @@ function Face(; font::Union{Nothing, String} = nothing,
                                } = nothing,
               strikethrough::Union{Nothing, Bool} = nothing,
               inverse::Union{Nothing, Bool} = nothing,
-              inherit::Union{Symbol, Vector{Symbol}} = Symbol[],
+              inherit::Union{Nothing, Symbol, Vector{Symbol}} = nothing,
               _...) # Simply ignore unrecognised keyword arguments.
     ascolor(::Nothing) = nothing
     ascolor(c::AbstractString) = parse(SimpleColor, c)
@@ -173,7 +173,7 @@ Base.:(==)(a::Face, b::Face) =
 Base.copy(f::Face) =
     Face(f.font, f.height, f.weight, f.slant,
          f.foreground, f.background, f.underline,
-         f.strikethrough, f.inverse, copy(f.inherit))
+         f.strikethrough, f.inverse, f.inherit === nothing ? f.inherit : copy(f.inherit))
 
 function Base.show(io::IO, ::MIME"text/plain", color::SimpleColor)
     skiptype = get(io, :typeinfo, nothing) === SimpleColor
@@ -228,7 +228,7 @@ function Base.show(io::IO, ::MIME"text/plain", face::Face)
                     show(io, getfield(face, field))
                 end
             end
-            if !isempty(face.inherit)
+            if !isnothing(face.inherit) && !isempty(face.inherit)
                 if isfirst; isfirst = false else print(io, ", ") end
                 print(io, "inherit=")
                 show(IOContext(io, :typeinfo => Vector{Symbol}), face.inherit)
@@ -274,7 +274,7 @@ function Base.show(io::IO, ::MIME"text/plain", face::Face)
                       getfield(face, field))
             end
         end
-        if !isempty(face.inherit)
+        if !isnothing(face.inherit) && !isempty(face.inherit)
             print(io, '\n', lpad("inherit", fieldnamepad, ' '), ": ")
             isfirst = true
             for iface in face.inherit
@@ -490,30 +490,30 @@ Merge the properties of the `initial` face and `others`, with
 later faces taking priority.
 """
 function Base.merge(a::Face, b::Face)
-    if isempty(b.inherit)
+    if isnothing(b.inherit) || isempty(b.inherit)
         # Extract the heights to help type inference a bit to be able
         # to narrow the types in e.g. `aheight * bheight`
         aheight = a.height
         bheight = b.height
-        Face(ifelse(isnothing(b.font),          a.font,          b.font),
+        Face(isnothing(b.font)          ? a.font          : b.font,
              if isnothing(bheight)      aheight
              elseif isnothing(aheight)  bheight
              elseif bheight isa Int     bheight
              elseif aheight isa Int     round(Int, aheight * bheight)
              else aheight * bheight end,
-             ifelse(isnothing(b.weight),        a.weight,        b.weight),
-             ifelse(isnothing(b.slant),         a.slant,         b.slant),
-             ifelse(isnothing(b.foreground),    a.foreground,    b.foreground),
-             ifelse(isnothing(b.background),    a.background,    b.background),
-             ifelse(isnothing(b.underline),     a.underline,     b.underline),
-             ifelse(isnothing(b.strikethrough), a.strikethrough, b.strikethrough),
-             ifelse(isnothing(b.inverse),       a.inverse,       b.inverse),
+             isnothing(b.weight)        ? a.weight        : b.weight,
+             isnothing(b.slant)         ? a.slant         : b.slant,
+             isnothing(b.foreground)    ? a.foreground    : b.foreground,
+             isnothing(b.background)    ? a.background    : b.background,
+             isnothing(b.underline)     ? a.underline     : b.underline,
+             isnothing(b.strikethrough) ? a.strikethrough : b.strikethrough,
+             isnothing(b.inverse)       ? a.inverse       : b.inverse,
              a.inherit)
     else
         b_noinherit = Face(
             b.font, b.height, b.weight, b.slant, b.foreground, b.background,
             b.underline, b.strikethrough, b.inverse, Symbol[])
-        b_inheritance = map(fname -> get(Face, FACES.current[], fname), Iterators.reverse(b.inherit))
+        b_inheritance = map(fname -> get(Face, FACES.current[], fname), b.inherit === nothing ? nothing : Iterators.reverse(b.inherit))
         b_resolved = merge(foldl(merge, b_inheritance), b_noinherit)
         merge(a, b_resolved)
     end
@@ -537,7 +537,7 @@ Obtain the final merged face from `faces`, an iterator of
 function getface(faces)
     isempty(faces) && return FACES.current[][:default]
     combined = mapfoldl(_mergedface, merge, faces)::Face
-    if !isempty(combined.inherit)
+    if !isnothing(combined.inherit) && !isempty(combined.inherit)
         combined = merge(Face(), combined)
     end
     merge(FACES.current[][:default], combined)