Allow duplicate values.

src/EnumX.jl

@@ -6,12 +6,15 @@ export @enumx
 
 abstract type Enum{T} <: Base.Enum{T} end
 
-panic(x) = throw(ArgumentError(x))
+@noinline panic(x) = throw(ArgumentError(x))
+@noinline panic() = error("unreachable")
 
 macro enumx(args...)
     return enumx(__module__, args...)
 end
 
+function symbol_map end
+
 function enumx(_module_, name, args...)
     if name isa Symbol
         modname = name
@@ -29,7 +32,7 @@ function enumx(_module_, name, args...)
     else
         syms = args
     end
-    namemap = Dict{baseT,Symbol}()
+    name_value_map = Vector{Pair{Symbol, baseT}}()
     next = zero(baseT)
     for s in syms
         s isa LineNumberNode && continue
@@ -52,46 +55,51 @@ function enumx(_module_, name, args...)
         else
             panic("invalid EnumX.@enumx entry: $(s)")
         end
-        if next in keys(namemap)
-            panic(
-                "duplicate value for Enum $(modname): $(modname).$(sym) = $(next)," *
-                " value already used for $(modname).$(namemap[next]) = $(next)."
-            )
-        elseif sym in values(namemap)
-            value = findfirst(x -> x === sym, namemap)
+        if (idx = findfirst(x -> x.first === sym, name_value_map); idx !== nothing)
+            v = name_value_map[idx].second
             panic(
                 "duplicate name for Enum $(modname): $(modname).$(sym) = $(next)," *
-                " name already used for $(modname).$(namemap[value]) = $(value)."
+                " name already used for $(modname).$(sym) = $(v)."
             )
         end
-        namemap[next] = sym
+        push!(name_value_map, sym => next)
 
         next += oneunit(baseT)
     end
+    value_name_map = Dict{baseT,Symbol}(v => k for (k, v) in reverse(name_value_map))
     module_block = quote
         primitive type Type <: Enum{$(baseT)} $(sizeof(baseT) * 8) end
-        let namemap = $(namemap)
-            check_valid(x) = x in keys(namemap) ||
+        let value_name_map = $(value_name_map)
+            check_valid(x) = x in keys(value_name_map) ||
                 throw(ArgumentError("invalid value for Enum $($(QuoteNode(modname))): $(x)."))
             global function $(esc(:Type))(x::Integer)
                 check_valid(x)
                 return Base.bitcast($(esc(:Type)), convert($(baseT), x))
             end
-            Base.Enums.namemap(::Base.Type{$(esc(:Type))}) = namemap
+            Base.Enums.namemap(::Base.Type{$(esc(:Type))}) = value_name_map
             Base.Enums.instances(::Base.Type{$(esc(:Type))}) =
-                ($([esc(k) for k in values(namemap)]...),)
+                ($([esc(k) for (k,v) in name_value_map]...),)
+            EnumX.symbol_map(::Base.Type{$(esc(:Type))}) = $(name_value_map)
         end
     end
-    for (k, v) in namemap
+    for (k, v) in name_value_map
         push!(module_block.args,
-            Expr(:const, Expr(:(=), esc(v), Expr(:call, esc(:Type), k)))
+            Expr(:const, Expr(:(=), esc(k), Expr(:call, esc(:Type), v)))
         )
     end
     return Expr(:toplevel, Expr(:module, false, esc(modname), module_block), nothing)
 end
 
 function Base.show(io::IO, ::MIME"text/plain", x::E) where E <: Enum
-    print(io, "$(nameof(parentmodule(E))).$(Symbol(x)::Symbol) = $(Integer(x))")
+    iob = IOBuffer()
+    ix = Integer(x)
+    for (k, v) in symbol_map(E)
+        if v == ix
+            print(iob, "$(nameof(parentmodule(E))).$(k) = ")
+        end
+    end
+    print(iob, "$(Integer(x))")
+    write(io, seekstart(iob))
     return nothing
 end
 function Base.show(io::IO, ::MIME"text/plain", ::Base.Type{E}) where E <: Enum
@@ -99,7 +107,7 @@ function Base.show(io::IO, ::MIME"text/plain", ::Base.Type{E}) where E <: Enum
     insts = Base.Enums.instances(E)
     n = length(insts)
     stringmap = Dict{String, Int32}(
-        string("$(nameof(parentmodule(E))).", v) => k for (k, v) in Base.Enums.namemap(E)
+        string("$(nameof(parentmodule(E))).", k) => v for (k, v) in symbol_map(E)
     )
     mx = maximum(textwidth, keys(stringmap); init = 0)
     print(iob,

test/runtests.jl

@@ -90,6 +90,7 @@ end
 
 try
     @macroexpand @enumx (Fr + uit) Apple
+    error()
 catch err
     err isa LoadError && (err = err.error)
     @test err isa ArgumentError
@@ -135,6 +136,7 @@ end
 
 try
     @macroexpand @enumx Fruit::Int8 Apple=typemax(Int8) Banana
+    error()
 catch err
     err isa LoadError && (err = err.error)
     @test err isa ArgumentError
@@ -142,6 +144,7 @@ catch err
 end
 try
     @macroexpand @enumx Fruit::Int8 Apple="apple"
+    error()
 catch err
     err isa LoadError && (err = err.error)
     @test err isa ArgumentError
@@ -149,6 +152,7 @@ catch err
 end
 try
     @macroexpand @enumx Fruit::Int8 Apple=128
+    error()
 catch err
     err isa LoadError && (err = err.error)
     @test err isa ArgumentError
@@ -156,24 +160,36 @@ catch err
 end
 try
     @macroexpand @enumx Fruit::Int8 Apple()
+    error()
 catch err
     err isa LoadError && (err = err.error)
     @test err isa ArgumentError
     @test err.msg == "invalid EnumX.@enumx entry: Apple()"
 end
-try
-    @macroexpand @enumx Fruit Apple=0 Banana=0
-catch err
-    err isa LoadError && (err = err.error)
-    @test err isa ArgumentError
-    @test err.msg == "duplicate value for Enum Fruit: Fruit.Banana = 0, value already used for Fruit.Apple = 0."
-end
 try
     @macroexpand @enumx Fruit Apple Apple
+    error()
 catch err
     err isa LoadError && (err = err.error)
     @test err isa ArgumentError
     @test err.msg == "duplicate name for Enum Fruit: Fruit.Apple = 1, name already used for Fruit.Apple = 0."
 end
 
+
+# Duplicate values
+@enumx FruitDup Apple=0 Banana=0
+@test FruitDup.Apple === FruitDup.Banana === FruitDup.Type(0)
+
+let io = IOBuffer()
+    show(io, "text/plain", FruitDup.Type)
+    str = String(take!(io))
+    @test str == "Enum type FruitDup.Type <: Enum{Int32} with 2 instances:\nFruitDup.Apple  = 0\nFruitDup.Banana = 0"
+    show(io, "text/plain", FruitDup.Apple)
+    str = String(take!(io))
+    @test str == "FruitDup.Apple = FruitDup.Banana = 0"
+    show(io, "text/plain", FruitDup.Banana)
+    str = String(take!(io))
+    @test str == "FruitDup.Apple = FruitDup.Banana = 0"
+end
+
 end # testset