Merge pull request #105 from JuliaCollections/constructors

Adds a couple new constructors for `LittleDict` and expands the vector type allowed from `Vector` to `AbstractVector` (solving #104). This also allows us to simplify the constructor methods while still ensuring that the eltype of the storage type matches the key/value of the dict.

Project.toml

@@ -1,6 +1,6 @@
 name = "OrderedCollections"
 uuid = "bac558e1-5e72-5ebc-8fee-abe8a469f55d"
-version = "1.6.1"
+version = "1.6.2"
 
 [compat]
 julia = "1.6"

src/little_dict.jl

@@ -1,4 +1,8 @@
-const StoreType = Union{<:Tuple, <:Vector}
+const StoreType{T} = Union{Tuple{Vararg{T}}, AbstractVector{T}}
+
+@noinline function _throw_unequal_lengths(nk::Int, nv::Int)
+    throw(ArgumentError("Number of keys ($nk) differs from number of values ($nv)."))
+end
 
 """
     LittleDict(keys, vals)<:AbstractDict
@@ -28,22 +32,18 @@ as well as on how many hash collisions occur etc.
     copies to create the `LittleDict`, so `LittleDict(ks::Tuple, vs::Tuple)`
     is the fastest constructor of all.
 """
-struct LittleDict{K,V,KS<:StoreType,VS<:StoreType} <: AbstractDict{K, V}
+struct LittleDict{K, V, KS<:StoreType{K}, VS<:StoreType{V}} <: AbstractDict{K, V}
     keys::KS
     vals::VS
 
-    function LittleDict{K,V,KS,VS}(keys,vals) where {K,V,KS,VS}
-        if length(keys) != length(vals)
-            throw(ArgumentError(
-                "Number of keys ($(length(keys))) differs from " *
-                "number of values ($(length(vals))"
-            ))
-        end
-        K<:eltype(KS) || ArgumentError("Invalid store type $KS, for key type $K")
-        V<:eltype(VS) || ArgumentError("Invalid store type $VS, for value type $K")
-
-        return new(keys,vals)
+    function LittleDict{K, V, KS, VS}(keys, vals) where {K, V, KS, VS}
+        nk = length(keys)
+        nv = length(vals)
+        nk == nv || _throw_unequal_lengths(Int(nk), Int(nv))
+        return new{K, V, KS, VS}(keys, vals)
     end
+    LittleDict{K, V, <:Tuple, <:Tuple}() where {K, V} = new{K, V, Tuple{}, Tuple{}}((), ())
+    LittleDict{K, V, KS, VS}() where {K, V, KS, VS} = LittleDict{K, V, KS, VS}(KS(), VS())
 end
 
 function LittleDict{K,V}(ks::KS, vs::VS) where {K,V, KS<:StoreType,VS<:StoreType}
@@ -54,7 +54,6 @@ function LittleDict(ks::KS, vs::VS) where {KS<:StoreType,VS<:StoreType}
     return LittleDict{eltype(KS), eltype(VS)}(ks, vs)
 end
 
-
 # Other iterators should be copied to a Vector
 LittleDict(ks, vs) = LittleDict(collect(ks), collect(vs))
 
@@ -110,8 +109,8 @@ end
 isordered(::Type{<:LittleDict}) = true
 
 # For now these are internal UnionAlls for dispatch purposes
-const UnfrozenLittleDict{K,V} = LittleDict{K,V, Vector{K}, Vector{V}}
-const FrozenLittleDict{K,V} = LittleDict{K,V, <:Tuple, <:Tuple}
+const UnfrozenLittleDict{K, V} = LittleDict{K, V, <:AbstractVector{K}, <:AbstractVector{V}}
+const FrozenLittleDict{K, V} = LittleDict{K, V, <:Tuple, <:Tuple}
 
 ##### Methods that all AbstractDicts should implement
 
@@ -184,7 +183,9 @@ function merge(
 end
 
 
-Base.empty(dd::LittleDict{K,V}) where {K,V} = LittleDict{K,V}()
+function Base.empty(dd::LittleDict{K,V}) where {K,V}
+    LittleDict{K, V}(empty(getfield(dd, :keys)), empty(getfield(dd, :vals)))
+end
 
 ######## Methods that all mutable AbstractDict's should implement
 

test/test_little_dict.jl

@@ -39,6 +39,7 @@ using OrderedCollections: FrozenLittleDict, UnfrozenLittleDict
     end
 
     @testset "Constructors" begin
+        @test isa(@inferred(LittleDict{Any, Any, <:Tuple, <:Tuple}()), LittleDict{Any, Any, Tuple{}, Tuple{}})
         @test isa(@inferred(LittleDict()), LittleDict{Any,Any})
         @test isa(@inferred(LittleDict([(1,2.0)])), LittleDict{Int,Float64})