Merge pull request #108 from maltezfaria/master

lazy reverse iteration of `OrderedDict`

Project.toml

@@ -1,6 +1,6 @@
 name = "OrderedCollections"
 uuid = "bac558e1-5e72-5ebc-8fee-abe8a469f55d"
-version = "1.6.2"
+version = "1.6.3"
 
 [compat]
 julia = "1.6"

src/little_dict.jl

@@ -156,6 +156,13 @@ function Base.iterate(dd::LittleDict, ii=1)
     return (dd.keys[ii] => dd.vals[ii], ii+1)
 end
 
+# lazy reverse iteration
+function Base.iterate(rdd::Iterators.Reverse{<:LittleDict}, ii=length(rdd.itr.keys))
+    dd = rdd.itr
+    ii < 1 && return nothing
+    return (dd.keys[ii] => dd.vals[ii], ii-1)
+end
+
 function merge(d1::LittleDict, others::AbstractDict...)
     return merge((x,y)->y, d1, others...)
 end

src/ordered_dict.jl

@@ -459,6 +459,21 @@ function iterate(t::OrderedDict, i)
     return (Pair(t.keys[i], t.vals[i]), i+1)
 end
 
+# lazy reverse iteration
+function iterate(rt::Iterators.Reverse{<:OrderedDict})
+    t = rt.itr
+    t.ndel > 0 && rehash!(t)
+    n = length(t.keys)
+    n < 1 && return nothing
+    return (Pair(t.keys[n], t.vals[n]), n - 1)
+end
+function iterate(rt::Iterators.Reverse{<:OrderedDict}, i)
+    t = rt.itr
+    i < 1 && return nothing
+    return (Pair(t.keys[i], t.vals[i]), i - 1)
+end
+
+
 function _merge_kvtypes(d, others...)
     K, V = keytype(d), valtype(d)
     for other in others

src/ordered_set.jl

@@ -54,6 +54,13 @@ function iterate(s::OrderedSet, i)
     return (s.dict.keys[i], i+1)
 end
 
+# lazy reverse iteration
+function iterate(rs::Iterators.Reverse{<:OrderedSet}, i = length(rs.itr))
+    s = rs.itr
+    i < 1 && return nothing
+    return (s.dict.keys[i], i-1)
+end
+
 pop!(s::OrderedSet) = pop!(s.dict)[1]
 popfirst!(s::OrderedSet) = popfirst!(s.dict)[1]
 

test/test_little_dict.jl

@@ -559,5 +559,18 @@ end # @testset LittleDict
         map!(v->v-1, values(testdict))
         @test testdict[:a] == 0
         @test testdict[:b] == 1
-end
+    end
+
+    @testset "lazy reverse iteration" begin
+        ks = collect('a':'z')
+        vs = collect(0:25)
+        ld = LittleDict(ks, vs)
+        pass = true
+        for (n,(k,v)) in enumerate(Iterators.reverse(ld))
+            pass &= reverse(ks)[n] == k
+            pass &= reverse(vs)[n] == v
+        end
+        @test pass
+    end
+
 end

test/test_ordered_dict.jl

@@ -456,10 +456,22 @@ using OrderedCollections, Test
     end
 
     @testset "ordered access" begin
-        od = OrderedDict(:a=>1, :b=>2, :c=>3)  
+        od = OrderedDict(:a=>1, :b=>2, :c=>3)
         @test popfirst!(od) == (:a => 1)
         @test :a ∉ keys(od)
         @test pop!(od) == (:c => 3)
         @test :c ∉ keys(od)
     end
+
+    @testset "lazy reverse iteration" begin
+        ks = collect('a':'z')
+        vs = collect(0:25)
+        od   = OrderedDict(k=>v for (k,v) in zip(ks, vs))
+        pass = true
+        for (n,(k,v)) in enumerate(Iterators.reverse(od))
+            pass &= reverse(ks)[n] == k
+            pass &= reverse(vs)[n] == v
+        end
+        @test pass
+    end
 end # @testset OrderedDict

test/test_ordered_set.jl

@@ -259,4 +259,13 @@ using OrderedCollections, Test
         @test issorted(ox; rev=true)
     end
 
+    @testset "lazy reverse iteration" begin
+        ks = collect('a':'z')
+        os  = OrderedSet(ks)
+        pass = true
+        for (n,k) in enumerate(Iterators.reverse(os))
+            pass &= reverse(ks)[n] == k
+        end
+        @test pass
+    end
 end # @testset OrderedSet