feat: StdPriorityQueue (#441)

* feat: StdPriorityQueue

* test: StdPriorityQueue

Author: PraneethJain

src/CxxWrap.jl

@@ -948,8 +948,8 @@ ConstCxxPtr, ConstCxxRef, CxxRef, CxxPtr,
 CppEnum, ConstArray, CxxBool, CxxLong, CxxULong, CxxChar, CxxChar16, CxxChar32, CxxWchar, CxxUChar, CxxSignedChar,
 CxxLongLong, CxxULongLong, ptrunion, gcprotect, gcunprotect, isnull
 
-using .StdLib: StdVector, StdString, StdWString, StdValArray, StdThread, StdDeque, StdQueue, StdSet, StdMultiset, StdUnorderedSet, StdUnorderedMultiset
+using .StdLib: StdVector, StdString, StdWString, StdValArray, StdThread, StdDeque, StdQueue, StdSet, StdMultiset, StdUnorderedSet, StdUnorderedMultiset, StdPriorityQueue
 
-export StdLib, StdVector, StdString, StdWString, StdValArray, StdThread, StdDeque, StdQueue, StdSet, StdMultiset, StdUnorderedSet, StdUnorderedMultiset
+export StdLib, StdVector, StdString, StdWString, StdValArray, StdThread, StdDeque, StdQueue, StdSet, StdMultiset, StdUnorderedSet, StdUnorderedMultiset, StdPriorityQueue
 
 end # module

src/StdLib.jl

@@ -230,6 +230,18 @@ for StdMultisetType in (StdMultiset, StdUnorderedMultiset)
   Base.count(x, v::StdMultisetType) = multiset_count(v, x)
 end
 
+Base.size(v::StdPriorityQueue) = (Int(cppsize(v)),)
+Base.length(v::StdPriorityQueue) = Int(cppsize(v))
+Base.isempty(v::StdPriorityQueue) = pq_isempty(v)
+Base.first(v::StdPriorityQueue) = isempty(v) ? nothing : pq_top(v)
+Base.push!(v::StdPriorityQueue, x) = (pq_push!(v, x); v)
+function Base.pop!(v::StdPriorityQueue)
+  isempty(v) && throw(ArgumentError("Cannot pop from an empty priority queue"))
+  val = pq_top(v)
+  pq_pop!(v)
+  return val
+end
+
 function Base.fill!(v::T, x) where T <: Union{StdVector, StdValArray, StdDeque}
   StdFill(v, x)
   return v

test/stdlib.jl

@@ -327,6 +327,26 @@ let
   @test length(queue) == 1
 end
 
+@testset "StdPriorityQueue" begin
+  pq = StdPriorityQueue{Int64}()
+  @test length(pq) == 0
+  push!(pq, 5)
+  push!(pq, 1)
+  @test isempty(pq) == false
+  pq = push!(pq, 4)
+  pq = push!(pq, 10)
+  @test length(pq) == 4
+  @test first(pq) == 10
+  @test pop!(pq) == 10
+  @test length(pq) == 3
+  @test pop!(pq) == 5
+  @test pop!(pq) == 4
+  @test pop!(pq) == 1
+  @test isempty(pq) == true
+  @test isnothing(first(pq))
+  @test_throws ArgumentError pop!(pq)
+end
+
 @testset "StdSet and StdUnorderedSet" begin
   for StdSetType in (StdSet, StdUnorderedSet)
     @testset "Set with integers" begin