Added pickup and drop actions

src/envs/doorkey.jl

@@ -6,7 +6,6 @@ mutable struct DoorKey{W<:GridWorldBase} <: AbstractGridWorld
     world::W
     agent_pos::CartesianIndex{2}
     agent::Agent
-    has_key::Bool
 end
 
 function DoorKey(;n=8, agent_start_pos=CartesianIndex(2,2), rng=Random.GLOBAL_RNG)
@@ -33,21 +32,22 @@ function DoorKey(;n=8, agent_start_pos=CartesianIndex(2,2), rng=Random.GLOBAL_RN
     world[EMPTY, key_pos] = false
     world[Key(:yellow), key_pos] = true
 
-    DoorKey(world, agent_start_pos, Agent(dir=RIGHT),false)
+    DoorKey(world, agent_start_pos, Agent(dir=RIGHT))
 end
 
 function (w::DoorKey)(::MoveForward)
     dir = get_dir(w.agent)
     dest = dir(w.agent_pos)
 
     if w.world[Key(:yellow), dest]
-        w.has_key = true
-        w.world[Key(:yellow), dest] = false
-        w.world[EMPTY, dest] = true
+        if PICKUP(w.agent, Key(:yellow))
+            w.world[Key(:yellow), dest] = false
+            w.world[EMPTY, dest] = true
+        end
         w.agent_pos = dest
-    elseif w.world[Door(:yellow), dest] && w.has_key
+    elseif w.world[Door(:yellow), dest] && w.agent.inv == Key(:yellow)
         w.agent_pos = dest
-    elseif w.world[Door(:yellow), dest] && !w.has_key
+    elseif w.world[Door(:yellow), dest] && w.agent.inv != Key(:yellow)
         nothing
     elseif dest ∈ CartesianIndices((size(w.world, 2), size(w.world, 3))) && !w.world[WALL,dest]
         w.agent_pos = dest

src/objects.jl

@@ -87,6 +87,7 @@ get_color(::Gem) = :magenta
 Base.@kwdef mutable struct Agent <: AbstractObject
     color::Symbol=:red
     dir::LRUD
+    inv::Union{AbstractObject, Nothing}=nothing
 end
 function Base.convert(::Type{Char}, a::Agent)
     if        a.dir === UP
@@ -102,3 +103,41 @@ end
 get_color(a::Agent) = a.color
 get_dir(a::Agent) = a.dir
 set_dir!(a::Agent, d) = a.dir = d
+
+#####
+# Pick Up and Drop
+#####
+
+struct Item end
+struct Nonitem end
+const ITEM = Item()
+const NONITEM = Nonitem()
+isitem(::Type{Key{T}}) where T = ITEM
+isitem(::Type{Gem}) = ITEM
+isitem() = NONITEM
+
+struct Pickup end
+const PICKUP = Pickup()
+
+(::Pickup)(a::Agent, o::T) where T = pickup(isitem(T), a, o)
+function pickup(::Item, a::Agent, o::AbstractObject) 
+    if a.inv == nothing
+        a.inv = o
+        return true
+    end
+    return false
+end
+pickup(a::Agent, ::Nonitem, o::AbstractObject) = nothing
+
+struct Drop end
+const DROP = Drop()
+
+function (::Drop)(a::Agent)
+    if a.inv != nothing
+        x = a.inv
+        a.inv = nothing
+        return x
+    end
+    return nothing
+end
+