added obs_weight

src/obs_weight.jl

@@ -0,0 +1,48 @@
+@generated function obs_weight(p, s, a, sp, o)
+    if implemented(obs_weight, Tuple{p, a, sp, o})
+        return :(obs_weight(p, a, sp, o))
+    elseif implemented(observation, Tuple{p, s, a, sp})
+        return :(pdf(observation(p, s, a, sp), o))
+    else
+        return :(throw(MethodError(obs_weight, (p,s,a,sp,o))))
+    end
+end
+
+@generated function obs_weight(p, a, sp, o)
+    if implemented(obs_weight, Tuple{p, sp, o})
+        return :(obs_weight(p, sp, o))
+    elseif implemented(observation, Tuple{p, a, sp})
+        return :(pdf(observation(p, a, sp), o))
+    else
+        return :(throw(MethodError(obs_weight, (p, a, sp, o))))
+    end
+end
+
+@generated function obs_weight(p, sp, o)
+    if implemented(observation, Tuple{p, sp})
+        return :(pdf(observation(p, sp), o))
+    else
+        return :(throw(MethodError(obs_weight, (p, sp, o))))
+    end
+end
+
+function implemented(f::typeof(obs_weight), TT::Type)
+    m = which(f, TT)
+    if length(TT.parameters) == 5
+        P, S, A, _, O = TT.parameters
+        reqs_met = implemented(observation, Tuple{P,S,A,S}) || implemented(obs_weight, Tuple{P,A,S,O})
+    elseif length(TT.parameters) == 4
+        P, A, S, O = TT.parameters
+        reqs_met = implemented(observation, Tuple{P,A,S}) || implemented(obs_weight, Tuple{P,S,O})
+    elseif length(TT.parameters) == 3
+        P, S, O = TT.parameters
+        reqs_met = implemented(observation, Tuple{P,S})
+    else
+        return method_exists(f, TT)
+    end
+    if m.module == ParticleFilters && !reqs_met
+        return false
+    else
+        true
+    end
+end