Added better error messages and use of last on iterators

Project.toml

@@ -1,7 +1,7 @@
 name = "Overseer"
 uuid = "1ada24be-c16d-4464-9f61-27c2e0f16645"
 authors = ["louisponet <[email protected]>"]
-version = "0.2.4"
+version = "0.2.5"
 
 [deps]
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"

src/entity.jl

@@ -80,6 +80,8 @@ function Base.show(io::IO, e::EntityState)
     end
 end
 
+Base.in(::Type{T}, e::EntityState{TT}) where {T, TT} = any(x->eltype(x) == T, TT.parameters)
+
 # TODO: Cleanup, can these two be merged?
 @generated function Base.getproperty(e::EntityState{TT}, f::Symbol) where {TT}
     fn_to_DT = Dict{Symbol, DataType}()
@@ -96,7 +98,7 @@ end
                 ex = MacroTools.postwalk(ex) do x
                     if @capture(x, return getfield(e[$DT_], $fnq)::$ft_)
                         return quote
-                            throw(error("Field $f found in multiple components in $e.\nPlease use entity_state[$($DT)].$f instead."))
+                            error("Field $f found in multiple components in $e.\nPlease use entity_state[$($DT)].$f instead.")
                         end
                     else
                         return x
@@ -131,7 +133,7 @@ end
                 ex = MacroTools.postwalk(ex) do x
                     if @capture(x, setfield!(e[$DT_], $fnq, val))
                         return quote
-                            throw(error("Field $f found in multiple components in $e.\nPlease use entity_state[$($DT)].$f instead."))
+                            error("Field $f found in multiple components in $e.\nPlease use entity_state[$($DT)].$f instead.")
                         end
                     else
                         return x
@@ -154,6 +156,9 @@ end
 
 @generated function component(e::EntityState{TT}, ::Type{T}) where {TT<:Tuple, T}
     id = findfirst(x -> x <: AbstractComponent ? eltype(x) == T : x == T, TT.parameters)
+    if id === nothing
+        error("EntityState{$TT} has no Component{$T}.")
+    end
     return quote
         $(Expr(:meta, :inline))
         @inbounds getfield(e,:components)[$id]

src/iteration.jl

@@ -27,6 +27,15 @@ Base.in(i::Int, it::AbstractIndicesIterator) = it.test(i)
     return it_length
 end
 
+@inline function Base.last(it::IndicesIterator)
+    for i = length(it.shortest):-1:1
+        @inbounds id = entity_index(it.shortest, i)
+        if it.test(id)
+            return id
+        end
+    end
+end
+
 Base.@propagate_inbounds @inline entity_index(c::Union{<:AbstractComponent, Indices}, i::Int) = indices(c).packed[i]
 
 @inline function Base.iterate(it::IndicesIterator, state=1)
@@ -60,6 +69,16 @@ end
     end
 end
 
+@inline function Base.last(it::ReverseIndicesIterator)
+    for i = 1:length(it.shortest)
+        @inbounds id = entity_index(it.shortest, i)
+        if it.test(id)
+            return id
+        end
+    end
+end
+
+
 for (m, it) in zip((:indices_in, :reverse_indices_in), (:IndicesIterator, :ReverseIndicesIterator))
     @eval macro $m(indices_expr)
         expr, t_sets, t_notsets, t_orsets = expand_indices_bool(indices_expr)
@@ -188,7 +207,7 @@ Base.in(e::AbstractEntity, i::EntityIterator) = in(e.id, i.it)
     return EntityState(e, i.components), n[2]
 end
 
-Base.getindex(iterator::EntityIterator, i) = Entity(iterator.it.shortest.packed[i])
+Base.last(i::EntityIterator) = EntityState(Entity(last(i.it)), i.components)
 
 for (m, it_short, it) in zip((:entities_in, :safe_entities_in), (:indices_iterator, :reverse_indices_iterator), (:IndicesIterator, :ReverseIndicesIterator))
     @eval macro $m(indices_expr)

src/ledger.jl

@@ -38,11 +38,7 @@ end
 Ledger(components::Type...) = Ledger(map(x -> component_type(x)(), components)...)
 
 function Ledger(stages::Stage...)
-    comps = Type[] 
-    for stage in stages
-        append!(comps, requested_components(stage)) 
-    end
-    m = Ledger(comps...)
+    m = Ledger()
     m.stages=[stages...]
     prepare(m)
     return m
@@ -261,8 +257,17 @@ function update(m::AbstractLedger)
     end
 end
 
+"""
+    prepare(m)
+
+Goes through all [`Stages`](@ref Stage) in `m`, makes sure that all [`requested_components`](@ref) are present in `m`,
+and then calls [`prepare`](@ref) on the [`Stage`](@ref).
+"""
 function prepare(m::AbstractLedger)
-    for s in stages(m)
-        prepare(s, m)
+    for stage in stages(m)
+        for ct in requested_components(stage)
+            ensure_component!(m, ct)
+        end
+        prepare(stage, m)
     end
 end