modify

Author: rafaqz

src/optics.jl

@@ -133,6 +133,8 @@ struct ConstructIfChanged{C}
     constructor::C
 end
 
+_constructor(x, t) = _constructor(x.handler, t)
+
 # TODO what do we call these things?
 struct Construct end
 _constructor(::Construct, ::Type{T}) where T = constructorof(T)
@@ -249,6 +251,19 @@ function modify(f, obj, w::If)
     end
 end
 
+struct Select{C}
+    select_condition::C
+end
+OpticStyle(::Type{<:If}) = ModifyBased()
+
+function modify(f, obj, w::If)
+    if w.modify_condition(obj)
+        (obj,)
+    else
+        ()
+    end
+end
+
 """
     mapproperties(f, obj)
 
@@ -265,24 +280,31 @@ julia> Accessors.mapproperties(x -> x+1, obj)
 ```
 $EXPERIMENTAL
 """
-function mapproperties(f, obj::O, handler=Construct(), itr=nothing) where O
+function mapproperties(f, obj::O, optic, itr::Nothing=nothing) where O
     # TODO move this helper elsewhere?
+    pnames = propertynames(obj)
+    if isempty(pnames)
+        return obj
+    else
+        ctor = constructorof(typeof(obj))
+        new_props = map(pnames) do p
+            f(getproperty(obj, p))
+        end
+        ctr = _constructor(optic, O)
+        return ctr(new_props...)
+    end
+end
+function mapproperties(f, obj::O, optic, itr::Int) where O
     pnames = propertynames(obj)
     if isempty(pnames)
         return _maybeitr(obj, itr)
     else
         # TODO: this is too slow
         new_props, itr = reduce(pnames; init=((), itr)) do (vals, itr), p
-            prop = getproperty(obj, p)
-            if itr isa Nothing
-                val = f(prop)
-                (vals..., val), itr
-            else
-                val, itr = f(prop, itr)
-                (vals..., val), itr
-            end
+            val, itr = f(getproperty(obj, p), itr)
+            (vals..., val), itr
         end
-        ctr = _constructor(handler, O)
+        ctr = _constructor(optic, O)
         return _maybeitr(ctr(new_props...), itr)
     end
 end
@@ -308,7 +330,10 @@ Based on [`mapproperties`](@ref).
 
 $EXPERIMENTAL
 """
-struct Properties end
+struct Properties{H}
+    handler::H
+end
+Properties() = Properties(Construct())
 OpticStyle(::Type{<:Properties}) = ModifyBased()
 modify(f, o, ::Properties) = mapproperties(f, o)
 
@@ -328,7 +353,7 @@ julia> Accessors.mapfields(x -> x+1, obj)
 ```
 $EXPERIMENTAL
 """
-@generated function mapfields(f, obj::O, handler::H=Construct(), itr::I=nothing) where {O,H,I}
+@generated function mapfields(f, obj::O, optic, itr::I=nothing) where {O,H,I}
     # TODO: This is how Flatten.jl works, but it's not really 
     # correct use of ConstructionBase as it assumers properties=fields
     fnames = fieldnames(O)
@@ -350,23 +375,23 @@ $EXPERIMENTAL
             end
             new_prop_exp = Expr(:tuple, val_exps...)
         end
-        # ret = if H == MaybeConstruct
-            # quote
+        ret = if H == MaybeConstruct
+            quote
                 # TODO: last type instability.
                 # replace this with val => Changed(), val => Unchanged()
                 # return values. 
                 #
                 # Don't construct when we don't absolutely have to.
                 # `constructorof` may not be defined for an object.
-                # if props === new_props
-                    # return obj, itr
-                # else
-                    # return _maybeitr($ctr(new_props...), itr)
-                # end
-            # end
-        # else 
+                if props === new_props
+                    return _maybeitr(obj, itr)
+                else
+                    return _maybeitr($ctr(new_props...), itr)
+                end
+            end
+        else 
             ret = :(return _maybeitr($ctr(new_props...), itr))
-        # end
+        end
         quote 
             props = $prop_exp
             new_props = $new_prop_exp
@@ -399,9 +424,12 @@ Based on [`mapfields`](@ref).
 
 $EXPERIMENTAL
 """
-struct Fields end
+struct Fields{H} 
+    handler::H
+end
+Fields() = Fields(Construct())
 OpticStyle(::Type{<:Fields}) = ModifyBased()
-modify(f, o, ::Fields) = mapfields(f, o)
+modify(f, o, optic::Fields) = mapfields(f, o, optic)
 
 """
     Recursive(descent_condition, optic)
@@ -505,7 +533,7 @@ struct Query{Select,Descend,Optic}
     descent_condition::Descend
     optic::Optic
 end
-Query(select, ignore = x -> true) = Query(select, ignore, Fields())
+Query(select, descend = x -> true) = Query(select, descend, Fields())
 Query(; select=Any, descend=x -> true, optic=Fields()) = Query(select, descend, optic)
 
 function (q::Query)(obj)
@@ -534,6 +562,8 @@ function _setquery(obj, q::Query, (val, itr))
     end
 end
 
-_query(f, o, ::Elements, handler, itr) = map(f, o)
-_query(f, o, ::Fields, handler, itr) = mapfields(f, o, handler, itr)
-_query(f, o, ::Properties, handler, itr) = mapproperties(f, o, handler, itr)
+modify(f, obj, q::Query) = set(obj, q, map(f, q(obj)))
+
+_query(f, o, ::Elements, itr) = map(f, o)
+_query(f, o, ::Fields, itr) = mapfields(f, o, itr)
+_query(f, o, ::Properties, itr) = mapproperties(f, o, itr)