Add reapply, revert and Base.inv fallbacks (#3)

* Add reapply, revert and Base.inv fallbacks

* Small fix to reapply test

* fix infinite loop and not implemented error

* improve error throwing for revert

Co-authored-by: Júlio Hoffimann <[email protected]>

* improve error throwing for revert

Co-authored-by: Júlio Hoffimann <[email protected]>

* improve error throwing for invert

Co-authored-by: Júlio Hoffimann <[email protected]>

* improve tests

* Update test/runtests.jl

* change testsets to normal tests

* attempt to fix broken CI tests

* Apply suggestions from code review

* Update test/runtests.jl

* Apply suggestions from code review

* Apply suggestions

* Update test/runtests.jl

---------

Co-authored-by: Júlio Hoffimann <[email protected]>

Author: EssamWisam

src/interface.jl

@@ -16,15 +16,6 @@ trait can be evaluated directly at any object.
 """
 abstract type Transform end
 
-"""
-    assertions(transform)
-
-Returns a list of assertion functions for the `transform`. An assertion
-function is a function that takes an object as input and checks if the
-object is valid for the `transform`.
-"""
-function assertions end
-
 """
     isrevertible(transform)
 
@@ -51,6 +42,15 @@ See also [`isrevertible`](@ref).
 """
 function isinvertible end
 
+"""
+    assertions(transform)
+
+Returns a list of assertion functions for the `transform`. An assertion
+function is a function that takes an object as input and checks if the
+object is valid for the `transform`.
+"""
+function assertions end
+
 """
     prep = preprocess(transform, object)
 
@@ -80,19 +80,16 @@ function revert end
 """
     newobject = reapply(transform, object, cache)
 
-Reapply the `transform` to (a possibly different) `object` using a `cache`
-that was created with a previous [`apply`](@ref) call.
+Reapply the `transform` to (a possibly different) `object`
+using a `cache` that was created with a previous [`apply`](@ref)
+call. Fallback to [`apply`](@ref) without using the `cache`.
 """
 function reapply end
 
 # --------------------
 # TRANSFORM FALLBACKS
 # --------------------
 
-assertions(transform::Transform) =
-  assertions(typeof(transform))
-assertions(::Type{<:Transform}) = []
-
 isrevertible(transform::Transform) =
   isrevertible(typeof(transform))
 isrevertible(::Type{<:Transform}) = false
@@ -101,8 +98,13 @@ isinvertible(transform::Transform) =
   isinvertible(typeof(transform))
 isinvertible(::Type{<:Transform}) = false
 
+assertions(transform::Transform) = []
+
 preprocess(transform::Transform, object) = nothing
 
+reapply(transform::Transform, object, cache) =
+  apply(transform, object) |> first
+
 (transform::Transform)(object) =
   apply(transform, object) |> first
 

test/runtests.jl

@@ -7,4 +7,14 @@ using Test
   @test inv(Identity()) == Identity()
   @test inv(Identity() → Identity()) == Identity()
   @test (Identity() → Identity()) == Identity()
+
+  # test fallbacks
+  struct TestTransform <: TransformsBase.Transform end
+  TransformsBase.apply(::TestTransform, x) = x, nothing
+  T = TestTransform()
+  @test !TransformsBase.isrevertible(T)
+  @test !TransformsBase.isinvertible(T)
+  @test TransformsBase.assertions(T) |> isempty
+  @test TransformsBase.preprocess(T, nothing) |> isnothing
+  @test TransformsBase.reapply(T, 1, nothing) == 1
 end