fix: generalize combine_operators

Author: MilesCranmer

src/ParametricExpression.jl

@@ -15,7 +15,6 @@ import ..NodeUtilsModule:
     get_constants,
     set_constants!
 import ..StringsModule: string_tree
-import ..SimplifyModule: combine_operators, simplify_tree!
 import ..EvaluateModule: eval_tree_array
 import ..EvaluateDerivativeModule: eval_grad_tree_array
 import ..EvaluationHelpersModule: _grad_evaluator

src/PatchMethods.jl

@@ -1,5 +1,6 @@
 module PatchMethodsModule
 
+using DynamicExpressions: get_contents, with_contents
 using ..OperatorEnumModule: AbstractOperatorEnum
 using ..NodeModule: constructorof
 using ..ExpressionModule: Expression, get_tree, get_operators
@@ -11,17 +12,15 @@ function combine_operators(
     ex::Union{Expression{T,N},ParametricExpression{T,N}},
     operators::Union{AbstractOperatorEnum,Nothing}=nothing,
 ) where {T,N}
-    return constructorof(typeof(ex))(
-        combine_operators(get_tree(ex)::N, get_operators(ex, operators)), ex.metadata
+    return with_contents(
+        ex, combine_operators(get_contents(ex), get_operators(ex, operators))
     )
 end
 function simplify_tree!(
     ex::Union{Expression{T,N},ParametricExpression{T,N}},
     operators::Union{AbstractOperatorEnum,Nothing}=nothing,
 ) where {T,N}
-    return constructorof(typeof(ex))(
-        simplify_tree!(get_tree(ex)::N, get_operators(ex, operators)), ex.metadata
-    )
+    return with_contents(ex, simplify_tree!(get_contents(ex), get_operators(ex, operators)))
 end
 
 end

src/Simplify.jl

@@ -15,7 +15,8 @@ is_commutative(_) = false
 is_subtraction(::typeof(-)) = true
 is_subtraction(_) = false
 
-# This is only defined for `Node` as it is not possible for
+combine_operators(tree::AbstractExpressionNode, ::AbstractOperatorEnum) = tree
+# This is only defined for `Node` as it is not possible for, e.g.,
 # `GraphNode`.
 function combine_operators(tree::Node{T}, operators::AbstractOperatorEnum) where {T}
     # NOTE: (const (+*-) const) already accounted for. Call simplify_tree! before.