Merge pull request #105 from SymbolicML/read-only-nodes

feat!: create `ReadOnlyNode` for `StructuredExpression` `get_tree` access

Author: MilesCranmer

Project.toml

@@ -1,7 +1,7 @@
 name = "DynamicExpressions"
 uuid = "a40a106e-89c9-4ca8-8020-a735e8728b6b"
 authors = ["MilesCranmer <[email protected]>"]
-version = "1.2.0"
+version = "1.3.0"
 
 [deps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"

src/DynamicExpressions.jl

@@ -21,6 +21,7 @@ using DispatchDoctor: @stable, @unstable
     include("Random.jl")
     include("Parse.jl")
     include("ParametricExpression.jl")
+    include("ReadOnlyNode.jl")
     include("StructuredExpression.jl")
 end
 
@@ -92,6 +93,7 @@ import .ExpressionModule:
 @reexport import .ParseModule: @parse_expression, parse_expression
 import .ParseModule: parse_leaf
 @reexport import .ParametricExpressionModule: ParametricExpression, ParametricNode
+import .ReadOnlyNodeModule: ReadOnlyNode
 @reexport import .StructuredExpressionModule: StructuredExpression
 import .StructuredExpressionModule: AbstractStructuredExpression
 

src/Interfaces.jl

@@ -52,6 +52,7 @@ using ..ExpressionModule:
     with_metadata,
     default_node_type
 using ..ParametricExpressionModule: ParametricExpression, ParametricNode
+using ..ReadOnlyNodeModule: AbstractReadOnlyNode
 using ..StructuredExpressionModule: StructuredExpression
 
 ###############################################################################
@@ -68,7 +69,7 @@ function _check_get_metadata(ex::AbstractExpression)
     return new_ex == ex && new_ex isa typeof(ex)
 end
 function _check_get_tree(ex::AbstractExpression{T,N}) where {T,N}
-    return get_tree(ex) isa N
+    return get_tree(ex) isa N || get_tree(ex) isa AbstractReadOnlyNode{T,N}
 end
 function _check_get_operators(ex::AbstractExpression)
     return get_operators(ex) isa AbstractOperatorEnum
@@ -134,7 +135,8 @@ function _check_constructorof(ex::AbstractExpression)
     return constructorof(typeof(ex)) isa Base.Callable
 end
 function _check_tree_mapreduce(ex::AbstractExpression{T,N}) where {T,N}
-    return tree_mapreduce(node -> [node], vcat, ex) isa Vector{N}
+    return tree_mapreduce(node -> [node], vcat, ex) isa
+           (Vector{N2} where {N2<:Union{N,AbstractReadOnlyNode{T,N}}})
 end
 
 #! format: off

src/ReadOnlyNode.jl

@@ -0,0 +1,30 @@
+module ReadOnlyNodeModule
+
+using ..NodeModule: AbstractExpressionNode, Node
+import ..NodeModule: default_allocator, with_type_parameters, constructorof
+
+abstract type AbstractReadOnlyNode{T,N<:AbstractExpressionNode{T}} <:
+              AbstractExpressionNode{T} end
+
+"""A type of expression node that also stores a parameter index"""
+struct ReadOnlyNode{T,N} <: AbstractReadOnlyNode{T,N}
+    _inner::N
+
+    ReadOnlyNode(n::N) where {T,N<:AbstractExpressionNode{T}} = new{T,N}(n)
+end
+constructorof(::Type{<:ReadOnlyNode}) = ReadOnlyNode
+@inline function Base.getproperty(n::AbstractReadOnlyNode, s::Symbol)
+    out = getproperty(getfield(n, :_inner), s)
+    if out isa AbstractExpressionNode
+        return constructorof(typeof(n))(out)
+    else
+        return out
+    end
+end
+function Base.setproperty!(::AbstractReadOnlyNode, ::Symbol, v)
+    return error("Cannot set properties on a ReadOnlyNode")
+end
+Base.propertynames(n::AbstractReadOnlyNode) = propertynames(getfield(n, :_inner))
+Base.copy(n::AbstractReadOnlyNode) = ReadOnlyNode(copy(getfield(n, :_inner)))
+
+end

src/StructuredExpression.jl

@@ -19,6 +19,7 @@ import ..ExpressionModule:
     node_type,
     get_scalar_constants,
     set_scalar_constants!
+import ..ReadOnlyNodeModule: ReadOnlyNode
 
 abstract type AbstractStructuredExpression{
     T,F<:Function,N<:AbstractExpressionNode{T},E<:AbstractExpression{T,N},D<:NamedTuple
@@ -129,7 +130,7 @@ function get_metadata(e::AbstractStructuredExpression)
     return e.metadata
 end
 function get_tree(e::AbstractStructuredExpression)
-    return get_tree(get_metadata(e).structure(get_contents(e)))
+    return ReadOnlyNode(get_tree(get_metadata(e).structure(get_contents(e))))
 end
 function get_operators(
     e::AbstractStructuredExpression, operators::Union{AbstractOperatorEnum,Nothing}=nothing

test/test_readonlynode.jl

@@ -0,0 +1,69 @@
+@testitem "ReadOnlyNode construction and access" begin
+    using DynamicExpressions
+    using DynamicExpressions: ReadOnlyNode
+
+    inner_node = Node{Float64}(; val=42.0)
+    readonly_node = ReadOnlyNode(inner_node)
+
+    @test readonly_node isa ReadOnlyNode
+    @test getfield(readonly_node, :_inner) === inner_node
+    @test readonly_node.degree == inner_node.degree
+    @test readonly_node.constant == inner_node.constant
+    @test readonly_node.val == inner_node.val
+end
+
+@testitem "ReadOnlyNode immutability" begin
+    using DynamicExpressions
+    using DynamicExpressions: ReadOnlyNode
+
+    inner_node = Node{Float64}(; val=42.0)
+    readonly_node = ReadOnlyNode(inner_node)
+
+    @test_throws ErrorException readonly_node.val = 100.0
+    @test_throws "Cannot set properties on a ReadOnlyNode" readonly_node.val = 100.0
+end
+
+@testitem "ReadOnlyNode - accessing children should return ReadOnlyNode" begin
+    using DynamicExpressions
+    using DynamicExpressions: ReadOnlyNode
+
+    operators = OperatorEnum(; binary_operators=(+, -, *, /), unary_operators=(sin, exp))
+    x1 = Node{Float64}(; feature=1)
+    x2 = Node{Float64}(; feature=2)
+    tree = 2 * x1 - sin(x2)
+    readonly_node = ReadOnlyNode(tree)
+
+    @test typeof(readonly_node.l) === typeof(readonly_node)
+end
+
+@testitem "ReadOnlyNode copy" begin
+    using DynamicExpressions
+    using DynamicExpressions: ReadOnlyNode
+
+    inner_node = Node{Float64}(; val=42.0)
+    readonly_node = ReadOnlyNode(inner_node)
+    copied_node = copy(readonly_node)
+
+    @test copied_node !== readonly_node
+    @test copied_node == readonly_node
+end
+
+@testitem "StructuredExpression returns ReadOnlyNode" begin
+    using DynamicExpressions
+    using DynamicExpressions: ReadOnlyNode
+    using DynamicExpressions: StructuredExpression
+
+    operators = OperatorEnum(; binary_operators=[+, -, *, /], unary_operators=[-, cos, exp])
+    variable_names = ["x", "y"]
+    kws = (; operators, variable_names)
+    f = parse_expression(:(x * x - cos(2.5f0 * y + -0.5f0)); kws...)
+    g = parse_expression(:(exp(-(y * y))); kws...)
+
+    structured_expr = StructuredExpression((; f, g); structure=nt -> nt.f + nt.g, kws...)
+
+    tree = get_tree(structured_expr)
+    @test tree isa ReadOnlyNode
+    @test string_tree(tree, operators; variable_names) ==
+        "((x * x) - cos((2.5 * y) + -0.5)) + exp(-(y * y))"
+    @test getfield(tree, :_inner) isa Node
+end

test/unittest.jl

@@ -129,3 +129,4 @@ include("test_operator_construction_edgecases.jl")
 include("test_node_interface.jl")
 include("test_expression_math.jl")
 include("test_structured_expression.jl")
+include("test_readonlynode.jl")