Merge pull request #474 from SciML/s/hash

hash for Operation

Author: ChrisRackauckas

Project.toml

@@ -43,7 +43,7 @@ RecursiveArrayTools = "2.3"
 SafeTestsets = "0.0.1"
 SpecialFunctions = "0.7, 0.8, 0.9, 0.10"
 StaticArrays = "0.10, 0.11, 0.12"
-SymbolicUtils = "0.3.3, 0.4"
+SymbolicUtils = "0.4.1"
 TreeViews = "0.3"
 UnPack = "0.1, 1.0"
 Unitful = "1.1"

src/equations.jl

@@ -13,6 +13,7 @@ struct Equation
     rhs::Expression
 end
 Base.:(==)(a::Equation, b::Equation) = isequal((a.lhs, a.rhs), (b.lhs, b.rhs))
+Base.hash(a::Equation, salt::UInt) = hash(a.lhs, hash(a.rhs, salt))
 
 """
 $(TYPEDSIGNATURES)

src/operations.jl

@@ -54,6 +54,8 @@ Base.isequal(::Variable , ::Operation) = false
 Base.isequal(::Operation, ::Constant ) = false
 Base.isequal(::Constant , ::Operation) = false
 
+Base.hash(o::Operation, salt::UInt) = hash(o.args, hash(o.op, salt))
+
 # provide iszero for Operations to help sparse addition and multiplication
 # e.g., we want to tell the sparse library that iszero(zero(Operation) + zero(Operation)) == true
 Base.iszero(x::Operation) = (_x = simplify(x); _x isa Constant && iszero(_x.value))

test/operation_overloads.jl

@@ -5,6 +5,18 @@ using Test
 
 @variables a,b,c,d
 
+# test hashing
+aa = a; # old a
+
+@variables a
+
+@test isequal(a, aa)
+@test hash(a) == hash(aa)
+
+@test isequal(get_variables(a+aa+1), [a])
+
+@test hash(a+b ~ c+d) == hash(a+b ~ c+d)
+
 # test some matrix operations don't throw errors
 X = [a b;c d]
 det(X)