updates for Add Mul Pow

Author: shashi

src/ModelingToolkit.jl

@@ -23,7 +23,7 @@ RuntimeGeneratedFunctions.init(@__MODULE__)
 using RecursiveArrayTools
 
 import SymbolicUtils
-import SymbolicUtils: Term, Sym, to_symbolic, FnType, @rule, Rewriters, substitute, similarterm
+import SymbolicUtils: Term, Add, Mul, Pow, Sym, to_symbolic, FnType, @rule, Rewriters, substitute, similarterm
 
 using LinearAlgebra: LU, BlasInt
 
@@ -72,7 +72,17 @@ Base.show(io::IO, n::Num) = show_numwrap[] ? print(io, :(Num($(value(n))))) : Ba
 
 Base.promote_rule(::Type{<:Number}, ::Type{<:Num}) = Num
 Base.promote_rule(::Type{<:Symbolic{<:Number}}, ::Type{<:Num}) = Num
-Base.getproperty(t::Term, f::Symbol) = f === :op ? operation(t) : f === :args ? arguments(t) : getfield(t, f)
+function Base.getproperty(t::Union{Add, Mul, Pow, Term}, f::Symbol)
+    if f === :op
+        Base.depwarn("`x.op` is deprecated, use `operation(x)` instead", :getproperty, force=true)
+        operation(t)
+    elseif f === :args
+        Base.depwarn("`x.args` is deprecated, use `arguments(x)` instead", :getproperty, force=true)
+        arguments(t)
+    else
+        getfield(t, f)
+    end
+end
 <ₑ(s::Num, x) = value(s) <ₑ value(x)
 <ₑ(s, x::Num) = value(s) <ₑ value(x)
 <ₑ(s::Num, x::Num) = value(s) <ₑ value(x)

src/context_dsl.jl

@@ -1,10 +1,14 @@
-import SymbolicUtils: symtype
+import SymbolicUtils: symtype, term
 struct Parameter{T} end
 
 isparameter(x) = false
 isparameter(::Sym{<:Parameter}) = true
 isparameter(::Sym{<:FnType{<:Any, <:Parameter}}) = true
 
+SymbolicUtils.@number_methods(Sym{Parameter{Real}},
+                              term(f, a),
+                              term(f, a, b), skipbasics)
+
 SymbolicUtils.symtype(s::Symbolic{Parameter{T}}) where T = T
 SymbolicUtils.similarterm(t::Term{T}, f, args) where {T<:Parameter} = Term{T}(f, args)
 

src/differentials.jl

@@ -61,9 +61,9 @@ $(SIGNATURES)
 
 TODO
 """
-function expand_derivatives(O::Term, simplify=true; occurances=nothing)
-    if isa(O.op, Differential)
-        @assert length(O.args) == 1
+function expand_derivatives(O::Symbolic, simplify=true; occurances=nothing)
+    if istree(O) && isa(operation(O), Differential)
+        @assert length(arguments(O)) == 1
         arg = expand_derivatives(O.args[1], false)
 
         if occurances == nothing
@@ -75,21 +75,21 @@ function expand_derivatives(O::Term, simplify=true; occurances=nothing)
 
         (D, o) = (O.op, arg)
 
-        if !isa(o, Term)
+        if !istree(o)
             return O # Cannot expand
-        elseif isa(o.op, Sym)
+        elseif isa(operation(o), Sym)
             return O # Cannot expand
-        elseif isa(o.op, Differential)
+        elseif isa(operation(o), Differential)
             # The recursive expand_derivatives was not able to remove
             # a nested Differential. We can attempt to differentiate the
             # inner expression wrt to the outer iv. And leave the
             # unexpandable Differential outside.
             if isequal(o.op.x, D.x)
                 return O
             else
-                inner = expand_derivatives(D(o.args[1]), false)
+                inner = expand_derivatives(D(arguments(o)[1]), false)
                 # if the inner expression is not expandable either, return
-                if inner isa Term && operation(inner) isa Differential
+                if istree(inner) && operation(inner) isa Differential
                     return O
                 else
                     return expand_derivatives(o.op(inner), simplify)
@@ -187,7 +187,9 @@ sin(x())
 ```
 """
 derivative_idx(O::Any, ::Any) = 0
-derivative_idx(O::Term, idx) = derivative(O.op, (O.args...,), Val(idx))
+function derivative_idx(O::Symbolic, idx)
+    istree(O) ? derivative(operation(O), (arguments(O)...,), Val(idx)) : 0
+end
 
 # Indicate that no derivative is defined.
 struct NoDeriv