refactor: remove ParameterIndexingProxy, add get_p and set_p functions

Author: AayushSabharwal

src/SymbolicIndexingInterface.jl

@@ -13,8 +13,8 @@ include("interface.jl")
 export SymbolCache
 include("symbol_cache.jl")
 
-export ParameterIndexingProxy, parameter_values
-include("parameter_indexing_proxy.jl")
+export parameter_values, getp, setp
+include("parameter_indexing.jl")
 
 @static if !isdefined(Base, :get_extension)
     function __init__()

src/parameter_indexing.jl

@@ -0,0 +1,89 @@
+"""
+    parameter_values(p)
+
+Return an indexable collection containing the value of each parameter in `p`.
+"""
+function parameter_values end
+
+"""
+    getp(sys, p)
+
+Return a function that takes an integrator or solution of `sys`, and returns the value of
+the parameter `p`. Requires that the integrator or solution implement
+[`parameter_values`](@ref).
+"""
+function getp(sys, p)
+    symtype = symbolic_type(p)
+    elsymtype = symbolic_type(eltype(p))
+    if symtype != NotSymbolic()
+        return _getp(sys, symtype, p)
+    else
+        return _getp(sys, elsymtype, p)
+    end
+end
+
+function _getp(sys, ::NotSymbolic, p)
+    return function getter(sol)
+        return parameter_values(sol)[p]
+    end
+end
+
+function _getp(sys, ::ScalarSymbolic, p)
+    idx = parameter_index(sys, p)
+    return function getter(sol)
+        return parameter_values(sol)[idx]
+    end
+end
+
+function _getp(sys, ::ScalarSymbolic, p::Union{Tuple,AbstractArray})
+    idxs = parameter_index.((sys,), p)
+    return function getter(sol)
+        return getindex.((parameter_values(sol),), idxs)
+    end
+end
+
+function _getp(sys, ::ArraySymbolic, p)
+    return getp(sys, collect(p))
+end
+
+"""
+    setp(sys, p)
+
+Return a function that takes an integrator of `sys` and a value, and sets the
+the parameter `p` to that value. Requires that the integrator implement
+[`parameter_values`](@ref) and the returned collection be a mutable reference
+to the parameter vector in the integrator.
+"""
+function setp(sys, p)
+    symtype = symbolic_type(p)
+    elsymtype = symbolic_type(eltype(p))
+    if symtype != NotSymbolic()
+        return _setp(sys, symtype, p)
+    else
+        return _setp(sys, elsymtype, p)
+    end
+end
+
+function _setp(sys, ::NotSymbolic, p)
+    return function setter!(sol, val)
+        parameter_values(sol)[p] = val
+    end
+end
+
+function _setp(sys, ::ScalarSymbolic, p)
+    idx = parameter_index(sys, p)
+    return function setter!(sol, val)
+        parameter_values(sol)[idx] = val
+    end
+end
+
+function _setp(sys, ::ScalarSymbolic, p::Union{Tuple,AbstractArray})
+    idxs = parameter_index.((sys,), p)
+    return function setter!(sol, val)
+        setindex!.((parameter_values(sol),), val, idxs)
+    end
+end
+
+function _setp(sys, ::ArraySymbolic, p)
+    return setp(sys, collect(p))
+end

src/parameter_indexing_proxy.jl

@@ -0,0 +1,23 @@
+using SymbolicIndexingInterface
+using Symbolics
+
+struct FakeIntegrator{P}
+    p::P
+end
+
+SymbolicIndexingInterface.symbolic_container(fp::FakeIntegrator) = fp.sys
+SymbolicIndexingInterface.parameter_values(fp::FakeIntegrator) = fp.p
+
+@variables a[1:2] b
+sys = SymbolCache([:x, :y, :z], [a[1], a[2], b], [:t])
+p = [1.0, 2.0, 3.0]
+fi = FakeIntegrator(copy(p))
+for (i, sym) in [(1, a[1]), (2, a[2]), (3, b), ([1,2], a), ([1, 3], [a[1], b]), ((2, 3), (a[2], b))]
+    get = getp(sys, sym)
+    set! = setp(sys, sym)
+    true_value = i isa Tuple ? getindex.((p,), i) : p[i]
+    @test get(fi) == true_value
+    set!(fi, 0.5 .* i)
+    @test get(fi) == 0.5 .* i
+    set!(fi, true_value)
+end

test/parameter_indexing_proxy_test.jl

@@ -13,6 +13,6 @@ end
 @testset "Fallback test" begin
     @time include("fallback_test.jl")
 end
-@testset "Parameter indexing proxy test" begin
-    @time include("parameter_indexing_proxy_test.jl")
+@testset "Parameter indexing test" begin
+    @time include("parameter_indexing_test.jl")
 end