Merge pull request #853 from SciML/new_conserved_quantities_metadata

Add `conservedquantity` metadata

src/network_analysis.jl

@@ -542,6 +542,23 @@ end
 
 ### Conservation Laws ###
 
+# Implements the `conserved` parameter metadata.
+struct ConservedParameter end
+Symbolics.option_to_metadata_type(::Val{:conserved}) = ConservedParameter
+
+"""
+isconserved(p)
+
+Checks if the input parameter (`p`) is a conserved quantity (i.e. have the `conserved`)
+metadata.
+"""
+isconserved(x::Num, args...) = isconserved(Symbolics.unwrap(x), args...)
+function isconserved(x, default = false)
+    p = Symbolics.getparent(x, nothing)
+    p === nothing || (x = p)
+    Symbolics.getmetadata(x, ConservedParameter, default)
+end
+
 """
     conservedequations(rn::ReactionSystem)
 
@@ -635,7 +652,8 @@ function cache_conservationlaw_eqs!(rn::ReactionSystem, N::AbstractMatrix, col_o
     indepspecs = sts[indepidxs]
     depidxs = col_order[(r + 1):end]
     depspecs = sts[depidxs]
-    constants = MT.unwrap.(MT.scalarize((@parameters Γ[1:nullity])[1]))
+    constants = MT.unwrap.(MT.scalarize(only(
+                @parameters $(CONSERVED_CONSTANT_SYMBOL)[1:nullity] [conserved=true])))
 
     conservedeqs = Equation[]
     constantdefs = Equation[]

test/network_analysis/conservation_laws.jl

@@ -142,4 +142,23 @@ let
     sprob3.g(g3, u3, sprob3.p, 1.0)
     @test isapprox(g1, g2[istsidxs, :])
     @test isapprox(g2[istsidxs, :], g3)
-end
+end
+
+### ConservedParameter Metadata Tests ###
+
+# Checks that `conserved` metadata is added correctly to parameters.
+# Checks that the `isconserved` getter function works correctly.
+let
+    # Creates ODESystem with conserved quantities.
+    rs = @reaction_network begin
+        (k1,k2), X1 <--> X2
+        (k1,k2), Y1 <--> Y2
+    end
+    osys = convert(ODESystem, rs; remove_conserved = true)
+
+    # Checks that the correct parameters have the `conserved` metadata.
+    @test Catalyst.isconserved(osys.Γ[1])
+    @test Catalyst.isconserved(osys.Γ[2])
+    @test !Catalyst.isconserved(osys.k1)
+    @test !Catalyst.isconserved(osys.k2)
+end