Allow system level metadata information

docs/src/basics/MTKLanguage.md

@@ -31,6 +31,7 @@ set to `false`.
   - `@equations`: for the list of equations
   - `@extend`: for extending a base system and unpacking its unknowns
   - `@icon` : for embedding the model icon
+  - `@metadata`: for assigning key-value pairs as model level metadata
   - `@parameters`: for specifying the symbolic parameters
   - `@structural_parameters`: for specifying non-symbolic parameters
   - `@variables`: for specifying the unknowns
@@ -94,6 +95,16 @@ end
         v_for_defaults => 2.0
     end
 end
+
+struct Author end
+struct ModelVersion end
+@mtkmodel ModelD begin
+    @description "A component with some metadata."
+    @metadata begin
+        Author = "Test Author"
+        ModelVersion = "1.0.0"
+    end
+end
 ```
 
 #### `@description`
@@ -257,6 +268,30 @@ using ModelingToolkit
 end
 ```
 
+#### `@metadata` begin block
+
+  - Assign key-value pairs as model level metadata.
+  - The keys must be `DataType` to avoid any key collisions.
+  - Assignments can be made using either `=` or `=>`.
+  - Metadata can be retrieved using [`getmetadata`](@ref).
+  - Metadata can be set using [`setmetadata`](@ref).
+
+```@example mtkmodel-example
+using ModelingToolkit
+
+struct Author end
+struct ModelVersion end
+
+@mtkmodel MetadataModel begin
+    @metadata begin
+        Author = "Test Author"
+        ModelVersion => "1.0.0"
+    end
+end
+@named model = MetadataModel()
+getmetadata(model, Author, nothing) == "Test Author"
+```
+
 #### A begin block
 
   - Any other Julia operations can be included with dedicated begin blocks.

src/systems/model_parsing.jl

@@ -55,7 +55,8 @@ function _model_macro(mod, fullname::Union{Expr, Symbol}, expr, isconnector)
     dict = Dict{Symbol, Any}(
         :defaults => Dict{Symbol, Any}(),
         :kwargs => Dict{Symbol, Dict}(),
-        :structural_parameters => Dict{Symbol, Dict}()
+        :structural_parameters => Dict{Symbol, Dict}(),
+        :metadata => Dict{Symbol, Any}()
     )
     comps = Union{Symbol, Expr}[]
     ext = []
@@ -127,6 +128,7 @@ function _model_macro(mod, fullname::Union{Expr, Symbol}, expr, isconnector)
 
     consolidate = get(dict, :consolidate, default_consolidate)
     description = get(dict, :description, "")
+    model_meta = get(dict, :metadata, Dict{Symbol, Any}())
 
     @inline pop_structure_dict!.(
         Ref(dict), [:defaults, :kwargs, :structural_parameters])
@@ -145,6 +147,14 @@ function _model_macro(mod, fullname::Union{Expr, Symbol}, expr, isconnector)
     isconnector && push!(exprs.args,
         :($Setfield.@set!(var"#___sys___".connector_type=$connector_type(var"#___sys___"))))
 
+    meta_exprs = quote
+        for (k, v) in $model_meta
+            var"#___sys___" = setmetadata(var"#___sys___", $get_var($mod, k), v)
+        end
+    end
+    push!(exprs.args, meta_exprs)
+    push!(exprs.args, :(var"#___sys___"))
+
     f = if length(where_types) == 0
         :($(Symbol(:__, name, :__))(; name, $(kwargs...)) = $exprs)
     else
@@ -678,6 +688,8 @@ function parse_model!(exprs, comps, ext, eqs, icon, vs, ps, sps, c_evts, d_evts,
         parse_costs!(costs, dict, body)
     elseif mname == Symbol("@consolidate")
         parse_consolidate!(body, dict)
+    elseif mname == Symbol("@metadata")
+        parse_metadata_block!(body, dict, mod)
     else
         error("$mname is not handled.")
     end
@@ -1254,6 +1266,21 @@ function parse_description!(body, dict)
     end
 end
 
+function parse_metadata_block!(body, dict, mod)
+    Base.remove_linenums!(body)
+    for arg in body.args
+        MLStyle.@match arg begin
+            Expr(:(=), a, b) => begin
+                dict[:metadata][a] = get_var(mod, b)
+            end
+            Expr(:call, :(=>), a, b) => begin
+                dict[:metadata][a] = get_var(mod, b)
+            end
+            _ => error("Invalid metadata entry: $arg. Expected key = value or key => value format.")
+        end
+    end
+end
+
 ### Parsing Components:
 
 function component_args!(a, b, varexpr, kwargs; index_name = nothing)

test/model_parsing.jl

@@ -1045,3 +1045,47 @@ end
     @test Example.structure[:constraints] == ["(EvalAt(0.3))(x) ~ 3", "y ≲ 4"]
     @test Example.structure[:costs] == ["x + y", "(EvalAt(1))(y) ^ 2"]
 end
+
+@testset "Model Level Metadata" begin
+    struct Author end
+    struct MyVersion end
+    struct License end
+    struct Category end
+    struct Tags end
+    struct MyBool end
+    struct NewInt end
+
+    @mtkmodel TestMetadataModel begin
+        @metadata begin
+            Author = "Test Author"
+            MyVersion = "1.0.0"
+            License = "MIT"
+            Category => "example"
+            Tags = ["test", "demo", "metadata"]
+            MyBool => false
+            NewInt => 1
+        end
+
+        @parameters begin
+            k = 1.0
+        end
+
+        @variables begin
+            x(t)
+            y(t)
+        end
+
+        @equations begin
+            D(x) ~ -k * x
+            y ~ x
+        end
+    end
+    @named test_model = TestMetadataModel()
+
+    struct UnknownMetaKey end
+    @test ModelingToolkit.getmetadata(test_model, Author, nothing) == "Test Author"
+    @test ModelingToolkit.getmetadata(test_model, MyVersion, nothing) == "1.0.0"
+    @test ModelingToolkit.getmetadata(test_model, UnknownMetaKey, nothing) === nothing
+    @test ModelingToolkit.getmetadata(test_model, MyBool, nothing) === false
+    @test ModelingToolkit.getmetadata(test_model, NewInt, nothing) === 1
+end