metagraphoptimization.jl/src/models/interface.jl

"""
    AbstractModel

Base type for all models. From this, [`AbstractProblemInstance`](@ref)s can be constructed.

See also: [`problem_instance`](@ref)
"""
abstract type AbstractModel end

"""
    problem_instance(::AbstractModel, ::Vararg)

Interface function that must be implemented for any implementation of [`AbstractModel`](@ref). This function should return a specific [`AbstractProblemInstance`](@ref) given some parameters.
"""
function problem_instance end

"""
    AbstractProblemInstance

Base type for problem instances. An object of this type of a corresponding [`AbstractModel`](@ref) should uniquely identify a problem instance of that model.

See also: [`parse_process`](@ref)
"""
abstract type AbstractProblemInstance end

"""
    input_type(problem::AbstractProblemInstance)

Return the fully specified input type for a specific [`AbstractProblemInstance`](@ref).
"""
function input_type end

"""
    graph(::AbstractProblemInstance)

Generate the [`DAG`](@ref) for the given [`AbstractProblemInstance`](@ref). Every entry node (see [`get_entry_nodes`](@ref)) to the graph must have a name set. Implement [`input_expr`](@ref) to return a valid expression for each of those names.
"""
function graph end

"""
    input_expr(::AbstractProblemInstance, input_sym::Symbol, name::String)

For a given [`AbstractProblemInstance`](@ref), a `Symbol` on which the problem input is available (see [`input_type`](@ref)), and entry node name, return an `Expr` getting that specific input value from the 
"""
function input_expr end