Julia Interfaces

interfaces.jl

_interfaces_func_key = Dict{Symbol,Vector{DataType}}()
# The values of the following dict are either nothing or a Vector of
# type tuples
_interfaces_signatures = Dict{(Symbol,DataType),Any}()

function addInterface(d::DataType, f::Symbol, signature=nothing)

    if haskey(_interfaces_func_key, f)
       push!(_interfaces_func_key[f], d) 
    else
       _interfaces_func_key[f] = DataType[d]
    end

    if haskey(_interfaces_signatures, (f,d))
        if _interfaces_signatures[(f,d)] != nothing
            push!(_interfaces_signatures[(f,d)], signature)
        end
    else
        if signature == nothing # now the signature will not be checked anymore
            _interfaces_signatures[(f,d)] = nothing
        else
            _interfaces_signatures[(f,d)] = [signature]
        end
    end
end

function checkInterface(d::DataType)
    
    for (f,itypes) in _interfaces_func_key
    
        isInInterfaceTable = false

        for it in itypes
            if d <: it
            
                isInMethodTable = false
            
                if !isdefined(f)
                    error("Interface not implemented! $d has to implement ", string(f), " in order to be subtype of $it !")
                end
                mt = methods(eval(f))
            
                if _interfaces_signatures[(f,it)] == nothing
                    for m in mt
                        if d <: m.sig[1]
                            isInMethodTable = true
                        end
                    end
                    if !isInMethodTable
                        error("Interface not implemented! $d has to implement ", string(f), " in order to be subtype of $it !")
                    end                    
                else 
                    for typeargs in _interfaces_signatures[(f,it)]
                        isInMethodTable = false
                        for m in mt
                            if length(m.sig) == length(typeargs)
                                same_signature = true
                                if !( d <: m.sig[1] )
                                    same_signature = false
                                end
                                for i=2:length(m.sig)
                                    if !( typeargs[i] <: m.sig[i] )
                                        same_signature = false
                                    end
                                end
                                if same_signature
                                    isInMethodTable = true
                                end
                            end
                        end
                        if !isInMethodTable
                            error("Interface not implemented! $d has to implement ", string(f), " in order to be subtype of $it !")
                        end                        
                    end
                end
            end
        end
    end    
    
    return true
end