local IdentityLayer = nerv.class('nerv.IdentityLayer', 'nerv.Layer')

function IdentityLayer:__init(id, global_conf, layer_conf)
    nerv.Layer.__init(self, id, global_conf, layer_conf)
    self:check_dim_len(1, 1)
    if self.dim_in[1] ~= self.dim_out[1] then
        nerv.error('mismatching dimensions of input and output')
    end
end

function IdentityLayer:init()
end

function IdentityLayer:batch_resize()
end

function IdentityLayer:propagate(input, output)
    output[1]:copy_from(input[1])
end

function IdentityLayer:back_propagate(bp_err, next_bp_err)
    next_bp_err[1]:copy_from(bp_err[1])
end

function IdentityLayer:update()
end

function IdentityLayer:get_params()
    return nerv.ParamRepo({}, self.loc_type)
end

function IdentityLayer:bind_params()
    -- do nothing
end