"""

A node in a stream computation graph that represents a computation step.

Types of nodes:

- **Source**: The node has no incoming edges, emits data.

- **Sink**: The node has no outgoing edges, consumes/stores data.

- **Operation**: The node has both incoming and outgoing edges, and performs a computation step.

- **Stateful**: The node has an internal state that is updated during computation.

- **Stateless**: The node has no internal state, and the output is a function of the input only.

"""

mutable struct StreamNode

index::Int

is_source::Bool

is_sink::Bool

operation::StreamOperation

input_bindings::Vector{InputBinding{StreamNode}}

output_type::Type

label::Symbol

field_name::Symbol

function StreamNode(

index,

is_source,

is_sink,

operation::StreamOperation,

output_type,

label::Symbol

)

input_bindings = InputBinding{StreamNode}[]

field_name = label

new(index, is_source, is_sink, operation, input_bindings,

output_type, label, field_name)

end

end

@inline is_source(node::StreamNode) = node.is_source

@inline is_sink(node::StreamNode) = node.is_sink

@inline label(node::StreamNode) = node.label