Struct OperatorWriteOutput 

#[non_exhaustive]
pub struct OperatorWriteOutput {
    pub write_prologue: TokenStream,
    pub write_prologue_after: TokenStream,
    pub write_iterator: TokenStream,
    pub write_iterator_after: TokenStream,
}

The code generated and returned by a OperatorConstraints::write_fn.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

write_prologue: TokenStream

Code which runs once outside any subgraphs, BEFORE subgraphs are initialized, to set up any external state (state API, chanels, network connections, etc.) to be used by the subgraph.

write_prologue_after: TokenStream

Code which runs once outside the subgraph, AFTER subgraphs are initialized, to set up state hooks which may need the subgraph ID.

write_iterator: TokenStream

Iterator (or pusherator) code inside the subgraphs. The code for each operator is emitted in order.

Emitted code should assign to WriteContextArgs::ident and use WriteContextArgs::inputs (pull iterators) or WriteContextArgs::outputs (pusherators).

write_iterator_after: TokenStream

Code which runs after iterators have been run. Mainly for flushing IO.

Trait Implementations

impl Default for OperatorWriteOutput

fn default() -> OperatorWriteOutput

Returns the “default value” for a type.