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use quote::quote_spanned;
use super::{
OperatorCategory, OperatorConstraints, OperatorWriteOutput, WriteContextArgs,
RANGE_0, RANGE_1,
};
/// > 1 input stream, 1 output stream
///
/// > Arguments: A Rust closure that handles an iterator
///
/// For each item `i` passed in, treat `i` as an iterator and map the closure to that
/// iterator to produce items one by one. The type of the input items must be iterable.
///
/// > Note: The closure has access to the [`context` object](surface_flows.mdx#the-context-object).
///
/// ```dfir
/// // should print out each character of each word on a separate line
/// source_iter(vec!["hello", "world"])
/// -> flat_map(|x| x.chars())
/// -> assert_eq(['h', 'e', 'l', 'l', 'o', 'w', 'o', 'r', 'l', 'd']);
/// ```
pub const FLAT_MAP: OperatorConstraints = OperatorConstraints {
name: "flat_map",
categories: &[OperatorCategory::Flatten],
hard_range_inn: RANGE_1,
soft_range_inn: RANGE_1,
hard_range_out: RANGE_1,
soft_range_out: RANGE_1,
num_args: 1,
persistence_args: RANGE_0,
type_args: RANGE_0,
is_external_input: false,
has_singleton_output: false,
flo_type: None,
ports_inn: None,
ports_out: None,
input_delaytype_fn: |_| None,
write_fn: |&WriteContextArgs {
root,
op_span,
ident,
inputs,
outputs,
is_pull,
arguments,
..
},
_| {
let func = &arguments[0];
let write_iterator = if is_pull {
let input = &inputs[0];
quote_spanned! {op_span=>
let #ident = #root::dfir_pipes::pull::Pull::flat_map(#input, #func);
}
} else {
let output = &outputs[0];
quote_spanned! {op_span=>
let #ident = #root::dfir_pipes::push::flat_map(#func, #output);
}
};
Ok(OperatorWriteOutput {
write_iterator,
..Default::default()
})
},
};