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use quote::quote_spanned;
use super::{
OperatorCategory, OperatorConstraints, OperatorWriteOutput, RANGE_0, RANGE_1, WriteContextArgs,
};
/// > Arguments: A single closure `FnMut(&Item)`.
///
/// An operator which allows you to "inspect" each element of a stream without
/// modifying it. The closure is called on a reference to each item. This is
/// mainly useful for debugging as in the example below, and it is generally an
/// anti-pattern to provide a closure with side effects.
///
/// > Note: The closure has access to the [`context` object](surface_flows.mdx#the-context-object).
///
/// ```dfir
/// source_iter([1, 2, 3, 4])
/// -> inspect(|x| println!("{}", x))
/// -> assert_eq([1, 2, 3, 4]);
/// ```
pub const INSPECT: OperatorConstraints = OperatorConstraints {
name: "inspect",
categories: &[OperatorCategory::Map],
hard_range_inn: RANGE_1,
soft_range_inn: RANGE_1,
hard_range_out: &(0..=1),
soft_range_out: &(0..=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::inspect(#input, #func);
}
} else if outputs.is_empty() {
quote_spanned! {op_span=>
let #ident = #root::dfir_pipes::push::inspect(#func, #root::dfir_pipes::push::for_each(::std::mem::drop));
}
} else {
let output = &outputs[0];
quote_spanned! {op_span=>
let #ident = #root::dfir_pipes::push::inspect(#func, #output);
}
};
Ok(OperatorWriteOutput {
write_iterator,
..Default::default()
})
},
};