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use quote::quote_spanned;
use syn::parse_quote_spanned;
use super::{
OperatorCategory, OperatorConstraints, WriteContextArgs, RANGE_0, RANGE_1,
};
/// > 1 input stream, 1 optional output stream
/// > Arguments: A Vector, Slice, or Array containing objects that will be compared to the input stream.
///
/// The input stream will be compared with the provided argument, element by element. If any elements do not match, `assert_eq` will panic.
/// If the input stream produces more elements than are in the provided argument, `assert_eq` will panic.
///
/// The input stream is passed through `assert_eq` unchanged to the output stream.
///
/// `assert_eq` is mainly useful for testing and documenting the behavior of dfir code inline.
///
/// `assert_eq` will remember the stream position across ticks, see example.
///
/// ```dfir
/// unioned = union();
///
/// source_iter([1]) -> assert_eq([1]) -> unioned;
/// source_iter([2]) -> defer_tick() -> assert_eq([2]) -> unioned;
///
/// unioned -> assert_eq([1, 2]);
/// ```
pub const ASSERT_EQ: OperatorConstraints = OperatorConstraints {
name: "assert_eq",
categories: &[OperatorCategory::Control],
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: |wc @ &WriteContextArgs {
context,
df_ident,
op_span,
arguments,
..
},
diagnostics| {
let assert_index_ident = wc.make_ident("assert_index");
let arg = &arguments[0];
let inspect_fn = parse_quote_spanned! {op_span=>
|item| {
// This is to help constrain the types so that type inference works nicely.
fn __constrain_types<T>(array: &impl ::std::ops::Index<usize, Output = T>, index: usize) -> &T {
&array[index]
}
unsafe {
// SAFETY: handle from `#df_ident.add_state(..)`.
let index = #context.state_ref_unchecked(#assert_index_ident).get();
::std::assert_eq!(__constrain_types(&#arg, index), item, "Item (right) at index {} does not equal expected (left).", index);
#context.state_ref_unchecked(#assert_index_ident).set(index + 1);
};
}
};
let wc = WriteContextArgs {
arguments: &inspect_fn,
..wc.clone()
};
let mut owo = (super::inspect::INSPECT.write_fn)(&wc, diagnostics)?;
let write_prologue = owo.write_prologue;
owo.write_prologue = quote_spanned! {op_span=>
let #assert_index_ident = #df_ident.add_state(
::std::cell::Cell::new(0usize)
);
#write_prologue
};
Ok(owo)
},
};