dfir_lang/graph/ops/
assert_eq.rs

Help
1use quote::quote_spanned;
2use syn::parse_quote_spanned;
3
4use super::{
5    OperatorCategory, OperatorConstraints, WriteContextArgs, RANGE_0, RANGE_1,
6};
7
8/// > 1 input stream, 1 optional output stream
9/// > Arguments: A Vector, Slice, or Array containing objects that will be compared to the input stream.
10///
11/// The input stream will be compared with the provided argument, element by element. If any elements do not match, `assert_eq` will panic.
12/// If the input stream produces more elements than are in the provided argument, `assert_eq` will panic.
13///
14/// The input stream is passed through `assert_eq` unchanged to the output stream.
15///
16/// `assert_eq` is mainly useful for testing and documenting the behavior of dfir code inline.
17///
18/// `assert_eq` will remember the stream position across ticks, see example.
19///
20/// ```dfir
21/// unioned = union();
22///
23/// source_iter([1]) -> assert_eq([1]) -> unioned;
24/// source_iter([2]) -> defer_tick() -> assert_eq([2]) -> unioned;
25///
26/// unioned -> assert_eq([1, 2]);
27/// ```
28pub const ASSERT_EQ: OperatorConstraints = OperatorConstraints {
29    name: "assert_eq",
30    categories: &[OperatorCategory::Control],
31    hard_range_inn: RANGE_1,
32    soft_range_inn: RANGE_1,
33    hard_range_out: &(0..=1),
34    soft_range_out: &(0..=1),
35    num_args: 1,
36    persistence_args: RANGE_0,
37    type_args: RANGE_0,
38    is_external_input: false,
39    has_singleton_output: false,
40    flo_type: None,
41    ports_inn: None,
42    ports_out: None,
43    input_delaytype_fn: |_| None,
44    write_fn: |wc @ &WriteContextArgs {
45                   context,
46                   df_ident,
47                   op_span,
48                   arguments,
49                   ..
50               },
51               diagnostics| {
52        let assert_index_ident = wc.make_ident("assert_index");
53
54        let arg = &arguments[0];
55
56        let inspect_fn = parse_quote_spanned! {op_span=>
57            |item| {
58                // This is to help constrain the types so that type inference works nicely.
59                fn __constrain_types<T>(array: &impl ::std::ops::Index<usize, Output = T>, index: usize) -> &T {
60                    &array[index]
61                }
62
63                unsafe {
64                    // SAFETY: handle from `#df_ident.add_state(..)`.
65                    let index = #context.state_ref_unchecked(#assert_index_ident).get();
66                    ::std::assert_eq!(__constrain_types(&#arg, index), item, "Item (right) at index {} does not equal expected (left).", index);
67                    #context.state_ref_unchecked(#assert_index_ident).set(index + 1);
68                };
69            }
70        };
71
72        let wc = WriteContextArgs {
73            arguments: &inspect_fn,
74            ..wc.clone()
75        };
76
77        let mut owo = (super::inspect::INSPECT.write_fn)(&wc, diagnostics)?;
78
79        let write_prologue = owo.write_prologue;
80        owo.write_prologue = quote_spanned! {op_span=>
81            let #assert_index_ident = #df_ident.add_state(
82                ::std::cell::Cell::new(0usize)
83            );
84
85            #write_prologue
86        };
87
88        Ok(owo)
89    },
90};
dfir_lang/graph/ops/assert_eq.rs

dfir_lang/graph/ops/
assert_eq.rs
