cairo_lang_utils/
extract_matches.rs

1/// Macro to try to evaluate an expression as a pattern and extract its fields.
2/// # Examples:
3/// ```
4/// use cairo_lang_utils::try_extract_matches;
5///
6/// #[derive(Debug, Clone, Copy)]
7/// struct Point {
8///     x: u32,
9///     y: u32,
10/// }
11/// #[derive(Debug)]
12/// enum MyEnum {
13///     Point(Point),
14///     Value(u32),
15/// }
16/// let p = MyEnum::Point(Point { x: 3, y: 5 });
17/// if let Some(Point { x, y: _ }) = try_extract_matches!(p, MyEnum::Point) {
18///     assert_eq!(x, 3);
19/// }
20/// ```
21#[macro_export]
22macro_rules! try_extract_matches {
23    ($e:expr, $variant:path) => {
24        if let $variant(x) = $e { Some(x) } else { None }
25    };
26}
27
28/// Macro to verify an expression matches a pattern and extract its fields.
29/// # Examples:
30/// ```
31/// use cairo_lang_utils::extract_matches;
32///
33/// #[derive(Debug, Clone, Copy)]
34/// struct Point {
35///     x: u32,
36///     y: u32,
37/// }
38/// #[derive(Debug)]
39/// enum MyEnum {
40///     Point(Point),
41///     Value(u32),
42/// }
43/// let p = MyEnum::Point(Point { x: 3, y: 5 });
44/// let Point { x, y: _ } = extract_matches!(p, MyEnum::Point);
45/// assert_eq!(x, 3);
46///
47/// // Would panic with 'assertion failed: `Point(Point { x: 3, y: 5 })` does not match `MyEnum::Value`:
48/// // Expected a point!'
49/// // let _value = extract_matches!(p, MyEnum::Value, "Expected a point!");
50/// ```
51#[macro_export]
52macro_rules! extract_matches {
53    ($e:expr, $variant:path) => {
54        match $e {
55            $variant(x) => x,
56            ref e => {
57                panic!("Variant extract failed: `{:?}` is not of variant `{}`", e, stringify!($variant))
58            }
59        }
60    };
61    ( $e:expr , $variant:path , $($arg:tt)* ) => {
62        match $e {
63            $variant(x) => x,
64            ref e => panic!("Variant extract failed: `{:?}` is not of variant `{}`: {}",
65                e, stringify!($variant), format_args!($($arg)*))
66        }
67    };
68}
cairo_lang_utils/extract_matches.rs

cairo_lang_utils/
extract_matches.rs
