Function expand_slice_assertion

assert-struct-macros/src/expand.rs:550–597

Generate slice assertion with error collection

(value_expr: &TokenStream, pattern: &PatternSlice)

/// Generate slice assertion with error collection
fn expand_slice_assertion(value_expr: &TokenStream, pattern: &PatternSlice) -> TokenStream {
    let mut pattern_parts = Vec::new();
    let mut bindings_and_assertions = Vec::new();

    for (i, elem) in pattern.elements.iter().enumerate() {
        match elem {
            Pattern::Range(PatternRange {
                expr: syn::Expr::Range(r),
                ..
            }) if r.start.is_none() && r.end.is_none() => {
                // RangeFull (..) in slice context is a rest pattern
                pattern_parts.push(quote! { .. });
            }
            Pattern::Wildcard(PatternWildcard { .. }) => {
                // Wildcard pattern matches any single element without binding
                pattern_parts.push(quote! { _ });
            }
            _ => {
                let binding = quote::format_ident!("__elem_{}", i);
                pattern_parts.push(quote! { #binding });

                let assertion = expand_pattern_assertion(&quote! { #binding }, elem);
                bindings_and_assertions.push(assertion);
            }
        }
    }

    // Convert Vec to slice for matching
    let slice_expr = quote! { (#value_expr).as_slice() };

    let error_push = generate_error_push(
        proc_macro2::Span::call_site(),
        quote!(format!("{:?}", &#value_expr)),
        quote!(None),
        pattern.node_id,
    );

    quote! {
        match #slice_expr {
            [#(#pattern_parts),*] => {
                #(#bindings_and_assertions)*
            }
            _ => {
                #error_push
            }
        }
    }
}

#[cfg(feature = "regex")]
/// Generate regex assertion with error collection