Function expand_struct_assertion

assert-struct-macros/src/expand.rs:131–199

Generate struct assertion with error collection for multiple field failures

(value_expr: &TokenStream, pattern: &PatternStruct)

/// Generate struct assertion with error collection for multiple field failures
fn expand_struct_assertion(value_expr: &TokenStream, pattern: &PatternStruct) -> TokenStream {
    let struct_path = &pattern.path;
    let fields = &pattern.fields;
    let rest = pattern.rest;

    // If struct_path is None, it's a wildcard pattern - use field access
    let Some(struct_path) = struct_path.as_ref() else {
        return expand_struct_wildcard_assertion(value_expr, fields);
    };

    // For nested field access, we need to collect unique field names only
    // If we have middle.inner.value and middle.count, we only want "middle" once
    let mut unique_field_names = HashSet::new();
    let field_names: Vec<_> = fields
        .iter()
        .filter_map(|f| {
            let field_name = f.operations.root_field_name();
            if unique_field_names.insert(field_name.clone()) {
                Some(field_name)
            } else {
                None
            }
        })
        .collect();

    let rest_pattern = if rest {
        quote! { , .. }
    } else {
        quote! {}
    };

    let field_assertions: Vec<_> = fields
        .iter()
        .map(|f| {
            let field_name = f.operations.root_field_name();

            // Expand the FieldAssertion starting from the bound field name
            let assertion = expand_field_assertion(&quote! { #field_name }, f);

            // Wrap the assertion with the span of the field pattern if available
            if let Some(span) = f.pattern.span() {
                quote_spanned! {span=> #assertion }
            } else {
                assertion
            }
        })
        .collect();

    let span = struct_path.span();

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

    quote_spanned! {span=>