Function macro_tools::exposed::item::ensure_comma

pub fn ensure_comma(input: &ItemStruct) -> ItemStruct

Ensures the last field in a struct has a trailing comma.

This function checks and modifies the fields of a given struct, input, ensuring that the last field, whether in named or unnamed structs, ends with a trailing comma. This adjustment is commonly needed in macro-generated code to maintain consistency and syntactical correctness across different struct types, including unit structs which are unaffected as they do not contain fields.

Arguments

• input - A reference to the struct (syn::ItemStruct) whose fields are to be checked and modified.

Returns

Returns a modified clone of the input struct (syn::ItemStruct) where the last field in named or unnamed structs has a trailing comma. Unit structs remain unchanged as they do not contain fields.

Examples

use macro_tools::
{
  syn::{ parse_quote, ItemStruct },
  quote::quote,
};

// Create a struct using `parse_quote!` macro
let input_struct : ItemStruct = parse_quote!
{
  struct Example
  {
    field1 : i32,
    field2 : String
  }
};

// Apply `ensure_comma` to ensure the last field has a trailing comma
let modified_struct = macro_tools::item::ensure_comma( &input_struct );

// Now `modified_struct` will have a trailing comma after `field2`
assert_eq!( quote!( #modified_struct ).to_string(), quote!
{
  struct Example
  {
    field1 : i32,
    field2 : String,
  }
}.to_string() );