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//! CustomDefault
//!
//! Provides derive macro for `Default` trait with customization point
//!
//! ## Attributes
//!
//! - `def_val=<value>` - Specifies default value for field. Panics on incorrect type of field.
//! - `def_exp="expression"` - Specifies expression to be placed as initializer to field. No pre-processing.
//!
//! ## Usage
//!
//! ```rust
//! use cute_custom_default::CustomDefault;
//!
//! pub fn default_value_string() -> &'static str {
//!     "default_value_string"
//! }
//!
//! #[derive(CustomDefault)]
//! pub struct MyStruct {
//!     #[def_val='c']
//!     pub custom_char: char,
//!     #[def_val=b"my_bytes"]
//!     pub custom_bytes: [u8; 8],
//!     #[def_val=b"my_bytes"]
//!     pub custom_bytes_slice: &'static [u8],
//!     #[def_val=b'b']
//!     pub custom_default: u8,
//!     #[def_val=true]
//!     pub custom_bool: bool,
//!     pub normal_bool: bool,
//!     #[def_exp="\"Just my string\".to_owned()"]
//!     pub expression: String,
//!     #[def_exp="default_value_string()"]
//!     pub static_str: &'static str,
//!     #[def_val="Just my string"]
//!     pub string: String,
//!     #[def_val="Just my string"]
//!     pub static_str_again: &'static str,
//!     #[def_val=666]
//!     pub u32_field: u32,
//!     #[def_exp="std::u16::MAX"]
//!     pub u16_field: u16,
//!     #[def_exp="-655_555"]
//!     pub i32_field: i32,
//! }
//!
//! fn main() {
//!     let my_struct = MyStruct::default();
//!     assert_eq!(my_struct.custom_char, 'c');
//!     assert_eq!(my_struct.custom_default, b'b');
//!     assert_eq!(&my_struct.custom_bytes, b"my_bytes");
//!     assert_eq!(my_struct.custom_bytes_slice, b"my_bytes");
//!     assert_eq!(my_struct.custom_bool, true);
//!     assert_eq!(my_struct.normal_bool, false);
//!     assert_eq!(my_struct.expression, "Just my string");
//!     assert_eq!(my_struct.static_str, default_value_string());
//!     assert_eq!(my_struct.string, "Just my string");
//!     assert_eq!(my_struct.static_str_again, "Just my string");
//!     assert_eq!(my_struct.u32_field, 666);
//!     assert_eq!(my_struct.u16_field, std::u16::MAX);
//!     assert_eq!(my_struct.i32_field, -655_555);
//! }
//!
//! ```

extern crate proc_macro;

mod derive;

use proc_macro::TokenStream;

#[proc_macro_derive(CustomDefault, attributes(def_val, def_exp))]
pub fn custom_default(input: TokenStream) -> TokenStream {
    let ast: syn::DeriveInput = syn::parse(input).unwrap();
    let gen = derive::CustomDefault::new(ast);
    gen.generate()
}