Macro serde::serde_if_integer128

macro_rules! serde_if_integer128 {
    ($($tt:tt)*) => { ... };
}

Conditional compilation depending on whether Serde is built with support for 128-bit integers.

Data formats that wish to support Rust compiler versions older than 1.26 may place the i128 / u128 methods of their Serializer and Deserializer behind this macro.

Data formats that require a minimum Rust compiler version of at least 1.26 do not need to bother with this macro and may assume support for 128-bit integers.

use serde::{serde_if_integer128, Serializer};

impl Serializer for MySerializer {
    type Ok = ();
    type Error = Error;

    fn serialize_i64(self, v: i64) -> Result<Self::Ok, Self::Error> {
        /* ... */
    }

    /* ... */

    serde_if_integer128! {
        fn serialize_i128(self, v: i128) -> Result<Self::Ok, Self::Error> {
            /* ... */
        }

        fn serialize_u128(self, v: u128) -> Result<Self::Ok, Self::Error> {
            /* ... */
        }
    }
}

When Serde is built with support for 128-bit integers, this macro expands transparently into just the input tokens.

macro_rules! serde_if_integer128 {
    ($($tt:tt)*) => {
        $($tt)*
    };
}

When built without support for 128-bit integers, this macro expands to nothing.

macro_rules! serde_if_integer128 {
    ($($tt:tt)*) => {};
}