Struct arithmetic derive

```rs

[derive(StructArithmetic)]

struct TokenMap { pub sol: u64, pub eth: u64, pub btc: u64, } ```

turns into

rs struct TokenMap { pub sol: u64, pub eth: u64, pub btc: u64, } impl TokenMap { pub fn new(sol: u64, eth: u64, btc: u64) -> TokenMap { TokenMap { sol, eth, btc, } } pub fn add(&self, other: TokenMap) -> TokenMap { TokenMap::new( sol: self.sol.checked_add(other.sol).unwrap(), eth: self.eth.checked_add(other.eth).unwrap(), btc: self.btc.checked_add(other.btc).unwrap(), ) } pub fn add_assign(&mut self, other: TokenMap) { self.sol = self.sol.checked_sub(other.sol).unwrap(); self.eth = self.eth.checked_sub(other.eth).unwrap(); self.btc = self.btc.checked_sub(other.btc).unwrap(); } ... }

You can also add a _reserved field (only with type [u8; N]!) which does not interfere with the arithmetics.

```rs

[derive(StructArithmetic)]

struct TokenMap { pub sol: u64, pub eth: u64, pub btc: u64, pub _reserved: [u8; 100], } ```

turns into

rs struct TokenMap { pub sol: u64, pub eth: u64, pub btc: u64, pub _reserved: [u8; 100], } impl TokenMap { pub fn new(sol: u64, eth: u64, btc: u64) -> TokenMap { TokenMap { sol, eth, btc, _reserved: [0; 100], } } pub fn add(&self, other: TokenMap) -> TokenMap { TokenMap::new( sol: self.sol.checked_add(other.sol).unwrap(), eth: self.eth.checked_add(other.eth).unwrap(), btc: self.btc.checked_add(other.btc).unwrap(), ) } pub fn add_assign(&mut self, other: TokenMap) { self.sol = self.sol.checked_sub(other.sol).unwrap(); self.eth = self.eth.checked_sub(other.eth).unwrap(); self.btc = self.btc.checked_sub(other.btc).unwrap(); } ...

It also supports adding and using non-reserved arrays of fixed lengths.

rs struct TokenMap { pub sol: u64, pub eth: u64, pub btc: u64, pub tk1: [u64; 2], pub _reserved: [u8; 128], pub tk2: [u128; 3], }

turns into

```rs struct TokenMap { pub sol: u64, pub eth: u64, pub btc: u64, pub tk1: [u64; 2], pub _reserved: [u8; 128], pub _reserved2: [u8; 256], pub tk2: [u128; 3], }

impl TokenMap { pub fn new(sol: u64, eth: u64, btc: u64, tk1: [u64; 2], tk2: [u128; 3]) -> TokenMap { TokenMap { sol, eth, btc, tk1, reserved: [0; 128], _reserved2: [0; 256], tk2, } } pub fn add(&self, other: &TokenMap) -> Option { let mut tk1 = [u64::default(); 2]; for i in 0..self.tk1.len() { tk1[i] = self.tk1[i].checkedadd(other.tk1[i])?; } let mut tk2 = [u128::default(); 3]; for i in 0..self.tk2.len() { tk2[i] = self.tk2[i].checkedadd(other.tk2[i])?; } Some(TokenMap::new( self.sol.checkedadd(other.sol)?, self.eth.checkedadd(other.eth)?, self.btc.checkedadd(other.btc)?, tk1, tk2, )) } pub fn addassign(&mut self, other: &TokenMap) -> Option<()> { self.sol = self.sol.checkedadd(other.sol)?; self.eth = self.eth.checkedadd(other.eth)?; self.btc = self.btc.checkedadd(other.btc)?; for i in 0..self.tk1.len() { self.tk1[i] = self.tk1[i].checkedadd(other.tk1[i])?; } for i in 0..self.tk2.len() { self.tk2[i] = self.tk2[i].checkedadd(other.tk2[i])?; } Some(()) } } ```