/*!
This crate provides several macros for deriving implementations of various traits for "newtype" wrappers (*i.e.* tuple structs with a single element).  That is, given a tuple struct with exactly one field (*e.g.* `struct Buckets(i32)`), these macros will derive "obvious" implementations of traits such as `Add`, `Neg`, `Index`, `Deref`, `From`, etc.

All of these macros are designed to be used with the [`custom_derive`](https://crates.io/crates/custom_derive) crate, though they can be used independent of it.

# Example

Create a simple integer wrapper with some arithmetic operators:

```rust
#[macro_use] extern crate custom_derive;
#[macro_use] extern crate newtype_derive;

custom_derive! {
    #[derive(NewtypeFrom, NewtypeAdd, NewtypeMul(i32))]
    pub struct Happy(i32);
}

# fn main() {
// Let's add some happy little ints.
let a = Happy::from(6);
let b = Happy::from(7);
let c = (a + b) * 3;
let d: i32 = c.into();
assert_eq!(d, 39);
# }
```

Create a "deref-transparent" wrapper around a type:

```rust
#[macro_use] extern crate custom_derive;
#[macro_use] extern crate newtype_derive;

custom_derive! {
    #[derive(NewtypeFrom,
        NewtypeDeref, NewtypeDerefMut,
        NewtypeIndex(usize), NewtypeIndexMut(usize)
        )]
    pub struct I32Array(Vec<i32>);
}

# fn main() {
let mut arr = I32Array::from(vec![1, 2, 3]);
arr.push(4);
arr[2] = 5;
assert_eq!(&**arr, &[1, 2, 5, 4]);
assert_eq!(arr.len(), 4);
# }
```

# Overview

This crate provides macros to derive implementations of the following traits for newtype structs:

- Binary Arithmetic Operators: Add, BitAnd, BitOr, BitXor, Div, Mul, Rem, Sub, Shl, Shr.
- Unary Arithmetic Operators: Neg, Not.
- Other Operators: Deref, DerefMut, Index, IndexMut.
- Miscellaneous: From.

All of these macros are named `Newtype$Trait`.

None of these macros currently support generic newtype structs.

## Binary Arithmetic Operators

Each of the binary arithmetic operators accept several deriving forms.  To use `Add` on a struct `T` as an example:

- `NewtypeAdd`: `impl Add<T, Output=T> for T`
- `NewtypeAdd(&self)`: `impl<'a> Add<&'a T, Output=T> for &'a T`
- `NewtypeAdd(U)`: `impl Add<U, Output=T> for T`
- `NewtypeAdd(&self, U)`: `impl<'a> Add<U, Output=T> for &'a T`

In all cases, the implementation unwraps the newtype (where necessary), forwards to the wrapped value's implementation, then re-wraps the result in the newtype.

## Unary Arithmetic Operators

Each of the binary arithmetic operators accept several deriving forms.  To use `Neg` on a struct `T` as an example:

- `NewtypeNeg`: `impl Neg<Output=T> for T`
- `NewtypeNeg(&self)`: `impl<'a> Neg<Output=T> for &'a T`

In all cases, the implementation unwraps the newtype, forwards to the wrapped value's implementation, then re-wraps the result in the newtype.

## Other Operators

`NewtypeDeref` and `NewtypeDerefMut` only support the argument-less form, and implements the corresponding trait such that the newtype structure derefs to a pointer to the wrapped value.

`NewtypeIndex` and `NewtypeIndexMut` must be used as `NewtypeIndex(usize)`, where the argument is the type to use for indexing.  The call is forwarded to the wrapped value's implementation.

## Miscellaneous

`NewtypeFrom` implements `std::convert::From` twice: once for converting from the wrapped type to the newtype, and once for converting from the newtype to the wrapped type.

## Using Without `custom_derive!`

Although designed to be used with `custom_derive!`, all of the macros in this crate can be used without it.  The following:

```rust
# #[macro_use] extern crate custom_derive;
# #[macro_use] extern crate newtype_derive;
custom_derive! {
    #[derive(Copy, Clone, Debug, NewtypeFrom, NewtypeAdd, NewtypeAdd(f32))]
    pub struct Meters(f32);
}
# fn main() {}
```

Can also be written as:

```rust
# #[macro_use] extern crate newtype_derive;
#[derive(Copy, Clone, Debug)]
pub struct Meters(f32);

NewtypeFrom! { () pub struct Meters(f32); }
NewtypeAdd! { () pub struct Meters(f32); }
NewtypeAdd! { (f32) pub struct Meters(f32); }
# fn main() {}
```
*/
/*
# `Newtype$binop` Template

Given `/\/\/\s*(ntbop\s+([A-Za-z0-9]+),\s*([a-z_]+))\n(^#\[.+?\]$\n)*^macro_rules!.*?\{$\n(^ +.*?$\n)*^\}$/`,

```
// \1
#[macro_export]
macro_rules! Newtype\2 {
    (() $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::\2)::\3, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::\2)::\3, kind: simple_ref, item: $($tts)* }
    };
    ((&self, $($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::\2)::\3, kind: ref_rhs_rewrap($($rhs)*), item: $($tts)* }
    };
    (($($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::\2)::\3, kind: rhs_rewrap($($rhs)*), item: $($tts)* }
    };
}
```

# `Newtype$unop` Template

Given `/\/\/\s*(ntuop\s+([A-Za-z0-9]+),\s*([a-z_]+))\n(^#\[.+?\]$\n)*^macro_rules!.*?\{$\n(^ +.*?$\n)*^\}$/`,

```
// \1
#[macro_export]
macro_rules! Newtype\2 {
    (() $($tts:tt)*) => {
        newtype_wrap_un_op! { trait: (::std::ops::\2)::\3, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_un_op! { trait: (::std::ops::\2)::\3, kind: simple_ref, item: $($tts)* }
    };
}
```
*/

#[doc(hidden)]
#[macro_export]
macro_rules! newtype_as_item {
    ($i:item) => {$i};
}

#[doc(hidden)]
#[macro_export]
macro_rules! newtype_wrap_bin_op {
    (
        trait: ($($tr:tt)*)::$meth:ident,
        kind: simple,
        item: $(pub)* struct $name:ident($(pub)* $t:ty);
    ) => {
        newtype_as_item! {
            impl $($tr)*<$name> for $name {
                type Output = $name;
                fn $meth(self, rhs: Self) -> $name {
                    $name((self.0).$meth(rhs.0))
                }
            }
        }
    };

    (
        trait: ($($tr:tt)*)::$meth:ident,
        kind: simple_ref,
        item: $(pub)* struct $name:ident($(pub)* $t:ty);
    ) => {
        newtype_as_item! {
            impl<'a> $($tr)*<&'a $name> for &'a $name {
                type Output = $name;
                fn $meth(self, rhs: Self) -> $name {
                    $name((self.0).$meth(rhs.0))
                }
            }
        }
    };

    (
        trait: ($($tr:tt)*)::$meth:ident,
        kind: rhs_rewrap($rhs:ty),
        item: $(pub)* struct $name:ident($(pub)* $t:ty);
    ) => {
        newtype_as_item! {
            impl $($tr)*<$rhs> for $name {
                type Output = $name;
                fn $meth(self, rhs: $rhs) -> $name {
                    $name((self.0).$meth(rhs))
                }
            }
        }
    };

    (
        trait: ($($tr:tt)*)::$meth:ident,
        kind: ref_rhs_rewrap($rhs:ty),
        item: $(pub)* struct $name:ident($(pub)* $t:ty);
    ) => {
        newtype_as_item! {
            impl<'a> $($tr)*<$rhs> for &'a $name {
                type Output = $name;
                fn $meth(self, rhs: $rhs) -> $name {
                    $name((self.0).$meth(rhs))
                }
            }
        }
    };
}

#[doc(hidden)]
#[macro_export]
macro_rules! newtype_wrap_un_op {
    (
        trait: ($($tr:tt)*)::$meth:ident,
        kind: simple,
        item: $(pub)* struct $name:ident($(pub)* $t:ty);
    ) => {
        newtype_as_item! {
            impl $($tr)* for $name {
                type Output = $name;
                fn $meth(self) -> $name {
                    $name((self.0).$meth())
                }
            }
        }
    };

    (
        trait: ($($tr:tt)*)::$meth:ident,
        kind: simple_ref,
        item: $(pub)* struct $name:ident($(pub)* $t:ty);
    ) => {
        newtype_as_item! {
            impl<'a> $($tr)* for &'a $name {
                type Output = $name;
                fn $meth(self) -> $name {
                    $name((self.0).$meth())
                }
            }
        }
    };
}

// ntbop Add,      add
#[macro_export]
macro_rules! NewtypeAdd {
    (() $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Add)::add, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Add)::add, kind: simple_ref, item: $($tts)* }
    };
    ((&self, $($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Add)::add, kind: ref_rhs_rewrap($($rhs)*), item: $($tts)* }
    };
    (($($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Add)::add, kind: rhs_rewrap($($rhs)*), item: $($tts)* }
    };
}

// ntbop BitAnd,   bitand
#[macro_export]
macro_rules! NewtypeBitAnd {
    (() $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::BitAnd)::bitand, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::BitAnd)::bitand, kind: simple_ref, item: $($tts)* }
    };
    ((&self, $($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::BitAnd)::bitand, kind: ref_rhs_rewrap($($rhs)*), item: $($tts)* }
    };
    (($($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::BitAnd)::bitand, kind: rhs_rewrap($($rhs)*), item: $($tts)* }
    };
}

// ntbop BitOr,    bitor
#[macro_export]
macro_rules! NewtypeBitOr {
    (() $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::BitOr)::bitor, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::BitOr)::bitor, kind: simple_ref, item: $($tts)* }
    };
    ((&self, $($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::BitOr)::bitor, kind: ref_rhs_rewrap($($rhs)*), item: $($tts)* }
    };
    (($($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::BitOr)::bitor, kind: rhs_rewrap($($rhs)*), item: $($tts)* }
    };
}

// ntbop BitXor,   bitxor
#[macro_export]
macro_rules! NewtypeBitXor {
    (() $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::BitXor)::bitxor, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::BitXor)::bitxor, kind: simple_ref, item: $($tts)* }
    };
    ((&self, $($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::BitXor)::bitxor, kind: ref_rhs_rewrap($($rhs)*), item: $($tts)* }
    };
    (($($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::BitXor)::bitxor, kind: rhs_rewrap($($rhs)*), item: $($tts)* }
    };
}

// ntbop Div,      div
#[macro_export]
macro_rules! NewtypeDiv {
    (() $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Div)::div, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Div)::div, kind: simple_ref, item: $($tts)* }
    };
    ((&self, $($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Div)::div, kind: ref_rhs_rewrap($($rhs)*), item: $($tts)* }
    };
    (($($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Div)::div, kind: rhs_rewrap($($rhs)*), item: $($tts)* }
    };
}

// ntbop Mul,      mul
#[macro_export]
macro_rules! NewtypeMul {
    (() $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Mul)::mul, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Mul)::mul, kind: simple_ref, item: $($tts)* }
    };
    ((&self, $($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Mul)::mul, kind: ref_rhs_rewrap($($rhs)*), item: $($tts)* }
    };
    (($($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Mul)::mul, kind: rhs_rewrap($($rhs)*), item: $($tts)* }
    };
}

// ntbop Rem,      rem
#[macro_export]
macro_rules! NewtypeRem {
    (() $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Rem)::rem, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Rem)::rem, kind: simple_ref, item: $($tts)* }
    };
    ((&self, $($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Rem)::rem, kind: ref_rhs_rewrap($($rhs)*), item: $($tts)* }
    };
    (($($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Rem)::rem, kind: rhs_rewrap($($rhs)*), item: $($tts)* }
    };
}

// ntbop Sub,      sub
#[macro_export]
macro_rules! NewtypeSub {
    (() $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Sub)::sub, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Sub)::sub, kind: simple_ref, item: $($tts)* }
    };
    ((&self, $($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Sub)::sub, kind: ref_rhs_rewrap($($rhs)*), item: $($tts)* }
    };
    (($($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Sub)::sub, kind: rhs_rewrap($($rhs)*), item: $($tts)* }
    };
}

// ntbop Shl,      shl
#[macro_export]
macro_rules! NewtypeShl {
    (() $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Shl)::shl, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Shl)::shl, kind: simple_ref, item: $($tts)* }
    };
    ((&self, $($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Shl)::shl, kind: ref_rhs_rewrap($($rhs)*), item: $($tts)* }
    };
    (($($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Shl)::shl, kind: rhs_rewrap($($rhs)*), item: $($tts)* }
    };
}

// ntbop Shr,      shr
#[macro_export]
macro_rules! NewtypeShr {
    (() $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Shr)::shr, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Shr)::shr, kind: simple_ref, item: $($tts)* }
    };
    ((&self, $($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Shr)::shr, kind: ref_rhs_rewrap($($rhs)*), item: $($tts)* }
    };
    (($($rhs:tt)*) $($tts:tt)*) => {
        newtype_wrap_bin_op! { trait: (::std::ops::Shr)::shr, kind: rhs_rewrap($($rhs)*), item: $($tts)* }
    };
}

// ntuop Neg,      neg
#[macro_export]
macro_rules! NewtypeNeg {
    (() $($tts:tt)*) => {
        newtype_wrap_un_op! { trait: (::std::ops::Neg)::neg, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_un_op! { trait: (::std::ops::Neg)::neg, kind: simple_ref, item: $($tts)* }
    };
}

// ntuop Not,      not
#[macro_export]
macro_rules! NewtypeNot {
    (() $($tts:tt)*) => {
        newtype_wrap_un_op! { trait: (::std::ops::Not)::not, kind: simple, item: $($tts)* }
    };
    ((&self) $($tts:tt)*) => {
        newtype_wrap_un_op! { trait: (::std::ops::Not)::not, kind: simple_ref, item: $($tts)* }
    };
}

#[macro_export]
macro_rules! NewtypeDeref {
    (() $(pub)* struct $name:ident($(pub)* $t0:ty);) => {
        impl ::std::ops::Deref for $name {
            type Target = $t0;
            fn deref(&self) -> &Self::Target {
                &self.0
            }
        }
    };
}

#[macro_export]
macro_rules! NewtypeDerefMut {
    (() $(pub)* struct $name:ident($(pub)* $t0:ty);) => {
        impl ::std::ops::DerefMut for $name {
            fn deref_mut(&mut self) -> &mut Self::Target {
                &mut self.0
            }
        }
    };
}

#[macro_export]
macro_rules! NewtypeIndex {
    (($index_ty:ty) $(pub)* struct $name:ident($(pub)* $t0:ty);) => {
        impl ::std::ops::Index<$index_ty> for $name {
            type Output = <$t0 as ::std::ops::Index<$index_ty>>::Output;
            fn index(&self, index: $index_ty) -> &Self::Output {
                (&self.0).index(index)
            }
        }
    };
}

#[macro_export]
macro_rules! NewtypeIndexMut {
    (($index_ty:ty) $(pub)* struct $name:ident($(pub)* $t0:ty);) => {
        impl ::std::ops::IndexMut<$index_ty> for $name {
            fn index_mut(&mut self, index: $index_ty) -> &mut Self::Output {
                (&mut self.0).index_mut(index)
            }
        }
    };
}

#[macro_export]
macro_rules! NewtypeFrom {
    (() $(pub)* struct $name:ident($(pub)* $t0:ty);) => {
        impl ::std::convert::From<$t0> for $name {
            fn from(v: $t0) -> Self {
                $name(v)
            }
        }
        impl ::std::convert::From<$name> for $t0 {
            fn from(v: $name) -> Self {
                v.0
            }
        }
    };
}