added README

Cargo.toml

@@ -1,9 +1,16 @@
 [package]
 name = "ad-hoc-iter"
 version = "0.1.0"
+description = "Ad-hoc exact size owning iterator macro and other optional utils"
+keywords = ["iterator", "macro", "iter"]
 authors = ["Avril <flanchan@cumallover.me>"]
 edition = "2018"
+license = "mit"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[features]
+default = ["maybe-many"]
+
+# Enable the `maybe` module
+maybe-many = []
 
 [dependencies]

README.md

@@ -0,0 +1,49 @@
+# Ad-hoc owning iterator types
+
+This crate defines the macro `iter!` which produces ad-hoc iterator types that own their values and have compile-time known exact sizes.
+
+# Usage
+This macro can be used exactly like `vec!`, except it produces an `impl Iterator` that does not allocate.
+This `impl Iterator` yields the values directly, **not references** to the values.
+
+This can be useful for when you want a ad-hoc iterator of a non-copy type, as sized slices and arrays currently do not implement `IntoIterator` in a way that moves their values, instead they yield references, causing the need for cloning.
+
+The `iter!` macro's iterator types move their values on calls to `next()` instead of returning references, and drop the non-consumed values when the iterator is dropped itself.
+
+## Example
+
+Concatenating a 'slice' of `String` without cloning.
+``` rust
+let whole: String = iter![String::from("Hell"),
+			  String::from("o "),
+			  String::from("world"),
+			  String::from("!")]
+    .collect();
+assert_eq!("Hello world!", &whole[..]);
+```
+
+## Functions
+The iterator types also have a few associated functions.
+
+### The length of the whole iterator
+```rust
+pub const fn len(&self) -> usize
+```
+
+### The rest of the iterator that has not been consumed.
+```rust
+pub fn rest(&self) -> &[T]
+```
+
+###  The whole array.
+All values that have not been consumed are initialised, values that have been consumed are uninitialised.
+```rust
+pub fn array(&self) -> &[MaybeUninit<T>; Self::LEN]
+```
+
+### How many items have since been consumed.
+```rust
+pub const fn consumed(&self) -> usize
+```
+# License
+MIT

src/lib.rs

@@ -1,12 +1,16 @@
-//! Iterator types
+//! Ad-hoc exact size owning iterator macro and other optional utils
+//!
+//! The macro can be used exactly as `vec!`.
 
-pub mod either;
+#[cfg(feature="maybe-many")] pub mod maybe;
 
 /// A bespoke iterator type with an exact size over elements.
 ///
 /// This has an advantage over using simple inline slices (e.g `[1,2,3]`) as they currently cannot implement `IntoIterator` properly, and will always yield references.
 /// This can be a hinderance when you want an ad-hoc iterator of non-`Copy` items.
+///
 /// The iterator types created from this macro consume the values.
+/// It has the advantage over `vec![].into_iter()` as there are no heap allocations needed and size of the iterator is known at compile time.
 ///
 /// # Example
 /// ```
@@ -14,10 +18,57 @@ pub mod either;
 /// let sum: i32 = iter![1, 2].chain(3..=4).chain(iter![5, 6]).sum();
 /// assert_eq!(sum, 21);
 /// ```
+/// # Functions
+/// The iterators returned from this method have these associated functions:
+///
+/// ## The length of the whole iterator
+/// ```
+/// pub const fn len(&self) -> usize
+/// ```
+///
+/// ## The rest of the iterator that has not been consumed.
+/// ```
+/// pub fn rest(&self) -> &[T]
+/// ```
+///
+/// ##  The whole array.
+///  All values that have not been consumed are initialised, values that have been consumed are uninitialised.
+/// ```
+/// pub fn array(&self) -> &[MaybeUninit<T>; Self::LEN]
+/// ```
+///
+/// ## How many items have since been consumed.
+/// ```
+/// pub const fn consumed(&self) -> usize
+/// ```
 #[macro_export] macro_rules! iter {
     (@) => (0usize);
     (@ $x:tt $($xs:tt)* ) => (1usize + $crate::iter!(@ $($xs)*));
 
+    () => {
+	{
+	    #[derive(Debug)]
+	    struct Empty;
+	    impl Iterator for Empty
+	    {
+		type Item = std::convert::Infallible;
+		fn next(&mut self) -> Option<Self::Item>
+		{
+		    None
+		}
+
+		fn size_hint(&self) -> (usize, Option<usize>)
+		{
+		    (0, Some(0))
+		}
+	    }
+	    impl ::std::iter::FusedIterator for Empty{}
+	    impl ::std::iter::ExactSizeIterator for Empty{}
+
+	    Empty
+	}
+    };
+    
     ($($value:expr),*) => {
 	{
 	    use ::std::mem::MaybeUninit;
@@ -25,7 +76,53 @@ pub mod either;
 	    struct Arr<T>([MaybeUninit<T>; $crate::iter!(@ $($value)*)], usize);
 	    impl<T> Arr<T>
 	    {
+		#![allow(dead_code)]
+		/// The length of the whole iterator
 		const LEN: usize = $crate::iter!(@ $($value)*);
+
+		/// The length of the whole iterator
+		// This exists as an associated function because this type is opaque.
+		#[inline] pub const fn len(&self) -> usize
+		{
+		    Self::LEN
+		}
+		
+		/// Consume this iterator into the backing buffer.
+		///
+		/// # Safety
+		/// Non-consumed items are safe to `assume_init`. However, items that have already been consumed are uninitialised.
+		fn into_inner(self) -> [MaybeUninit<T>; $crate::iter!(@ $($value)*)]
+		{
+		    //XXX: We will have to do something really unsafe for this to work on stable...
+		    todo!()
+		}
+
+		/// The rest of the iterator that has not been consumed.
+		///
+		// # Safety
+		// All values in this slice are initialised.
+		#[inline] pub fn rest(&self) -> &[T]
+		{
+		    let slice = &self.0[self.1..];
+		    //std::mem::MaybeUninit::slice_get_ref(&self.0[self.1..]) //nightly only...
+		    
+		    unsafe { &*(slice as *const [std::mem::MaybeUninit<T>] as *const [T]) }
+		}
+
+		/// The whole array.
+		///
+		/// # Safety
+		/// All values that have not been consumed are initialised, values that have been consumed are uninitialised.
+		#[inline] pub fn array(&self) -> &[MaybeUninit<T>; $crate::iter!(@ $($value)*)]
+		{
+		    &self.0
+		}
+
+		/// How many items have since been consumed.
+		pub const fn consumed(&self) -> usize
+		{
+		    self.1
+		}
 	    }
 	    impl<T> Iterator for Arr<T>
 	    {
@@ -84,15 +181,42 @@ mod tests
 	
     }
 
+    
+    macro_rules! string {
+	($val:literal) => (String::from($val));
+    }
     #[test]
     fn non_copy()
     {
-	macro_rules! string {
-	    ($val:literal) => (String::from($val));
-	}
 
 	const EXPECT: &str = "Hello world!";
 	let whole: String = iter![string!("Hell"), string!("o "), string!("world"), string!("!")].collect();
 	assert_eq!(EXPECT, &whole[..]);
     }
+
+    #[test]
+    fn empty()
+    {
+	let empty: Vec<_> = iter![].collect();
+	assert_eq!(empty.len(), 0);
+    }
+
+    #[test]
+    fn assoc()
+    {
+	let mut iter = iter![1,2,3,4];
+
+	assert_eq!(iter.len(), 4);
+	iter.next();
+	assert_eq!(iter.consumed(), 1);
+	assert_eq!(iter.rest(), &[2,3,4]);
+
+	
+	let mut iter = iter![string!("Hell"), string!("o "), string!("world"), string!("!")];
+	
+	iter.next();
+	iter.next();
+	
+	assert_eq!(iter.rest().iter().map(|x| x.as_str()).collect::<Vec<_>>().as_slice(), &["world", "!"]);
+    }
 }