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+//! This package contains just four macros, which enable the creation
+//! of array references to portions of arrays or slices (or things
+//! that can be sliced).
+//!
+//! # Examples
+//!
+//! Here is a simple example of slicing and dicing a slice into array
+//! references with these macros. Here we implement a simple
+//! little-endian conversion from bytes to `u16`, and demonstrate code
+//! that uses `array_ref!` to extract an array reference from a larger
+//! array. Note that the documentation for each macro also has an
+//! example of its use.
+//!
+//! ```
+//! #[macro_use]
+//! extern crate arrayref;
+//!
+//! fn read_u16(bytes: &[u8; 2]) -> u16 {
+//! bytes[0] as u16 + ((bytes[1] as u16) << 8)
+//! }
+//! // ...
+//! # fn main() {
+//! let data = [0,1,2,3,4,0,6,7,8,9];
+//! assert_eq!(256, read_u16(array_ref![data,0,2]));
+//! assert_eq!(4, read_u16(array_ref![data,4,2]));
+//! # }
+//! ```
+#![deny(warnings)]
+#![no_std]
+
+#[cfg(test)]
+#[macro_use]
+extern crate std;
+
+/// You can use `array_ref` to generate an array reference to a subset
+/// of a sliceable bit of data (which could be an array, or a slice,
+/// or a Vec).
+///
+/// **Panics** if the slice is out of bounds.
+///
+/// ```
+/// #[macro_use]
+/// extern crate arrayref;
+///
+/// fn read_u16(bytes: &[u8; 2]) -> u16 {
+/// bytes[0] as u16 + ((bytes[1] as u16) << 8)
+/// }
+/// // ...
+/// # fn main() {
+/// let data = [0,1,2,3,4,0,6,7,8,9];
+/// assert_eq!(256, read_u16(array_ref![data,0,2]));
+/// assert_eq!(4, read_u16(array_ref![data,4,2]));
+/// # }
+/// ```
+
+#[macro_export]
+macro_rules! array_ref {
+ ($arr:expr, $offset:expr, $len:expr) => {{
+ {
+ #[inline]
+ unsafe fn as_array<T>(slice: &[T]) -> &[T; $len] {
+ &*(slice.as_ptr() as *const [_; $len])
+ }
+ let offset = $offset;
+ let slice = & $arr[offset..offset + $len];
+ #[allow(unused_unsafe)]
+ unsafe {
+ as_array(slice)
+ }
+ }
+ }}
+}
+
+/// You can use `array_refs` to generate a series of array references
+/// to an input array reference. The idea is if you want to break an
+/// array into a series of contiguous and non-overlapping arrays.
+/// `array_refs` is a bit funny in that it insists on slicing up the
+/// *entire* array. This is intentional, as I find it handy to make
+/// me ensure that my sub-arrays add up to the entire array. This
+/// macro will *never* panic, since the sizes are all checked at
+/// compile time.
+///
+/// Note that unlike `array_ref!`, `array_refs` *requires* that the
+/// first argument be an array reference. The following arguments are
+/// the lengths of each subarray you wish a reference to. The total
+/// of these arguments *must* equal the size of the array itself.
+///
+/// ```
+/// #[macro_use]
+/// extern crate arrayref;
+///
+/// fn read_u16(bytes: &[u8; 2]) -> u16 {
+/// bytes[0] as u16 + ((bytes[1] as u16) << 8)
+/// }
+/// // ...
+/// # fn main() {
+/// let data = [0,1,2,3,4,0,6,7];
+/// let (a,b,c) = array_refs![&data,2,2,4];
+/// assert_eq!(read_u16(a), 256);
+/// assert_eq!(read_u16(b), 3*256+2);
+/// assert_eq!(*c, [4,0,6,7]);
+/// # }
+/// ```
+#[macro_export]
+macro_rules! array_refs {
+ ( $arr:expr, $( $pre:expr ),* ; .. ; $( $post:expr ),* ) => {{
+ {
+ use std::slice;
+ #[inline]
+ #[allow(unused_assignments)]
+ #[allow(eval_order_dependence)]
+ unsafe fn as_arrays<T>(a: &[T]) -> ( $( &[T; $pre], )* &[T], $( &[T; $post], )*) {
+ let min_len = $( $pre + )* $( $post + )* 0;
+ let var_len = a.len() - min_len;
+ assert!(a.len() >= min_len);
+ let mut p = a.as_ptr();
+ ( $( {
+ let aref = & *(p as *const [T; $pre]);
+ p = p.offset($pre as isize);
+ aref
+ } ),* , {
+ let sl = slice::from_raw_parts(p as *const T, var_len);
+ p = p.offset(var_len as isize);
+ sl
+ }, $( {
+ let aref = & *(p as *const [T; $post]);
+ p = p.offset($post as isize);
+ aref
+ } ),*)
+ }
+ let input = $arr;
+ #[allow(unused_unsafe)]
+ unsafe {
+ as_arrays(input)
+ }
+ }
+ }};
+ ( $arr:expr, $( $len:expr ),* ) => {{
+ {
+ #[inline]
+ #[allow(unused_assignments)]
+ #[allow(eval_order_dependence)]
+ unsafe fn as_arrays<T>(a: &[T; $( $len + )* 0 ]) -> ( $( &[T; $len], )* ) {
+ let mut p = a.as_ptr();
+ ( $( {
+ let aref = &*(p as *const [T; $len]);
+ p = p.offset($len as isize);
+ aref
+ } ),* )
+ }
+ let input = $arr;
+ #[allow(unused_unsafe)]
+ unsafe {
+ as_arrays(input)
+ }
+ }
+ }}
+}
+
+
+/// You can use `mut_array_refs` to generate a series of mutable array
+/// references to an input mutable array reference. The idea is if
+/// you want to break an array into a series of contiguous and
+/// non-overlapping mutable array references. Like `array_refs!`,
+/// `mut_array_refs!` is a bit funny in that it insists on slicing up
+/// the *entire* array. This is intentional, as I find it handy to
+/// make me ensure that my sub-arrays add up to the entire array.
+/// This macro will *never* panic, since the sizes are all checked at
+/// compile time.
+///
+/// Note that unlike `array_mut_ref!`, `mut_array_refs` *requires*
+/// that the first argument be a mutable array reference. The
+/// following arguments are the lengths of each subarray you wish a
+/// reference to. The total of these arguments *must* equal the size
+/// of the array itself. Also note that this macro allows you to take
+/// out multiple mutable references to a single object, which is both
+/// weird and powerful.
+///
+/// ```
+/// #[macro_use]
+/// extern crate arrayref;
+///
+/// fn write_u16(bytes: &mut [u8; 2], num: u16) {
+/// bytes[0] = num as u8;
+/// bytes[1] = (num >> 8) as u8;
+/// }
+/// fn write_u32(bytes: &mut [u8; 4], num: u32) {
+/// bytes[0] = num as u8;
+/// bytes[1] = (num >> 8) as u8; // this is buggy to save space...
+/// }
+/// // ...
+/// # fn main() {
+/// let mut data = [0,1,2,3,4,0,6,7];
+/// let (a,b,c) = mut_array_refs![&mut data,2,2,4];
+/// // let's write out some nice prime numbers!
+/// write_u16(a, 37);
+/// write_u16(b, 73);
+/// write_u32(c, 137); // approximate inverse of the fine structure constant!
+/// # }
+/// ```
+#[macro_export]
+macro_rules! mut_array_refs {
+ ( $arr:expr, $( $pre:expr ),* ; .. ; $( $post:expr ),* ) => {{
+ {
+ use std::slice;
+ #[inline]
+ #[allow(unused_assignments)]
+ #[allow(eval_order_dependence)]
+ unsafe fn as_arrays<T>(a: &mut [T]) -> ( $( &mut [T; $pre], )* &mut [T], $( &mut [T; $post], )*) {
+ let min_len = $( $pre + )* $( $post + )* 0;
+ let var_len = a.len() - min_len;
+ assert!(a.len() >= min_len);
+ let mut p = a.as_mut_ptr();
+ ( $( {
+ let aref = &mut *(p as *mut [T; $pre]);
+ p = p.offset($pre as isize);
+ aref
+ } ),* , {
+ let sl = slice::from_raw_parts_mut(p as *mut T, var_len);
+ p = p.offset(var_len as isize);
+ sl
+ }, $( {
+ let aref = &mut *(p as *mut [T; $post]);
+ p = p.offset($post as isize);
+ aref
+ } ),*)
+ }
+ let input = $arr;
+ #[allow(unused_unsafe)]
+ unsafe {
+ as_arrays(input)
+ }
+ }
+ }};
+ ( $arr:expr, $( $len:expr ),* ) => {{
+ {
+ #[inline]
+ #[allow(unused_assignments)]
+ #[allow(eval_order_dependence)]
+ unsafe fn as_arrays<T>(a: &mut [T; $( $len + )* 0 ]) -> ( $( &mut [T; $len], )* ) {
+ let mut p = a.as_mut_ptr();
+ ( $( {
+ let aref = &mut *(p as *mut [T; $len]);
+ p = p.offset($len as isize);
+ aref
+ } ),* )
+ }
+ let input = $arr;
+ #[allow(unused_unsafe)]
+ unsafe {
+ as_arrays(input)
+ }
+ }
+ }};
+}
+
+/// You can use `array_mut_ref` to generate a mutable array reference
+/// to a subset of a sliceable bit of data (which could be an array,
+/// or a slice, or a Vec).
+///
+/// **Panics** if the slice is out of bounds.
+///
+/// ```
+/// #[macro_use]
+/// extern crate arrayref;
+///
+/// fn write_u16(bytes: &mut [u8; 2], num: u16) {
+/// bytes[0] = num as u8;
+/// bytes[1] = (num >> 8) as u8;
+/// }
+/// // ...
+/// # fn main() {
+/// let mut data = [0,1,2,3,4,0,6,7,8,9];
+/// write_u16(array_mut_ref![data,0,2], 1);
+/// write_u16(array_mut_ref![data,2,2], 5);
+/// assert_eq!(*array_ref![data,0,4], [1,0,5,0]);
+/// *array_mut_ref![data,4,5] = [4,3,2,1,0];
+/// assert_eq!(data, [1,0,5,0,4,3,2,1,0,9]);
+/// # }
+/// ```
+#[macro_export]
+macro_rules! array_mut_ref {
+ ($arr:expr, $offset:expr, $len:expr) => {{
+ {
+ #[inline]
+ unsafe fn as_array<T>(slice: &mut [T]) -> &mut [T; $len] {
+ &mut *(slice.as_mut_ptr() as *mut [_; $len])
+ }
+ let offset = $offset;
+ let slice = &mut $arr[offset..offset + $len];
+ #[allow(unused_unsafe)]
+ unsafe {
+ as_array(slice)
+ }
+ }
+ }}
+}
+
+
+#[cfg(test)]
+mod test {
+
+extern crate quickcheck;
+
+use std::vec::Vec;
+
+// use super::*;
+
+#[test]
+#[should_panic]
+fn checks_bounds() {
+ let foo: [u8; 11] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+ let bar = array_ref!(foo, 1, 11);
+ println!("I am checking that I can dereference bar[0] = {}", bar[0]);
+}
+
+#[test]
+fn simple_case_works() {
+ fn check(expected: [u8; 3], actual: &[u8; 3]) {
+ for (e, a) in (&expected).iter().zip(actual.iter()) {
+ assert_eq!(e, a)
+ }
+ }
+ let mut foo: [u8; 11] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+ {
+ let bar = array_ref!(foo, 2, 3);
+ check([2, 3, 4], bar);
+ }
+ check([0, 1, 2], array_ref!(foo, 0, 3));
+ fn zero2(x: &mut [u8; 2]) {
+ x[0] = 0;
+ x[1] = 0;
+ }
+ zero2(array_mut_ref!(foo, 8, 2));
+ check([0, 0, 10], array_ref!(foo, 8, 3));
+}
+
+
+#[test]
+fn check_array_ref_5() {
+ fn f(data: Vec<u8>, offset: usize) -> quickcheck::TestResult {
+ if data.len() < offset + 5 {
+ return quickcheck::TestResult::discard();
+ }
+ let out = array_ref!(data, offset, 5);
+ quickcheck::TestResult::from_bool(out.len() == 5)
+ }
+ quickcheck::quickcheck(f as fn(Vec<u8>, usize) -> quickcheck::TestResult);
+}
+
+#[test]
+fn check_array_ref_out_of_bounds_5() {
+ fn f(data: Vec<u8>, offset: usize) -> quickcheck::TestResult {
+ if data.len() >= offset + 5 {
+ return quickcheck::TestResult::discard();
+ }
+ quickcheck::TestResult::must_fail(move || {
+ array_ref!(data, offset, 5);
+ })
+ }
+ quickcheck::quickcheck(f as fn(Vec<u8>, usize) -> quickcheck::TestResult);
+}
+
+#[test]
+fn check_array_mut_ref_7() {
+ fn f(mut data: Vec<u8>, offset: usize) -> quickcheck::TestResult {
+ if data.len() < offset + 7 {
+ return quickcheck::TestResult::discard();
+ }
+ let out = array_mut_ref!(data, offset, 7);
+ out[6] = 3;
+ quickcheck::TestResult::from_bool(out.len() == 7)
+ }
+ quickcheck::quickcheck(f as fn(Vec<u8>, usize) -> quickcheck::TestResult);
+}
+
+
+#[test]
+fn check_array_mut_ref_out_of_bounds_32() {
+ fn f(mut data: Vec<u8>, offset: usize) -> quickcheck::TestResult {
+ if data.len() >= offset + 32 {
+ return quickcheck::TestResult::discard();
+ }
+ quickcheck::TestResult::must_fail(move || {
+ array_mut_ref!(data, offset, 32);
+ })
+ }
+ quickcheck::quickcheck(f as fn(Vec<u8>, usize) -> quickcheck::TestResult);
+}
+
+
+#[test]
+fn test_5_array_refs() {
+ let mut data: [usize; 128] = [0; 128];
+ for i in 0..128 {
+ data[i] = i;
+ }
+ let data = data;
+ let (a,b,c,d,e) = array_refs!(&data, 1, 14, 3, 100, 10);
+ assert_eq!(a.len(), 1 as usize);
+ assert_eq!(b.len(), 14 as usize);
+ assert_eq!(c.len(), 3 as usize);
+ assert_eq!(d.len(), 100 as usize);
+ assert_eq!(e.len(), 10 as usize);
+ assert_eq!(a, array_ref![data, 0, 1]);
+ assert_eq!(b, array_ref![data, 1, 14]);
+ assert_eq!(c, array_ref![data, 15, 3]);
+ assert_eq!(e, array_ref![data, 118, 10]);
+}
+
+#[test]
+fn test_5_array_refs_dotdot() {
+ let mut data: [usize; 128] = [0; 128];
+ for i in 0..128 {
+ data[i] = i;
+ }
+ let data = data;
+ let (a,b,c,d,e) = array_refs!(&data, 1, 14, 3; ..; 10);
+ assert_eq!(a.len(), 1 as usize);
+ assert_eq!(b.len(), 14 as usize);
+ assert_eq!(c.len(), 3 as usize);
+ assert_eq!(d.len(), 100 as usize);
+ assert_eq!(e.len(), 10 as usize);
+ assert_eq!(a, array_ref![data, 0, 1]);
+ assert_eq!(b, array_ref![data, 1, 14]);
+ assert_eq!(c, array_ref![data, 15, 3]);
+ assert_eq!(e, array_ref![data, 118, 10]);
+}
+
+
+#[test]
+fn test_5_mut_xarray_refs() {
+ let mut data: [usize; 128] = [0; 128];
+ {
+ // temporarily borrow the data to modify it.
+ let (a,b,c,d,e) = mut_array_refs!(&mut data, 1, 14, 3, 100, 10);
+ assert_eq!(a.len(), 1 as usize);
+ assert_eq!(b.len(), 14 as usize);
+ assert_eq!(c.len(), 3 as usize);
+ assert_eq!(d.len(), 100 as usize);
+ assert_eq!(e.len(), 10 as usize);
+ *a = [1; 1];
+ *b = [14; 14];
+ *c = [3; 3];
+ *d = [100; 100];
+ *e = [10; 10];
+ }
+ assert_eq!(&[1;1], array_ref![data, 0, 1]);
+ assert_eq!(&[14;14], array_ref![data, 1, 14]);
+ assert_eq!(&[3;3], array_ref![data, 15, 3]);
+ assert_eq!(&[10;10], array_ref![data, 118, 10]);
+}
+
+#[test]
+fn test_5_mut_xarray_refs_with_dotdot() {
+ let mut data: [usize; 128] = [0; 128];
+ {
+ // temporarily borrow the data to modify it.
+ let (a,b,c,d,e) = mut_array_refs!(&mut data, 1, 14, 3; ..; 10);
+ assert_eq!(a.len(), 1 as usize);
+ assert_eq!(b.len(), 14 as usize);
+ assert_eq!(c.len(), 3 as usize);
+ assert_eq!(d.len(), 100 as usize);
+ assert_eq!(e.len(), 10 as usize);
+ *a = [1; 1];
+ *b = [14; 14];
+ *c = [3; 3];
+ *e = [10; 10];
+ }
+ assert_eq!(&[1;1], array_ref![data, 0, 1]);
+ assert_eq!(&[14;14], array_ref![data, 1, 14]);
+ assert_eq!(&[3;3], array_ref![data, 15, 3]);
+ assert_eq!(&[10;10], array_ref![data, 118, 10]);
+}
+
+} // mod test
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