Crate typed_tuple 

Typed Tuple

Type-safe access, isolation and mutation of primitive tuple segments and elements. Supports both type and/or numeric indexing for all operations.

Functionality

typed_tuple enables typed or numeric index access to tuple elements. All operations support access by either numeric index/indices, or type inferred access, Some use-cases for these operations may include:

• Getting an element by specifying a unique type (eg. u32).
• Getting a subset of elements by specifying a unique type range (eg. (u32, _, _, _)).
• Getting or splitting the first n elements (eg. ((_, _, _), _)).
• Getting or splitting the last n elements (eg. (_, (_, _, _))).
• Any combination of the above.

Example

let mut tuple = (0u8, 1u16, 2u32, 3u64, 'a', 'b', 'c');

// Get the (unique) `u64` element.
let element_u64: u64 = tuple.get();
assert_eq!(element_u64, 3);

// Mutate the (unique) `u16` element.
let mut element_u16: &mut u16 = (&mut tuple).get();
*element_u16 = 100;
assert_eq!(element_u16, &mut 100);

// Split the tuple returning a right segment of exactly 3 elements.
let (left, right): (_, (_, _, _)) = tuple.split();
assert_eq!(left, (0, 100, 2, 3));
assert_eq!(right, ('a', 'b', 'c'));

// Extract (with mutable borrow) the 3 elements starting at the `u32` field.
let mut extracted: (&mut u32, &mut _, &mut _) = (&mut tuple).extract();
assert_eq!(extracted, (&mut 2, &mut 3, &mut 'a'));

// Get the (unique) `&mut char` type from the extracted segment.
let mut ext_char: &mut char = extracted.get();
*ext_char = 'x';

assert_eq!(tuple, (0u8, 100u16, 2u32, 3u64, 'x', 'b', 'c'));

Operation Arguments

Elements are accessed by an index/indices inferred by the return type. Explict numeric indices can be specified in cases where type inferred indices are not possible/preferable. See trait-level documentation for examples of explicit/inferred index operations.

Example

let mut tuple = (0u8, 1u16, 2u32, 3u64, 4u128);

// Split the last element off the tuple.
let (left_inferred, right_inferred): (_, (_,)) = tuple.split();
// Split the tuple at index 4 (left-exclusive).
let (left_explicit, right_explicit) = TypedSplit::<4, _, _>::split(tuple);

assert_eq!(left_inferred, left_explicit);
assert_eq!(right_inferred, right_explicit);

Ownership

Operations can either return owned, borrowed or mutable borrowed elements. Element state follows the borrow state of the tuple. Given a tuple Self containing the element T, operations exhibit the following behaviour:

Tuple State	Element State	Behaviour	Example
Self	T	Consume the tuple returning owned element(s)	tuple.get()
&Self	&T	Borrow the tuple returning borrowed element(s)	(&tuple).get()
&mut Self	&mut T	Borrow the tuple returning mutable borrowed element(s)	(&mut tuple).get()

Features

Functionality can be enabled/disabled through the following features (all enabled by default).

Feature	Description	Exposed Type
index	Enables retrieving an element by type/index.	TypedIndex
split	Enables splitting a tuple by type/index.	TypedSplit
extract	Enables extracting a tuple segment by type/indices.	TypedExtract

Limitations

• typed_tuple can impact readability. Types should be explicit if not immediately obvious. Prefer let a: usize = tuple.get() over let a = tuple.get().
• TypedTuple is implemented on tuples of up to 12 elements in length. This was chosen as it is the limit of many tuple trait implementations (PartialEq, Eq, etc.), however can be extended to support a higher number of elements if needed.

Traits

TypedExtract

TypedExtract

TypedIndex

TypedIndex

TypedSplit

TypedSplit