What is bracket syntax in structure field?

JayZhan · June 11, 2020, 1:44am

for example, on line 67 and 68, is there any more detail of this syntax?

rust-lang/rust/blob/ec42485ee95e3843a65b47533f6bcbcf06d9564e/src/liballoc/collections/btree/node.rs#L49-L69


      
          struct LeafNode<K, V> {
              /// We use `*const` as opposed to `*mut` so as to be covariant in `K` and `V`.
              /// This either points to an actual node or is null.
              parent: *const InternalNode<K, V>,
          
          
    /// This node's index into the parent node's `edges` array.
              /// `*node.parent.edges[node.parent_idx]` should be the same thing as `node`.
              /// This is only guaranteed to be initialized when `parent` is non-null.
              parent_idx: MaybeUninit<u16>,
          
          
    /// The number of keys and values this node stores.
              ///
              /// This next to `parent_idx` to encourage the compiler to join `len` and
              /// `parent_idx` into the same 32-bit word, reducing space overhead.
              len: u16,
          
          
    /// The arrays storing the actual data of the node. Only the first `len` elements of each
              /// array are initialized and valid.
              keys: [MaybeUninit<K>; CAPACITY],
              vals: [MaybeUninit<V>; CAPACITY],
          }

OptimisticPeach · June 11, 2020, 1:47am

These are arrays. They're of type MaybeUninit<K/V> and always CAPACITY long.

system · September 9, 2020, 1:48am

This topic was automatically closed 90 days after the last reply. We invite you to open a new topic if you have further questions or comments.

Topic		Replies	Views
How to initialize a structure field? help	7	952	August 31, 2020
Understanding Rust Struct Initialization and Colon Semantics help	3	101	March 8, 2025
Syntax survey for a potential RFC (please participate, especially if you don't know Rust too well :) )	57	3492	April 14, 2022
On-Disk B+ Tree help	13	3989	January 12, 2023
Help with simple B+ tree implementation help	13	3132	March 27, 2020

What is bracket syntax in structure field?

Related topics