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• [2] H3FVSQIQ Unsized pages

Change contents

• file addition: cursor.rs (-xw-x--x--)
  [2.22910]
  + use super::{header, Header};

  +

  + #[derive(Debug, Clone, Copy)]

  + pub struct PageCursor {

  + pub cur: isize,

  + pub total: usize,

  + pub is_leaf: bool,

  + }

  +

  + impl PageCursor {

  + /// Initialise a cursor on page `p` at position `cur`, checking

  + /// that `cur` is a valid position.

  + pub fn new(p: &crate::CowPage, cur: isize) -> Self {

  + let hdr = unsafe { &*(p.data as *const Header) };

  + assert!(cur >= -1 && cur < hdr.n() as isize);

  + PageCursor {

  + cur,

  + total: hdr.n() as usize,

  + is_leaf: hdr.is_leaf(),

  + }

  + }

  + /// Initialise a cursor set after the last entry of page `p`.

  + pub fn after(p: &crate::CowPage) -> Self {

  + let hdr = unsafe { &*(p.data as *const Header) };

  + let total = hdr.n();

  + PageCursor {

  + cur: total as isize,

  + total: total as usize,

  + is_leaf: hdr.is_leaf(),

  + }

  + }

  + /// Initialise a cursor set on the last entry of page `p`.

  + pub fn last(p: crate::Page) -> Self {

  + let hdr = header(p);

  + let total = hdr.n();

  + PageCursor {

  + cur: (total - 1) as isize,

  + total: total as usize,

  + is_leaf: hdr.is_leaf(),

  + }

  + }

  + }