Trait sanakirja::Representable

pub trait Representable: Copy + Debug {
    type PageOffsets: Iterator<Item = u64>;
    fn onpage_size(&self) -> u16;
    unsafe fn write_value(&self, p: *mut u8);
    unsafe fn read_value(p: *const u8) -> Self;
    unsafe fn cmp_value<T: LoadPage>(&self, txn: &T, x: Self) -> Ordering;
    fn page_offsets(&self) -> Self::PageOffsets;

    fn alignment() -> Alignment { ... }
    unsafe fn skip(p: *mut u8) -> *mut u8 { ... }
    fn drop_value<T, R: Rng>(
        &self, 
        _: &mut MutTxn<T>, 
        _: &mut R
    ) -> Result<(), Error> { ... }
}

Types that can be stored in a Sanakirja database, as keys or values. Some care must be taken when storing things.

Associated Types

type PageOffsets: Iterator<Item = u64>

An iterator over the offsets to pages contained in this value. Only values from this crate can generate non-empty iterators, but combined values (like tuples) must chain the iterators returned by method page_offsets.

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Required methods

fn onpage_size(&self) -> u16

How much space this value occupies on the page (not counting alignment padding).

unsafe fn write_value(&self, p: *mut u8)

Write this value to a u8 pointer, guaranteed to be a multiple of self.alignment().

unsafe fn read_value(p: *const u8) -> Self

Read value from an onpage pointer, guaranteed to be a multiple of self.alignment().

unsafe fn cmp_value<T: LoadPage>(&self, txn: &T, x: Self) -> Ordering

Compare a value with an onpage value. The current transaction is sometimes helpful, for instance when the page only stores a pointer to another page.

fn page_offsets(&self) -> Self::PageOffsets

If this value is an offset to another page at offset offset, return Some(offset). Return None else.

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Provided methods

fn alignment() -> Alignment

Alignment of this type. Allowed values are 1, 2, 4 and 8.

unsafe fn skip(p: *mut u8) -> *mut u8

First pointer strictly after this value's pointer. The default implementation is basically p.offset(self.onpage_size() as isize), but their might be more efficient implementations in some cases.

fn drop_value<T, R: Rng>(
    &self,
    _: &mut MutTxn<T>,
    _: &mut R
) -> Result<(), Error>

How to free the pages used by this value. The default implementation doesn't do anything, which is fine for types stored directly on B tree pages.

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Implementations on Foreign Types

impl<A: Representable, B: Representable> Representable for (A, B)

fn alignment() -> Alignment

fn onpage_size(&self) -> u16

unsafe fn write_value(&self, p: *mut u8)

unsafe fn read_value(p: *const u8) -> Self

unsafe fn cmp_value<T: LoadPage>(&self, txn: &T, x: Self) -> Ordering

type PageOffsets = Chain<A::PageOffsets, B::PageOffsets>

fn page_offsets(&self) -> Self::PageOffsets

fn drop_value<T, R: Rng>(
    &self,
    txn: &mut MutTxn<T>,
    rng: &mut R
) -> Result<(), Error>

impl<A: Representable, B: Representable, C: Representable> Representable for (A, B, C)

fn alignment() -> Alignment

fn onpage_size(&self) -> u16

unsafe fn write_value(&self, p: *mut u8)

unsafe fn read_value(p: *const u8) -> Self

unsafe fn cmp_value<T: LoadPage>(&self, txn: &T, x: Self) -> Ordering

type PageOffsets = Chain<Chain<A::PageOffsets, B::PageOffsets>, C::PageOffsets>

fn page_offsets(&self) -> Self::PageOffsets

fn drop_value<T, R: Rng>(
    &self,
    txn: &mut MutTxn<T>,
    rng: &mut R
) -> Result<(), Error>

impl<A: Representable, B: Representable, C: Representable, D: Representable> Representable for (A, B, C, D)

fn alignment() -> Alignment

fn onpage_size(&self) -> u16

unsafe fn write_value(&self, p: *mut u8)

unsafe fn read_value(p: *const u8) -> Self

unsafe fn cmp_value<T: LoadPage>(&self, txn: &T, x: Self) -> Ordering

type PageOffsets = Chain<Chain<A::PageOffsets, B::PageOffsets>, Chain<C::PageOffsets, D::PageOffsets>>

fn page_offsets(&self) -> Self::PageOffsets

fn drop_value<T, R: Rng>(
    &self,
    txn: &mut MutTxn<T>,
    rng: &mut R
) -> Result<(), Error>

impl Representable for f64

fn alignment() -> Alignment

fn onpage_size(&self) -> u16

unsafe fn skip(p: *mut u8) -> *mut u8

unsafe fn write_value(&self, p: *mut u8)

unsafe fn read_value(p: *const u8) -> Self

unsafe fn cmp_value<T: LoadPage>(&self, _: &T, x: Self) -> Ordering

type PageOffsets = Empty<u64>

fn page_offsets(&self) -> Self::PageOffsets

impl Representable for u64

fn alignment() -> Alignment

fn onpage_size(&self) -> u16

unsafe fn skip(p: *mut u8) -> *mut u8

unsafe fn write_value(&self, p: *mut u8)

unsafe fn read_value(p: *const u8) -> Self

unsafe fn cmp_value<T: LoadPage>(&self, _: &T, x: Self) -> Ordering

type PageOffsets = Empty<u64>

fn page_offsets(&self) -> Self::PageOffsets

impl Representable for u32

fn alignment() -> Alignment

fn onpage_size(&self) -> u16

unsafe fn skip(p: *mut u8) -> *mut u8

unsafe fn write_value(&self, p: *mut u8)

unsafe fn read_value(p: *const u8) -> Self

unsafe fn cmp_value<T: LoadPage>(&self, _: &T, x: Self) -> Ordering

type PageOffsets = Empty<u64>

fn page_offsets(&self) -> Self::PageOffsets

impl Representable for i64

fn alignment() -> Alignment

fn onpage_size(&self) -> u16

unsafe fn skip(p: *mut u8) -> *mut u8

unsafe fn write_value(&self, p: *mut u8)

unsafe fn read_value(p: *const u8) -> Self

unsafe fn cmp_value<T: LoadPage>(&self, _: &T, x: Self) -> Ordering

type PageOffsets = Empty<u64>

fn page_offsets(&self) -> Self::PageOffsets

impl Representable for i32

fn alignment() -> Alignment

fn onpage_size(&self) -> u16

unsafe fn skip(p: *mut u8) -> *mut u8

unsafe fn write_value(&self, p: *mut u8)

unsafe fn read_value(p: *const u8) -> Self

unsafe fn cmp_value<T: LoadPage>(&self, _: &T, x: Self) -> Ordering

type PageOffsets = Empty<u64>

fn page_offsets(&self) -> Self::PageOffsets

impl Representable for ()

fn alignment() -> Alignment

fn onpage_size(&self) -> u16

unsafe fn skip(p: *mut u8) -> *mut u8

unsafe fn write_value(&self, _: *mut u8)

unsafe fn read_value(_: *const u8) -> Self

unsafe fn cmp_value<T: LoadPage>(&self, _: &T, _: Self) -> Ordering

type PageOffsets = Empty<u64>

fn page_offsets(&self) -> Self::PageOffsets

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Implementors

impl Representable for UnsafeValue

fn onpage_size(&self) -> u16

unsafe fn write_value(&self, ptr: *mut u8)

unsafe fn read_value(ptr: *const u8) -> Self

unsafe fn cmp_value<T: LoadPage>(&self, txn: &T, y: Self) -> Ordering

fn drop_value<T, R>(&self, txn: &mut MutTxn<T>, _: &mut R) -> Result<(), Error>

type PageOffsets = IntoIter<u64>

fn page_offsets(&self) -> Self::PageOffsets

impl<K: Representable, V: Representable> Representable for Db<K, V>

fn alignment() -> Alignment

fn onpage_size(&self) -> u16

unsafe fn skip(p: *mut u8) -> *mut u8

unsafe fn write_value(&self, p: *mut u8)

unsafe fn read_value(p: *const u8) -> Self

unsafe fn cmp_value<T: LoadPage>(&self, _: &T, x: Db<K, V>) -> Ordering

type PageOffsets = Once<u64>

fn page_offsets(&self) -> Self::PageOffsets

fn drop_value<T, R: Rng>(
    &self,
    txn: &mut MutTxn<T>,
    rng: &mut R
) -> Result<(), Error>

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