Struct DatabaseFlags

pub struct DatabaseFlags(/* private fields */);

LMDB database flags (see http://www.lmdb.tech/doc/group__mdb__dbi__open.html for more details).

Implementations

impl DatabaseFlags

pub const REVERSE_KEY: Self = _

Use reverse string keys.

use heed::types::*;
use heed::byteorder::BigEndian;


let mut wtxn = env.write_txn()?;
let db = env.database_options()
    .types::<Str, Unit>()
    .flags(DatabaseFlags::REVERSE_KEY)
    .name("reverse-key")
    .create(&mut wtxn)?;

db.put(&mut wtxn, &"bonjour", &())?;
db.put(&mut wtxn, &"hello", &())?;
db.put(&mut wtxn, &"holla", &())?;

let mut iter = db.iter(&wtxn)?;
assert_eq!(iter.next().transpose()?, Some(("holla", ())));
assert_eq!(iter.next().transpose()?, Some(("hello", ())));
assert_eq!(iter.next().transpose()?, Some(("bonjour", ())));
assert_eq!(iter.next().transpose()?, None);
drop(iter);

let mut iter = db.rev_iter(&wtxn)?;
assert_eq!(iter.next().transpose()?, Some(("bonjour", ())));
assert_eq!(iter.next().transpose()?, Some(("hello", ())));
assert_eq!(iter.next().transpose()?, Some(("holla", ())));
assert_eq!(iter.next().transpose()?, None);
drop(iter);

wtxn.commit()?;

pub const DUP_SORT: Self = _

Use sorted duplicates.

use heed::types::*;
use heed::byteorder::BigEndian;

type BEI64 = I64<BigEndian>;

let mut wtxn = env.write_txn()?;
let db = env.database_options()
    .types::<BEI64, BEI64>()
    .flags(DatabaseFlags::DUP_SORT)
    .name("dup-sort")
    .create(&mut wtxn)?;

db.put(&mut wtxn, &68, &120)?;
db.put(&mut wtxn, &68, &121)?;
db.put(&mut wtxn, &68, &122)?;
db.put(&mut wtxn, &68, &123)?;
db.put(&mut wtxn, &92, &32)?;
db.put(&mut wtxn, &35, &120)?;
db.put(&mut wtxn, &0, &120)?;
db.put(&mut wtxn, &42, &120)?;

let mut iter = db.get_duplicates(&wtxn, &68)?.expect("the key exists");
assert_eq!(iter.next().transpose()?, Some((68, 120)));
assert_eq!(iter.next().transpose()?, Some((68, 121)));
assert_eq!(iter.next().transpose()?, Some((68, 122)));
assert_eq!(iter.next().transpose()?, Some((68, 123)));
assert_eq!(iter.next().transpose()?, None);
drop(iter);

let mut iter = db.get_duplicates(&wtxn, &68)?.expect("the key exists");
assert_eq!(iter.last().transpose()?, Some((68, 123)));

assert!(db.delete_one_duplicate(&mut wtxn, &68, &121)?, "The entry must exist");

let mut iter = db.get_duplicates(&wtxn, &68)?.expect("the key exists");
assert_eq!(iter.next().transpose()?, Some((68, 120)));
// No more (68, 121) returned here!
assert_eq!(iter.next().transpose()?, Some((68, 122)));
assert_eq!(iter.next().transpose()?, Some((68, 123)));
assert_eq!(iter.next().transpose()?, None);
drop(iter);

wtxn.commit()?;

pub const INTEGER_KEY: Self = _

Numeric keys in native byte order: either u32 or usize. The keys must all be of the same size.

use heed::types::*;
use heed::byteorder::BigEndian;

type BEI32 = I32<BigEndian>;

let mut wtxn = env.write_txn()?;
let db = env.database_options()
    .types::<BEI32, BEI32>()
    .flags(DatabaseFlags::INTEGER_KEY)
    .name("integer-key")
    .create(&mut wtxn)?;

db.put(&mut wtxn, &68, &120)?;
db.put(&mut wtxn, &92, &32)?;
db.put(&mut wtxn, &35, &120)?;
db.put(&mut wtxn, &0, &120)?;
db.put(&mut wtxn, &42, &120)?;

let mut iter = db.iter(&wtxn)?;
assert_eq!(iter.next().transpose()?, Some((0, 120)));
assert_eq!(iter.next().transpose()?, Some((35, 120)));
assert_eq!(iter.next().transpose()?, Some((42, 120)));
assert_eq!(iter.next().transpose()?, Some((68, 120)));
assert_eq!(iter.next().transpose()?, Some((92, 32)));
assert_eq!(iter.next().transpose()?, None);
drop(iter);

wtxn.commit()?;

pub const DUP_FIXED: Self = _

With DatabaseFlags::DUP_SORT, sorted dup items have fixed size.

use heed::types::*;
use heed::byteorder::BigEndian;

type BEI64 = I64<BigEndian>;

let mut wtxn = env.write_txn()?;
let db = env.database_options()
    .types::<BEI64, BEI64>()
    .flags(DatabaseFlags::DUP_SORT | DatabaseFlags::DUP_FIXED)
    .name("dup-sort-fixed")
    .create(&mut wtxn)?;

db.put(&mut wtxn, &68, &120)?;
db.put(&mut wtxn, &68, &121)?;
db.put(&mut wtxn, &68, &122)?;
db.put(&mut wtxn, &68, &123)?;
db.put(&mut wtxn, &92, &32)?;
db.put(&mut wtxn, &35, &120)?;
db.put(&mut wtxn, &0, &120)?;
db.put(&mut wtxn, &42, &120)?;

let mut iter = db.get_duplicates(&wtxn, &68)?.expect("the key exists");
assert_eq!(iter.next().transpose()?, Some((68, 120)));
assert_eq!(iter.next().transpose()?, Some((68, 121)));
assert_eq!(iter.next().transpose()?, Some((68, 122)));
assert_eq!(iter.next().transpose()?, Some((68, 123)));
assert_eq!(iter.next().transpose()?, None);
drop(iter);

let mut iter = db.get_duplicates(&wtxn, &68)?.expect("the key exists");
assert_eq!(iter.last().transpose()?, Some((68, 123)));

assert!(db.delete_one_duplicate(&mut wtxn, &68, &121)?, "The entry must exist");

let mut iter = db.get_duplicates(&wtxn, &68)?.expect("the key exists");
assert_eq!(iter.next().transpose()?, Some((68, 120)));
// No more (68, 121) returned here!
assert_eq!(iter.next().transpose()?, Some((68, 122)));
assert_eq!(iter.next().transpose()?, Some((68, 123)));
assert_eq!(iter.next().transpose()?, None);
drop(iter);

wtxn.commit()?;

pub const INTEGER_DUP: Self = _

With [DatabaseKey::DUP_SORT], dups are [DatabaseKey::INTEGER_KEY]-style integers.

use heed::types::*;
use heed::byteorder::BigEndian;

type BEI32 = I32<BigEndian>;

let mut wtxn = env.write_txn()?;
let db = env.database_options()
    .types::<BEI32, BEI32>()
    .flags(DatabaseFlags::DUP_SORT | DatabaseFlags::INTEGER_DUP)
    .name("dup-sort-integer-dup")
    .create(&mut wtxn)?;

db.put(&mut wtxn, &68, &120)?;
db.put(&mut wtxn, &68, &121)?;
db.put(&mut wtxn, &68, &122)?;
db.put(&mut wtxn, &68, &123)?;
db.put(&mut wtxn, &92, &32)?;
db.put(&mut wtxn, &35, &120)?;
db.put(&mut wtxn, &0, &120)?;
db.put(&mut wtxn, &42, &120)?;

let mut iter = db.get_duplicates(&wtxn, &68)?.expect("the key exists");
assert_eq!(iter.next().transpose()?, Some((68, 120)));
assert_eq!(iter.next().transpose()?, Some((68, 121)));
assert_eq!(iter.next().transpose()?, Some((68, 122)));
assert_eq!(iter.next().transpose()?, Some((68, 123)));
assert_eq!(iter.next().transpose()?, None);
drop(iter);

let mut iter = db.get_duplicates(&wtxn, &68)?.expect("the key exists");
assert_eq!(iter.last().transpose()?, Some((68, 123)));

assert!(db.delete_one_duplicate(&mut wtxn, &68, &121)?, "The entry must exist");

let mut iter = db.get_duplicates(&wtxn, &68)?.expect("the key exists");
assert_eq!(iter.next().transpose()?, Some((68, 120)));
// No more (68, 121) returned here!
assert_eq!(iter.next().transpose()?, Some((68, 122)));
assert_eq!(iter.next().transpose()?, Some((68, 123)));
assert_eq!(iter.next().transpose()?, None);
drop(iter);

wtxn.commit()?;

pub const REVERSE_DUP: Self = _

With [DatabaseKey::DUP_SORT], use reverse string dups.

use heed::types::*;
use heed::byteorder::BigEndian;

type BEI64 = I64<BigEndian>;

let mut wtxn = env.write_txn()?;
let db = env.database_options()
    .types::<BEI64, Str>()
    .flags(DatabaseFlags::DUP_SORT | DatabaseFlags::REVERSE_DUP)
    .name("dup-sort")
    .create(&mut wtxn)?;

db.put(&mut wtxn, &68, &"bonjour")?;
db.put(&mut wtxn, &68, &"holla")?;
db.put(&mut wtxn, &68, &"hello")?;
db.put(&mut wtxn, &92, &"hallo")?;

let mut iter = db.get_duplicates(&wtxn, &68)?.expect("the key exists");
assert_eq!(iter.next().transpose()?, Some((68, "holla")));
assert_eq!(iter.next().transpose()?, Some((68, "hello")));
assert_eq!(iter.next().transpose()?, Some((68, "bonjour")));
assert_eq!(iter.next().transpose()?, None);
drop(iter);

wtxn.commit()?;

impl DatabaseFlags

pub const fn empty() -> Self

Get a flags value with all bits unset.

pub const fn all() -> Self

Get a flags value with all known bits set.

pub const fn bits(&self) -> u32

Get the underlying bits value.

The returned value is exactly the bits set in this flags value.

pub const fn from_bits(bits: u32) -> Option<Self>

Convert from a bits value.

This method will return None if any unknown bits are set.

pub const fn from_bits_truncate(bits: u32) -> Self

Convert from a bits value, unsetting any unknown bits.

pub const fn from_bits_retain(bits: u32) -> Self

Convert from a bits value exactly.

pub fn from_name(name: &str) -> Option<Self>

Get a flags value with the bits of a flag with the given name set.

This method will return None if name is empty or doesn’t correspond to any named flag.

pub const fn is_empty(&self) -> bool

Whether all bits in this flags value are unset.

pub const fn is_all(&self) -> bool

Whether all known bits in this flags value are set.

pub const fn intersects(&self, other: Self) -> bool

Whether any set bits in a source flags value are also set in a target flags value.

pub const fn contains(&self, other: Self) -> bool

Whether all set bits in a source flags value are also set in a target flags value.

pub fn insert(&mut self, other: Self)

The bitwise or (|) of the bits in two flags values.

pub fn remove(&mut self, other: Self)

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. remove won’t truncate other, but the ! operator will.

pub fn toggle(&mut self, other: Self)

The bitwise exclusive-or (^) of the bits in two flags values.

pub fn set(&mut self, other: Self, value: bool)

Call insert when value is true or remove when value is false.

pub const fn intersection(self, other: Self) -> Self

The bitwise and (&) of the bits in two flags values.

pub const fn union(self, other: Self) -> Self

The bitwise or (|) of the bits in two flags values.

pub const fn difference(self, other: Self) -> Self

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. difference won’t truncate other, but the ! operator will.

pub const fn symmetric_difference(self, other: Self) -> Self

The bitwise exclusive-or (^) of the bits in two flags values.

pub const fn complement(self) -> Self

The bitwise negation (!) of the bits in a flags value, truncating the result.

impl DatabaseFlags

pub const fn iter(&self) -> Iter<DatabaseFlags>

Yield a set of contained flags values.

Each yielded flags value will correspond to a defined named flag. Any unknown bits will be yielded together as a final flags value.

pub const fn iter_names(&self) -> IterNames<DatabaseFlags>

Yield a set of contained named flags values.

This method is like iter, except only yields bits in contained named flags. Any unknown bits, or bits not corresponding to a contained flag will not be yielded.

Trait Implementations

impl Binary for DatabaseFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl BitAnd for DatabaseFlags

fn bitand(self, other: Self) -> Self

The bitwise and (&) of the bits in two flags values.

type Output = DatabaseFlags

The resulting type after applying the & operator.

impl BitAndAssign for DatabaseFlags

fn bitand_assign(&mut self, other: Self)

The bitwise and (&) of the bits in two flags values.

impl BitOr for DatabaseFlags

fn bitor(self, other: DatabaseFlags) -> Self

The bitwise or (|) of the bits in two flags values.

type Output = DatabaseFlags

The resulting type after applying the | operator.

impl BitOrAssign for DatabaseFlags

fn bitor_assign(&mut self, other: Self)

The bitwise or (|) of the bits in two flags values.

impl BitXor for DatabaseFlags

fn bitxor(self, other: Self) -> Self

The bitwise exclusive-or (^) of the bits in two flags values.

type Output = DatabaseFlags

The resulting type after applying the ^ operator.

impl BitXorAssign for DatabaseFlags

fn bitxor_assign(&mut self, other: Self)

The bitwise exclusive-or (^) of the bits in two flags values.

impl Clone for DatabaseFlags

fn clone(&self) -> DatabaseFlags

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for DatabaseFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Extend<DatabaseFlags> for DatabaseFlags

fn extend<T: IntoIterator<Item = Self>>(&mut self, iterator: T)

The bitwise or (|) of the bits in each flags value.

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl Flags for DatabaseFlags

const FLAGS: &'static [Flag<DatabaseFlags>] = _

The set of defined flags.

type Bits = u32

The underlying bits type.

fn bits(&self) -> u32

Get the underlying bits value.

fn from_bits_retain(bits: u32) -> DatabaseFlags

Convert from a bits value exactly.

fn empty() -> Self

Get a flags value with all bits unset.

fn all() -> Self

Get a flags value with all known bits set.

fn from_bits(bits: Self::Bits) -> Option<Self>

Convert from a bits value.

fn from_bits_truncate(bits: Self::Bits) -> Self

Convert from a bits value, unsetting any unknown bits.

fn from_name(name: &str) -> Option<Self>

Get a flags value with the bits of a flag with the given name set.

fn iter(&self) -> Iter<Self>

Yield a set of contained flags values.

fn iter_names(&self) -> IterNames<Self>

Yield a set of contained named flags values.

fn is_empty(&self) -> bool

Whether all bits in this flags value are unset.

fn is_all(&self) -> bool

Whether all known bits in this flags value are set.

fn intersects(&self, other: Self) -> bool

where Self: Sized,

Whether any set bits in a source flags value are also set in a target flags value.

fn contains(&self, other: Self) -> bool

where Self: Sized,

Whether all set bits in a source flags value are also set in a target flags value.

fn insert(&mut self, other: Self)

where Self: Sized,

The bitwise or (|) of the bits in two flags values.

fn remove(&mut self, other: Self)

where Self: Sized,

The intersection of a source flags value with the complement of a target flags value (&!).

fn toggle(&mut self, other: Self)

where Self: Sized,

The bitwise exclusive-or (^) of the bits in two flags values.

fn set(&mut self, other: Self, value: bool)

where Self: Sized,

Call Flags::insert when value is true or Flags::remove when value is false.

fn intersection(self, other: Self) -> Self

The bitwise and (&) of the bits in two flags values.

fn union(self, other: Self) -> Self

The bitwise or (|) of the bits in two flags values.

fn difference(self, other: Self) -> Self

The intersection of a source flags value with the complement of a target flags value (&!).

fn symmetric_difference(self, other: Self) -> Self

The bitwise exclusive-or (^) of the bits in two flags values.

fn complement(self) -> Self

The bitwise negation (!) of the bits in a flags value, truncating the result.

impl FromIterator<DatabaseFlags> for DatabaseFlags

fn from_iter<T: IntoIterator<Item = Self>>(iterator: T) -> Self

The bitwise or (|) of the bits in each flags value.

impl Hash for DatabaseFlags

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl IntoIterator for DatabaseFlags

type Item = DatabaseFlags

The type of the elements being iterated over.

type IntoIter = Iter<DatabaseFlags>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl LowerHex for DatabaseFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Not for DatabaseFlags

fn not(self) -> Self

The bitwise negation (!) of the bits in a flags value, truncating the result.

type Output = DatabaseFlags

The resulting type after applying the ! operator.

impl Octal for DatabaseFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Ord for DatabaseFlags

fn cmp(&self, other: &DatabaseFlags) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for DatabaseFlags

fn eq(&self, other: &DatabaseFlags) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for DatabaseFlags

fn partial_cmp(&self, other: &DatabaseFlags) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl PublicFlags for DatabaseFlags

type Primitive = u32

The type of the underlying storage.

type Internal = InternalBitFlags

The type of the internal field on the generated flags type.

impl Sub for DatabaseFlags

fn sub(self, other: Self) -> Self

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. difference won’t truncate other, but the ! operator will.

type Output = DatabaseFlags

The resulting type after applying the - operator.

impl SubAssign for DatabaseFlags

fn sub_assign(&mut self, other: Self)

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. difference won’t truncate other, but the ! operator will.

impl UpperHex for DatabaseFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Copy for DatabaseFlags

impl Eq for DatabaseFlags

impl StructuralPartialEq for DatabaseFlags

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 4 bytes