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 self 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 other are also set in self.

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

Whether all set bits in other are also set in self.

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

The bitwise or (|) of the bits in self and other.

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

The intersection of self with the complement of other (&!).

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 self and other.

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 self and other.

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

The bitwise or (|) of the bits in self and other.

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

The intersection of self with the complement of other (&!).

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 self and other.

pub const fn complement(self) -> Self

The bitwise negation (!) of the bits in self, 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 self and other.

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 self and other.

impl BitOr for DatabaseFlags

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

The bitwise or (|) of the bits in self and other.

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 self and other.

impl BitXor for DatabaseFlags

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

The bitwise exclusive-or (^) of the bits in self and other.

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 self and other.

impl Clone for DatabaseFlags

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for DatabaseFlags

impl Debug for DatabaseFlags

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

Formats the value using the given formatter.

impl Eq for DatabaseFlags

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: T)

🔬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 all_named() -> DatabaseFlags

Get a flags value with all bits from named flags set.

fn empty() -> Self

Get a flags value with all bits unset.

fn all() -> Self

Get a flags value with all known bits set.

fn known_bits(&self) -> Self::Bits

Get the known bits from a flags value.

fn unknown_bits(&self) -> Self::Bits

Get the unknown bits from a flags value.

fn contains_unknown_bits(&self) -> bool

This method will return true if any unknown bits are 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 iter_defined_names() -> IterDefinedNames<Self>

Yield a set of all named flags defined by Self::FLAGS.

fn iter_equal_names(&self) -> IterEqualNames<Self>

Get an iterator over all defined names for this flags value.

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 other are also set in self.

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

where Self: Sized,

Whether all set bits in other are also set in self.

fn truncate(&mut self)

where Self: Sized,

Remove any unknown bits from the flags.

fn insert(&mut self, other: Self)

where Self: Sized,

The bitwise or (|) of the bits in self and other.

fn remove(&mut self, other: Self)

where Self: Sized,

The intersection of self with the complement of other (&!).

fn toggle(&mut self, other: Self)

where Self: Sized,

The bitwise exclusive-or (^) of the bits in self and other.

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 clear(&mut self)

where Self: Sized,

Unsets all bits in the flags.

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

The bitwise and (&) of the bits in self and other.

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

The bitwise or (|) of the bits in self and other.

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

The intersection of self with the complement of other (&!).

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

The bitwise exclusive-or (^) of the bits in self and other.

fn complement(self) -> Self

The bitwise negation (!) of the bits in self, 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 self, 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: &Self) -> 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.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

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

Restrict a value to a certain range.

impl PartialEq for DatabaseFlags

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

Equality operator ==.

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

Inequality operator !=.

impl PartialOrd for DatabaseFlags

fn partial_cmp(&self, other: &Self) -> 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 StructuralPartialEq for DatabaseFlags

impl Sub for DatabaseFlags

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

The intersection of self with the complement of other (&!).

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 self with the complement of other (&!).

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.