[−][src]Struct exonum_merkledb::indexes::ListIndex
A list of items where elements are added to the end of the list and are removed starting from the end of the list.
Access to the elements is obtained using the indexes of the list items.
ListIndex
implements an array list, storing the elements as values and
using u64
as an index. ListIndex
requires that elements implement the
BinaryValue
trait.
Methods
impl<T, V> ListIndex<T, V> where
T: RawAccess,
V: BinaryValue,
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T: RawAccess,
V: BinaryValue,
pub fn get(&self, index: u64) -> Option<V>
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Returns an element at the indicated position or None
if the indicated
position is out of bounds.
Examples
use exonum_merkledb::{access::CopyAccessExt, TemporaryDB, Database, ListIndex}; let db = TemporaryDB::new(); let fork = db.fork(); let mut index = fork.get_list("name"); assert_eq!(None, index.get(0)); index.push(42); assert_eq!(Some(42), index.get(0));
pub fn last(&self) -> Option<V>
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Returns the last element of the list or None
if the list is empty.
Examples
use exonum_merkledb::{access::CopyAccessExt, TemporaryDB, Database, ListIndex}; let db = TemporaryDB::new(); let fork = db.fork(); let mut index = fork.get_list("name"); assert_eq!(None, index.last()); index.push(42); assert_eq!(Some(42), index.last());
pub fn is_empty(&self) -> bool
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Returns true
if the list contains no elements.
Examples
use exonum_merkledb::{access::CopyAccessExt, TemporaryDB, Database, ListIndex}; let db = TemporaryDB::new(); let fork = db.fork(); let mut index = fork.get_list("name"); assert!(index.is_empty()); index.push(42); assert!(!index.is_empty());
pub fn len(&self) -> u64
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Returns the number of elements in the list.
Examples
use exonum_merkledb::{access::CopyAccessExt, TemporaryDB, Database, ListIndex}; let db = TemporaryDB::new(); let fork = db.fork(); let mut index = fork.get_list("name"); assert_eq!(0, index.len()); index.push(10); assert_eq!(1, index.len()); index.push(100); assert_eq!(2, index.len());
pub fn iter(&self) -> Values<V>
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Returns an iterator over the list values.
Examples
use exonum_merkledb::{access::CopyAccessExt, TemporaryDB, Database, ListIndex}; let db = TemporaryDB::new(); let fork = db.fork(); let mut index = fork.get_list("name"); index.extend([1, 2, 3, 4, 5].iter().cloned()); for val in index.iter() { println!("{}", val); }
pub fn iter_from(&self, from: u64) -> Values<V>
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Returns an iterator over the list values starting from the specified position.
Examples
use exonum_merkledb::{access::CopyAccessExt, TemporaryDB, Database, ListIndex}; let db = TemporaryDB::new(); let fork = db.fork(); let mut index = fork.get_list("name"); index.extend([1, 2, 3, 4, 5].iter().cloned()); for val in index.iter_from(3) { println!("{}", val); }
impl<T, V> ListIndex<T, V> where
T: RawAccessMut,
V: BinaryValue,
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T: RawAccessMut,
V: BinaryValue,
pub fn push(&mut self, value: V)
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Appends an element to the back of the list.
Examples
use exonum_merkledb::{access::CopyAccessExt, TemporaryDB, Database, ListIndex}; let db = TemporaryDB::new(); let fork = db.fork(); let mut index = fork.get_list("name"); index.push(1); assert!(!index.is_empty());
pub fn pop(&mut self) -> Option<V>
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Removes the last element from the list and returns it, or returns None
if the list is empty.
Examples
use exonum_merkledb::{access::CopyAccessExt, TemporaryDB, Database, ListIndex}; let db = TemporaryDB::new(); let fork = db.fork(); let mut index = fork.get_list("name"); assert_eq!(None, index.pop()); index.push(1); assert_eq!(Some(1), index.pop());
pub fn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = V>,
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I: IntoIterator<Item = V>,
Extends the list with the contents of an iterator.
Examples
use exonum_merkledb::{access::CopyAccessExt, TemporaryDB, Database, ListIndex}; let db = TemporaryDB::new(); let fork = db.fork(); let mut index = fork.get_list("name"); assert!(index.is_empty()); index.extend([1, 2, 3].iter().cloned()); assert_eq!(3, index.len());
pub fn truncate(&mut self, len: u64)
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Shortens the list, keeping the indicated number of first len
elements
and dropping the rest.
If len
is greater than the current state of the list, this has no effect.
Examples
use exonum_merkledb::{access::CopyAccessExt, TemporaryDB, Database, ListIndex}; let db = TemporaryDB::new(); let fork = db.fork(); let mut index = fork.get_list("name"); index.extend([1, 2, 3, 4, 5].iter().cloned()); assert_eq!(5, index.len()); index.truncate(3); assert_eq!(3, index.len());
pub fn set(&mut self, index: u64, value: V)
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Changes a value at the specified position.
Panics
Panics if the indicated position (index
) is equal to or greater than
the current state of the list.
Examples
use exonum_merkledb::{access::CopyAccessExt, TemporaryDB, Database, ListIndex}; let db = TemporaryDB::new(); let fork = db.fork(); let mut index = fork.get_list("name"); index.push(1); assert_eq!(Some(1), index.get(0)); index.set(0, 10); assert_eq!(Some(10), index.get(0));
pub fn clear(&mut self)
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Clears the list, removing all values.
Notes
Currently, this method is not optimized to delete a large set of data. During the execution of this method, the amount of allocated memory is linearly dependent on the number of elements in the index.
Examples
use exonum_merkledb::{access::CopyAccessExt, TemporaryDB, Database, ListIndex}; let db = TemporaryDB::new(); let fork = db.fork(); let mut index = fork.get_list("name"); index.push(1); assert!(!index.is_empty()); index.clear(); assert!(index.is_empty());
Trait Implementations
impl<T: Debug + RawAccess, V: Debug> Debug for ListIndex<T, V>
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impl<T, V> FromAccess<T> for ListIndex<T::Base, V> where
T: Access,
V: BinaryValue,
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T: Access,
V: BinaryValue,
fn from_access(access: T, addr: IndexAddress) -> Result<Self, AccessError>
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fn from_root(access: T) -> Result<Self, AccessError>
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impl<T, V> IndexIterator for ListIndex<T, V> where
T: RawAccess,
V: BinaryValue,
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T: RawAccess,
V: BinaryValue,
type Key = u64
Type encompassing index keys.
type Value = V
Type encompassing index values.
fn index_iter(&self, from: Option<&u64>) -> Entries<u64, V>
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impl<'a, T, V> IntoIterator for &'a ListIndex<T, V> where
T: RawAccess,
V: BinaryValue,
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T: RawAccess,
V: BinaryValue,
Auto Trait Implementations
impl<T, V> RefUnwindSafe for ListIndex<T, V> where
T: RefUnwindSafe,
V: RefUnwindSafe,
<T as RawAccess>::Changes: RefUnwindSafe,
T: RefUnwindSafe,
V: RefUnwindSafe,
<T as RawAccess>::Changes: RefUnwindSafe,
impl<T, V> Send for ListIndex<T, V> where
T: Send,
V: Send,
<T as RawAccess>::Changes: Send,
T: Send,
V: Send,
<T as RawAccess>::Changes: Send,
impl<T, V> Sync for ListIndex<T, V> where
T: Sync,
V: Sync,
<T as RawAccess>::Changes: Sync,
T: Sync,
V: Sync,
<T as RawAccess>::Changes: Sync,
impl<T, V> Unpin for ListIndex<T, V> where
T: Unpin,
V: Unpin,
<T as RawAccess>::Changes: Unpin,
T: Unpin,
V: Unpin,
<T as RawAccess>::Changes: Unpin,
impl<T, V> UnwindSafe for ListIndex<T, V> where
T: UnwindSafe,
V: UnwindSafe,
<T as RawAccess>::Changes: UnwindSafe,
T: UnwindSafe,
V: UnwindSafe,
<T as RawAccess>::Changes: UnwindSafe,
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<V, T> VZip<V> for T where
V: MultiLane<T>,
V: MultiLane<T>,