Enum symbol_map::indexing::Insertion

pub enum Insertion<T> {
    Present(T),
    New(T),
}

Indicates whether the result of a symbol lookup had to create a new table entry.

Variants

Present(T)

Result came from an item that was already present in table.

New(T)

Result came from an item that was not present in table, and a new entry was created.

Methods

impl<T> Insertion<T>

fn map<F, X>(&self, f: F) -> Insertion<X> where F: FnOnce(&T) -> X

Maps over the type returned by an Insertion to produce a new value that may be of a different type.

Example

use symbol_map::indexing::{HashIndexing, Indexing, Insertion};
use std::str::FromStr;

let mut index = HashIndexing::<String, usize>::default();
let s1 = String::from_str("value1").unwrap();
let s2 = String::from_str("value1").unwrap();
let s3 = String::from_str("value2").unwrap();
// get_or_insert normally returns an Insertion that borrows the
// structure on which it was invoked. We map the symbol reference
// returned after each insertion to a copy of the ID that was mapped to.
let id1: Insertion<usize> = index.get_or_insert(s1).map(|symbol| *symbol.id());
let id2: Insertion<usize> = index.get_or_insert(s2).map(|symbol| *symbol.id());
let id3: Insertion<usize> = index.get_or_insert(s3).map(|symbol| *symbol.id());
// The Insertion values are not the same because one was an insertion and
// the other a retrieval.
assert!(id1 != id2);
assert!(id1 != id3);
// But the symbol IDs for identical values are the same.
assert!(id1.unwrap() == id2.unwrap());

fn unwrap(self) -> T

Unwraps an Insertion to produce the value which it wraps.

Trait Implementations

impl<T: Clone> Clone for Insertion<T>

fn clone(&self) -> Insertion<T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: Eq> Eq for Insertion<T>

impl<T: Ord> Ord for Insertion<T>

fn cmp(&self, __arg_0: &Insertion<T>) -> Ordering

This method returns an Ordering between self and other.

impl<T: Hash> Hash for Insertion<T>

fn hash<__HT: Hasher>(&self, __arg_0: &mut __HT)

Feeds this value into the state given, updating the hasher as necessary.

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

Feeds a slice of this type into the state provided.

impl<T: PartialEq> PartialEq for Insertion<T>

fn eq(&self, __arg_0: &Insertion<T>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, __arg_0: &Insertion<T>) -> bool

This method tests for !=.

impl<T: PartialOrd> PartialOrd for Insertion<T>

fn partial_cmp(&self, __arg_0: &Insertion<T>) -> Option<Ordering>

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

fn lt(&self, __arg_0: &Insertion<T>) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, __arg_0: &Insertion<T>) -> bool

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

fn gt(&self, __arg_0: &Insertion<T>) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, __arg_0: &Insertion<T>) -> bool

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