Struct Prefix 

pub struct Prefix { /* private fields */ }

A partial, owned hash possibly identifying an object uniquely, whose non-prefix bytes are zeroed.

An example would 0000000000000000000000000000000032bd3242, where 32bd3242 is the prefix, which would be able to match all hashes that start with 32bd3242.

Implementations

impl Prefix

pub const MIN_HEX_LEN: usize = 4usize

The smallest allowed prefix length below which chances for collisions are too high even in small repositories.

pub fn new(id: &oid, hex_len: usize) -> Result<Self, Error>

Create a new instance by taking a full id as input and truncating it to hex_len.

For instance, with hex_len of 7 the resulting prefix is 3.5 bytes, or 3 bytes and 4 bits wide, with all other bytes and bits set to zero.

pub fn as_oid(&self) -> &oid

Returns the prefix as object id.

Note that it may be deceptive to use given that it looks like a full object id, even though its post-prefix bytes/bits are set to zero.

pub fn hex_len(&self) -> usize

Return the amount of hexadecimal characters that are set in the prefix.

This gives the prefix a granularity of 4 bits.

pub fn cmp_oid(&self, candidate: &oid) -> Ordering

Provided with candidate id which is a full hash, determine how this prefix compares to it, only looking at the prefix bytes, ignoring everything behind that.

pub fn from_hex(value: &str) -> Result<Self, Error>

Create an instance from the given hexadecimal prefix value, e.g. 35e77c16 would yield a Prefix with hex_len() = 8. Note that the minimum hex length is 4 - use Self::from_hex_nonempty().

pub fn from_hex_nonempty(value: &str) -> Result<Self, Error>

Create an instance from the given hexadecimal prefix value, e.g. 35e would yield a Prefix with hex_len() = 3. Note that this function supports all non-empty hex input - for a more typical implementation, use Self::from_hex().

Trait Implementations

impl Clone for Prefix

fn clone(&self) -> Prefix

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Prefix

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Prefix

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for Prefix

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

Formats the value using the given formatter.

impl From<ObjectId> for Prefix

fn from(oid: ObjectId) -> Self

Converts to this type from the input type.

impl Hash for Prefix

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 Ord for Prefix

fn cmp(&self, other: &Prefix) -> 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 Prefix

fn eq(&self, other: &Prefix) -> 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 Prefix

fn partial_cmp(&self, other: &Prefix) -> 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 Serialize for Prefix

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl TryFrom<&str> for Prefix

Create an instance from the given hexadecimal prefix, e.g. 35e77c16 would yield a Prefix with hex_len() = 8.

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &str) -> Result<Self, Self::Error>

Performs the conversion.

impl Copy for Prefix

impl Eq for Prefix

impl StructuralPartialEq for Prefix