Enum IndexEncoding 

#[repr(u8)]
pub enum IndexEncoding {
    Unknown = 0,
    Integer = 1,
    FixedString = 2,
    LengthPrefixed = 3,
    Implied = 4,
    IpAddress = 5,
}

How an INDEX component maps to instance-identifier sub-identifiers (RFC 2578, Section 7.7).

When a table row is identified by its index values, those values are encoded as OID sub-identifiers appended to the column OID. The encoding strategy depends on the index object’s BaseType and constraints:

• Integer types use a single sub-identifier containing the value.
• Fixed-length strings (with a single-value SIZE constraint like SIZE (6)) use one sub-identifier per octet, with no length prefix.
• Variable-length strings are length-prefixed: one sub-identifier for the length, followed by one per octet.
• The IMPLIED keyword omits the length prefix, but can only be used on the last index component since there is no way to tell where it ends otherwise.

This encoding matters when constructing or parsing instance OIDs programmatically (e.g. building an SNMP GET request for a specific table row).

Variants

Unknown = 0

Encoding not yet determined.

Integer = 1

Single sub-identifier for integer-valued indexes.

FixedString = 2

Fixed number of sub-identifiers (SIZE-constrained OCTET STRING). No length prefix; the number of sub-identifiers equals the fixed SIZE.

LengthPrefixed = 3

Length prefix followed by that many sub-identifiers. Used for variable-length OCTET STRING and OBJECT IDENTIFIER indexes.

Implied = 4

No length prefix; the index value extends to the end of the OID. Only valid for the last index component (uses the IMPLIED keyword).

IpAddress = 5

Four sub-identifiers encoding an IPv4 address (one per octet).

Trait Implementations

impl Clone for IndexEncoding

fn clone(&self) -> IndexEncoding

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for IndexEncoding

impl Debug for IndexEncoding

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

Formats the value using the given formatter.

impl Default for IndexEncoding

fn default() -> IndexEncoding

Returns the “default value” for a type.

impl Display for IndexEncoding

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

Formats the value using the given formatter.

impl Eq for IndexEncoding

impl Hash for IndexEncoding

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 PartialEq for IndexEncoding

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for IndexEncoding