Struct RelationHeader 

pub struct RelationHeader { /* private fields */ }

Metadata for a relation: its name, attribute names, and arity.

A header is named when attrs is non-empty (then arity == attrs.len()) and positional when attrs is empty (then arity is the only authoritative column count). Orthogonally, a header is nameless when its name is empty — used for intermediate or projected relations whose origin no longer matters.

Implementations

impl RelationHeader

pub fn new(name: impl Into<String>, attrs: Vec<String>) -> Self

Creates a named header with the given attribute names. Arity is derived from attrs.len().

pub fn new_nameless(attrs: Vec<String>) -> Self

Creates a nameless header with the given attribute names. Arity is inferred from the length of attrs.

pub fn new_positional(name: impl Into<String>, arity: usize) -> Self

Creates a named header with positional (unnamed) attributes.

pub fn new_nameless_positional(arity: usize) -> Self

Creates a nameless header with positional attributes of the given arity.

pub fn is_nameless(&self) -> bool

Returns true if this header has an empty name (i.e. was created via one of the new_nameless* constructors).

pub fn name(&self) -> &str

Returns the relation’s name (empty string for nameless headers).

pub fn attrs(&self) -> &[String]

Returns the attribute names. Empty for positional headers.

pub fn arity(&self) -> usize

Returns the arity (number of columns) of the relation.

pub fn model_type(&self) -> ModelType

Returns ModelType::Named when attribute names are set, otherwise ModelType::Positional.

Trait Implementations

impl Clone for RelationHeader

fn clone(&self) -> RelationHeader

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for RelationHeader

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

Formats the value using the given formatter.

impl From<usize> for RelationHeader

fn from(value: usize) -> RelationHeader

Converts to this type from the input type.