Struct ExprId 

pub struct ExprId(pub u32);

Identifies one expression within the file it was parsed from.

The id is assigned by number_unit once the file has been parsed, not by the parser itself: an expression the parser builds carries ExprId::UNSET until that pass has run over the whole unit. parse_file runs it, so a tree a caller receives never holds an unset id.

An id is unique within one SourceUnit and means nothing outside it. Every file numbers from zero, so an id is only ever readable alongside the file it came from, and comparing ids across files compares nothing.

It exists so that a pass can record what it worked out about an expression in a side table indexed by the id — a Vec as long as the file has expressions — instead of a map keyed by a hash of the expression. A hash cannot tell two identical subexpressions apart, and an address does not survive the tree being moved or cloned; a dense index does both, and is a load rather than a lookup.

Tuple Fields

0: u32

Implementations

impl ExprId

pub const UNSET: ExprId

The id an expression has before number_unit has run.

Every expression the parser builds starts here and none keeps it, so this value marks a tree that was built by hand or never numbered rather than one position within a file.

Trait Implementations

impl Clone for ExprId

fn clone(&self) -> ExprId

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ExprId

impl Debug for ExprId

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

Formats the value using the given formatter.

impl Eq for ExprId

impl Hash for ExprId

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 ExprId

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

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

fn partial_cmp(&self, other: &ExprId) -> 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 StructuralPartialEq for ExprId