Struct Span

pub struct Span(/* private fields */);

A unique identifier for a syntax node.

This is used throughout the compiler to track which source section an error or element stems from. Can be mapped back to a byte range for user facing display.

During editing, the span values stay mostly stable, even for nodes behind an insertion. This is not true for simple ranges as they would shift. Spans can be used as inputs to memoized functions without hurting cache performance when text is inserted somewhere in the document other than the end.

Span ids are ordered in the syntax tree to enable quickly finding the node with some id:

• The id of a parent is always smaller than the ids of any of its children.
• The id of a node is always greater than any id in the subtrees of any left sibling and smaller than any id in the subtrees of any right sibling.

This type takes up 8 bytes and is null-optimized (i.e. Option<Span> also takes 8 bytes).

Implementations

impl Span

pub const fn detached() -> Span

Create a span that does not point into any source file.

pub const fn is_detached(self) -> bool

Whether the span is detached.

pub const fn id(self) -> Option<FileId>

The id of the source file the span points into.

Returns None if the span is detached.

pub const fn number(self) -> u64

The unique number of the span within its Source.

pub fn or(self, other: Span) -> Span

Return other if self is detached and self otherwise.

pub fn find(iter: impl IntoIterator<Item = Span>) -> Span

Find the first non-detached span in the iterator.

pub fn resolve_path(self, path: &str) -> Result<FileId, EcoString>

Resolve a file location relative to this span’s source.

Trait Implementations

impl Clone for Span

fn clone(&self) -> Span

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Span

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

Formats the value using the given formatter.

impl Hash for Span

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

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 Span

fn eq(&self, other: &Span) -> 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 Copy for Span

impl Eq for Span

impl StructuralPartialEq for Span