Struct Spanned 

pub struct Spanned<T> {
    pub span: Span,
    pub value: T,
}

A value together with the source Span it was parsed from.

Spanned<T> is the wrapper a parser puts around every token and AST node so the value carries its location without the value type itself knowing anything about positions. It is a transparent pair — both fields are public — and it is Copy whenever T is, so wrapping a small token in a span costs nothing.

Spans order before values, so a slice of Spanned<T> sorts into source order when T: Ord.

Examples

use span_lang::{Span, Spanned};

// A token: the identifier `width` at bytes 4..9.
let ident = Spanned::new(Span::new(4, 9), "width");
assert_eq!(ident.value, "width");
assert_eq!(ident.span, Span::new(4, 9));

// Transform the value, keeping the span.
let len = ident.map(|s| s.len());
assert_eq!(len.value, 5);
assert_eq!(len.span, Span::new(4, 9));

Fields

span: Span

The source span the value was read from.

value: T

The wrapped value.

Implementations

impl<T> Spanned<T>

pub const fn new(span: Span, value: T) -> Self

Pairs a value with its span.

Examples

use span_lang::{Span, Spanned};

let node = Spanned::new(Span::new(0, 3), 42);
assert_eq!(node.value, 42);

pub fn map<U>(self, f: impl FnOnce(T) -> U) -> Spanned<U>

Applies f to the value, keeping the span unchanged.

This is how a parser lifts a raw token into a typed node without losing where it came from — for example, turning a Spanned<&str> lexeme into a Spanned<Ident>.

Examples

use span_lang::{Span, Spanned};

let raw = Spanned::new(Span::new(2, 5), "10");
let parsed = raw.map(|s| s.parse::<u32>().unwrap());
assert_eq!(parsed.value, 10);
assert_eq!(parsed.span, Span::new(2, 5));

pub fn as_ref(&self) -> Spanned<&T>

Borrows the value, yielding a Spanned<&T> with the same span.

Mirrors Option::as_ref: it lets you inspect or map the value without consuming the original Spanned.

Examples

use span_lang::{Span, Spanned};

let owned = Spanned::new(Span::new(0, 4), String::from("name"));
let borrowed = owned.as_ref().map(|s| s.len());
assert_eq!(borrowed.value, 4);
// `owned` is still usable.
assert_eq!(owned.value, "name");

Trait Implementations

impl<T: Clone> Clone for Spanned<T>

fn clone(&self) -> Spanned<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Copy> Copy for Spanned<T>

impl<T: Debug> Debug for Spanned<T>

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

Formats the value using the given formatter.

impl<'de, T> Deserialize<'de> for Spanned<T>

where T: Deserialize<'de>,

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<T: Display> Display for Spanned<T>

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

Formats as value @ start..end.

impl<T: Eq> Eq for Spanned<T>

impl<T: Hash> Hash for Spanned<T>

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<T: Ord> Ord for Spanned<T>

fn cmp(&self, other: &Spanned<T>) -> 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<T: PartialEq> PartialEq for Spanned<T>

fn eq(&self, other: &Spanned<T>) -> 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<T: PartialOrd> PartialOrd for Spanned<T>

fn partial_cmp(&self, other: &Spanned<T>) -> 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<T> Serialize for Spanned<T>

where T: Serialize,

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl<T: PartialEq> StructuralPartialEq for Spanned<T>