Struct lexpr::Datum

pub struct Datum { /* fields omitted */ }

Combines an S-expression value with location information.

A Datum keeps, along with a plain Value, information about the text location the value was parsed from. For compound values, such as lists and vectors, that includes information for all contained values, recursively.

A Datum can be obtained by using the parse_datum and expect_datum methods on Parser.

Methods

impl Datum

pub fn value(&self) -> &Value

Returns a reference to the contained value.

pub fn span(&self) -> Span

Returns the span for the compelete value.

pub fn as_ref(&self) -> Ref

Returns a reference to the datum.

pub fn list_iter(&self) -> Option<ListIter>

Returns an iterator over the elements of a list.

If the value contained in the datum is not either a cons cell or Null, None is returned.

Note that the returned iterator has special behavior for improper lists, yielding the element after the dot after returning None the first time.

use lexpr::sexp;

let datum = lexpr::datum::from_str("(1 2 . 3)").unwrap();
let mut iter = datum.list_iter().unwrap();
let one = iter.next().unwrap();
assert_eq!(one.value(), &sexp!(1));
let two = iter.next().unwrap();
assert_eq!(two.value(), &sexp!(2));
assert_eq!(iter.next(), None);
let three = iter.next().unwrap();
assert_eq!(three.value(), &sexp!(3));
assert_eq!(iter.next(), None);

pub fn vector_iter(&self) -> Option<VectorIter>

Returns an iterator over the elements of a vector.

If the value contained in the datum is not a vector, None is returned.

Trait Implementations

impl Clone for Datum

fn clone(&self) -> Datum

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Datum

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

Formats the value using the given formatter.

impl From<Datum> for Value

fn from(datum: Datum) -> Self

Performs the conversion.

impl<'a> From<Ref<'a>> for Datum

fn from(r: Ref<'a>) -> Self

Turns a reference into an owned Datum, by cloning the referenced value and location information.

impl PartialEq<Datum> for Datum

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

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=.

impl StructuralPartialEq for Datum