Struct Span

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pub struct Span { /* private fields */ }

Expand description

A Span is metadata which indicates the start and end positions.

Spans are combined with AnchorLocations to form another type of metadata, a Tag. A Span’s end position must be greater than or equal to its start position.

Implementations§

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impl Span

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pub fn default() -> Self

Creates a default new Span that has 0 start and 0 end.

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pub fn unknown() -> Span

Creates a new Span that has 0 start and 0 end.

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pub fn from_list(list: &[impl HasSpan]) -> Span

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pub fn new(start: usize, end: usize) -> Span

Creates a new Span from start and end inputs. The end parameter must be greater than or equal to the start parameter.

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pub fn new_option(start: usize, end: usize) -> Option

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pub fn for_char(pos: usize) -> Span

Creates a Span with a length of 1 from the given position.

§Example

let char_span = Span::for_char(5);

assert_eq!(char_span.start(), 5);
assert_eq!(char_span.end(), 6);

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pub fn contains(&self, pos: usize) -> bool

Returns a bool indicating if the given position falls inside the current Span.

§Example

let span = Span::new(2, 8);

assert_eq!(span.contains(5), true);
assert_eq!(span.contains(8), false);
assert_eq!(span.contains(100), false);

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pub fn since(&self, other: impl Into) -> Span

Returns a new Span by merging an earlier Span with the current Span.

The resulting Span will have the same start position as the given Span and same end as the current Span.

§Example

let original_span = Span::new(4, 6);
let earlier_span = Span::new(1, 3);
let merged_span = origin_span.since(earlier_span);

assert_eq!(merged_span.start(), 1);
assert_eq!(merged_span.end(), 6);

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pub fn until(&self, other: impl Into) -> Span

Returns a new Span by merging a later Span with the current Span.

The resulting Span will have the same start position as the current Span and same end as the given Span.

§Example

let original_span = Span::new(4, 6);
let later_span = Span::new(9, 11);
let merged_span = origin_span.until(later_span);

assert_eq!(merged_span.start(), 4);
assert_eq!(merged_span.end(), 11);

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pub fn merge(&self, other: impl Into) -> Span

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pub fn until_option(&self, other: Option<impl Into>) -> Span

Returns a new Span by merging a later Span with the current Span.

If the given Span is of the None variant, A Span with the same values as the current Span is returned.

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pub fn start(&self) -> usize

Returns the start position of the current Span.

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pub fn end(&self) -> usize

Returns the end position of the current Span.

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pub fn is_unknown(&self) -> bool

Returns a bool if the current Span indicates an “unknown” position.

§Example

let unknown_span = Span::unknown();
let known_span = Span::new(4, 6);

assert_eq!(unknown_span.is_unknown(), true);
assert_eq!(known_span.is_unknown(), false);

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pub fn is_closed(&self) -> bool

Returns a bool if the current Span does not cover.

§Example

//  make clean
//  ----
//  (0,4)
//
//       ^(5,5)

let make_span = Span::new(0,4);
let clean_span = Span::new(5,5);

assert_eq!(make_span.is_closed(), false);
assert_eq!(clean_span.is_closed(), true);