Struct SourceSpan

Source

pub struct SourceSpan {
    pub file: PathBuf,
    start: usize,
    end: usize,
}

Expand description

A byte-range location in a source file (manifest §6 stage 1).

§Examples

use std::path::PathBuf;

use mos_core::SourceSpan;

let span = SourceSpan::new(PathBuf::from("main.mos"), 2, 8);

assert_eq!(span.start(), 2);

start and end are private so the start <= end invariant cannot be violated after construction; read them through SourceSpan::start, SourceSpan::end, or SourceSpan::range.

Fields§

§file: PathBuf

The source file this range points into.

§start: usize

Byte offset of the first covered byte (inclusive).

§end: usize

Byte offset one past the last covered byte (exclusive); always >= start.

Implementations§

Source §

impl SourceSpan

Source

pub fn new(file: PathBuf, start: usize, end: usize) -> Self

Construct a span covering start..end in file.

§Examples

use std::path::PathBuf;

use mos_core::SourceSpan;

let span = SourceSpan::new(PathBuf::from("main.mos"), 4, 9);

assert_eq!(span.end(), 9);

§Panics

Panics in debug builds if start > end; a backwards span is a programmer error, never user input.

Source

pub const fn start(&self) -> usize

Byte offset of the first covered byte (inclusive).

Source

pub const fn end(&self) -> usize

Byte offset one past the last covered byte (exclusive); always >= start.

Source

pub fn range(&self) -> Range<usize>

The covered byte range, ready to slice the source text it points into.

§Examples

use std::path::PathBuf;

use mos_core::SourceSpan;

let src = "let x = 1;";
let span = SourceSpan::new(PathBuf::from("main.mos"), 4, 5);

assert_eq!(&src[span.range()], "x");

Source

pub fn set_start(&mut self, start: usize)

Move the start of the span to start, preserving start <= end.

§Panics

Panics if start would exceed the current end. Enforced in all builds so an inverted span can never escape into release.

Source

pub fn set_end(&mut self, end: usize)

Move the end of the span to end, preserving start <= end.

§Panics

Panics if end would fall below the current start. Enforced in all builds so an inverted span can never escape into release.

Source

pub fn placeholder(file: PathBuf) -> Self

A zero-length placeholder span anchored at the start of file.

§Examples

use std::path::PathBuf;

use mos_core::SourceSpan;

let span = SourceSpan::placeholder(PathBuf::from("main.mos"));

assert_eq!((span.start(), span.end()), (0, 0));