Struct Pos 

pub struct Pos {
    pub line: u32,
    pub col: u32,
}

Native position inside a text document/string. Points to a valid position before the character inside a UTF8-encoded string.

Why use Pos instead of raw usize offset

This depends on the use-case. Often raw usize or a newtype wrapper around usize is sufficient. However, raw byte offsets are not stable at all when a text document changes.

Usually, a text document is an input to later stages of the pipelines. Let’s take a simple incremental pipeline:

text: string ->
 symbols: Symbol { ..., start: usize, end: usize } ->
 diagnostics: Diag { ..., start: usize, end: usize }

Now, any change to text on line N will shift all start and end offsets, which will invalidate all symbols and diagnostics following the change and require recomputation.

However, if start and end are Poses then only the line where the change was made is affected. Symbols and diagnostic for other lines won’t be invalidated.

Fields

line: u32

0-indexed line inside the text document.

col: u32

0-indexed byte offset from the beginning of the line. The offset is at a valid char boundary.

Implementations

impl Pos

pub fn new(line: u32, col: u32) -> Self

Create a new Pos. This method shouldn’t be required to use most of the time!

line is 0-indexed, col is a 0-indexed byte-offset from the beginning of the line to a valid char position.

Trait Implementations

impl Clone for Pos

fn clone(&self) -> Pos

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Pos

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

Formats the value using the given formatter.

impl Hash for Pos

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 Ord for Pos

fn cmp(&self, other: &Self) -> 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 PartialEq for Pos

fn eq(&self, other: &Pos) -> 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 PartialOrd for Pos

fn partial_cmp(&self, other: &Self) -> 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 Copy for Pos

impl Eq for Pos

impl StructuralPartialEq for Pos