Struct source_span::Position

pub struct Position {
    pub line: usize,
    pub column: usize,
}

Position in a source file.

This holds the line and column position of a character in a source file. Some operations are available to move position in a file. In partular, the next method computes the next cursor position after reading a given char.

Display

The struct implements two different format traits:

• fmt::Display will format the position as line {line} column {column}
• fmt::Debug will format the position as {line}:{column}.

Both of them will display lines and columns starting at 1 even though the internal representation starts at 0.

Fields

line: usize

Line number, starting at 0.

column: usize

Column number, starting at 0.

Methods

impl Position

pub fn new(line: usize, column: usize) -> Position

Create a new position given a line and column.

Indexes starts at 0.

pub fn end() -> Position

Return the maximum position.

Defined as (std::usize::MAX, std::usize::MAX).

pub fn next_column(&self) -> Position

Move to the next column.

pub fn reset_column(&self) -> Position

Move to the begining of the line.

pub fn next_line(&self) -> Position

Move to the next line, and reset the column position.

pub fn next(&self, c: char) -> Position

Move to the position following the given char.

Control characters

This crate is intended to help with incremental lexing/parsing. Therefore, any control character moving the cursor backward will be ignored: it will be treated as a 0-width character with no semantics.

New lines

The \n character is interpreted with the Unix semantics, as the new line (NL) character. It will reset the column position to 0 and move to the next line.

Tabulations

The \t will move the cursor to the next horizontal tab-top. This function assumes there is a tab-stop every 8 columns. Note that there is no standard on the size of a tabulation, however a length of 8 columns seems typical.

As of today, there is no way to use another tab length.

I understand that this lacks of flexibility may become an issue in the near future, and I will try to add this possibility. In the meantime, you are very welcome to contribute if you need this feature right away.

Full-width characters

As for now, double-width characters of full-width characters are not supported. They will move the cursor by only one column as any other regular-width character. You are welcome to contribute to handle them.

Trait Implementations

impl Clone for Position

fn clone(&self) -> Position

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Ord for Position

fn cmp(&self, other: &Position) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

🔬 This is a nightly-only experimental API. (clamp)

Restrict a value to a certain interval.

impl Default for Position

fn default() -> Position

Returns the "default value" for a type.

impl From<Position> for Span

fn from(pos: Position) -> Span

Performs the conversion.

impl PartialOrd<Position> for Position

fn partial_cmp(&self, other: &Position) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use] fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use] fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use] fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use] fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl PartialEq<Position> for Position

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

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

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

This method tests for !=.

impl Copy for Position

impl Eq for Position

impl Display for Position

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

Formats the value using the given formatter.

impl Debug for Position

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

Formats the value using the given formatter.

impl Hash for Position

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, 

Feeds a slice of this type into the given [Hasher].