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use core::{cmp::Ordering, fmt};
/// Represents the position of a cell in a table
#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
#[cfg_attr(feature = "serde-1", derive(serde::Serialize, serde::Deserialize))]
pub struct Position {
/// Represents the row number of a cell starting from 0
pub row: usize,
/// Represents the coumn number of a cell starting from 0
pub col: usize,
}
impl Position {
/// Creates a new position with the given row and column
pub fn new(row: usize, col: usize) -> Self {
Self { row, col }
}
}
impl fmt::Display for Position {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{},{}", self.row, self.col)
}
}
impl PartialOrd for Position {
/// Compares positions in terms of order by seeing if one comes before/after
/// another in rows. If on the same row, then the columns are compared.
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl Ord for Position {
/// Compares positions in terms of order by seeing if one comes before/after
/// another in rows. If on the same row, then the columns are compared.
///
/// ### Examples
///
/// ```
/// # use memtable_core::Position;
/// // Row is first used for comparisons
/// assert!(Position { row: 0, col: 1 } < Position { row: 1, col: 0 });
/// assert!(Position { row: 1, col: 0 } > Position { row: 0, col: 1 });
///
/// // Column is used for comparisons if rows are equal
/// assert!(Position { row: 0, col: 0 } < Position { row: 0, col: 1 });
/// assert!(Position { row: 0, col: 1 } > Position { row: 0, col: 0 });
///
/// // Row & column need to match for equality
/// assert_eq!(Position { row: 0, col: 0 }, Position { row: 0, col: 0 });
/// ```
fn cmp(&self, other: &Self) -> Ordering {
match self.row.cmp(&other.row) {
Ordering::Equal => self.col.cmp(&other.col),
x => x,
}
}
}