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//! Matrix shape validation helpers.
use crate::ast::{ExprKind, Expression};
impl Expression {
/// Returns whether this expression is a well-formed rectangular matrix.
///
/// A valid matrix has at least one row, and all rows have the same length.
/// Returns `false` for non-Matrix expressions.
///
/// Parsers always produce valid matrices. This method is useful for
/// validating manually constructed matrices.
///
/// # Examples
///
/// ```
/// use mathlex::ast::{Expression, ExprKind};
///
/// let valid: Expression = ExprKind::Matrix(vec![
/// vec![Expression::integer(1), Expression::integer(2)],
/// vec![Expression::integer(3), Expression::integer(4)],
/// ]).into();
/// assert!(valid.is_valid_matrix());
///
/// let ragged: Expression = ExprKind::Matrix(vec![
/// vec![Expression::integer(1), Expression::integer(2)],
/// vec![Expression::integer(3)],
/// ]).into();
/// assert!(!ragged.is_valid_matrix());
///
/// let not_matrix = Expression::integer(42);
/// assert!(!not_matrix.is_valid_matrix());
/// ```
pub fn is_valid_matrix(&self) -> bool {
match &self.kind {
ExprKind::Matrix(rows) => {
if rows.is_empty() {
return false;
}
let cols = rows[0].len();
cols > 0 && rows.iter().all(|row| row.len() == cols)
}
_ => false,
}
}
/// Returns the dimensions `(rows, cols)` of a valid rectangular matrix.
///
/// Returns `None` if this is not a Matrix expression or if the matrix is
/// empty or ragged (non-rectangular).
///
/// # Examples
///
/// ```
/// use mathlex::ast::{Expression, ExprKind};
///
/// let matrix: Expression = ExprKind::Matrix(vec![
/// vec![Expression::integer(1), Expression::integer(2), Expression::integer(3)],
/// vec![Expression::integer(4), Expression::integer(5), Expression::integer(6)],
/// ]).into();
/// assert_eq!(matrix.matrix_dimensions(), Some((2, 3)));
///
/// let not_matrix = Expression::integer(42);
/// assert_eq!(not_matrix.matrix_dimensions(), None);
/// ```
pub fn matrix_dimensions(&self) -> Option<(usize, usize)> {
if self.is_valid_matrix() {
if let ExprKind::Matrix(rows) = &self.kind {
return Some((rows.len(), rows[0].len()));
}
}
None
}
}