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Do bounds update in finish_cell_transitions

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Merged the functionality of update_bounds into finish_cell_transitions,
eliminating a loop.
This commit is contained in:
Jon Fetter-Degges
2022-10-11 16:26:28 -04:00
parent 0d2b7c6559
commit a068af4bc9
1 changed files with 52 additions and 55 deletions
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107
55_Life/rust/src/main.rs
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@@ -52,7 +52,6 @@ fn main() {
loop {
finish_cell_transitions(&mut board);
print_board(&board);
update_bounds(&mut board);
update_board(&mut board);
if board.population == 0 {
break; // this isn't in the original implementation but I wanted it
@@ -135,8 +134,16 @@ fn parse_pattern(rows: Vec<String>) -> Board {
}
fn finish_cell_transitions(board: &mut Board) {
for row in board.cells[board.min_row-1..=board.max_row+1].iter_mut() {
for cell in row[board.min_col-1..=board.max_col+1].iter_mut() {
// In the BASIC implementation, this happens in the same loop that prints the board.
// We're breaking it out to improve separation of concerns.
let mut min_row = HEIGHT - 1;
let mut max_row = 0usize;
let mut min_col = WIDTH - 1;
let mut max_col = 0usize;
for row_index in board.min_row-1..=board.max_row+1 {
let mut any_alive_this_row = false;
for col_index in board.min_col-1..=board.max_col+1 {
let cell = &mut board.cells[row_index][col_index];
if *cell == CellState::AboutToBeBorn {
*cell = CellState::Alive;
board.population += 1;
@@ -144,8 +151,50 @@ fn finish_cell_transitions(board: &mut Board) {
*cell = CellState::Empty;
board.population -= 1;
}
if *cell == CellState::Alive {
any_alive_this_row = true;
if min_col > col_index {
min_col = col_index;
}
if max_col < col_index {
max_col = col_index;
}
}
}
if any_alive_this_row {
if min_row > row_index {
min_row = row_index;
}
if max_row < row_index {
max_row = row_index;
}
}
}
// If anything is alive within two cells of the boundary, mark the board invalid and
// clamp the bounds. We need a two-cell margin because we'll count neighbors on cells
// one space outside the min/max, and when we count neighbors we go out by an
// additional space.
if min_row < 2 {
min_row = 2;
board.invalid = true;
}
if max_row > HEIGHT - 3 {
max_row = HEIGHT - 3;
board.invalid = true;
}
if min_col < 2 {
min_col = 2;
board.invalid = true;
}
if max_col > WIDTH - 3 {
max_col = WIDTH - 3;
board.invalid = true;
}
board.min_row = min_row;
board.max_row = max_row;
board.min_col = min_col;
board.max_col = max_col;
}
fn print_board(board: &Board) {
@@ -164,58 +213,6 @@ fn print_board(board: &Board) {
}
}
fn update_bounds(board: &mut Board) {
// In the BASIC implementation, this happens in the same loop that prints the board.
// We're breaking it out to improve separation of concerns.
// We could improve efficiency here by only searching one row outside the previous bounds.
board.min_row = HEIGHT;
board.max_row = 0;
board.min_col = WIDTH;
board.max_col = 0;
for (irow, row) in board.cells.iter().enumerate() {
let mut any_set = false;
for (icol, cell) in row.iter().enumerate() {
if *cell == CellState::Alive {
any_set = true;
if board.min_col > icol {
board.min_col = icol;
}
if board.max_col < icol {
board.max_col = icol;
}
}
}
if any_set {
if board.min_row > irow {
board.min_row = irow;
}
if board.max_row < irow {
board.max_row = irow;
}
}
}
// If anything is alive within two cells of the boundary, mark the board invalid and
// clamp the bounds. We need a two-cell margin because we'll count neighbors on cells
// one space outside the min/max, and when we count neighbors we go out by an
// additional space.
if board.min_row < 2 {
board.min_row = 2;
board.invalid = true;
}
if board.max_row > HEIGHT - 3 {
board.max_row = HEIGHT - 3;
board.invalid = true;
}
if board.min_col < 2 {
board.min_col = 2;
board.invalid = true;
}
if board.max_col > WIDTH - 3 {
board.max_col = WIDTH - 3;
board.invalid = true;
}
}
fn count_neighbors(board: &Board, row_index: usize, col_index: usize) -> i32 {
let mut count = 0;
assert!((1..=HEIGHT-2).contains(&row_index));