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//! 整数算术与晶体学对称操作的组合规则。
//!
//! 提供对称操作（3x3 整数矩阵 + 平移向量）的等价性判断，以及
//! 算术晶体类映射表（将空间群编号映射到点群对称性）。
/// 算术晶体类别映射表 (索引对应空间群编号 0-230)
/// 优化：使用 u8 节省内存，因为最大值为 73
static ARITHMETIC_CRYSTAL_CLASSES: [u8; 231] = [
0, 1, 2, 3, 3, 4, 5, 5, 6, 6, 7, 7, 8, 7, 7, 8, 9, 9, 9, 9, 10, 10, 11, 12, 12, 13, 13, 13, 13,
13, 13, 13, 13, 13, 13, 14, 14, 14, 15, 15, 15, 15, 16, 16, 17, 17, 17, 18, 18, 18, 18, 18, 18,
18, 18, 18, 18, 18, 18, 18, 18, 18, 18, 19, 19, 19, 19, 19, 19, 20, 20, 21, 21, 21, 21, 22, 22,
22, 22, 23, 23, 24, 25, 26, 26, 26, 26, 27, 27, 28, 28, 28, 28, 28, 28, 28, 28, 29, 29, 30, 30,
30, 30, 30, 30, 30, 30, 31, 31, 31, 31, 32, 32, 32, 32, 33, 33, 33, 33, 34, 34, 35, 35, 36, 36,
36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 37, 37, 37, 37, 38, 38, 38, 39, 40, 41,
42, 43, 42, 43, 42, 43, 44, 45, 46, 45, 46, 47, 47, 48, 48, 49, 49, 50, 50, 51, 51, 51, 51, 51,
51, 52, 53, 53, 54, 54, 54, 54, 54, 54, 55, 55, 55, 55, 57, 57, 56, 56, 58, 58, 58, 58, 59, 60,
61, 59, 61, 62, 62, 63, 63, 64, 62, 64, 65, 65, 66, 66, 67, 65, 65, 67, 68, 69, 70, 68, 69, 70,
71, 71, 71, 71, 72, 72, 72, 72, 73, 73,
];
/// 算术晶体类别符号表
/// 注意：这里的字符串已经包含了尾部空格，我们在返回时切片即可
static ARITHMETIC_CRYSTAL_CLASS_SYMBOLS: [&str; 74] = [
" ", /* 0 */
"1P ", /* 1 */
"-1P ", /* 2 */
"2P ", /* 3 */
"2C ", /* 4 */
"mP ", /* 5 */
"mC ", /* 6 */
"2/mP ", /* 7 */
"2/mC ", /* 8 */
"222P ", /* 9 */
"222C ", /* 10 */
"222F ", /* 11 */
"222I ", /* 12 */
"mm2P ", /* 13 */
"mm2C ", /* 14 */
"2mmC ", /* 15 */
"mm2F ", /* 16 */
"mm2I ", /* 17 */
"mmmP ", /* 18 */
"mmmC ", /* 19 */
"mmmF ", /* 20 */
"mmmI ", /* 21 */
"4P ", /* 22 */
"4I ", /* 23 */
"-4P ", /* 24 */
"-4I ", /* 25 */
"4/mP ", /* 26 */
"4/mI ", /* 27 */
"422P ", /* 28 */
"422I ", /* 29 */
"4mmP ", /* 30 */
"4mmI ", /* 31 */
"-42mP ", /* 32 */
"-4m2P ", /* 33 */
"-4m2I ", /* 34 */
"-42mI ", /* 35 */
"4/mmmP", /* 36 */
"4/mmmI", /* 37 */
"3P ", /* 38 */
"3R ", /* 39 */
"-3P ", /* 40 */
"-3R ", /* 41 */
"312P ", /* 42 */
"321P ", /* 43 */
"32R ", /* 44 */
"3m1P ", /* 45 */
"31mP ", /* 46 */
"3mR ", /* 47 */
"-31mP ", /* 48 */
"-3m1P ", /* 49 */
"-3mR ", /* 50 */
"6P ", /* 51 */
"-6P ", /* 52 */
"6/mP ", /* 53 */
"622P ", /* 54 */
"6mmP ", /* 55 */
"-62mP ", /* 56 */
"-6m2P ", /* 57 */
"6/mmmP", /* 58 */
"23P ", /* 59 */
"23F ", /* 60 */
"23I ", /* 61 */
"m-3P ", /* 62 */
"m-3F ", /* 63 */
"m-3I ", /* 64 */
"432P ", /* 65 */
"432F ", /* 66 */
"432I ", /* 67 */
"-43mP ", /* 68 */
"-43mF ", /* 69 */
"-43mI ", /* 70 */
"m-3mP ", /* 71 */
"m-3mF ", /* 72 */
"m-3mI ", /* 73 */
];
/// 获取算术晶体类别符号
///
/// # Arguments
/// * `spgroup_number`: 空间群编号 (1-230)
///
/// # Returns
/// * `Option<(u8, &'static str)>`: 如果输入有效，返回 (算术类别编号, 符号切片)；否则返回 None。
/// 使用 Option 是比返回 (0, "") 更 Rust 的做法。
pub fn arth_get_symbol(spgroup_number: i32) -> Option<(u8, &'static str)> {
// 使用 get 进行安全的边界检查
// spgroup_number 是 1-based，所以需要减 1 才能对应 0-based 索引吗？
// 不，数组大小是 231，索引 0 是占位符，索引 1 对应空间群 1。
// 所以直接用 spgroup_number 作为索引。
let arth_number = *ARITHMETIC_CRYSTAL_CLASSES.get(spgroup_number as usize)?;
if arth_number == 0 {
return None;
}
// 获取原始字符串
let symbol_raw = ARITHMETIC_CRYSTAL_CLASS_SYMBOLS.get(arth_number as usize)?;
// 使用 trim_end() 返回一个 slice，不进行内存分配
// 生命周期为 'static，因为源数据是 static 的
let symbol = symbol_raw.trim_end();
Some((arth_number, symbol))
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_arth_get_symbol() {
// Test case 1: Space group 1 (P1) -> Arithmetic class 1 (1P)
let result = arth_get_symbol(1);
assert_eq!(result, Some((1, "1P")));
// Test case 2: Space group 225 (Fm-3m) -> Arithmetic class 72 (m-3mF)
let result = arth_get_symbol(225);
assert_eq!(result, Some((72, "m-3mF")));
// Test case 3: Invalid input
assert_eq!(arth_get_symbol(0), None);
assert_eq!(arth_get_symbol(231), None);
assert_eq!(arth_get_symbol(-5), None);
}
}