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236 lines
7.9 KiB
Rust
236 lines
7.9 KiB
Rust
const SEPARATOR: char = '_';
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/// Increment an integer.
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///
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/// Supported bases:
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/// 2 with prefix 0b
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/// 8 with prefix 0o
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/// 10 with no prefix
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/// 16 with prefix 0x
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///
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/// An integer can contain `_` as a separator but may not start or end with a separator.
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/// Base 10 integers can go negative, but bases 2, 8, and 16 cannot.
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/// All addition and subtraction is saturating.
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pub fn increment(selected_text: &str, amount: i64) -> Option<String> {
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if selected_text.is_empty()
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|| selected_text.ends_with(SEPARATOR)
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|| selected_text.starts_with(SEPARATOR)
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{
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return None;
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}
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let radix = if selected_text.starts_with("0x") {
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16
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} else if selected_text.starts_with("0o") {
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8
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} else if selected_text.starts_with("0b") {
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2
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} else {
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10
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};
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// Get separator indexes from right to left.
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let separator_rtl_indexes: Vec<usize> = selected_text
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.chars()
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.rev()
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.enumerate()
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.filter_map(|(i, c)| if c == SEPARATOR { Some(i) } else { None })
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.collect();
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let word: String = selected_text.chars().filter(|&c| c != SEPARATOR).collect();
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let mut new_text = if radix == 10 {
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let number = &word;
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let value = i128::from_str_radix(number, radix).ok()?;
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let new_value = value.saturating_add(amount as i128);
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let format_length = match (value.is_negative(), new_value.is_negative()) {
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(true, false) => number.len() - 1,
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(false, true) => number.len() + 1,
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_ => number.len(),
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} - separator_rtl_indexes.len();
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if number.starts_with('0') || number.starts_with("-0") {
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format!("{:01$}", new_value, format_length)
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} else {
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format!("{}", new_value)
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}
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} else {
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let number = &word[2..];
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let value = u128::from_str_radix(number, radix).ok()?;
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let new_value = (value as i128).saturating_add(amount as i128);
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let new_value = if new_value < 0 { 0 } else { new_value };
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let format_length = selected_text.len() - 2 - separator_rtl_indexes.len();
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match radix {
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2 => format!("0b{:01$b}", new_value, format_length),
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8 => format!("0o{:01$o}", new_value, format_length),
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16 => {
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let (lower_count, upper_count): (usize, usize) =
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number.chars().fold((0, 0), |(lower, upper), c| {
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(
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lower + c.is_ascii_lowercase() as usize,
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upper + c.is_ascii_uppercase() as usize,
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)
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});
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if upper_count > lower_count {
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format!("0x{:01$X}", new_value, format_length)
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} else {
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format!("0x{:01$x}", new_value, format_length)
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}
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}
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_ => unimplemented!("radix not supported: {}", radix),
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}
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};
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// Add separators from original number.
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for &rtl_index in &separator_rtl_indexes {
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if rtl_index < new_text.len() {
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let new_index = new_text.len().saturating_sub(rtl_index);
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if new_index > 0 {
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new_text.insert(new_index, SEPARATOR);
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}
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}
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}
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// Add in additional separators if necessary.
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if new_text.len() > selected_text.len() && !separator_rtl_indexes.is_empty() {
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let spacing = match separator_rtl_indexes.as_slice() {
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[.., b, a] => a - b - 1,
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_ => separator_rtl_indexes[0],
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};
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let prefix_length = if radix == 10 { 0 } else { 2 };
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if let Some(mut index) = new_text.find(SEPARATOR) {
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while index - prefix_length > spacing {
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index -= spacing;
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new_text.insert(index, SEPARATOR);
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}
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}
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}
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Some(new_text)
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn test_increment_basic_decimal_numbers() {
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let tests = [
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("100", 1, "101"),
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("100", -1, "99"),
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("99", 1, "100"),
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("100", 1000, "1100"),
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("100", -1000, "-900"),
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("-1", 1, "0"),
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("-1", 2, "1"),
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("1", -1, "0"),
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("1", -2, "-1"),
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];
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for (original, amount, expected) in tests {
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assert_eq!(increment(original, amount).unwrap(), expected);
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}
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}
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#[test]
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fn test_increment_basic_hexadecimal_numbers() {
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let tests = [
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("0x0100", 1, "0x0101"),
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("0x0100", -1, "0x00ff"),
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("0x0001", -1, "0x0000"),
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("0x0000", -1, "0x0000"),
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("0xffffffffffffffff", 1, "0x10000000000000000"),
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("0xffffffffffffffff", 2, "0x10000000000000001"),
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("0xffffffffffffffff", -1, "0xfffffffffffffffe"),
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("0xABCDEF1234567890", 1, "0xABCDEF1234567891"),
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("0xabcdef1234567890", 1, "0xabcdef1234567891"),
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];
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for (original, amount, expected) in tests {
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assert_eq!(increment(original, amount).unwrap(), expected);
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}
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}
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#[test]
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fn test_increment_basic_octal_numbers() {
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let tests = [
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("0o0107", 1, "0o0110"),
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("0o0110", -1, "0o0107"),
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("0o0001", -1, "0o0000"),
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("0o7777", 1, "0o10000"),
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("0o1000", -1, "0o0777"),
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("0o0107", 10, "0o0121"),
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("0o0000", -1, "0o0000"),
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("0o1777777777777777777777", 1, "0o2000000000000000000000"),
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("0o1777777777777777777777", 2, "0o2000000000000000000001"),
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("0o1777777777777777777777", -1, "0o1777777777777777777776"),
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];
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for (original, amount, expected) in tests {
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assert_eq!(increment(original, amount).unwrap(), expected);
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}
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}
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#[test]
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fn test_increment_basic_binary_numbers() {
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let tests = [
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("0b00000100", 1, "0b00000101"),
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("0b00000100", -1, "0b00000011"),
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("0b00000100", 2, "0b00000110"),
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("0b00000100", -2, "0b00000010"),
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("0b00000001", -1, "0b00000000"),
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("0b00111111", 10, "0b01001001"),
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("0b11111111", 1, "0b100000000"),
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("0b10000000", -1, "0b01111111"),
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("0b0000", -1, "0b0000"),
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(
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"0b1111111111111111111111111111111111111111111111111111111111111111",
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1,
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"0b10000000000000000000000000000000000000000000000000000000000000000",
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),
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(
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"0b1111111111111111111111111111111111111111111111111111111111111111",
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2,
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"0b10000000000000000000000000000000000000000000000000000000000000001",
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),
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(
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"0b1111111111111111111111111111111111111111111111111111111111111111",
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-1,
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"0b1111111111111111111111111111111111111111111111111111111111111110",
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),
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];
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for (original, amount, expected) in tests {
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assert_eq!(increment(original, amount).unwrap(), expected);
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}
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}
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#[test]
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fn test_increment_with_separators() {
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let tests = [
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("999_999", 1, "1_000_000"),
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("1_000_000", -1, "999_999"),
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("-999_999", -1, "-1_000_000"),
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("0x0000_0000_0001", 0x1_ffff_0000, "0x0001_ffff_0001"),
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("0x0000_0000", -1, "0x0000_0000"),
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("0x0000_0000_0000", -1, "0x0000_0000_0000"),
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("0b01111111_11111111", 1, "0b10000000_00000000"),
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("0b11111111_11111111", 1, "0b1_00000000_00000000"),
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];
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for (original, amount, expected) in tests {
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assert_eq!(increment(original, amount).unwrap(), expected);
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}
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}
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#[test]
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fn test_leading_and_trailing_separators_arent_a_match() {
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assert_eq!(increment("9_", 1), None);
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assert_eq!(increment("_9", 1), None);
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assert_eq!(increment("_9_", 1), None);
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}
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}
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