dre_protocol/
util.rs

1//! Small helpers shared by core and first-party plugins, so each rule has one implementation.
2
3/// Parse decimal text (`"-12.30"`) into an integer scaled by `10^scale` for an Arrow decimal.
4/// Negative scales are allowed (`"1200"` at scale -2 is `12`). Digits that the scale would
5/// drop must be zero: a value that doesn't fit the scale is an error, never silently cut.
6pub fn scaled_decimal(text: &str, scale: i8) -> Result<i128, String> {
7    let bad = || format!("`{text}` isn't a decimal that fits scale {scale}");
8    let t = text.trim();
9    let (neg, t) = match t.strip_prefix('-') {
10        Some(r) => (true, r),
11        None => (false, t.strip_prefix('+').unwrap_or(t)),
12    };
13    let (int, frac) = t.split_once('.').unwrap_or((t, ""));
14    if int.is_empty() && frac.is_empty() || !int.bytes().chain(frac.bytes()).all(|b| b.is_ascii_digit()) {
15        return Err(bad());
16    }
17    // All digits, and the power of ten of the last one.
18    let mut digits = format!("{int}{frac}");
19    let mut exp = -(frac.len() as i32);
20    let target = -i32::from(scale);
21    // Drop trailing digits below the scale; they must be zeros.
22    while exp < target {
23        match digits.pop() {
24            Some('0') => exp += 1,
25            Some(_) => return Err(bad()),
26            None => break,
27        }
28    }
29    while exp > target {
30        digits.push('0');
31        exp -= 1;
32    }
33    let digits = digits.trim_start_matches('0');
34    let v: i128 = if digits.is_empty() {
35        0
36    } else {
37        digits.parse().map_err(|_| bad())?
38    };
39    Ok(if neg { -v } else { v })
40}
41
42/// Parse a cell reference (`B12`, `$B$12`) into zero-based `(row, col)`. `$` may only appear
43/// directly before the column letters and before the row number.
44pub fn parse_cell(s: &str) -> Option<(u32, u16)> {
45    let s = s.trim();
46    let s = s.strip_prefix('$').unwrap_or(s);
47    let split = s.find(|c: char| !c.is_ascii_alphabetic())?;
48    let (letters, rest) = s.split_at(split);
49    let digits = rest.strip_prefix('$').unwrap_or(rest);
50    if letters.is_empty()
51        || letters.len() > 3
52        || digits.is_empty()
53        || !digits.bytes().all(|b| b.is_ascii_digit())
54    {
55        return None;
56    }
57    let col = letters
58        .to_ascii_uppercase()
59        .bytes()
60        .fold(0u32, |acc, b| acc * 26 + u32::from(b - b'A' + 1));
61    let row: u32 = digits.parse().ok()?;
62    if col == 0 || col > 16_384 || row == 0 || row > 1_048_576 {
63        return None;
64    }
65    Some((row - 1, (col - 1) as u16))
66}
67
68/// Percent-encode everything except RFC 3986 unreserved characters and, if `keep_slash`, `/`.
69pub fn percent_encode(s: &str, keep_slash: bool) -> String {
70    let mut out = String::with_capacity(s.len());
71    for b in s.bytes() {
72        match b {
73            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' => out.push(b as char),
74            b'/' if keep_slash => out.push('/'),
75            b => out.push_str(&format!("%{b:02X}")),
76        }
77    }
78    out
79}
80
81/// One line, at most `max` characters, for quoting SQL in messages.
82pub fn summarize(text: &str, max: usize) -> String {
83    let one = text.split_whitespace().collect::<Vec<_>>().join(" ");
84    if one.chars().count() > max {
85        format!("{}…", one.chars().take(max).collect::<String>())
86    } else {
87        one
88    }
89}
90
91#[cfg(test)]
92mod tests {
93    use super::*;
94
95    #[test]
96    fn scales_decimals_exactly() {
97        assert_eq!(scaled_decimal("12.34", 2), Ok(1234));
98        assert_eq!(scaled_decimal("-0.5", 3), Ok(-500));
99        assert_eq!(scaled_decimal("7", 2), Ok(700));
100        assert_eq!(scaled_decimal("12.3400", 2), Ok(1234));
101        assert_eq!(scaled_decimal("1200", -2), Ok(12));
102        assert_eq!(scaled_decimal("0.000", 0), Ok(0));
103    }
104
105    #[test]
106    fn refuses_to_drop_significant_digits() {
107        assert!(scaled_decimal("12.345", 2).is_err());
108        assert!(scaled_decimal("1250", -2).is_err());
109        assert!(scaled_decimal("abc", 2).is_err());
110        assert!(scaled_decimal("", 2).is_err());
111    }
112
113    #[test]
114    fn parses_cell_references() {
115        assert_eq!(parse_cell("A1"), Some((0, 0)));
116        assert_eq!(parse_cell("$B$12"), Some((11, 1)));
117        assert_eq!(parse_cell("b12"), Some((11, 1)));
118        assert_eq!(parse_cell("XFD1048576"), Some((1_048_575, 16_383)));
119        for bad in ["XFE1", "A0", "1A", "B$1$2", "$$A1", "A", "12", "A1B"] {
120            assert_eq!(parse_cell(bad), None, "{bad}");
121        }
122    }
123
124    #[test]
125    fn percent_encodes() {
126        assert_eq!(percent_encode("a b/c.csv", true), "a%20b/c.csv");
127        assert_eq!(percent_encode("a b/c", false), "a%20b%2Fc");
128    }
129}
dre_protocol/util.rs

dre_protocol/
util.rs
