vertical_multiplication/steps/
steps.rs

1use super::*;
2
3impl Display for MultiplicationSteps {
4    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
5        let max_indent = self.max_digits() + 3;
6        let a = self.lhs.to_str_radix(self.base);
7        let b = self.rhs.to_str_radix(self.base);
8        let r = self.result.to_str_radix(self.base);
9        writeln!(f, "{space}{}", a, space = " ".repeat(max_indent - a.len()))?;
10        writeln!(f, " ×{space}{}", b, space = " ".repeat(max_indent - b.len() - 2))?;
11        writeln!(f, "{}", "-".repeat(max_indent + 1))?;
12        for (i, add) in self.steps.iter().enumerate() {
13            if i == 0 {
14                writeln!(f, "{}", add.pretty_format(max_indent, " = ", self.base))?;
15            }
16            else {
17                writeln!(f, "{}", add.pretty_format(max_indent, " + ", self.base))?;
18            }
19        }
20        writeln!(f, "{}", "-".repeat(max_indent + 1))?;
21        write!(f, " = {result}", result = r)
22    }
23}
24
25impl MultiplicationSteps {
26    /// Create a new `MultiplicationSteps` instance
27    pub fn new(a: &BigInt, b: &BigInt) -> MultiplicationSteps {
28        Self { lhs: a.clone(), rhs: b.clone(), steps: vec![], result: a.mul(b), base: 10 }
29    }
30    /// Set the base of this multiplication
31    pub fn with_base(mut self, base: u32) -> Self {
32        assert!(base > 1);
33        self.base = base;
34        self
35    }
36    /// Get the base of this multiplication
37    pub fn push_step(&mut self, step: ShiftAdd) {
38        self.steps.push(step);
39    }
40    /// Get the number of digits in the largest step
41    pub fn max_digits(&self) -> usize {
42        self.steps.iter().map(|x| x.count_digits(self.base)).max().unwrap_or(0)
43    }
44}
vertical_multiplication/steps/steps.rs

vertical_multiplication/steps/
steps.rs
