Start work on engineering display mode

src/calc/constants.rs

@@ -85,7 +85,7 @@ impl fmt::Display for CalculatorDisplayMode {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             CalculatorDisplayMode::Default => write!(f, "DEF"),
-            CalculatorDisplayMode::Separated(c) => write!(f, "DEF({})", c),
+            CalculatorDisplayMode::Separated(c) => write!(f, "SEP({})", c),
             CalculatorDisplayMode::Scientific(p) => write!(f, "SCI({})", p),
             CalculatorDisplayMode::Engineering(p) => write!(f, "ENG({})", p),
             CalculatorDisplayMode::Fixed(p) => write!(f, "FIX({})", p),

src/main.rs

@@ -119,12 +119,14 @@ fn main() -> Result<(), Box<dyn Error>> {
                     let content = vec![Spans::from(Span::raw(
                         match app.calculator.get_display_mode() {
                             CalculatorDisplayMode::Default => format!("{:>2}: {}", i, *m),
-                            CalculatorDisplayMode::Separated(c) => fmt_separated(i, *m, *c),
+                            CalculatorDisplayMode::Separated(c) => {
-                            CalculatorDisplayMode::Scientific(precision) => {
+                                format!("{:>2}: {}", i, fmt_separated(*m, *c))
-                                fmt_scientific(i, *m, *precision)
                             }
-                            CalculatorDisplayMode::Engineering(_precision) => {
+                            CalculatorDisplayMode::Scientific(precision) => {
-                                format!("{:>2}: {}", i, m)
+                                format!("{:>2}: {}", i, fmt_scientific(*m, *precision))
+                            }
+                            CalculatorDisplayMode::Engineering(precision) => {
+                                format!("{:>2}: {}", i, fmt_engineering(*m, *precision))
                             }
                             CalculatorDisplayMode::Fixed(precision) => {
                                 format!("{:>2}: {:.precision$}", i, m, precision = precision)
@@ -389,30 +391,36 @@ fn draw_clippy_rect<T: std::io::Write>(c: ClippyRectangle, f: &mut Frame<Termion
 }
 
 // Based on https://stackoverflow.com/a/65266882
-fn fmt_scientific(i: usize, f: f64, precision: usize) -> String {
+fn fmt_scientific(f: f64, precision: usize) -> String {
     let mut ret = format!("{:.precision$E}", f, precision = precision);
     let exp = ret.split_off(ret.find('E').unwrap_or(0));
-    let (pow_sign, exp) = if let Some(stripped) = exp.strip_prefix("E-") {
+    let (exp_sign, exp) = if let Some(stripped) = exp.strip_prefix("E-") {
         ('-', stripped)
     } else {
         ('+', &exp[1..])
     };
 
     let sign = if !ret.starts_with('-') { " " } else { "" };
-    format!(
+    format!("{}{}E{}{:0>pad$}", sign, ret, exp_sign, exp, pad = 2)
-        "{:>2}: {}{}E{}{:0>pad$}",
-        i,
-        sign,
-        ret,
-        pow_sign,
-        exp,
-        pad = 2
-    )
 }
+// (a)E(c)
+// E power = f.log10().div_euclid(3) * 3
+// left portion = f.log10().rem_euclid(3) + 1
+// .0001 - 100E-6 - 1E-4
+// .001  -   1E-3 - 1E-3 => -3
+// .01   -  10E-3 - 1E-2
+// .1    - 100E-3 - 1E-1
+// 1     -   1E+0 - 1E+0 => 0
+// 10    -  10E+0 - 1E+1
+// 100   - 100E+0 - 1E+2
+// 1000  -   1E+3 - 1E+3 => 3
+// 10000 -  10E+3 - 1E+4
 
-// // 100 E+3
 // fn fmt_engineering(i: usize, f: f64, precision: usize) -> String {
-//     let mut ret = format!("  {:.precision$e}", f, precision = precision + 2);
+//     // TODO: There is probably a more efficent way to do this using slices or something
+//     let mut all = format!("{:.precision$e}", f, precision = precision + 2).replacen(".", "", 1);
+//     // The left 1, 2, or 3 digits
+//     let left = all.split_off(f.log10().rem_euclid(3) + 1);
 //     // The length of ret will always be at least 5 -- 2 leading spaces, integer portion, and precision + 2
 //     let exp = ret.split_off(ret.find('E').unwrap_or(0));
 //     let left = ret[()..()]
@@ -435,14 +443,33 @@ fn fmt_scientific(i: usize, f: f64, precision: usize) -> String {
 //     )
 // }
 
-fn fmt_separated(i: usize, f: f64, sep: char) -> String {
+fn fmt_engineering(f: f64, precision: usize) -> String {
+    let all = format!("{:.precision$E}", f, precision = precision + 2).replacen(".", "", 1);
+    let (mantissa_str, pow_str) = all.split_at(all.find('E').unwrap_or(0));
+    let pow = pow_str[1..].parse::<isize>().unwrap();
+    let display_pow_sign = if let Some(stripped) = pow_str.strip_prefix("E-") {
+        '-'
+    } else {
+        '+'
+    };
+    let display_pow = (pow.div_euclid(3) * 3).abs();
+    let num_digits = pow.rem_euclid(3) as usize + 1;
+    let whole = &mantissa_str[0..num_digits];
+    let decimal = &mantissa_str[num_digits..];
+    format!(
+        "{: >3}.{} * 10 ^ {}{}",
+        whole, decimal, display_pow_sign, display_pow
+    )
+}
+
+fn fmt_separated(f: f64, sep: char) -> String {
     let mut ret = f.to_string();
     let start = if ret.starts_with('-') { 1 } else { 0 };
     let end = ret.find('.').unwrap_or_else(|| ret.len());
     for i in 0..((end - start - 1).div_euclid(3)) {
         ret.insert(end - (i + 1) * 3, sep);
     }
-    format!("{:>2}: {}", i, ret)
+    format!("{}", ret)
 }
 
 #[cfg(test)]
@@ -450,47 +477,47 @@ mod tests {
     use super::*;
     #[test]
     fn test_fmt_scientific() {
-        for (i, f, p, s) in vec![
+        for (f, p, s) in vec![
             // Basic
-            (0, 1.0, 0, " 0:  1E+00"),
+            (1.0, 0, " 1E+00"),
-            (0, -1.0, 0, " 0: -1E+00"),
+            (-1.0, 0, "-1E+00"),
-            (0, 100.0, 0, " 0:  1E+02"),
+            (100.0, 0, " 1E+02"),
-            (0, 0.1, 0, " 0:  1E-01"),
+            (0.1, 0, " 1E-01"),
-            (0, 0.01, 0, " 0:  1E-02"),
+            (0.01, 0, " 1E-02"),
-            (0, -0.1, 0, " 0: -1E-01"),
+            (-0.1, 0, "-1E-01"),
             // i
-            (22, 1.0, 0, "22:  1E+00"),
+            (1.0, 0, " 1E+00"),
             // Precision
-            (0, -0.123456789, 3, " 0: -1.235E-01"),
+            (-0.123456789, 3, "-1.235E-01"),
-            (0, -0.123456789, 2, " 0: -1.23E-01"),
+            (-0.123456789, 2, "-1.23E-01"),
-            (0, -0.123456789, 2, " 0: -1.23E-01"),
+            (-0.123456789, 2, "-1.23E-01"),
-            (0, -1e99, 2, " 0: -1.00E+99"),
+            (-1e99, 2, "-1.00E+99"),
-            (0, -1e100, 2, " 0: -1.00E+100"),
+            (-1e100, 2, "-1.00E+100"),
         ] {
-            assert_eq!(fmt_scientific(i, f, p), s);
+            assert_eq!(fmt_scientific(f, p), s);
         }
     }
 
     #[test]
     fn test_fmt_separated() {
-        for (i, f, c, s) in vec![
+        for (f, c, s) in vec![
-            (10, 100.0, ',', "10: 100"),
+            (100.0, ',', "100"),
-            (0, 100.0, ',', " 0: 100"),
+            (100.0, ',', "100"),
-            (0, -100.0, ',', " 0: -100"),
+            (-100.0, ',', "-100"),
-            (0, 1_000.0, ',', " 0: 1,000"),
+            (1_000.0, ',', "1,000"),
-            (0, -1_000.0, ',', " 0: -1,000"),
+            (-1_000.0, ',', "-1,000"),
-            (0, 10_000.0, ',', " 0: 10,000"),
+            (10_000.0, ',', "10,000"),
-            (0, -10_000.0, ',', " 0: -10,000"),
+            (-10_000.0, ',', "-10,000"),
-            (0, 100_000.0, ',', " 0: 100,000"),
+            (100_000.0, ',', "100,000"),
-            (0, -100_000.0, ',', " 0: -100,000"),
+            (-100_000.0, ',', "-100,000"),
-            (0, 1_000_000.0, ',', " 0: 1,000,000"),
+            (1_000_000.0, ',', "1,000,000"),
-            (0, -1_000_000.0, ',', " 0: -1,000,000"),
+            (-1_000_000.0, ',', "-1,000,000"),
-            (0, 1_000_000.123456789, ',', " 0: 1,000,000.123456789"),
+            (1_000_000.123456789, ',', "1,000,000.123456789"),
-            (0, -1_000_000.123456789, ',', " 0: -1,000,000.123456789"),
+            (-1_000_000.123456789, ',', "-1,000,000.123456789"),
-            (0, 1_000_000.123456789, ' ', " 0: 1 000 000.123456789"),
+            (1_000_000.123456789, ' ', "1 000 000.123456789"),
-            (0, 1_000_000.123456789, ' ', " 0: 1 000 000.123456789"),
+            (1_000_000.123456789, ' ', "1 000 000.123456789"),
         ] {
-            assert_eq!(fmt_separated(i, f, c), s);
+            assert_eq!(fmt_separated(f, c), s);
         }
     }
 }