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Fix formatting of decimal powers below 1 million #2431

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Merged
coolreader18 merged 1 commit into from
Feb 1, 2021
Merged

Fix formatting of decimal powers below 1 million #2431

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59 changes: 55 additions & 4 deletions common/src/float_ops.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -137,12 +137,32 @@ pub fn format_exponent(precision: usize, magnitude: f64, case: Case) -> String {
}
}

/// If s represents a floating point value, trailing zeros and a possibly trailing
/// decimal point will be removed.
/// This function does NOT work with decimal commas.
fn remove_trailing_redundant_chars(s: String) -> String {
if s.contains('.') {
// only truncate floating point values
let s = remove_trailing_zeros(s);
remove_trailing_decimal_point(s)
} else {
s
}
}

fn remove_trailing_zeros(s: String) -> String {
let mut s = s;
while s.ends_with('0') || s.ends_with('.') {
s.truncate(s.len() - 1);
while s.ends_with('0') {
s.pop();
}
s
}

fn remove_trailing_decimal_point(s: String) -> String {
let mut s = s;
if s.ends_with('.') {
s.pop();
}
s
}

Expand All @@ -159,12 +179,12 @@ pub fn format_general(precision: usize, magnitude: f64, case: Case) -> String {
Case::Upper => 'E',
};

let base = remove_trailing_zeros(format!("{:.*}", precision + 1, base));
let base = remove_trailing_redundant_chars(format!("{:.*}", precision + 1, base));
format!("{}{}{:+#03}", base, e, exponent)
} else {
let precision = (precision as i64) - 1 - exponent;
let precision = precision as usize;
remove_trailing_zeros(format!("{:.*}", precision, magnitude))
remove_trailing_redundant_chars(format!("{:.*}", precision, magnitude))
}
}
magnitude if magnitude.is_nan() => format_nan(case),
Expand Down Expand Up @@ -362,3 +382,34 @@ fn test_to_hex() {
assert!(f == roundtrip, "{} {} {}", f, hex, roundtrip);
}
}

#[test]
fn test_remove_trailing_zeros() {
assert!(remove_trailing_zeros(String::from("100")) == String::from("1"));
assert!(remove_trailing_zeros(String::from("100.00")) == String::from("100."));

// leave leading zeros untouched
assert!(remove_trailing_zeros(String::from("001")) == String::from("001"));

// leave strings untouched if they don't end with 0
assert!(remove_trailing_zeros(String::from("101")) == String::from("101"));
}

#[test]
fn test_remove_trailing_decimal_point() {
assert!(remove_trailing_decimal_point(String::from("100.")) == String::from("100"));
assert!(remove_trailing_decimal_point(String::from("1.")) == String::from("1"));

// leave leading decimal points untouched
assert!(remove_trailing_decimal_point(String::from(".5")) == String::from(".5"));
}

#[test]
fn test_remove_trailing_redundant_chars() {
assert!(remove_trailing_redundant_chars(String::from("100.")) == String::from("100"));
assert!(remove_trailing_redundant_chars(String::from("1.")) == String::from("1"));
assert!(remove_trailing_redundant_chars(String::from("10.0")) == String::from("10"));

// don't truncate integers
assert!(remove_trailing_redundant_chars(String::from("1000")) == String::from("1000"));
}
4 changes: 3 additions & 1 deletion extra_tests/snippets/strings.py
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Original file line number Diff line number Diff line change
Expand Up @@ -545,6 +545,8 @@ def try_mutate_str():
assert '{:E}'.format(float('inf')) == 'INF'

# Test g & G formatting
assert '{:g}'.format(10.0) == '10'
assert '{:g}'.format(100000.0) == '100000'
assert '{:g}'.format(123456.78901234567890) == '123457'
assert '{:.0g}'.format(123456.78901234567890) == '1e+05'
assert '{:.1g}'.format(123456.78901234567890) == '1e+05'
Expand Down Expand Up @@ -699,4 +701,4 @@ def test_removesuffix_types():
skip_if_unsupported(3,9,test_removeprefix)
skip_if_unsupported(3,9,test_removeprefix_types)
skip_if_unsupported(3,9,test_removesuffix)
skip_if_unsupported(3,9,test_removesuffix_types)
skip_if_unsupported(3,9,test_removesuffix_types)