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#[derive(Clone, Debug, PartialEq)]
pub struct Number {
value: f64,
unit: Option<String>,
}
impl Number {
pub fn new(value: f64, unit: Option<String>) -> Self {
Self { value, unit }
}
pub fn value(&self) -> f64 {
self.value
}
pub fn unit(&self) -> Option<&str> {
self.unit.as_ref().map(|unit| unit.as_ref())
}
pub fn from_encoded_json_string(
json_string: &str,
) -> Result<Self, ParseNumberError> {
let json_string = json_string.replacen("n:", "", 1);
let mut split = json_string.trim().split(' ');
let number_str = split.next();
let unit_str = split.next();
if let Some(number_str) = number_str {
let number = if number_str == "INF" {
std::f64::INFINITY
} else if number_str == "-INF" {
std::f64::NEG_INFINITY
} else {
number_str
.parse()
.map_err(|_| ParseNumberError::from_str(&json_string))?
};
let unit = unit_str.map(|unit_str| unit_str.trim().to_string());
Ok(Number::new(number, unit))
} else {
Err(ParseNumberError::from_str(&json_string))
}
}
}
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct ParseNumberError {
unparsable_number: String,
}
impl ParseNumberError {
pub(crate) fn from_str(s: &str) -> Self {
Self {
unparsable_number: s.to_string(),
}
}
}
impl std::fmt::Display for ParseNumberError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(
f,
"Could not parse Number from string {}",
self.unparsable_number
)
}
}
impl std::error::Error for ParseNumberError {}
#[cfg(test)]
mod test {
use super::Number;
#[test]
fn from_encoded_json_string() {
let unitless = "n:45.5";
assert_eq!(
Number::from_encoded_json_string(unitless).unwrap().value(),
45.5
);
let unit = "n:73.2 °F";
let number_with_unit = Number::from_encoded_json_string(unit).unwrap();
assert_eq!(number_with_unit.value(), 73.2);
assert_eq!(number_with_unit.unit(), Some("°F"))
}
#[test]
fn from_encoded_json_string_infinity() {
let unitless = "n:INF";
assert_eq!(
Number::from_encoded_json_string(unitless).unwrap().value(),
std::f64::INFINITY,
);
let unit = "n:INF °F";
let number_with_unit = Number::from_encoded_json_string(unit).unwrap();
assert_eq!(number_with_unit.value(), std::f64::INFINITY);
assert_eq!(number_with_unit.unit(), Some("°F"))
}
#[test]
fn from_encoded_json_string_neg_infinity() {
let unitless = "n:-INF";
assert_eq!(
Number::from_encoded_json_string(unitless).unwrap().value(),
std::f64::NEG_INFINITY,
);
let unit = "n:-INF °F";
let number_with_unit = Number::from_encoded_json_string(unit).unwrap();
assert_eq!(number_with_unit.value(), std::f64::NEG_INFINITY);
assert_eq!(number_with_unit.unit(), Some("°F"))
}
#[test]
fn from_encoded_json_string_signless_nan() {
let unitless = "n:NaN";
assert!(Number::from_encoded_json_string(unitless)
.unwrap()
.value()
.is_nan());
let unit = "n:NaN °F";
let number_with_unit = Number::from_encoded_json_string(unit).unwrap();
assert!(number_with_unit.value().is_nan());
assert_eq!(number_with_unit.unit(), Some("°F"))
}
#[test]
fn from_encoded_json_string_signed_nan() {
let unitless = "n:-NaN";
assert!(Number::from_encoded_json_string(unitless)
.unwrap()
.value()
.is_nan());
let unit = "n:+NaN °F";
let number_with_unit = Number::from_encoded_json_string(unit).unwrap();
assert!(number_with_unit.value().is_nan());
assert_eq!(number_with_unit.unit(), Some("°F"))
}
}