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use std::{error, fmt};
use indexmap::IndexMap;
pub type Fields = IndexMap<String, String>;
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum Value {
String(String),
Map(Fields),
}
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum TryFromIteratorError {
Empty,
DuplicateTag(String),
}
impl error::Error for TryFromIteratorError {}
impl fmt::Display for TryFromIteratorError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::Empty => f.write_str("empty input"),
Self::DuplicateTag(tag) => write!(f, "duplicate tag: {}", tag),
}
}
}
impl Value {
pub fn try_from_iter<I, K, V>(iter: I) -> Result<Self, TryFromIteratorError>
where
I: IntoIterator<Item = (K, V)>,
K: Into<String>,
V: Into<String>,
{
let mut fields = Fields::new();
for (k, v) in iter {
let key = k.into();
let value = v.into();
if fields.insert(key.clone(), value).is_some() {
return Err(TryFromIteratorError::DuplicateTag(key));
}
}
if fields.is_empty() {
return Err(TryFromIteratorError::Empty);
}
Ok(Value::Map(fields))
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_try_from_iter() {
assert_eq!(
Value::try_from_iter(vec![(String::from("VN"), String::from("1.6")),]),
Ok(Value::Map(
vec![(String::from("VN"), String::from("1.6")),]
.into_iter()
.collect()
))
);
assert_eq!(
Value::try_from_iter(vec![
(String::from("VN"), String::from("1.6")),
(String::from("VN"), String::from("1.6")),
]),
Err(TryFromIteratorError::DuplicateTag(String::from("VN")))
);
assert_eq!(
Value::try_from_iter(Vec::<(String, String)>::new()),
Err(TryFromIteratorError::Empty)
);
}
}