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use std::fmt;
use crate::unicode as U;
use super::{Group, Number, Gender, Case};
#[derive(Clone, Debug)]
pub struct Indeclinable {
declension: String,
gender: Gender,
}
#[derive(Clone, Debug)]
pub enum IndeclinableError {
EmptyDeclension(),
}
impl fmt::Display for IndeclinableError {
fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
match self {
IndeclinableError::EmptyDeclension() => {
write!(f, "The declension string is empty.")
},
}
}
}
impl Indeclinable {
/// This function is used to create indeclinable Latin nouns.
///
/// Certain Latin nouns cannot be declined. These nouns, not surprisingly,
/// are referred to as indeclinable nouns. When [`decline`] is called on a
/// noun created with this function, it will always return the singular
/// nominative form.
///
/// # Example
/// ```
/// use verba::noun::{Noun};
///
/// use verba::noun as N;
///
/// let nom = "nīl".to_string();
///
/// let noun = N::Indeclinable::new(nom, N::Gender::Neuter).unwrap();
///
/// assert_eq!(noun.decline(N::Number::Singular, N::Case::Nominative), Some(vec!["nīl".to_string()]));
/// assert_eq!(noun.decline(N::Number::Singular, N::Case::Genitive), Some(vec!["nīl".to_string()]));
/// assert_eq!(noun.decline(N::Number::Singular, N::Case::Dative), Some(vec!["nīl".to_string()]));
/// assert_eq!(noun.decline(N::Number::Singular, N::Case::Accusative), Some(vec!["nīl".to_string()]));
/// assert_eq!(noun.decline(N::Number::Singular, N::Case::Ablative), Some(vec!["nīl".to_string()]));
/// assert_eq!(noun.decline(N::Number::Singular, N::Case::Vocative), Some(vec!["nīl".to_string()]));
/// assert_eq!(noun.decline(N::Number::Plural, N::Case::Nominative), Some(vec!["nīl".to_string()]));
/// assert_eq!(noun.decline(N::Number::Plural, N::Case::Genitive), Some(vec!["nīl".to_string()]));
/// assert_eq!(noun.decline(N::Number::Plural, N::Case::Dative), Some(vec!["nīl".to_string()]));
/// assert_eq!(noun.decline(N::Number::Plural, N::Case::Accusative), Some(vec!["nīl".to_string()]));
/// assert_eq!(noun.decline(N::Number::Plural, N::Case::Ablative), Some(vec!["nīl".to_string()]));
/// assert_eq!(noun.decline(N::Number::Plural, N::Case::Vocative), Some(vec!["nīl".to_string()]));
/// ```
pub fn new(declension: String, gender: Gender) -> Result<Indeclinable, IndeclinableError> {
if declension.is_empty() {
Err(IndeclinableError::EmptyDeclension())
} else {
let declension = U::normalize(declension);
Ok(Indeclinable {
declension,
gender,
})
}
}
}
impl super::Noun for Indeclinable {
fn gender(&self) -> Gender {
self.gender
}
fn stem(&self) -> Option<&str> {
None
}
fn group(&self) -> Option<Group> {
None
}
fn decline(&self, _number: Number, _case: Case) -> Option<Vec<String>> {
Some(vec![self.declension.to_string()])
}
}
#[cfg(test)]
mod test {
use super::*;
use crate::noun::{Noun, Number, Gender, Case};
use unicode_normalization::{is_nfc};
#[test]
fn test_new() {
match Indeclinable::new("nīl".to_string(), Gender::Neuter) {
Ok(noun) => {
assert!(is_nfc(&noun.declension), "Declension is not in NFC form.");
assert_eq!(noun.gender(), Gender::Neuter, "Indeclinable::gender returned an incorrect gender.");
assert_eq!(noun.group(), None, "Indeclinable::group didn't return None.");
assert_eq!(noun.stem(), None, "Indeclinable::stem didn't return None.");
}
Err(error) => panic!("Failed to create indeclinable noun {}. Received the following error: {}", "nīl", error),
}
}
/// Takes two Vec<String> arguments. The first is a value returned from
/// Noun::decline and the second is the expected values.
///
/// First the two arguments are checked to make sure they have the same
/// length. If they are, then each element in the first argument's Unicode
/// normalized form is checked to be composed. If it is, then the function
/// checks if the element is stored in the second argument. If it is, then
/// the function returns true.
fn verify_declension(declension: &Option<Vec<String>>, correct: &Option<Vec<String>>) {
match (declension, correct) {
(Some(declension), Some(correct)) => {
assert!(declension.len() == correct.len(), "The Vecs `declension` and `correct` are not the same length.");
for (index, form) in declension.iter().enumerate() {
// First check to ensure the element is in normalized composed
// form. If it's not, the second check may return false even if the
// strings appears equal.
assert!(is_nfc(form), "{} is not in normalized composed form.", form);
assert!(form == &correct[index], "Element {}, {}, from `declension` is not equal to element {}, {}, from `correct`.", index, form, index, &correct[index]);
}
},
(Some(_), None) => panic!("Vec `declension` contained data but `correct` was None."),
(None, Some(_)) => panic!("Vec `declension` was None but `correct` contained data."),
(None, None) => (),
}
}
#[test]
fn test_indeclinable_nil() {
let nom = "nīl".to_string();
match Indeclinable::new(nom, Gender::Neuter) {
Ok(noun) => {
verify_declension(&noun.decline(Number::Singular, Case::Nominative), &Some(vec!["nīl".to_string()]));
verify_declension(&noun.decline(Number::Singular, Case::Genitive), &Some(vec!["nīl".to_string()]));
verify_declension(&noun.decline(Number::Singular, Case::Dative), &Some(vec!["nīl".to_string()]));
verify_declension(&noun.decline(Number::Singular, Case::Accusative), &Some(vec!["nīl".to_string()]));
verify_declension(&noun.decline(Number::Singular, Case::Ablative), &Some(vec!["nīl".to_string()]));
verify_declension(&noun.decline(Number::Singular, Case::Vocative), &Some(vec!["nīl".to_string()]));
verify_declension(&noun.decline(Number::Plural, Case::Nominative), &Some(vec!["nīl".to_string()]));
verify_declension(&noun.decline(Number::Plural, Case::Genitive), &Some(vec!["nīl".to_string()]));
verify_declension(&noun.decline(Number::Plural, Case::Dative), &Some(vec!["nīl".to_string()]));
verify_declension(&noun.decline(Number::Plural, Case::Accusative), &Some(vec!["nīl".to_string()]));
verify_declension(&noun.decline(Number::Plural, Case::Ablative), &Some(vec!["nīl".to_string()]));
verify_declension(&noun.decline(Number::Plural, Case::Vocative), &Some(vec!["nīl".to_string()]));
},
Err(_) => panic!("Failed to create indeclinable noun nīl"),
}
}
}