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use std::iter::FromIterator;
pub enum Case {
SnakeCase,
PascalCase,
CamelCase,
}
impl Case {
pub fn transform(&self, string: &str) -> String {
let mut chars: Vec<char> = vec![];
return match self {
Self::SnakeCase=> {
for ch in string.chars() {
if ch.is_uppercase() {
chars.push('_');
chars.extend(ch.to_lowercase());
} else {
chars.push(ch);
}
}
let first_is_underscore = chars.first().map_or(false, |ch| *ch == '_');
if first_is_underscore {
String::from_iter(chars.into_iter().skip(1))
} else {
String::from_iter(chars)
}
}
Self::PascalCase => {
let mut uppercase_next = false;
for (i, ch) in string.chars().enumerate() {
if i == 0 {
chars.extend(ch.to_uppercase())
} else if ch == '_' {
uppercase_next = true;
} else if uppercase_next {
chars.extend(ch.to_uppercase());
uppercase_next = false;
} else {
chars.push(ch);
}
}
String::from_iter(chars)
}
Self::CamelCase => {
let mut uppercase_next = false;
for (i, ch) in string.chars().enumerate() {
if i == 0 {
chars.extend(ch.to_lowercase())
} else if ch == '_' {
uppercase_next = true;
} else if uppercase_next {
chars.extend(ch.to_uppercase());
uppercase_next = false;
} else {
chars.push(ch);
}
}
String::from_iter(chars)
}
}
}
}
#[cfg(test)]
mod tests {
use super::Case::*;
#[test]
fn camel_to_snake() {
let input = "camelToSnake";
let expected = "camel_to_snake";
assert_eq!(expected, SnakeCase.transform(input))
}
#[test]
fn pascal_to_snake() {
let input = "PascalToSnake";
let expected = "pascal_to_snake";
assert_eq!(expected, SnakeCase.transform(input))
}
#[test]
fn snake_to_camel() {
let input = "snake_to_camel";
let expected = "snakeToCamel";
assert_eq!(expected, CamelCase.transform(input))
}
#[test]
fn pascal_to_camel() {
let input = "PascalToCamel";
let expected = "pascalToCamel";
assert_eq!(expected, CamelCase.transform(input))
}
#[test]
fn snake_to_pascal() {
let input = "snake_to_pascal";
let expected = "SnakeToPascal";
assert_eq!(expected, PascalCase.transform(input))
}
#[test]
fn camel_to_pascal() {
let input = "camelToPascal";
let expected = "CamelToPascal";
assert_eq!(expected, PascalCase.transform(input))
}
}