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extern crate ascii;
#[macro_use]
extern crate error_chain;
use std::ascii::AsciiExt;
use ascii::{AsAsciiStr, AsciiStr, AsciiChar};
pub(crate) use result::*;
pub use result::Error;
static PRIMES: [u64; 26] = [
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71,
73, 79, 83, 89, 97, 101,
];
fn anagram_to_prime_product(input: &AsciiStr) -> u64 {
input
.chars()
.map(AsciiChar::to_ascii_lowercase)
.map(|c| (c as u8) - b'a')
.map(|idx| PRIMES[idx as usize])
.product()
}
pub trait IsAnagram {
fn is_anagram_of(&self, rhs: &str) -> Result<bool>;
}
impl<'a> IsAnagram for &'a str {
fn is_anagram_of(&self, rhs: &str) -> Result<bool> {
ensure!(self.len() == rhs.len(), ErrorKind::DifferentLength);
ensure!(!self.is_empty(), ErrorKind::NotOneWord);
ensure!(!rhs.is_empty(), ErrorKind::NotOneWord);
ensure!(!self.contains(' '), ErrorKind::NotOneWord);
ensure!(!rhs.contains(' '), ErrorKind::NotOneWord);
let lhs_product = anagram_to_prime_product(self.as_ascii_str()?);
let rhs_product = anagram_to_prime_product(rhs.as_ascii_str()?);
Ok(lhs_product == rhs_product)
}
}
mod result {
error_chain! {
foreign_links {
Ascii(::ascii::AsAsciiStrError);
}
errors {
DifferentLength {
description("Words have different lengths")
}
NotOneWord {
description("Input is not a single word")
}
}
}
}
#[cfg(test)]
mod tests {
use super::IsAnagram;
#[test]
fn postive() {
assert!("banana".is_anagram_of("nabana").unwrap());
}
#[test]
fn negative() {
assert!(!"banana".is_anagram_of("pineap").unwrap());
assert!(!"lorem".is_anagram_of("ipsum").unwrap());
}
macro_rules! assert_err {
($got:expr, $expected:pat) => {{
assert!($got.is_err(), "Expected error, got {:?}", $got);
let err = $got.unwrap_err();
let kind = err.kind();
if let $expected = *kind {
println!("Found `{}` as expected", stringify!($expected));
} else {
panic!("Got `{:?}`, but expected type `{}`", kind, stringify!($expected));
}
}}
}
#[test]
fn errors() {
use ::result::ErrorKind;
assert_err!("a".is_anagram_of(""), ErrorKind::DifferentLength);
assert_err!("".is_anagram_of("a"), ErrorKind::DifferentLength);
assert_err!(
"banana".is_anagram_of("pineapple"),
ErrorKind::DifferentLength
);
assert_err!("foo bar".is_anagram_of("bar foo"), ErrorKind::NotOneWord);
}
}