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extern crate pad; use self::pad::{PadStr, Alignment}; use spec::PaddingDirection; use std::fmt::{Display, Formatter, Error as FmtError}; #[derive(Debug)] pub struct Error { repr: Box<::std::error::Error + Send + Sync> } impl Clone for Error { fn clone(&self) -> Self { Error::new("") } } impl Error { pub fn new<E>(error: E) -> Self where E: Into<Box<::std::error::Error + Send + Sync>> { Error { repr: error.into() } } pub fn downcast<E: ::std::error::Error + Send + Sync + 'static>(self) -> ::std::result::Result<E, Self> { Ok(*(self.repr.downcast::<E>().map_err(|e| Error { repr: e })?)) } pub fn downcast_ref<E: ::std::error::Error + Send + Sync + 'static>(&self) -> Option<&E> { self.repr.downcast_ref::<E>() } } impl ::std::error::Error for Error { fn description(&self) -> &str { self.repr.description() } fn cause(&self) -> Option<&::std::error::Error> { self.repr.cause() } } impl Display for Error { fn fmt(&self, f: &mut Formatter) -> ::std::result::Result<(), FmtError> { Display::fmt(&*self.repr, f) } } type Result<T> = ::std::result::Result<T, Error>; pub trait Padder { fn pad(&self, data: String, length: usize, padding: &String, direction: PaddingDirection) -> Result<String>; } impl<'a, T> Padder for &'a T where T: 'a + Padder { fn pad(&self, data: String, length: usize, padding: &String, direction: PaddingDirection) -> Result<String> { (**self).pad(data, length, padding, direction) } } pub trait UnPadder { fn unpad(&self, data: String, padding: &String, direction: PaddingDirection) -> Result<String>; } impl<'a, T> UnPadder for &'a T where T: 'a + UnPadder { fn unpad(&self, data: String, padding: &String, direction: PaddingDirection) -> Result<String> { (**self).unpad(data, padding, direction) } } pub struct DefaultPadder; #[derive(Debug)] pub enum PaddingError { PaddingLongerThanOne(usize) } impl ::std::error::Error for PaddingError { fn description(&self) -> &str { match *self { PaddingError::PaddingLongerThanOne(_) => "The padding string must be only one char long to use this padder" } } } impl Display for PaddingError { fn fmt(&self, f: &mut Formatter) -> ::std::result::Result<(), FmtError> { match *self { PaddingError::PaddingLongerThanOne(len) => write!( f, "the padding string was {} chars long it can only be at most 1 char long", len ) } } } impl From<PaddingError> for Error { fn from(e: PaddingError) -> Self { Error::new(e) } } impl DefaultPadder { fn get_char(padding: &String) -> ::std::result::Result<char, PaddingError> { if padding.len() > 1 { Err(PaddingError::PaddingLongerThanOne(padding.len())) } else { Ok(padding.chars().next().or(Some(' ')).expect("should have a some no matter what")) } } } impl Padder for DefaultPadder { fn pad(&self, data: String, length: usize, padding: &String, direction: PaddingDirection) -> Result<String> { Ok(data.pad( length, Self::get_char(padding)?, match direction { PaddingDirection::Left => Alignment::Right, PaddingDirection::Right => Alignment::Left, }, false )) } } impl UnPadder for DefaultPadder { fn unpad(&self, data: String, padding: &String, direction: PaddingDirection) -> Result<String> { Ok(match direction { PaddingDirection::Left => data.trim_left_matches(Self::get_char(padding)?).to_string(), PaddingDirection::Right => data.trim_right_matches(Self::get_char(padding)?).to_string(), }) } } pub struct IdentityPadder; impl Padder for IdentityPadder { fn pad(&self, data: String, _: usize, _: &String, _: PaddingDirection) -> Result<String> { Ok(data) } } impl UnPadder for IdentityPadder { fn unpad(&self, data: String, _: &String, _: PaddingDirection) -> Result<String> { Ok(data) } } #[cfg(test)] mod test { use super::*; use spec::*; #[test] fn default_padder() { let padder = DefaultPadder; let data = "qwer".to_string(); assert_result!(Ok("qwer333333".to_string()), padder.pad(data.clone(), 10, &"3".to_string(), PaddingDirection::Right)); let data = "qwer".to_string(); assert_result!(Ok("333333qwer".to_string()), padder.pad(data.clone(), 10, &"3".to_string(), PaddingDirection::Left)); assert_result!( Err(PaddingError::PaddingLongerThanOne(2)), padder.pad(data.clone(), 10, &"33".to_string(), PaddingDirection::Left).map_err(|e| e.downcast::<PaddingError>().unwrap()) ); let data = "qwer333333".to_string(); assert_result!(Ok("qwer".to_string()), padder.unpad(data.clone(), &"3".to_string(), PaddingDirection::Right)); let data = "333333qwer".to_string(); assert_result!(Ok("qwer".to_string()), padder.unpad(data.clone(), &"3".to_string(), PaddingDirection::Left)); assert_result!( Err(PaddingError::PaddingLongerThanOne(2)), padder.unpad(data.clone(), &"33".to_string(), PaddingDirection::Left).map_err(|e| e.downcast::<PaddingError>().unwrap()) ); } #[test] fn identity_padder() { let padder = IdentityPadder; let data = "qwer".to_string(); assert_result!(Ok(data.clone()), padder.pad(data.clone(), 10, &"3".to_string(), PaddingDirection::Right)); assert_result!(Ok(data.clone()), padder.pad(data.clone(), 10, &"3".to_string(), PaddingDirection::Left)); assert_result!(Ok(data.clone()), padder.unpad(data.clone(), &"3".to_string(), PaddingDirection::Right)); assert_result!(Ok(data.clone()), padder.unpad(data.clone(), &"3".to_string(), PaddingDirection::Left)); } #[test] fn padder_reference() { let padder = IdentityPadder; let data = "qwer".to_string(); assert_result!(Ok(data.clone()), Padder::pad(&&padder, data.clone(), 10, &"3".to_string(), PaddingDirection::Right)); assert_result!(Ok(data.clone()), UnPadder::unpad(&&padder, data.clone(), &"3".to_string(), PaddingDirection::Right)); } #[test] fn error() { let error = Error::new(PaddingError::PaddingLongerThanOne(23)); assert_option!(Some(&PaddingError::PaddingLongerThanOne(23)), error.downcast_ref::<PaddingError>()); assert_option!(Some(&PaddingError::PaddingLongerThanOne(23)), error.downcast_ref::<PaddingError>()); match error.downcast::<PaddingError>() { Ok(PaddingError::PaddingLongerThanOne(23)) => (), e => panic!("bad result returned {:?}", e) } } }