mail_headers/data/

inner_item.rs

use std::ops::Deref;
use std::sync::Arc;
use std::borrow::ToOwned;

use owning_ref::OwningRef;
use soft_ascii_string::{SoftAsciiString, SoftAsciiStr};

#[cfg(feature="serde")]
use serde::{Serialize, Deserialize, Serializer, Deserializer, de::Error as __Error};


/// InnerAscii is string data container which can contain either a
/// owned `SoftAsciiString` or a `SoftAsciiStr` reference into a shared
/// string buffer.
#[derive(Debug, Clone, Hash, Eq)]
pub enum InnerAscii {
    Owned(SoftAsciiString),
    //by using String+SoftAsciiStr we can eliminate unessesary copies
    Shared(OwningRef<Arc<String>, SoftAsciiStr>)
}

impl InnerAscii {

    /// converts this container into on which uses underlying shared data
    ///
    /// if the data is already shared nothing is done.
    /// If not the owned data is converted into the underlying string buffer
    /// and `OwningRef` is used to enable the shared reference
    ///
    /// Note that the underlying buffer is no an `SoftAsciiString` but a
    /// `String` (from which we happend to know that it fulfills the "is
    ///  us-ascii" soft constraint). This allows us to have an `InnerAscii`
    /// share data with a possible non us-ascii string buffer as long as
    /// the part accessable through the `SoftAsciiStr` is ascii. Or at last
    /// should be ascii as it's a soft constraint.
    pub fn into_shared(self) -> Self {
        match self {
            InnerAscii::Owned(value) => {
                let buffer: Arc<String> = Arc::new(value.into());
                let orf = OwningRef::new(buffer).map(|data: &String| {
                    // we got it from a SoftAsciiString so no check here
                    SoftAsciiStr::from_unchecked(&**data)
                });
                InnerAscii::Shared(orf)
            }
            v => v
        }
    }
}

/// InnerUtf8 is string data container which can contain either a
/// owned `String` or a `str` reference into a shared
/// string buffer.
#[derive(Debug, Clone, Hash, Eq)]
pub enum InnerUtf8 {
    Owned(String),
    //by using String+SoftAsciiStr we can eliminate unessesary copies
    Shared(OwningRef<Arc<String>, str>)
}

impl InnerUtf8 {

    /// converts this container into on which uses underlying shared data
    ///
    /// if the data is already shared nothing is done.
    /// If not the owned data is converted into the underlying string buffer
    /// and `OwningRef` is used to enable the shared reference
    pub fn into_shared(self) -> Self {
        match self {
            InnerUtf8::Owned(value) => {
                let buffer = Arc::new(value);
                let orf = OwningRef::new(buffer)
                    .map(|rced| &**rced);
                InnerUtf8::Shared(orf)
            }
            v => v
        }
    }
}


macro_rules! inner_impl {
    ($name:ident, $owned_form:ty, $borrowed_form:ty) => (
        impl $name {
            pub fn new<S: Into<$owned_form>>( data: S ) -> Self {
                $name::Owned( data.into() )
            }
        }
        impl From<$owned_form> for $name {
            fn from( data: $owned_form ) -> Self {
                Self::new( data )
            }
        }

        impl Into<$owned_form> for $name {
            fn into(self) -> $owned_form {
                match self {
                    $name::Owned( owned ) => owned,
                    $name::Shared( shared ) => {
                        let as_ref: &$borrowed_form = &*shared;
                        as_ref.to_owned()
                    }
                }
            }
        }

        impl Deref for $name {
            type Target = $borrowed_form;

            fn deref( &self ) -> &$borrowed_form{
                match *self {
                    $name::Owned( ref string ) => &*string,
                    $name::Shared( ref owning_ref ) => &*owning_ref
                }
            }
        }

        #[cfg(feature="serde")]
        impl Serialize for $name {
            fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
                where S: Serializer
            {
                let borrowed: &$borrowed_form = &*self;
                let as_ref: &str = borrowed.as_ref();
                serializer.serialize_str( as_ref )
            }
        }

        impl PartialEq for $name {
            fn eq(&self, other: &$name) -> bool {
                let me: &$borrowed_form = &*self;
                let other: &$borrowed_form = &*other;
                me == other
            }
        }

        impl AsRef<str> for $name {
            fn as_ref(&self) -> &str {
                self.as_str()
            }
        }
    );
}

inner_impl!{ InnerAscii, SoftAsciiString,  SoftAsciiStr }
inner_impl!{ InnerUtf8, String, str }
//inner_impl!{ InnerOtherItem, OtherString, OtherStr }

impl InnerAscii {
    pub fn as_str( &self ) -> &str {
        match *self {
            InnerAscii::Owned( ref owned ) => owned.as_str(),
            InnerAscii::Shared( ref shared ) => shared.as_str()
        }
    }
}

#[cfg(feature="serde")]
impl<'de> Deserialize<'de> for InnerAscii {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
        where D: Deserializer<'de>
    {
        let content = String::deserialize(deserializer)
            .map_err(|err| D::Error::custom(err))?;
        let content = SoftAsciiString::from_string(content)
            .map_err(|err| D::Error::custom(err))?;
        Ok(InnerAscii::from(content))
    }
}

impl InnerUtf8 {
    pub fn as_str( &self ) -> &str {
        match *self {
            InnerUtf8::Owned( ref owned ) => owned.as_str(),
            InnerUtf8::Shared( ref shared ) => &**shared
        }
    }
}

#[cfg(feature="serde")]
impl<'de> Deserialize<'de> for InnerUtf8 {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
        where D: Deserializer<'de>
    {
        let content = String::deserialize(deserializer)
            .map_err(|err| D::Error::custom(err))?;
        Ok(InnerUtf8::from(content))
    }
}


#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn inner_ascii_item_eq() {
        let a = InnerAscii::Owned( SoftAsciiString::from_string( "same" ).unwrap() );
        let b = InnerAscii::Shared(
            OwningRef::new(Arc::new("same".to_owned()))
                .map(|v| SoftAsciiStr::from_unchecked(&**v))
        );
        assert_eq!( a, b );
    }

    #[test]
    fn inner_ascii_item_neq() {
        let a = InnerAscii::Owned( SoftAsciiString::from_string( "same" ).unwrap() );
        let b = InnerAscii::Shared(
            OwningRef::new(Arc::new("not same".to_owned()))
                .map(|v| SoftAsciiStr::from_unchecked(&**v))
        );
        assert_ne!( a, b );
    }

    #[test]
    fn inner_utf8_item_eq() {
        let a = InnerUtf8::Owned( String::from( "same" ) );
        let b = InnerUtf8::Shared(
            OwningRef::new(
                Arc::new( String::from( "same" ) ) )
                .map(|v| &**v)
        );
        assert_eq!( a, b );
    }

    #[test]
    fn inner_utf8_item_neq() {
        let a = InnerUtf8::Owned( String::from( "same" ) );
        let b = InnerUtf8::Shared(
            OwningRef::new(
                Arc::new( String::from( "not same" ) ) )
                .map(|v| &**v)
        );
        assert_ne!( a, b );
    }

    #[test]
    fn has_as_str() {
        use std::borrow::ToOwned;

        assert_eq!(
            "hy",
            InnerAscii::Owned( SoftAsciiStr::from_unchecked("hy").to_owned() ).as_str()
        );
        assert_eq!(
            "hy",
            InnerUtf8::Owned( "hy".into() ).as_str()
        );
    }
}