1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153

use std::borrow::{Borrow, BorrowMut};
use std::ffi::{CStr, FromBytesWithNulError};
use std::fmt;
use std::mem;
use std::ops::{Index, RangeFull};
use std::str::{Utf8Error, from_utf8, from_utf8_unchecked};

use bow::ToBox;
use extra_default::DefaultRef;
use len_trait::{CapacityMut, Len, LenMut, SplitAt, SplitAtMut};
use push_trait::PushBack;
use void::Void;

/// Required for `StrLike::Data`.
pub trait StrData
    : ToBox + Len + SplitAt<usize> + Index<RangeFull, Output = Self> + DefaultRef
    {
}
impl<
    T: ?Sized + ToBox + Len + SplitAt<usize> + Index<RangeFull, Output = Self> + DefaultRef,
> StrData for T {
}


/// Required for `StrLike::OwnedData`.
pub trait OwnsStrData<D: ?Sized>
    : LenMut + CapacityMut + for<'a> PushBack<&'a D> + Into<Box<D>> {
}
impl<
    D: ?Sized,
    T: ?Sized + LenMut + CapacityMut + for<'a> PushBack<&'a D> + Into<Box<D>>,
> OwnsStrData<D> for T {
}


/// String-like container.
pub trait StrLike: Len + ToOwned + DefaultRef + 'static {
    /// Data backing this string.
    type Data: ?Sized + StrData + ToOwned<Owned = Self::OwnedData> + 'static;

    /// Owned data.
    type OwnedData: OwnsStrData<Self::Data> + Borrow<Self::Data>;

    /// Error that comes up when converting data back into a string.
    type ConvError: fmt::Display;

    /// Converts this string into its data backend.
    fn to_data(&self) -> &Self::Data;

    /// Coerces a string from its backend data, performing validation if necessary.
    fn from_data(data: &Self::Data) -> Result<&Self, Self::ConvError>;

    /// Similar to `from_data`, ignoring validity checking.
    unsafe fn from_data_unchecked(data: &Self::Data) -> &Self;
}

/// Extension to `StrLike`: types where concatenating data is equivalent to concatenating strings.
pub unsafe trait DataConcat: StrLike {}

/// Extension to `StrLike`: has mutable version.
pub trait StrLikeMut: StrLike
where
    Self::Data: SplitAtMut<usize>,
    Self::OwnedData: BorrowMut<Self::Data>,
{
    /// Mutable version of `to_data`.
    unsafe fn to_data_mut(&mut self) -> &mut Self::Data;

    /// Mutable version of `from_data`.
    fn from_data_mut(data: &mut Self::Data) -> Result<&mut Self, Self::ConvError>;

    /// Mutable version of `from_data_unchecked`.
    unsafe fn from_data_mut_unchecked(data: &mut Self::Data) -> &mut Self;
}

impl<T: 'static + Copy> StrLike for [T] {
    type Data = [T];
    type OwnedData = Vec<T>;

    type ConvError = Void;

    fn to_data(&self) -> &[T] {
        self
    }
    fn from_data(data: &[T]) -> Result<&[T], Void> {
        Ok(data)
    }
    unsafe fn from_data_unchecked(data: &[T]) -> &[T] {
        data
    }
}

impl StrLike for str {
    type Data = [u8];
    type OwnedData = Vec<u8>;

    type ConvError = Utf8Error;

    fn to_data(&self) -> &[u8] {
        self.as_bytes()
    }
    fn from_data(data: &[u8]) -> Result<&str, Utf8Error> {
        from_utf8(data)
    }
    unsafe fn from_data_unchecked(data: &[u8]) -> &str {
        from_utf8_unchecked(data)
    }
}

impl StrLike for CStr {
    type Data = [u8];
    type OwnedData = Vec<u8>;

    type ConvError = FromBytesWithNulError;

    fn to_data(&self) -> &[u8] {
        self.to_bytes_with_nul()
    }
    fn from_data(data: &[u8]) -> Result<&CStr, FromBytesWithNulError> {
        CStr::from_bytes_with_nul(data)
    }
    unsafe fn from_data_unchecked(data: &[u8]) -> &CStr {
        CStr::from_bytes_with_nul_unchecked(data)
    }
}

unsafe impl DataConcat for str {}
unsafe impl<T: 'static + Copy> DataConcat for [T] {}

impl<T: 'static + Copy> StrLikeMut for [T] {
    unsafe fn to_data_mut(&mut self) -> &mut [T] {
        self
    }
    fn from_data_mut(data: &mut [T]) -> Result<&mut [T], Void> {
        Ok(data)
    }
    unsafe fn from_data_mut_unchecked(data: &mut [T]) -> &mut [T] {
        data
    }
}

impl StrLikeMut for str {
    unsafe fn to_data_mut(&mut self) -> &mut [u8] {
        mem::transmute(self)
    }
    fn from_data_mut(data: &mut [u8]) -> Result<&mut str, Utf8Error> {
        from_utf8(data)?;
        Ok(unsafe { mem::transmute(data) })
    }
    unsafe fn from_data_mut_unchecked(data: &mut [u8]) -> &mut str {
        mem::transmute(data)
    }
}