arrayref 0.3.1

Macros to take array references of slices
Documentation 
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
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241

//! This package contains just two macros, for the taking of array
//! references to slices of anything that can be sliced.
//!
//! # Examples
//!
//! Here is a simple example of slicing and dicing a slice into array
//! references with these macros.
//!
//! I would give a real example here, but I can't figure out how to
//! make my doctest actually load the macros...
//!
//! let mut foobar = [0; 512];
//! let bar = array_ref!(foobar, 0, u16, 8); // first 8 elements
//!

#![deny(warnings)]

#[cfg(test)]
extern crate quickcheck;

/// You can use `array_ref` to generate an array reference to a subset
/// of a sliceable bit of data (which could be an array, or a slice,
/// or a Vec).
///
/// **Panics** if the slice is out of bounds.
#[macro_export]
macro_rules! array_ref {
    ($arr:expr, $offset:expr, $len:expr) => {{
        {
            #[inline]
            unsafe fn as_array<T>(slice: &[T]) -> &[T; $len] {
                &*(slice.as_ptr() as *const [_; $len])
            }
            let offset = $offset;
            let slice = & $arr[offset..offset + $len];
            unsafe {
                as_array(slice)
            }
        }
    }}
}

/// You can use `array_refs` to generate a series of array references
/// to an input array reference.  The idea is if you want to break an
/// array into a series of contiguous and non-overlapping arrays.
#[macro_export]
macro_rules! array_refs {
    ( $arr:expr, $( $len:expr ),* ) => {{
        {
            #[inline]
            #[allow(unused_assignments)]
            unsafe fn as_arrays<T>(a: &[T; $( $len + )* 0 ]) -> ( $( &[T; $len], )* ) {
                let mut p = a.as_ptr();
                ( $( {
                    let aref = &*(p as *const [T; $len]);
                    p = p.offset($len);
                    aref
                } ),* )
            }
            let input = $arr;
            unsafe {
                as_arrays(input)
            }
        }
    }}
}


/// You can use `mut_array_refs` to generate a series of mutable array
/// references to an input mutable array reference.  The idea is if
/// you want to break an array into a series of contiguous and
/// non-overlapping arrays.
#[macro_export]
macro_rules! mut_array_refs {
    ( $arr:expr, $( $len:expr ),* ) => {{
        {
            #[inline]
            #[allow(unused_assignments)]
            unsafe fn as_arrays<T>(a: &mut [T; $( $len + )* 0 ]) -> ( $( &mut [T; $len], )* ) {
                let mut p = a.as_mut_ptr();
                ( $( {
                    let aref = &mut *(p as *mut [T; $len]);
                    p = p.offset($len);
                    aref
                } ),* )
            }
            let input = $arr;
            unsafe {
                as_arrays(input)
            }
        }
    }}
}

/// You can use `array_mut_ref` to generate a mutable array reference
/// to a subset of a sliceable bit of data (which could be an array,
/// or a slice, or a Vec).
///
/// **Panics** if the slice is out of bounds.
#[macro_export]
macro_rules! array_mut_ref {
    ($arr:expr, $offset:expr, $len:expr) => {{
        {
            #[inline]
            unsafe fn as_array<T>(slice: &mut [T]) -> &mut [T; $len] {
                &mut *(slice.as_mut_ptr() as *mut [_; $len])
            }
            let offset = $offset;
            let slice = &mut $arr[offset..offset + $len];
            unsafe {
                as_array(slice)
            }
        }
    }}
}

#[test]
#[should_panic]
fn checks_bounds() {
    let foo: [u8; 11] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
    let bar = array_ref!(foo, 1, 11);
    bar[0];
}

#[test]
fn simple_case_works() {
    fn check(expected: [u8; 3], actual: &[u8; 3]) {
        for (e, a) in (&expected).iter().zip(actual.iter()) {
            assert_eq!(e, a)
        }
    }
    let mut foo: [u8; 11] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
    {
        let bar = array_ref!(foo, 2, 3);
        check([2, 3, 4], bar);
    }
    check([0, 1, 2], array_ref!(foo, 0, 3));
    fn zero2(x: &mut [u8; 2]) {
        x[0] = 0;
        x[1] = 0;
    }
    zero2(array_mut_ref!(foo, 8, 2));
    check([0, 0, 10], array_ref!(foo, 8, 3));
}


#[test]
fn check_array_ref_5() {
    fn f(data: Vec<u8>, offset: usize) -> quickcheck::TestResult {
        if data.len() < offset + 5 {
            return quickcheck::TestResult::discard();
        }
        let out = array_ref!(data, offset, 5);
        quickcheck::TestResult::from_bool(out.len() == 5)
    }
    quickcheck::quickcheck(f as fn(Vec<u8>, usize) -> quickcheck::TestResult);
}

#[test]
fn check_array_ref_out_of_bounds_5() {
    fn f(data: Vec<u8>, offset: usize) -> quickcheck::TestResult {
        if data.len() >= offset + 5 {
            return quickcheck::TestResult::discard();
        }
        quickcheck::TestResult::must_fail(move || {
            array_ref!(data, offset, 5);
        })
    }
    quickcheck::quickcheck(f as fn(Vec<u8>, usize) -> quickcheck::TestResult);
}

#[test]
fn check_array_mut_ref_7() {
    fn f(mut data: Vec<u8>, offset: usize) -> quickcheck::TestResult {
        if data.len() < offset + 7 {
            return quickcheck::TestResult::discard();
        }
        let out = array_mut_ref!(data, offset, 7);
        out[6] = 3;
        quickcheck::TestResult::from_bool(out.len() == 7)
    }
    quickcheck::quickcheck(f as fn(Vec<u8>, usize) -> quickcheck::TestResult);
}


#[test]
fn check_array_mut_ref_out_of_bounds_32() {
    fn f(mut data: Vec<u8>, offset: usize) -> quickcheck::TestResult {
        if data.len() >= offset + 32 {
            return quickcheck::TestResult::discard();
        }
        quickcheck::TestResult::must_fail(move || {
            array_mut_ref!(data, offset, 32);
        })
    }
    quickcheck::quickcheck(f as fn(Vec<u8>, usize) -> quickcheck::TestResult);
}


#[test]
fn test_5_array_refs() {
    let mut data: [usize; 128] = [0; 128];
    for i in 0..128 {
        data[i] = i;
    }
    let data = data;
    let (a,b,c,d,e) = array_refs!(&data, 1, 14, 3, 100, 10);
    assert_eq!(a.len(), 1 as usize);
    assert_eq!(b.len(), 14 as usize);
    assert_eq!(c.len(), 3 as usize);
    assert_eq!(d.len(), 100 as usize);
    assert_eq!(e.len(), 10 as usize);
    assert_eq!(a, array_ref![data, 0, 1]);
    assert_eq!(b, array_ref![data, 1, 14]);
    assert_eq!(c, array_ref![data, 15, 3]);
    assert_eq!(e, array_ref![data, 118, 10]);
}


#[test]
fn test_5_mut_xarray_refs() {
    let mut data: [usize; 128] = [0; 128];
    {
        // temporarily borrow the data to modify it.
        let (a,b,c,d,e) = mut_array_refs!(&mut data, 1, 14, 3, 100, 10);
        assert_eq!(a.len(), 1 as usize);
        assert_eq!(b.len(), 14 as usize);
        assert_eq!(c.len(), 3 as usize);
        assert_eq!(d.len(), 100 as usize);
        assert_eq!(e.len(), 10 as usize);
        *a = [1; 1];
        *b = [14; 14];
        *c = [3; 3];
        *d = [100; 100];
        *e = [10; 10];
    }
    assert_eq!(&[1;1], array_ref![data, 0, 1]);
    assert_eq!(&[14;14], array_ref![data, 1, 14]);
    assert_eq!(&[3;3], array_ref![data, 15, 3]);
    assert_eq!(&[10;10], array_ref![data, 118, 10]);
}