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
//! ASN.1 `SEQUENCE OF` support.

use crate::{
    arrayvec, ord::iter_cmp, ArrayVec, Decode, DecodeValue, DerOrd, Encode, EncodeValue, FixedTag,
    Header, Length, Reader, Result, Tag, ValueOrd, Writer,
};
use core::cmp::Ordering;

#[cfg(feature = "alloc")]
use alloc::vec::Vec;

/// ASN.1 `SEQUENCE OF` backed by an array.
///
/// This type implements an append-only `SEQUENCE OF` type which is stack-based
/// and does not depend on `alloc` support.
// TODO(tarcieri): use `ArrayVec` when/if it's merged into `core`
// See: https://github.com/rust-lang/rfcs/pull/2990
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct SequenceOf<T, const N: usize> {
    inner: ArrayVec<T, N>,
}

impl<T, const N: usize> SequenceOf<T, N> {
    /// Create a new [`SequenceOf`].
    pub fn new() -> Self {
        Self {
            inner: ArrayVec::new(),
        }
    }

    /// Add an element to this [`SequenceOf`].
    pub fn add(&mut self, element: T) -> Result<()> {
        self.inner.push(element)
    }

    /// Get an element of this [`SequenceOf`].
    pub fn get(&self, index: usize) -> Option<&T> {
        self.inner.get(index)
    }

    /// Iterate over the elements in this [`SequenceOf`].
    pub fn iter(&self) -> SequenceOfIter<'_, T> {
        SequenceOfIter {
            inner: self.inner.iter(),
        }
    }

    /// Is this [`SequenceOf`] empty?
    pub fn is_empty(&self) -> bool {
        self.inner.is_empty()
    }

    /// Number of elements in this [`SequenceOf`].
    pub fn len(&self) -> usize {
        self.inner.len()
    }
}

impl<T, const N: usize> Default for SequenceOf<T, N> {
    fn default() -> Self {
        Self::new()
    }
}

impl<'a, T, const N: usize> DecodeValue<'a> for SequenceOf<T, N>
where
    T: Decode<'a>,
{
    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
        reader.read_nested(header.length, |reader| {
            let mut sequence_of = Self::new();

            while !reader.is_finished() {
                sequence_of.add(T::decode(reader)?)?;
            }

            Ok(sequence_of)
        })
    }
}

impl<T, const N: usize> EncodeValue for SequenceOf<T, N>
where
    T: Encode,
{
    fn value_len(&self) -> Result<Length> {
        self.iter()
            .fold(Ok(Length::ZERO), |len, elem| len + elem.encoded_len()?)
    }

    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
        for elem in self.iter() {
            elem.encode(writer)?;
        }

        Ok(())
    }
}

impl<T, const N: usize> FixedTag for SequenceOf<T, N> {
    const TAG: Tag = Tag::Sequence;
}

impl<T, const N: usize> ValueOrd for SequenceOf<T, N>
where
    T: DerOrd,
{
    fn value_cmp(&self, other: &Self) -> Result<Ordering> {
        iter_cmp(self.iter(), other.iter())
    }
}

/// Iterator over the elements of an [`SequenceOf`].
#[derive(Clone, Debug)]
pub struct SequenceOfIter<'a, T> {
    /// Inner iterator.
    inner: arrayvec::Iter<'a, T>,
}

impl<'a, T> Iterator for SequenceOfIter<'a, T> {
    type Item = &'a T;

    fn next(&mut self) -> Option<&'a T> {
        self.inner.next()
    }
}

impl<'a, T> ExactSizeIterator for SequenceOfIter<'a, T> {}

impl<'a, T, const N: usize> DecodeValue<'a> for [T; N]
where
    T: Decode<'a>,
{
    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
        let sequence_of = SequenceOf::<T, N>::decode_value(reader, header)?;

        // TODO(tarcieri): use `[T; N]::try_map` instead of `expect` when stable
        if sequence_of.inner.len() == N {
            Ok(sequence_of
                .inner
                .into_array()
                .map(|elem| elem.expect("arrayvec length mismatch")))
        } else {
            Err(Self::TAG.length_error())
        }
    }
}

impl<T, const N: usize> EncodeValue for [T; N]
where
    T: Encode,
{
    fn value_len(&self) -> Result<Length> {
        self.iter()
            .fold(Ok(Length::ZERO), |len, elem| len + elem.encoded_len()?)
    }

    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
        for elem in self {
            elem.encode(writer)?;
        }

        Ok(())
    }
}

impl<T, const N: usize> FixedTag for [T; N] {
    const TAG: Tag = Tag::Sequence;
}

impl<T, const N: usize> ValueOrd for [T; N]
where
    T: DerOrd,
{
    fn value_cmp(&self, other: &Self) -> Result<Ordering> {
        iter_cmp(self.iter(), other.iter())
    }
}

#[cfg(feature = "alloc")]
impl<'a, T> DecodeValue<'a> for Vec<T>
where
    T: Decode<'a>,
{
    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
        reader.read_nested(header.length, |reader| {
            let mut sequence_of = Self::new();

            while !reader.is_finished() {
                sequence_of.push(T::decode(reader)?);
            }

            Ok(sequence_of)
        })
    }
}

#[cfg(feature = "alloc")]
impl<T> EncodeValue for Vec<T>
where
    T: Encode,
{
    fn value_len(&self) -> Result<Length> {
        self.iter()
            .fold(Ok(Length::ZERO), |len, elem| len + elem.encoded_len()?)
    }

    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
        for elem in self {
            elem.encode(writer)?;
        }

        Ok(())
    }
}

#[cfg(feature = "alloc")]
impl<T> FixedTag for Vec<T> {
    const TAG: Tag = Tag::Sequence;
}

#[cfg(feature = "alloc")]
impl<T> ValueOrd for Vec<T>
where
    T: DerOrd,
{
    fn value_cmp(&self, other: &Self) -> Result<Ordering> {
        iter_cmp(self.iter(), other.iter())
    }
}