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

use crate::{
    num_conv::universal_decode_number, transmute::vec_into_boxed_slice, DecodeError,
    DecodeErrorHandler, NestedDecodeInput, OwnedBytesNestedDecodeInput, TryStaticCast,
};
use alloc::{boxed::Box, vec::Vec};

/// Trait that abstracts away an underlying API for a top-level object deserializer.
/// The underlying API can provide pre-parsed i64/u64 or pre-bundled boxed slices.
pub trait TopDecodeInput: Sized {
    type NestedBuffer: NestedDecodeInput;

    /// Length of the underlying data, in bytes.
    fn byte_len(&self) -> usize;

    /// Provides the underlying data as an owned byte slice box.
    /// Consumes the input object in the process.
    fn into_boxed_slice_u8(self) -> Box<[u8]>;

    /// Puts the underlying data into a fixed size byte buffer
    /// and returns the populated data slice from this buffer.
    ///
    /// Will return an error if the data exceeds the provided buffer.
    fn into_max_size_buffer<H, const MAX_LEN: usize>(
        self,
        buffer: &mut [u8; MAX_LEN],
        h: H,
    ) -> Result<&[u8], H::HandledErr>
    where
        H: DecodeErrorHandler;

    /// Retrieves the underlying data as a pre-parsed u64.
    /// Expected to panic if the conversion is not possible.
    ///
    /// Consumes the input object in the process.
    fn into_u64<H>(self, h: H) -> Result<u64, H::HandledErr>
    where
        H: DecodeErrorHandler,
    {
        let mut buffer = [0u8; 8];
        let slice = self.into_max_size_buffer(&mut buffer, h)?;
        Ok(universal_decode_number(slice, false))
    }

    /// Retrieves the underlying data as a pre-parsed i64.
    /// Expected to panic if the conversion is not possible.
    ///
    /// Consumes the input object in the process.
    fn into_i64<H>(self, h: H) -> Result<i64, H::HandledErr>
    where
        H: DecodeErrorHandler,
    {
        let mut buffer = [0u8; 8];
        let slice = self.into_max_size_buffer(&mut buffer, h)?;
        Ok(universal_decode_number(slice, true) as i64)
    }

    #[inline]
    fn supports_specialized_type<T: TryStaticCast>() -> bool {
        false
    }

    fn into_specialized<T, H>(self, h: H) -> Result<T, H::HandledErr>
    where
        T: TryStaticCast,
        H: DecodeErrorHandler,
    {
        Err(h.handle_error(DecodeError::UNSUPPORTED_OPERATION))
    }

    fn into_nested_buffer(self) -> Self::NestedBuffer;
}

impl TopDecodeInput for Box<[u8]> {
    type NestedBuffer = OwnedBytesNestedDecodeInput;

    fn byte_len(&self) -> usize {
        self.len()
    }

    fn into_boxed_slice_u8(self) -> Box<[u8]> {
        self
    }

    fn into_max_size_buffer<H, const MAX_LEN: usize>(
        self,
        buffer: &mut [u8; MAX_LEN],
        h: H,
    ) -> Result<&[u8], H::HandledErr>
    where
        H: DecodeErrorHandler,
    {
        (&*self).into_max_size_buffer(buffer, h)
    }

    fn into_nested_buffer(self) -> Self::NestedBuffer {
        OwnedBytesNestedDecodeInput::new(self)
    }
}

impl TopDecodeInput for Vec<u8> {
    type NestedBuffer = OwnedBytesNestedDecodeInput;

    fn byte_len(&self) -> usize {
        self.len()
    }

    fn into_boxed_slice_u8(self) -> Box<[u8]> {
        vec_into_boxed_slice(self)
    }

    fn into_max_size_buffer<H, const MAX_LEN: usize>(
        self,
        buffer: &mut [u8; MAX_LEN],
        h: H,
    ) -> Result<&[u8], H::HandledErr>
    where
        H: DecodeErrorHandler,
    {
        self.as_slice().into_max_size_buffer(buffer, h)
    }

    fn into_nested_buffer(self) -> Self::NestedBuffer {
        OwnedBytesNestedDecodeInput::new(self.into_boxed_slice())
    }
}

impl<'a> TopDecodeInput for &'a [u8] {
    type NestedBuffer = &'a [u8];

    fn byte_len(&self) -> usize {
        self.len()
    }

    fn into_boxed_slice_u8(self) -> Box<[u8]> {
        Box::from(self)
    }

    fn into_max_size_buffer<H, const MAX_LEN: usize>(
        self,
        buffer: &mut [u8; MAX_LEN],
        h: H,
    ) -> Result<&[u8], H::HandledErr>
    where
        H: DecodeErrorHandler,
    {
        let l = self.len();
        if l > MAX_LEN {
            return Err(h.handle_error(DecodeError::INPUT_TOO_LONG));
        }
        buffer[..l].copy_from_slice(self);
        Ok(&buffer[..l])
    }

    #[inline]
    fn into_u64<H>(self, _h: H) -> Result<u64, H::HandledErr>
    where
        H: DecodeErrorHandler,
    {
        Ok(universal_decode_number(self, false))
    }

    #[inline]
    fn into_i64<H>(self, _h: H) -> Result<i64, H::HandledErr>
    where
        H: DecodeErrorHandler,
    {
        Ok(universal_decode_number(self, true) as i64)
    }

    fn into_nested_buffer(self) -> Self::NestedBuffer {
        self
    }
}