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

// Copyright (C) 2019-2023 Aleo Systems Inc.
// This file is part of the snarkVM library.

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at:
// http://www.apache.org/licenses/LICENSE-2.0

// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use super::*;

impl<A: Aleo> FromBits for Plaintext<A> {
    type Boolean = Boolean<A>;

    /// Initializes a new plaintext from a list of little-endian bits *without* trailing zeros.
    fn from_bits_le(bits_le: &[Boolean<A>]) -> Self {
        let bits = bits_le;

        // The starting index used to create subsequent subslices of the `bits` slice.
        let mut index = 0;

        // Helper function to get the next n bits as a slice.
        let mut next_bits = |n: usize| -> &[Boolean<A>] {
            // Safely procure a subslice with the length `n` starting at `index`.
            let subslice = bits.get(index..index + n);
            // Check if the range is within bounds.
            if let Some(next_bits) = subslice {
                // Move the starting index.
                index += n;
                // Return the subslice.
                next_bits
            } else {
                A::halt("Insufficient bits.")
            }
        };

        let mut variant = next_bits(2).iter().map(|b| b.eject_value());
        let variant1 = variant.next().unwrap();
        let variant2 = variant.next().unwrap();
        let variant = [variant1, variant2];

        // Literal
        if variant == [false, false] {
            let literal_variant = U8::from_bits_le(next_bits(8));
            let literal_size = U16::from_bits_le(next_bits(16)).eject_value();
            let literal = Literal::from_bits_le(&literal_variant, next_bits(*literal_size as usize));

            // Cache the plaintext bits, and return the literal.
            Self::Literal(literal, OnceCell::with_value(bits_le.to_vec()))
        }
        // Struct
        else if variant == [false, true] {
            let num_members = U8::from_bits_le(next_bits(8)).eject_value();

            let mut members = IndexMap::with_capacity(*num_members as usize);
            for _ in 0..*num_members {
                let identifier_size = U8::from_bits_le(next_bits(8)).eject_value();
                let identifier = Identifier::from_bits_le(next_bits(*identifier_size as usize));

                let member_size = U16::from_bits_le(next_bits(16)).eject_value();
                let value = Plaintext::from_bits_le(next_bits(*member_size as usize));

                members.insert(identifier, value);
            }

            // Cache the plaintext bits, and return the struct.
            Self::Struct(members, OnceCell::with_value(bits_le.to_vec()))
        }
        // Unknown variant.
        else {
            A::halt("Unknown plaintext variant.")
        }
    }

    /// Initializes a new plaintext from a list of big-endian bits *without* trailing zeros.
    fn from_bits_be(bits_be: &[Boolean<A>]) -> Self {
        let bits = bits_be;

        // The starting index used to create subsequent subslices of the `bits` slice.
        let mut index = 0;

        // Helper function to get the next n bits as a slice.
        let mut next_bits = |n: usize| -> &[Boolean<A>] {
            // Safely procure a subslice with the length `n` starting at `index`.
            let subslice = bits.get(index..index + n);
            // Check if the range is within bounds.
            if let Some(next_bits) = subslice {
                // Move the starting index.
                index += n;
                // Return the subslice.
                next_bits
            } else {
                A::halt("Insufficient bits.")
            }
        };

        let mut variant = next_bits(2).iter().map(|b| b.eject_value());
        let variant1 = variant.next().unwrap();
        let variant2 = variant.next().unwrap();
        let variant = [variant1, variant2];

        // Literal
        if variant == [false, false] {
            let literal_variant = U8::from_bits_be(next_bits(8));
            let literal_size = U16::from_bits_be(next_bits(16)).eject_value();
            let literal = Literal::from_bits_be(&literal_variant, next_bits(*literal_size as usize));

            // Cache the plaintext bits, and return the literal.
            Self::Literal(literal, OnceCell::with_value(bits_be.to_vec()))
        }
        // Struct
        else if variant == [false, true] {
            let num_members = U8::from_bits_be(next_bits(8)).eject_value();

            let mut members = IndexMap::with_capacity(*num_members as usize);
            for _ in 0..*num_members {
                let identifier_size = U8::from_bits_be(next_bits(8)).eject_value();
                let identifier = Identifier::from_bits_be(next_bits(*identifier_size as usize));

                let member_size = U16::from_bits_be(next_bits(16)).eject_value();
                let value = Plaintext::from_bits_be(next_bits(*member_size as usize));

                members.insert(identifier, value);
            }

            // Cache the plaintext bits, and return the struct.
            Self::Struct(members, OnceCell::with_value(bits_be.to_vec()))
        }
        // Unknown variant.
        else {
            A::halt("Unknown plaintext variant.")
        }
    }
}