snarkvm_circuit_program/data/literal/cast/
mod.rs

1// Copyright (c) 2019-2025 Provable Inc.
2// This file is part of the snarkVM library.
3
4// Licensed under the Apache License, Version 2.0 (the "License");
5// you may not use this file except in compliance with the License.
6// You may obtain a copy of the License at:
7
8// http://www.apache.org/licenses/LICENSE-2.0
9
10// Unless required by applicable law or agreed to in writing, software
11// distributed under the License is distributed on an "AS IS" BASIS,
12// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13// See the License for the specific language governing permissions and
14// limitations under the License.
15
16mod boolean;
17mod field;
18mod integer;
19mod scalar;
20
21use crate::data::{CastLossy, Literal};
22use console::LiteralType;
23use snarkvm_circuit_network::Aleo;
24use snarkvm_circuit_types::prelude::{
25    Address,
26    BitOr,
27    Boolean,
28    Environment,
29    Field,
30    FromBits,
31    FromField,
32    FromGroup,
33    Group,
34    IntegerType,
35    MSB,
36    One,
37    Result,
38    Scalar,
39    ToBits,
40    ToField,
41    ToGroup,
42    Zero,
43    bail,
44    integers::Integer,
45};
46
47#[cfg(test)]
48use snarkvm_circuit_types::prelude::{I8, I16, I32, I64, I128, U8, U16, U32, U64, U128};
49
50/// Unary operator for casting values of one type to another.
51pub trait Cast<T: Sized = Self> {
52    /// Casts the value of `self` into a value of type `T`.
53    ///
54    /// This method checks that the cast does not lose any bits of information.
55    fn cast(&self) -> T;
56}
57
58impl<A: Aleo> Literal<A> {
59    /// Casts the literal to the given literal type.
60    ///
61    /// This method checks that the cast does not lose any bits of information,
62    /// and returns an error if it does.
63    ///
64    /// The hierarchy of casting is as follows:
65    ///  - (`Address`, `Group`) <-> `Field` <-> `Scalar` <-> `Integer` <-> `Boolean`
66    ///  - `Signature` (not supported)
67    ///  - `String` (not supported)
68    ///
69    /// Note that casting to left along the hierarchy always preserves information.
70    pub fn cast(&self, to_type: LiteralType) -> Result<Self> {
71        match self {
72            Self::Address(address) => cast_group_to_type(&address.to_group(), to_type),
73            Self::Boolean(boolean) => cast_boolean_to_type(boolean, to_type),
74            Self::Field(field) => cast_field_to_type(field, to_type),
75            Self::Group(group) => cast_group_to_type(group, to_type),
76            Self::I8(integer) => cast_integer_to_type(integer, to_type),
77            Self::I16(integer) => cast_integer_to_type(integer, to_type),
78            Self::I32(integer) => cast_integer_to_type(integer, to_type),
79            Self::I64(integer) => cast_integer_to_type(integer, to_type),
80            Self::I128(integer) => cast_integer_to_type(integer, to_type),
81            Self::U8(integer) => cast_integer_to_type(integer, to_type),
82            Self::U16(integer) => cast_integer_to_type(integer, to_type),
83            Self::U32(integer) => cast_integer_to_type(integer, to_type),
84            Self::U64(integer) => cast_integer_to_type(integer, to_type),
85            Self::U128(integer) => cast_integer_to_type(integer, to_type),
86            Self::Scalar(scalar) => cast_scalar_to_type(scalar, to_type),
87            Self::Signature(..) => bail!("Cannot cast a signature literal to another type."),
88            Self::String(..) => bail!("Cannot cast a string literal to another type."),
89        }
90    }
91}
92
93/// A helper macro to implement the body of the `cast` methods.
94macro_rules! impl_cast_body {
95    ($type_name:ident, $cast:ident, $input:expr, $to_type:expr) => {
96        match $to_type {
97            LiteralType::Address => Ok(Literal::Address($input.$cast())),
98            LiteralType::Boolean => Ok(Literal::Boolean($input.$cast())),
99            LiteralType::Field => Ok(Literal::Field($input.$cast())),
100            LiteralType::Group => Ok(Literal::Group($input.$cast())),
101            LiteralType::I8 => Ok(Literal::I8($input.$cast())),
102            LiteralType::I16 => Ok(Literal::I16($input.$cast())),
103            LiteralType::I32 => Ok(Literal::I32($input.$cast())),
104            LiteralType::I64 => Ok(Literal::I64($input.$cast())),
105            LiteralType::I128 => Ok(Literal::I128($input.$cast())),
106            LiteralType::U8 => Ok(Literal::U8($input.$cast())),
107            LiteralType::U16 => Ok(Literal::U16($input.$cast())),
108            LiteralType::U32 => Ok(Literal::U32($input.$cast())),
109            LiteralType::U64 => Ok(Literal::U64($input.$cast())),
110            LiteralType::U128 => Ok(Literal::U128($input.$cast())),
111            LiteralType::Scalar => Ok(Literal::Scalar($input.$cast())),
112            LiteralType::Signature => {
113                bail!(concat!("Cannot cast a ", stringify!($type_name), " literal to a signature type."))
114            }
115            LiteralType::String => {
116                bail!(concat!("Cannot cast a ", stringify!($type_name), " literal to a string type."))
117            }
118        }
119    };
120}
121
122/// Casts a boolean literal to the given literal type.
123fn cast_boolean_to_type<A: Aleo>(input: &Boolean<A>, to_type: LiteralType) -> Result<Literal<A>> {
124    impl_cast_body!(boolean, cast, input, to_type)
125}
126
127/// Casts a field literal to the given literal type.
128fn cast_field_to_type<A: Aleo>(input: &Field<A>, to_type: LiteralType) -> Result<Literal<A>> {
129    impl_cast_body!(field, cast, input, to_type)
130}
131
132/// Casts a group literal to the given literal type.
133fn cast_group_to_type<A: Aleo>(input: &Group<A>, to_type: LiteralType) -> Result<Literal<A>> {
134    match to_type {
135        LiteralType::Address => Ok(Literal::Address(Address::from_group(input.clone()))),
136        LiteralType::Group => Ok(Literal::Group(input.clone())),
137        _ => cast_field_to_type(&input.to_x_coordinate(), to_type),
138    }
139}
140
141/// Casts an integer literal to the given literal type.
142fn cast_integer_to_type<A: Aleo, I: IntegerType>(input: &Integer<A, I>, to_type: LiteralType) -> Result<Literal<A>> {
143    impl_cast_body!(integer, cast, input, to_type)
144}
145
146/// Casts a scalar literal to the given literal type.
147fn cast_scalar_to_type<A: Aleo>(input: &Scalar<A>, to_type: LiteralType) -> Result<Literal<A>> {
148    impl_cast_body!(scalar, cast, input, to_type)
149}
150
151#[cfg(test)]
152macro_rules! impl_check_cast {
153    ($fun:ident, $circuit_type:ty, $console_type:ty) => {
154        fn check_cast<CircuitType, ConsoleType>(mode: Mode, count: UpdatableCount)
155        where
156            CircuitType: Eject,
157            <CircuitType as Eject>::Primitive: Debug + PartialEq<ConsoleType>,
158            ConsoleType: Debug,
159            $console_type: console::Cast<ConsoleType>,
160            $circuit_type: crate::Cast<CircuitType>,
161        {
162            let rng = &mut TestRng::default();
163            for i in 0..ITERATIONS {
164                let (console_value, circuit_value) = sample_values(i, mode, rng);
165                match console_value.$fun() {
166                    // If the console cast fails and the mode is constant, then the circuit cast should fail.
167                    Err(_) if mode == Mode::Constant => {
168                        assert!(
169                            std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| circuit_value.$fun())).is_err()
170                        )
171                    }
172                    // If the console cast fails, the circuit cast can either fail by panicking or fail by being unsatisfied.
173                    Err(_) => {
174                        Circuit::scope("test", || {
175                            if std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| circuit_value.$fun())).is_ok() {
176                                assert!(!Circuit::is_satisfied());
177                                count.assert_matches(
178                                    Circuit::num_constants_in_scope(),
179                                    Circuit::num_public_in_scope(),
180                                    Circuit::num_private_in_scope(),
181                                    Circuit::num_constraints_in_scope(),
182                                );
183                            }
184                        });
185                    }
186                    // If the console cast succeeds, the circuit cast should succeed and the values should match.
187                    Ok(expected) => Circuit::scope("test", || {
188                        let result = circuit_value.$fun();
189                        assert_eq!(result.eject_value(), expected);
190                        assert!(Circuit::is_satisfied());
191                        count.assert_matches(
192                            Circuit::num_constants_in_scope(),
193                            Circuit::num_public_in_scope(),
194                            Circuit::num_private_in_scope(),
195                            Circuit::num_constraints_in_scope(),
196                        );
197                    }),
198                };
199                Circuit::reset();
200            }
201        }
202    };
203}
204#[cfg(test)]
205pub(super) use impl_check_cast;
snarkvm_circuit_program/data/literal/cast/mod.rs

snarkvm_circuit_program/data/literal/cast/
mod.rs
