snarkvm-synthesizer-program 4.6.1

// Copyright (c) 2019-2026 Provable 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 crate::{Opcode, Operand, RegistersCircuit, RegistersTrait, StackTrait, register_types_equivalent};
use console::{
    network::prelude::*,
    program::{Literal, LiteralType, Plaintext, PlaintextType, Register, RegisterType, Value},
    types::Boolean,
};

/// Computes whether `first` equals `second` as a boolean, storing the outcome in `destination`.
pub type IsEq<N> = IsInstruction<N, { Variant::IsEq as u8 }>;
/// Computes whether `first` does **not** equals `second` as a boolean, storing the outcome in `destination`.
pub type IsNeq<N> = IsInstruction<N, { Variant::IsNeq as u8 }>;

enum Variant {
    IsEq,
    IsNeq,
}

/// Computes an equality operation on two operands, and stores the outcome in `destination`.
#[derive(Clone, PartialEq, Eq, Hash)]
pub struct IsInstruction<N: Network, const VARIANT: u8> {
    /// The operands.
    operands: Vec<Operand<N>>,
    /// The destination register.
    destination: Register<N>,
}

impl<N: Network, const VARIANT: u8> IsInstruction<N, VARIANT> {
    /// Initializes a new `is` instruction.
    pub fn new(operands: Vec<Operand<N>>, destination: Register<N>) -> Result<Self> {
        // Sanity check the number of operands.
        ensure!(operands.len() == 2, "Instruction '{}' must have two operands", Self::opcode());
        // Return the instruction.
        Ok(Self { operands, destination })
    }

    /// Returns the opcode.
    pub const fn opcode() -> Opcode {
        match VARIANT {
            0 => Opcode::Is("is.eq"),
            1 => Opcode::Is("is.neq"),
            _ => panic!("Invalid 'is' instruction opcode"),
        }
    }

    /// Returns the operands in the operation.
    #[inline]
    pub fn operands(&self) -> &[Operand<N>] {
        // Sanity check that the operands is exactly two inputs.
        debug_assert!(self.operands.len() == 2, "Instruction '{}' must have two operands", Self::opcode());
        // Return the operands.
        &self.operands
    }

    /// Returns the destination register.
    #[inline]
    pub fn destinations(&self) -> Vec<Register<N>> {
        vec![self.destination.clone()]
    }

    /// Returns whether this instruction refers to an external struct.
    #[inline]
    pub fn contains_external_struct(&self) -> bool {
        false
    }
}

impl<N: Network, const VARIANT: u8> IsInstruction<N, VARIANT> {
    /// Evaluates the instruction.
    pub fn evaluate(&self, stack: &impl StackTrait<N>, registers: &mut impl RegistersTrait<N>) -> Result<()> {
        // Ensure the number of operands is correct.
        if self.operands.len() != 2 {
            bail!("Instruction '{}' expects 2 operands, found {} operands", Self::opcode(), self.operands.len())
        }

        // Retrieve the inputs.
        let input_a = registers.load(stack, &self.operands[0])?;
        let input_b = registers.load(stack, &self.operands[1])?;

        // Check the inputs.
        let output = match VARIANT {
            0 => Literal::Boolean(Boolean::new(input_a == input_b)),
            1 => Literal::Boolean(Boolean::new(input_a != input_b)),
            _ => bail!("Invalid 'is' variant: {VARIANT}"),
        };
        // Store the output.
        registers.store(stack, &self.destination, Value::Plaintext(Plaintext::from(output)))
    }

    /// Executes the instruction.
    pub fn execute<A: circuit::Aleo<Network = N>>(
        &self,
        stack: &impl StackTrait<N>,
        registers: &mut impl RegistersCircuit<N, A>,
    ) -> Result<()> {
        // Ensure the number of operands is correct.
        if self.operands.len() != 2 {
            bail!("Instruction '{}' expects 2 operands, found {} operands", Self::opcode(), self.operands.len())
        }

        // Retrieve the inputs.
        let input_a = registers.load_circuit(stack, &self.operands[0])?;
        let input_b = registers.load_circuit(stack, &self.operands[1])?;

        // Check the inputs.
        let output = match VARIANT {
            0 => circuit::Literal::Boolean(input_a.is_equal(&input_b)),
            1 => circuit::Literal::Boolean(input_a.is_not_equal(&input_b)),
            _ => bail!("Invalid 'is' variant: {VARIANT}"),
        };
        // Convert the output to a stack value.
        let output = circuit::Value::Plaintext(circuit::Plaintext::Literal(output, Default::default()));
        // Store the output.
        registers.store_circuit(stack, &self.destination, output)
    }

    /// Finalizes the instruction.
    #[inline]
    pub fn finalize(&self, stack: &impl StackTrait<N>, registers: &mut impl RegistersTrait<N>) -> Result<()> {
        self.evaluate(stack, registers)
    }

    /// Returns the output type from the given program and input types.
    pub fn output_types(
        &self,
        stack: &impl StackTrait<N>,
        input_types: &[RegisterType<N>],
    ) -> Result<Vec<RegisterType<N>>> {
        // Ensure the number of input types is correct.
        if input_types.len() != 2 {
            bail!("Instruction '{}' expects 2 inputs, found {} inputs", Self::opcode(), input_types.len())
        }
        // Ensure the operands are of the same type.
        if !register_types_equivalent(stack, &input_types[0], stack, &input_types[1])? {
            bail!(
                "Instruction '{}' expects inputs of the same type. Found inputs of type '{}' and '{}'",
                Self::opcode(),
                input_types[0],
                input_types[1]
            )
        }
        // Ensure the number of operands is correct.
        if self.operands.len() != 2 {
            bail!("Instruction '{}' expects 2 operands, found {} operands", Self::opcode(), self.operands.len())
        }

        match VARIANT {
            0 | 1 => Ok(vec![RegisterType::Plaintext(PlaintextType::Literal(LiteralType::Boolean))]),
            _ => bail!("Invalid 'is' variant: {VARIANT}"),
        }
    }
}

impl<N: Network, const VARIANT: u8> Parser for IsInstruction<N, VARIANT> {
    /// Parses a string into an operation.
    fn parse(string: &str) -> ParserResult<Self> {
        // Parse the opcode from the string.
        let (string, _) = tag(*Self::opcode())(string)?;
        // Parse the whitespace from the string.
        let (string, _) = Sanitizer::parse_whitespaces(string)?;
        // Parse the first operand from the string.
        let (string, first) = Operand::parse(string)?;
        // Parse the whitespace from the string.
        let (string, _) = Sanitizer::parse_whitespaces(string)?;
        // Parse the second operand from the string.
        let (string, second) = Operand::parse(string)?;
        // Parse the whitespace from the string.
        let (string, _) = Sanitizer::parse_whitespaces(string)?;
        // Parse the "into" from the string.
        let (string, _) = tag("into")(string)?;
        // Parse the whitespace from the string.
        let (string, _) = Sanitizer::parse_whitespaces(string)?;
        // Parse the destination register from the string.
        let (string, destination) = Register::parse(string)?;

        Ok((string, Self { operands: vec![first, second], destination }))
    }
}

impl<N: Network, const VARIANT: u8> FromStr for IsInstruction<N, VARIANT> {
    type Err = Error;

    /// Parses a string into an operation.
    fn from_str(string: &str) -> Result<Self> {
        match Self::parse(string) {
            Ok((remainder, object)) => {
                // Ensure the remainder is empty.
                ensure!(remainder.is_empty(), "Failed to parse string. Found invalid character in: \"{remainder}\"");
                // Return the object.
                Ok(object)
            }
            Err(error) => bail!("Failed to parse string. {error}"),
        }
    }
}

impl<N: Network, const VARIANT: u8> Debug for IsInstruction<N, VARIANT> {
    /// Prints the operation as a string.
    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
        Display::fmt(self, f)
    }
}

impl<N: Network, const VARIANT: u8> Display for IsInstruction<N, VARIANT> {
    /// Prints the operation to a string.
    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
        // Ensure the number of operands is 2.
        if self.operands.len() != 2 {
            return Err(fmt::Error);
        }
        // Print the operation.
        write!(f, "{} ", Self::opcode())?;
        self.operands.iter().try_for_each(|operand| write!(f, "{operand} "))?;
        write!(f, "into {}", self.destination)
    }
}

impl<N: Network, const VARIANT: u8> FromBytes for IsInstruction<N, VARIANT> {
    /// Reads the operation from a buffer.
    fn read_le<R: Read>(mut reader: R) -> IoResult<Self> {
        // Initialize the vector for the operands.
        let mut operands = Vec::with_capacity(2);
        // Read the operands.
        for _ in 0..2 {
            operands.push(Operand::read_le(&mut reader)?);
        }
        // Read the destination register.
        let destination = Register::read_le(&mut reader)?;

        // Return the operation.
        Ok(Self { operands, destination })
    }
}

impl<N: Network, const VARIANT: u8> ToBytes for IsInstruction<N, VARIANT> {
    /// Writes the operation to a buffer.
    fn write_le<W: Write>(&self, mut writer: W) -> IoResult<()> {
        // Ensure the number of operands is 2.
        if self.operands.len() != 2 {
            return Err(error(format!("The number of operands must be 2, found {}", self.operands.len())));
        }
        // Write the operands.
        self.operands.iter().try_for_each(|operand| operand.write_le(&mut writer))?;
        // Write the destination register.
        self.destination.write_le(&mut writer)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use console::network::MainnetV0;

    type CurrentNetwork = MainnetV0;

    #[test]
    fn test_parse() {
        let (string, is) = IsEq::<CurrentNetwork>::parse("is.eq r0 r1 into r2").unwrap();
        assert!(string.is_empty(), "Parser did not consume all of the string: '{string}'");
        assert_eq!(is.operands.len(), 2, "The number of operands is incorrect");
        assert_eq!(is.operands[0], Operand::Register(Register::Locator(0)), "The first operand is incorrect");
        assert_eq!(is.operands[1], Operand::Register(Register::Locator(1)), "The second operand is incorrect");
        assert_eq!(is.destination, Register::Locator(2), "The destination register is incorrect");

        let (string, is) = IsNeq::<CurrentNetwork>::parse("is.neq r0 r1 into r2").unwrap();
        assert!(string.is_empty(), "Parser did not consume all of the string: '{string}'");
        assert_eq!(is.operands.len(), 2, "The number of operands is incorrect");
        assert_eq!(is.operands[0], Operand::Register(Register::Locator(0)), "The first operand is incorrect");
        assert_eq!(is.operands[1], Operand::Register(Register::Locator(1)), "The second operand is incorrect");
        assert_eq!(is.destination, Register::Locator(2), "The destination register is incorrect");
    }
}