Struct ark_relations::r1cs::ConstraintSystem

pub struct ConstraintSystem<F: Field> {
    pub mode: SynthesisMode,
    pub num_instance_variables: usize,
    pub num_witness_variables: usize,
    pub num_constraints: usize,
    pub num_linear_combinations: usize,
    pub optimization_goal: OptimizationGoal,
    pub instance_assignment: Vec<F>,
    pub witness_assignment: Vec<F>,
    pub cache_map: Rc<RefCell<BTreeMap<TypeId, Box<dyn Any>>>>,
    // some fields omitted
}

An Rank-One ConstraintSystem. Enforces constraints of the form ⟨a_i, z⟩ ⋅ ⟨b_i, z⟩ = ⟨c_i, z⟩, where a_i, b_i, and c_i are linear combinations over variables, and z is the concrete assignment to these variables.

Fields

mode: SynthesisMode

The mode in which the constraint system is operating. self can either be in setup mode (i.e., self.mode == SynthesisMode::Setup) or in proving mode (i.e., self.mode == SynthesisMode::Prove). If we are in proving mode, then we have the additional option of whether or not to construct the A, B, and C matrices of the constraint system (see below).

num_instance_variables: usize

The number of variables that are “public inputs” to the constraint system.

num_witness_variables: usize

The number of variables that are “private inputs” to the constraint system.

num_constraints: usize

The number of constraints in the constraint system.

num_linear_combinations: usize

The number of linear combinations

optimization_goal: OptimizationGoal

The parameter we aim to minimize in this constraint system (either the number of constraints or their total weight).

instance_assignment: Vec<F>

Assignments to the public input variables. This is empty if self.mode == SynthesisMode::Setup.

witness_assignment: Vec<F>

Assignments to the private input variables. This is empty if self.mode == SynthesisMode::Setup.

cache_map: Rc<RefCell<BTreeMap<TypeId, Box<dyn Any>>>>

Map for gadgets to cache computation results.

Implementations

impl<F: Field> ConstraintSystem<F>

pub fn new() -> Self

Construct an empty ConstraintSystem.

pub fn new_ref() -> ConstraintSystemRef<F>

Create a new ConstraintSystemRef<F>.

pub fn set_mode(&mut self, mode: SynthesisMode)

Set self.mode to mode.

pub fn is_in_setup_mode(&self) -> bool

Check whether self.mode == SynthesisMode::Setup.

pub fn optimization_goal(&self) -> OptimizationGoal

Check whether this constraint system aims to optimize weight, number of constraints, or neither.

pub fn set_optimization_goal(&mut self, goal: OptimizationGoal)

Specify whether this constraint system should aim to optimize weight, number of constraints, or neither.

pub fn should_construct_matrices(&self) -> bool

Check whether or not self will construct matrices.

pub fn zero() -> Variable

Return a variable representing the constant “zero” inside the constraint system.

pub fn one() -> Variable

Return a variable representing the constant “one” inside the constraint system.

pub fn new_input_variable<Func>(&mut self, f: Func) -> Result<Variable> where
    Func: FnOnce() -> Result<F>, 

Obtain a variable representing a new public instance input.

pub fn new_witness_variable<Func>(&mut self, f: Func) -> Result<Variable> where
    Func: FnOnce() -> Result<F>, 

Obtain a variable representing a new private witness input.

pub fn new_lc(&mut self, lc: LinearCombination<F>) -> Result<Variable>

Obtain a variable representing a linear combination.

pub fn enforce_constraint(
    &mut self,
    a: LinearCombination<F>,
    b: LinearCombination<F>,
    c: LinearCombination<F>
) -> Result<()>

Enforce a R1CS constraint with the name name.

pub fn transform_lc_map(
    &mut self,
    transformer: &mut dyn FnMut(&ConstraintSystem<F>, usize, &mut LinearCombination<F>) -> (usize, Option<Vec<F>>)
)

Transform the map of linear combinations. Specifically, allow the creation of additional witness assignments.

This method is used as a subroutine of inline_all_lcs and outline_lcs.

The transformer function is given a references of this constraint system (&self), number of times used, and a mutable reference of the linear combination to be transformed. (&ConstraintSystem, usize, &mut LinearCombination)

The transformer function returns the number of new witness variables needed and a vector of new witness assignments (if not in the setup mode). (usize, Option<Vec>)

pub fn inline_all_lcs(&mut self)

Naively inlines symbolic linear combinations into the linear combinations that use them.

Useful for standard pairing-based SNARKs where addition gates are cheap. For example, in the SNARKs such as [Groth16] and [Groth-Maller17], addition gates do not contribute to the size of the multi-scalar multiplication, which is the dominating cost.

pub fn finalize(&mut self)

Finalize the constraint system (either by outlining or inlining, if an optimization goal is set).

pub fn to_matrices(&self) -> Option<ConstraintMatrices<F>>

This step must be called after constraint generation has completed, and after all symbolic LCs have been inlined into the places that they are used.

pub fn is_satisfied(&self) -> Result<bool>

If self is satisfied, outputs Ok(true). If self is unsatisfied, outputs Ok(false). If self.is_in_setup_mode(), outputs Err(()).

pub fn which_is_unsatisfied(&self) -> Result<Option<String>>

If self is satisfied, outputs Ok(None). If self is unsatisfied, outputs Some(i), where i is the index of the first unsatisfied constraint. If self.is_in_setup_mode(), outputs Err(()).

pub fn assigned_value(&self, v: Variable) -> Option<F>

Obtain the assignment corresponding to the Variable v.

Trait Implementations

impl<F: Clone + Field> Clone for ConstraintSystem<F>

fn clone(&self) -> ConstraintSystem<F>

Returns a copy of the value.

pub fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<F: Debug + Field> Debug for ConstraintSystem<F>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<F: Field> Default for ConstraintSystem<F>

fn default() -> Self

Returns the “default value” for a type.