witness.hpp

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// === AUDIT STATUS ===
// internal:    { status: not started, auditors: [], date: YYYY-MM-DD }
// external_1:  { status: not started, auditors: [], date: YYYY-MM-DD }
// external_2:  { status: not started, auditors: [], date: YYYY-MM-DD }
// =====================
 
#pragma once
#include "barretenberg/ecc/curves/bn254/fr.hpp"
#include "barretenberg/stdlib/primitives//circuit_builders/circuit_builders.hpp"
 
namespace bb::stdlib {
 
// indicates whether a witness index actually contains a constant
static constexpr uint32_t IS_CONSTANT = UINT32_MAX;
 
template <typename Builder> class witness_t {
  public:
    witness_t() = default;
 
    witness_t(Builder* parent_context, const bb::fr& in)
    {
        context = parent_context;
        witness = in;
        witness_index = context->add_variable(witness);
    }
 
    witness_t(Builder* parent_context, const bool in)
    {
        context = parent_context;
        if (in) {
            bb::fr::__copy(bb::fr::one(), witness);
        } else {
            bb::fr::__copy(bb::fr::zero(), witness);
        }
        witness_index = context->add_variable(witness);
    }
 
    witness_t(Builder* parent_context, IntegralOrEnum auto const in)
    {
        context = parent_context;
        witness = bb::fr{ static_cast<uint64_t>(in), 0, 0, 0 }.to_montgomery_form();
        witness_index = context->add_variable(witness);
    }
 
    static witness_t create_constant_witness(Builder* parent_context, const bb::fr& in)
    {
        witness_t out(parent_context, in);
        parent_context->assert_equal_constant(out.witness_index, in, "Failed to create constant witness.");
        return out;
    }
 
    bool is_constant() const { return witness_index == IS_CONSTANT; }
 
    bb::fr witness;
    uint32_t witness_index = IS_CONSTANT;
    Builder* context = nullptr;
};
 
template <typename Builder> class public_witness_t : public witness_t<Builder> {
  public:
    using witness_t<Builder>::context;
    using witness_t<Builder>::witness;
    using witness_t<Builder>::witness_index;
 
    public_witness_t() = default;
    public_witness_t(Builder* parent_context, const bb::fr& in)
    {
        context = parent_context;
        bb::fr::__copy(in, witness);
        witness_index = context->add_public_variable(witness);
    }
 
    public_witness_t(Builder* parent_context, const bool in)
    {
        context = parent_context;
        if (in) {
            bb::fr::__copy(bb::fr::one(), witness);
        } else {
            bb::fr::__copy(bb::fr::zero(), witness);
        }
        witness_index = context->add_public_variable(witness);
    }
 
    template <typename T> public_witness_t(Builder* parent_context, T const in)
    {
        context = parent_context;
        witness = bb::fr{ static_cast<uint64_t>(in), 0, 0, 0 }.to_montgomery_form();
        witness_index = context->add_public_variable(witness);
    }
};
 
} // namespace bb::stdlib