C++ to other contract calls

How contract calls happen from the C++ side in AppLayer.

The ContractHost class employs templated functions to support flexible and efficient interaction with contracts. These templates enable passing any combination of arguments and return types (including void) to and from other types of contracts. This use of templates helps to leverage the fast ABI encoding/decoding processes, ensuring optimal performance and flexibility during contract execution:

template <typename R, typename C, typename... Args> R
callContractViewFunction(
    const BaseContract* caller,
    const Address& targetAddr,
    R(C::*func)(const Args&...) const, const
    Args&... args) const;

template <typename R, typename C> R
callContractViewFunction(
    const BaseContract* caller,
    const Address& targetAddr,
    R(C::*func)() const) const;

template <typename R, typename C, typename... Args>
requires (!std::is_same<R, void>::value)
R callContractFunction(
  BaseContract* caller, const Address& targetAddr,
  const uint256_t& value,
  R(C::*func)(const Args&...), const Args&... args
)

template <typename R, typename C, typename... Args>
requires (std::is_same<R, void>::value)
void callContractFunction(
  BaseContract* caller, const Address& targetAddr,
  const uint256_t& value,
  R(C::*func)(const Args&...), const Args&... args
)

template <typename R, typename C, typename... Args>
requires (!std::is_same<R, void>::value)
R callContractFunction(
  BaseContract* caller, const Address& targetAddr,
  const uint256_t& value,
  R(C::*func)(const Args&...), const Args&... args
)

template <typename R, typename C>
requires (!std::is_same<R, void>::value)
R callContractFunction(
  BaseContract* caller, const Address& targetAddr,
  const uint256_t& value, R(C::*func)()
)

This approach allows for dynamic interaction with contracts without pre-defining all possible function signatures, accommodating various contract behaviors and states dynamically.