Class InputStack

src/script/miniscript.h:308–342

An object representing a sequence of witness stack elements.

//! An object representing a sequence of witness stack elements.
struct InputStack {
    /** Whether this stack is valid for its intended purpose (satisfaction or dissatisfaction of a Node).
     *  The MAYBE value is used for size estimation, when keys/preimages may actually be unavailable,
     *  but may be available at signing time. This makes the InputStack structure and signing logic,
     *  filled with dummy signatures/preimages usable for witness size estimation.
     */
    Availability available = Availability::YES;
    //! Whether this stack contains a digital signature.
    bool has_sig = false;
    //! Whether this stack is malleable (can be turned into an equally valid other stack by a third party).
    bool malleable = false;
    //! Whether this stack is non-canonical (using a construction known to be unnecessary for satisfaction).
    //! Note that this flag does not affect the satisfaction algorithm; it is only used for sanity checking.
    bool non_canon = false;
    //! Serialized witness size.
    size_t size = 0;
    //! Data elements.
    std::vector<std::vector<unsigned char>> stack;
    //! Construct an empty stack (valid).
    InputStack() = default;
    //! Construct a valid single-element stack (with an element up to 75 bytes).
    InputStack(std::vector<unsigned char> in) : size(in.size() + 1), stack(Vector(std::move(in))) {}
    //! Change availability
    InputStack& SetAvailable(Availability avail);
    //! Mark this input stack as having a signature.
    InputStack& SetWithSig();
    //! Mark this input stack as non-canonical (known to not be necessary in non-malleable satisfactions).
    InputStack& SetNonCanon();
    //! Mark this input stack as malleable.
    InputStack& SetMalleable(bool x = true);
    //! Concatenate two input stacks.
    friend InputStack operator+(InputStack a, InputStack b);
    //! Choose between two potential input stacks.
    friend InputStack operator|(InputStack a, InputStack b);
};

/** A stack consisting of a single zero-length element (interpreted as 0 by the script interpreter in numeric context). */
static const auto ZERO = InputStack(std::vector<unsigned char>());