Function transformNamedArguments

src/rpc/server.cpp:368–470

* Process named arguments into a vector of positional arguments, based on the * passed-in specification for the RPC call's arguments. */

 * passed-in specification for the RPC call's arguments.
 */
static inline JSONRPCRequest transformNamedArguments(const JSONRPCRequest& in, const std::vector<std::pair<std::string, bool>>& argNames)
{
    JSONRPCRequest out = in;
    out.params = UniValue(UniValue::VARR);
    // Build a map of parameters, and remove ones that have been processed, so that we can throw a focused error if
    // there is an unknown one.
    const std::vector<std::string>& keys = in.params.getKeys();
    const std::vector<UniValue>& values = in.params.getValues();
    std::unordered_map<std::string, const UniValue*> argsIn;
    for (size_t i=0; i<keys.size(); ++i) {
        auto [_, inserted] = argsIn.emplace(keys[i], &values[i]);
        if (!inserted) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Parameter " + keys[i] + " specified multiple times");
        }
    }
    // Process expected parameters. If any parameters were left unspecified in
    // the request before a parameter that was specified, null values need to be
    // inserted at the unspecified parameter positions, and the "hole" variable
    // below tracks the number of null values that need to be inserted.
    // The "initial_hole_size" variable stores the size of the initial hole,
    // i.e. how many initial positional arguments were left unspecified. This is
    // used after the for-loop to add initial positional arguments from the
    // "args" parameter, if present.
    int hole = 0;
    int initial_hole_size = 0;
    const std::string* initial_param = nullptr;
    UniValue options{UniValue::VOBJ};
    for (const auto& [argNamePattern, named_only]: argNames) {
        std::vector<std::string> vargNames = SplitString(argNamePattern, '|');
        auto fr = argsIn.end();
        for (const std::string & argName : vargNames) {
            fr = argsIn.find(argName);
            if (fr != argsIn.end()) {
                break;
            }
        }

        // Handle named-only parameters by pushing them into a temporary options
        // object, and then pushing the accumulated options as the next
        // positional argument.
        if (named_only) {
            if (fr != argsIn.end()) {
                if (options.exists(fr->first)) {
                    throw JSONRPCError(RPC_INVALID_PARAMETER, "Parameter " + fr->first + " specified multiple times");
                }
                options.pushKVEnd(fr->first, *fr->second);
                argsIn.erase(fr);
            }
            continue;
        }

        if (!options.empty() || fr != argsIn.end()) {
            for (int i = 0; i < hole; ++i) {
                // Fill hole between specified parameters with JSON nulls,
                // but not at the end (for backwards compatibility with calls
                // that act based on number of specified parameters).
                out.params.push_back(UniValue());
            }