mra/QCCalculationParametersBase.h

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/*
 * QCCalculationParametersBase.h
 *
 *  Created on: 27 Jun 2019
 *      Author: fbischoff
 */
 
#ifndef SRC_APPS_CHEM_QCCALCULATIONPARAMETERSBASE_H_
#define SRC_APPS_CHEM_QCCALCULATIONPARAMETERSBASE_H_
 
#include <madness/madness_config.h>
#include <string>
#include <algorithm>
#include <iomanip>
#include <typeindex>
#include <map>
#include <set>
#include <fstream>
#include <typeinfo>
// #include <madness/external/gtest/include/gtest/internal/gtest-type-util.h>
 
#include "madness/misc/misc.h"
#include "madness/world/archive.h"
#include "madness/world/world.h"
#include "madness/mra/commandlineparser.h"
#include <nlohmann/json.hpp>
 
 
namespace madness {
    using json = nlohmann::json;
 
    template <typename T>
    static typename std::enable_if<std::is_floating_point<T>::value, void>::type
    check_for_inf(const std::string& str, T& arg) {
        std::string sinf;
        std::stringstream ss;
        ss << std::numeric_limits<T>::infinity();
        sinf = ss.str();
 
        if (sinf == str) arg = std::numeric_limits<T>::infinity();
    }
 
    template <typename T>
    static typename std::enable_if<!std::is_floating_point<T>::value, void>::type
    check_for_inf(const std::string& str, T& arg) {
        return;
    }
 
    /// inverting the print method from print.h for std::vector
    /// TODO: move this where it belongs (into print.h ??)
    template <typename T, typename A=std::allocator<T>>
    std::istream& operator>>(std::istream& is, std::vector<T, A>& v) {
        // get the full line from opening to closing brackets [ .. ]
        std::string word, line = "";
        while (is >> word) {
            line += word;
            if (word.find(']') != std::string::npos) break;
        }
        if (line.size() != 0) is.clear();
 
        // remove enclosing brackets and commas
        auto find_c = [](char& c) { return ((c == ',') or (c == '[') or (c == ']')); };
        std::replace_if(line.begin(), line.end(), find_c, ' '); // 0 2 0 4 0 6 0 8 0
 
        // stream the values into the container
        std::stringstream sline(line);
        T tmp;
        while (sline >> word) {
            std::stringstream sword(word);
            sword >> tmp;
            check_for_inf(word, tmp);
            v.push_back(tmp);
        }
        if (sline.bad()) {
            madness::print("error while reading vector from istream: ");
            madness::print(line, "\n");
            throw std::runtime_error("IO error");
        }
 
        return is;
    }
 
 
    /// inverting the print method from print.h for std::vector
    /// TODO: move this where it belongs (into print.h ??)
    template <typename Q, typename T>
    std::istream& operator>>(std::istream& is, std::pair<T, Q>& p) {
        // get all words from the line
        std::string word, line = "";
        while (is >> word) {
            line += word + " ";
        };
        // have to set this here to account for the error handling later..
        is.clear();
 
        // remove enclosing brackets and commas
        auto find_c = [](char& c) { return ((c == ',') or (c == '(') or (c == ')')); };
        std::replace_if(line.begin(), line.end(), find_c, ' '); // 0 2 0 4 0 6 0 8 0
 
        // stream the values into the container
        std::stringstream sline(line);
        T tmp1;
        Q tmp2;
        sline >> tmp1 >> tmp2;
        if (sline.bad() or sline.fail()) {
            madness::print("error while reading vector from istream: ");
            madness::print(line, "\n");
            throw std::runtime_error("IO error");
        }
        p = std::pair<T, Q>(tmp1, tmp2);
 
        return is;
    }
 
 
    /// structure holding the value for a given parameter
 
    /// keeps logic about default, derived and user-defined settings (with increasing priority),
    /// as well as comments for the user (e.g. a recommended range for a given parameter).
    ///
    /// might be extended to hold allowed values for certain parameters, e.g. localization procedures.
    ///
    /// all values are stored as strings and must be converted to their respective types by the
    /// QCCalculationParametersBase class (see below)
    struct QCParameter {
    public:
        QCParameter() {};
 
        QCParameter(const std::string v, const std::string t, const std::string comment = "",
                    const std::vector<std::string> allowed_values1 = {})
            : default_value(v), type(t), comment(comment), allowed_values(allowed_values1) {
            static int i = 0;
            print_order = i++;
            set_all();
        }
 
        void set_derived_value(const std::string val) {
            precedence = std::max(derived, precedence);
            derived_value = val;
            set_all();
        }
 
        void set_user_defined_value(const std::string val) {
            precedence = std::max(defined, precedence);
            user_defined_value = val;
            set_all();
        }
 
        bool is_user_defined() const {
            return (precedence == defined);
        }
 
        std::string get_value() const { return value; }
        std::string get_type() const { return type; }
        std::string get_comment() const { return comment; }
 
        std::string print_precedence() const {
            if (precedence == def) return "default";
            if (precedence == derived) return "derived";
            if (precedence == defined) return "defined";
            std::stringstream sprecedence;
            sprecedence << precedence;
            throw std::runtime_error("unknown precedence in QCParameter" + sprecedence.str());
            return "darn";
        }
 
        int get_print_order() const { return print_order; }
 
        std::string print_line(const std::string& key) const {
            auto fill_left = [](const int size, const std::string word) {
                int nspaces = std::max(int(0), size - int(word.length()));
                return std::string(nspaces, ' ') + word;
            };
            auto fill_right = [](const int size, const std::string word) {
                int nspaces = std::max(int(0), size - int(word.length()));
                return word + std::string(nspaces, ' ');
            };
 
            // key-value block
            std::string keyval = fill_left(20, key) + "  " + fill_right(10, get_value()) + " # " + fill_right(
                10, print_precedence());
            std::string empty_keyval(keyval.size(), ' ');
            empty_keyval[33] = '#';
 
            std::string allowed_val;
            if (allowed_values.size() > 0) {
                using madness::operators::operator<<;
                std::stringstream ss;
                ss << allowed_values;
                allowed_val += ss.str();
            }
 
            // split comment into several lines: split onto words and add linebreak
            bool leave_space_for_allowed_values = (allowed_val.size() > 0);
 
            // first line breaks after 80 characters, all other lines after 120 (leave space f
            long keyvalsize = keyval.size(); // length of key, value, precedence
            std::string comment1 = get_comment();
            auto commentwords = commandlineparser::split(comment1, " ");
            std::vector<std::string> commentlines(1);
            long nchar = 0;
            for (auto word : commentwords) {
                bool is_first_line = commentlines.size() == 1;
                long thislinebreak = 120;
                if (is_first_line and leave_space_for_allowed_values) thislinebreak = 80;
                long commentsize = thislinebreak - keyvalsize;
 
                nchar += word.size() + 1;
                if (nchar > commentsize) { // start newline
                    commentlines.push_back("");
                    nchar = word.size() + 1;
                }
                commentlines.back() += word + " ";
            }
 
            std::string result;
            for (size_t i = 0; i < commentlines.size(); ++i) {
                if (i == 0) result = keyval + fill_right(40, commentlines[i]) + allowed_val;
                else result += "\n" + empty_keyval + commentlines[i];
            }
 
            // trim result
            std::size_t last = result.find_last_not_of(' ');
            return result.substr(0, last + 1);
        }
 
        template <typename Archive>
        void serialize(Archive& ar) {
            ar & value & default_value & derived_value & user_defined_value & type & null &
                comment & allowed_values & print_order & precedence;
        }
 
        enum { def, derived, defined } precedence = def;
 
        bool operator==(const QCParameter& other) const {
            return (value == other.value and default_value == other.default_value and
                    derived_value == other.derived_value and user_defined_value == other.user_defined_value and
                    type == other.type and null == other.null and comment == other.comment and
                    allowed_values == other.allowed_values and print_order == other.print_order);
        }
 
        hashT hash() const {
            return hash_value(value);
        }
 
    private:
        void set_all() {
            value = default_value;
            if (derived_value != null) value = derived_value;
            if (user_defined_value != null) value = user_defined_value;
            if (not check_allowed()) throw std::invalid_argument(not_allowed_errmsg());
        }
 
        bool check_allowed() {
            if (allowed_values.size() == 0) return true;
            auto it = std::find(allowed_values.begin(), allowed_values.end(), value);
            return (it != allowed_values.end());
        }
 
        std::string not_allowed_errmsg() const {
            using madness::operators::operator<<;
            std::stringstream ss;
            ss << allowed_values;
            std::string errmsg = "\ntrying to assign a value that's not allowed\n\n";
            errmsg += "\tuser-defined value: " + value + "\n";
            errmsg += "\tallowed values:     " + ss.str() + "\n\n";
            return errmsg;
        }
 
 
        std::string value;
        std::string default_value = "";
        std::string derived_value = "";
        std::string user_defined_value = "";
        std::string type = "";
        std::string null = "";
        std::string comment = "";
        std::vector<std::string> allowed_values = std::vector<std::string>();
        int print_order = 0; // use this for printing the parameters in the same order as they are defined
    };
 
    /// class for holding the parameters for calculation
 
    /// Actual parameter classes will be derived from this class with a simple constructor
    /// (see test_QCCalculationParametersBase.cc for an example) and convenience
    /// getters for the parameters of each parameter class.
    /// Having the base class will allow consistent parameter input/output handling
    /// for all madness programs and reuse of the parsing methods.
    /// Even if the same parameter is used in different programs, default might differ
    /// (i.e. econv for 3D/6D calculations). The parameter class will effectively serve as
    /// a factory for the calculation classes (SCF, nemo, mp2, etc)
    ///
    /// parameters are kept in a map with key (string) and value (QCParameter),
    /// types are converted whenever a parameter is accessed (i.e. should not be
    /// done too frequently in an inner loop)
    class QCCalculationParametersBase {
    public:
        /// print all parameters
        void print(const std::string header = "", const std::string footer = "") const;
 
        virtual std::string get_tag() const = 0;
 
        std::string print_to_string(const std::list<std::string> precedences={"all"}) const;
 
        template <typename T>
        T get(const std::string key) const {
            const QCParameter& parameter = get_parameter(key);
            MADNESS_ASSERT(check_type<T>(key,parameter));
            if (std::is_same<T, std::string>::value) {
                return fromstring<T>(add_quotes(parameter.get_value()));
            }
            return fromstring<T>(parameter.get_value());
        }
 
        bool is_user_defined(std::string key) const {
            return get_parameter(key).is_user_defined();
        }
 
        template <typename Archive>
        void serialize(Archive& ar) {
            ar & parameters & print_debug;
        }
 
        hashT hash() const {
            return hash_range(parameters.begin(), parameters.end());
        }
 
    protected:
        typedef std::map<std::string, QCParameter> ParameterContainerT;
        ParameterContainerT parameters;
 
        void read_input_and_commandline_options(World& world,
                                                        const commandlineparser& parser,
                                                        const std::string tag) {
            try {
                // check that user-defined input files actually exist
                bool file_ok = true;
                if (parser.key_exists("user_defined_input_file")) file_ok = file_exists(world, parser.value("input"));
                if (file_ok) read_input(world, parser.value("input"), tag);
                else {
                    std::string msg = "could not find user-defined input file: " + parser.value("input") + "\n";
                    throw std::invalid_argument(msg);
                }
            }
            catch (std::invalid_argument& e) {
                throw;
            } catch (std::exception& e) {
                madness::print(e.what());
            }
            read_commandline_options(world, parser, tag);
        }
 
    public:
        bool file_exists(World& world, std::string filename) const;
 
        /// Apply `--<tag>=key=val` command-line overrides on top of the current
        /// values. Public so ParameterManager::initFromJson can layer CLI
        /// overrides after from_json (the text path gets them via the ctor's
        /// read_input_and_commandline_options; JSON decks otherwise ignored them).
        void read_commandline_options(World& world, const commandlineparser& parser, const std::string tag);
 
    private:
        /// read the parameters from file
 
        /// only world.rank()==0 reads the input file and broadcasts to all other nodes,
        /// so we don't need to serialize the ParameterMap
        void read_input(World& world, const std::string filename, const std::string tag);
 
    protected:
        bool print_debug = false;
        bool ignore_unknown_keys = true;
        bool ignore_unknown_keys_silently = false;
        bool throw_if_datagroup_not_found = false;
 
        /// ctor for testing
        QCCalculationParametersBase() {}
 
        /// copy ctor
        QCCalculationParametersBase(const QCCalculationParametersBase& other)
            : parameters(other.parameters)
              , print_debug(other.print_debug) {}
 
        /// destructor
        virtual ~QCCalculationParametersBase() {}
 
        template <typename T>
        void initialize(const std::string& key, const T& value, const std::string comment = "",
                        const std::vector<T> allowed_values = {}) {
            if (parameters.find(key) != parameters.end()) {
                madness::print("you cannot initialize a parameter twice: ", key);
                throw std::runtime_error("initialization error");
            }
 
            std::string svalue = tostring(value);
            std::string type = std::type_index(typeid(T)).name();
 
            // transform everything to lower case
            std::string key_lower = key;
            std::transform(key_lower.begin(), key_lower.end(), key_lower.begin(), ::tolower);
            std::transform(svalue.begin(), svalue.end(), svalue.begin(), ::tolower);
            std::vector<std::string> av_lower_vec;
            for (const T& av : allowed_values) {
                std::string av_lower = tostring(av);
                std::transform(av_lower.begin(), av_lower.end(), av_lower.begin(), ::tolower);
                av_lower_vec.push_back(av_lower);
            }
 
            parameters.insert(std::make_pair<std::string, QCParameter>
                (std::string(key_lower), QCParameter(svalue, type, comment, av_lower_vec)));
        }
 
    public:
        /// keys whose string values must NOT be case-folded
 
        /// String parameter values are lowercased on the way in so that enum-like
        /// knobs match their lowercased \c allowed_values (`xc=HF`, `units=Bohr`).
        /// That is wrong for free-form values such as paths and filenames, which
        /// are case-sensitive on the filesystem. Derived classes list those keys
        /// here and they are then stored verbatim -- the parameter-store analogue
        /// of \c commandlineparser::set_keyval_keep_case.
        virtual std::set<std::string> case_sensitive_keys() const { return {}; }
 
        bool keeps_case(const std::string& key) const {
            const auto keys = case_sensitive_keys();
            return keys.find(key) != keys.end();
        }
 
        template <typename T>
        void set_derived_value(const std::string& key, const T& value) {
            QCParameter& parameter = get_parameter(key);
            if (not check_type_silent<T>(parameter)) {
                throw std::runtime_error("type error in set_derived_value for key " + key);
            }
            parameter.set_derived_value(to_stored_string(key, value));
        }
 
        ParameterContainerT get_all_parameters() const {
            return parameters;
        }
 
    protected:
        /// helper function for try_setting_user_defined_value
        template <typename Tuple, std::size_t... I>
        bool try_setting_any_impl(const std::string& key, const std::string& value, Tuple, std::index_sequence<I...>) {
            bool success = false;
            (void)std::initializer_list<int>{
                (success = try_setting_user_defined_value<std::tuple_element_t<I, Tuple>>(key, value) || success, 0)...
            };
            return success;
        }
 
        /// helper function for try_setting_user_defined_value
        template <typename Tuple>
        bool try_setting_any(const std::string& key, const std::string& value) {
            return try_setting_any_impl(key, value, Tuple{}, std::make_index_sequence<std::tuple_size<Tuple>::value>{});
        }
 
        /// helper function for try_setting_user_defined_value
        template <typename T>
        bool try_setting_user_defined_value(const std::string& key, const std::string& val) {
            if (not check_type_silent<T>(get_parameter(key))) return false;
 
            if (print_debug) ::madness::print("key:", key, "will set type", std::type_index(typeid(T)).name());
            T value = fromstring<T>(val);
            set_user_defined_value<T>(key, value);
            return true;
        }
 
    public:
 
        template <typename... Types>
        bool try_set_from_json(QCParameter& parameter, const nlohmann::json& value) {
            bool success = false;
            (void)std::initializer_list<int>{
                (parameter.get_type() == std::type_index(typeid(Types)).name()
                    ? (parameter.set_user_defined_value(QCCalculationParametersBase::tostring(value.get<Types>())), success = true, 0)
                    : 0)...
            };
            return success;
        }
 
        void from_json(const json& j) {
            for (const auto& [key, value1] : j.items()) {
                const auto& value = value1; // avoid shadowing
                QCParameter& parameter = get_parameter(key);
                using all_types = all_parameter_types;
                bool ok = false;
                std::apply([&](auto&&... args) {
                    ok = try_set_from_json<std::decay_t<decltype(args)>...>(parameter, value);
                }, all_types{});
                if (!ok) {
                    throw std::runtime_error("Unsupported parameter type for key: " + key);
                }
            }
        }
        // Helper to forward tuple types to qcparameter_to_json
        template <typename... Types>
        void qcparameter_to_json(json& j, const std::pair<std::string, QCParameter>& p,
                                 const std::tuple<Types...>&) const {
            (void)std::initializer_list<int>{
                (check_type_silent<Types>(p.second) ? (j[p.first] = get<Types>(p.first), 0) : 0)...
            };
        }
 
        // Helper to forward tuple types to qcparameter_to_json
        template <typename Tuple>
        void qcparameter_to_json_from_tuple(json& j, const std::pair<std::string, QCParameter>& p, const Tuple&) const {
            std::apply([&](auto&&... args) {
                qcparameter_to_json(j, p, std::tuple<std::decay_t<decltype(args)>...>{});
            }, Tuple{});
        }
 
        /// convert all parameters to a json object
        [[nodiscard]] json to_json() const {
            json j_params = {};
            to_json(j_params);
            return j_params;
        }
 
        /// convert all parameters to a json object
        void to_json(json& j) const {
            json j_params = {};
            for (auto& p : parameters) {
                qcparameter_to_json_from_tuple(j_params, p, all_parameter_types{});
            }
            j["parameters"] = j_params;
        }
 
        /// convert all parameters to a json object, but only those with a given precedence
        [[nodiscard]] json to_json_if_precedence(
            const std::string& precedence) const {
            json j_params = {};
            for (auto& p : parameters) {
                if (p.second.print_precedence() == precedence) {
                    qcparameter_to_json_from_tuple(j_params, p, all_parameter_types{});
                }
            }
            return j_params;
        }
 
        template <typename T>
        void set_user_defined_value(const std::string& key, const T& value) {
            QCParameter& parameter = get_parameter(key);
            if (not check_type_silent<T>(parameter)) {
                throw std::runtime_error("type error in set_user_defined_value");
            }
 
            // Name the key in the allowed-values message. QCParameter does not
            // know its own key, so an out-of-range value used to report only the
            // value and the list of alternatives, leaving the reader to guess
            // which keyval it came from -- an input may set several that have
            // allowed values.
            try {
                parameter.set_user_defined_value(to_stored_string(key, value));
            } catch (const std::invalid_argument& e) {
                throw std::invalid_argument("in keyword `" + key + "`: " + e.what());
            }
        }
 
        /// stringify \p value for storage, honoring case_sensitive_keys()
        template <typename T>
        std::string to_stored_string(const std::string& key, const T& value) const {
            if constexpr (std::is_same<T, std::string>::value) {
                if (keeps_case(key)) return value;
            }
            return tostring(value);
        }
 
        friend bool operator==(const QCCalculationParametersBase& p1,
                        const QCCalculationParametersBase& p2);
 
    protected:
        const QCParameter& get_parameter(const std::string& key) const {
            if (not parameter_exists(key)) {
                throw std::runtime_error("could not find parameter for key " + key);
            }
            const QCParameter& parameter = parameters.find(key)->second;
            return parameter;
        }
 
    public:
        QCParameter& get_parameter(const std::string key) {
            if (not parameter_exists(key)) {
                madness::print("\ncould not find parameter for key", key, "\n");
                throw std::runtime_error("could not find parameter for key " + key);
            }
            QCParameter& parameter = parameters.find(key)->second;
            return parameter;
        }
 
        bool parameter_exists(const std::string& key) const {
            return (parameters.find(key) != parameters.end());
        }
 
        template <typename T>
        static bool check_type(const std::string key, const QCParameter& parameter) {
            if (check_type_silent<T>(parameter))
                return true;
 
            madness::print(
                "trying to get the wrong type in QCCalculationParametersBase");
            madness::print("key             ", key);
            madness::print("parameter type  ", parameter.get_type());
            madness::print("setting type    ", std::type_index(typeid(T)).name());
            madness::print("value           ", parameter.get_value());
            return false;
        }
 
        template <typename T>
        static bool check_type_silent(const QCParameter& parameter) {
            return (parameter.get_type() == std::type_index(typeid(T)).name());
        }
 
        /// read the stream, starting from tag
 
        /// only parameters that are defined in the constructor will be processed,
        /// all others will be discarded.
        virtual void read_internal(World& world, std::string& filecontents,
                                   std::string tag);
 
        static std::string tostring(const bool& arg) {
            std::ostringstream ss;
            ss << std::boolalpha << arg;
            return ss.str();
        }
 
        template <typename T>
        static std::string tostring(const T& arg) {
            using madness::operators::operator<<;
            std::ostringstream ss;
            static_assert(not std::is_same<T, bool>::value, "you need to specialize tostring for this type");
 
            ss << std::scientific << std::setprecision(4) << arg;
            std::string str = ss.str();
            std::transform(str.begin(), str.end(), str.begin(), ::tolower);
 
            overwrite_if_inf(str, arg);
            return str;
        }
 
        template <typename T>
        static typename std::enable_if<std::is_floating_point<T>::value, void>::type
        overwrite_if_inf(std::string& str, const T& arg) {
            MADNESS_PRAGMA_CLANG(diagnostic push)
            MADNESS_PRAGMA_CLANG(diagnostic ignored "-Wtautological-constant-compare")
            if (std::isinf(arg)) {
                std::stringstream ss;
                ss << std::numeric_limits<T>::infinity();
                str = ss.str();
            }
            MADNESS_PRAGMA_CLANG(diagnostic pop)
        }
 
        template <typename T>
        static typename std::enable_if<!std::is_floating_point<T>::value, void>::type
        overwrite_if_inf(std::string& str, const T& arg) {
            return;
        }
 
        template <typename T>
        static typename std::enable_if<!std::is_same<T, bool>::value, T>::type
        fromstring(const std::string& arg) {
            std::stringstream ssvalue(arg);
 
            // if argument is std::string read the everything between possible double quotes
            T result = read_quotes<T>(ssvalue);
 
            bool type_conversion_failed = ssvalue.fail();
 
            // check for infinity in floating point conversions
            if (type_conversion_failed and (std::is_floating_point<T>::value)) {
                const static T inf = std::numeric_limits<T>::infinity();
                std::string sinf = tostring(inf); // repeat type conversion from above
                if (sinf == arg)
                    result = inf;
                type_conversion_failed = false;
            }
 
            if (type_conversion_failed) {
                std::string errmsg = "error in type conversion for argument >> " + arg +
                    " << to type " + std::type_index(typeid(T)).name();
                throw std::runtime_error(errmsg);
            }
 
            // check for trailing characters
            std::string word;
            while (ssvalue >> word) {
                std::string errmsg = "trailing characters in arguement >> " + arg + " <<";
                throw std::runtime_error(errmsg);
            }
            return result;
        }
 
        template <typename T>
        static typename std::enable_if<std::is_same<T, std::string>::value, T>::type
        read_quotes(std::stringstream& ssvalue) {
            T arg = ssvalue.str();
            T result;
 
            if (arg.find("\"") == std::string::npos) { // no double quotes found
                ssvalue >> result;
            }
            else { // found double quotes
                int counter = 0;
                while (counter < 2) {
                    T tmp;
                    ssvalue >> tmp;
                    if (ssvalue.fail()) {
                        std::string errmsg = "missing closing double quote in line >> " + arg;
                        throw std::runtime_error(errmsg);
                    }
                    result += " " + tmp;
                    counter = std::count(result.begin(), result.end(), '"');
                }
 
                // use only the text between the double quotes
                result = trim_blanks(trim_quotes(result));
            }
            return result;
        }
 
        static std::string trim_blanks(const std::string arg) {
            std::size_t first = arg.find_first_not_of(' ');
            std::size_t last = arg.find_last_not_of(' ');
            return arg.substr(first, last - first + 1);
        }
 
        static std::string trim_quotes(const std::string arg) {
            std::size_t first = arg.find_first_of('"');
            std::size_t last = arg.find_last_of('"');
            return arg.substr(first + 1, last - first - 1);
        }
 
        static std::string add_quotes(const std::string arg) {
            return "\"" + arg + "\"";
        }
 
        template <typename T>
        static typename std::enable_if<!std::is_same<T, std::string>::value, T>::type
        read_quotes(std::stringstream& ssvalue) {
            T result;
            ssvalue >> result;
            return result;
        }
 
        template <typename T>
        static typename std::enable_if<std::is_same<T, bool>::value, T>::type
        fromstring(const std::string& arg) {
            std::string str = arg;
            std::transform(str.begin(), str.end(), str.begin(), ::tolower);
            if (str == "true" or str == "1" or str == "yes")
                return true;
            if (str == "false" or str == "0" or str == "no")
                return false;
            std::string errmsg = "error in type conversion for argument >> " + arg +
                " << to type " + std::type_index(typeid(T)).name();
            throw std::runtime_error(errmsg);
            return 0;
        }
 
 
        // a templated list of all acceptable parameter types for looping in a parameter pack
        using all_parameter_types = std::tuple<
            double, int, unsigned int, long, std::size_t, bool, std::string,
            std::vector<double>, std::vector<int>, std::vector<std::size_t>,
            std::vector<std::string>, std::pair<std::string, double>>;
    };
 
    bool operator!=(const QCCalculationParametersBase& p1,
                    const QCCalculationParametersBase& p2);
} /* namespace madness */
 
#endif /* SRC_APPS_CHEM_QCCALCULATIONPARAMETERSBASE_H_ */