Castable.h

/*
 
MIT License
 
Copyright (c) 2017 FMI Open Development / Markus Peura, first.last@fmi.fi
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
 
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
 
*/
/*
Part of Rack development has been done in the BALTRAD projects part-financed
by the European Union (European Regional Development Fund and European
Neighbourhood Partnership Instrument, Baltic Sea Region Programme 2007-2013)
*/
 
#ifndef DRAIN_CASTABLE2
#define DRAIN_CASTABLE2 "drain::Castable"
 
#include <string.h> // Old C
#include <cstddef>
#include <typeinfo>
#include <stdexcept>
#include <iostream>
#include <vector>
#include <list>
#include <set>
#include <string>
 
#include "Caster.h"
#include "Sprinter.h"
#include "String.h"
#include "UniTuple.h"
 
 
namespace drain {
 
// Forward declaration
// class Variable;
 
// Forward declaration
// class Referencer;
 
 
class Castable  {
 
// Optionally, constructors of this base class could be protected.
public:
 
    inline
    Castable() : fillArray(false), elementCount(0){
        setSeparator();
        caster.unsetType();
    };
 
    inline
    Castable(const Castable &c) : fillArray(false), elementCount(0) {
        copyFormat(c); // modifies elementCount = misleading; rename?
        setPtr(c.caster.ptr, c.caster.getType(), c.elementCount);
    }
 
    template <class F>
    Castable(F &p) : fillArray(false), elementCount(0) {
        setSeparator();
        setPtr(p);
    }
 
    // Obsolete?
    template <class F>
    Castable(F *p) : fillArray(false), elementCount(0) {
        setSeparator();
        setPtr(p, typeid(F));
        // std::cerr << "Castable(F *p) type=" << typeid(F).name() << " value=" << *p << " (" << (double)*p << ")" << std::endl;
    }
 
 
    inline virtual
    ~Castable(){};
 
 
    virtual inline
    bool typeIsSet() const {
        return caster.typeIsSet();
    };
 
 
    bool empty() const;
 
    virtual inline
    const std::type_info & getType() const {
        return caster.getType();
    };
 
    inline
    bool isValid() const {
        return (caster.typeIsSet()) && (caster.ptr != nullptr);
    };
 
 
    virtual inline
    bool isLinking() const { // rename: external?
        return isValid(); // return false, if nullptr
        // return true;
    }
 
 
    virtual inline
    bool isVariable() const { // needed?
        return false;
    }
 
    inline
    bool isCharArrayString() const {
        return ((caster.getType() == typeid(char)) && (outputSeparator=='\0'));  // "close enough" guess, or a definition?
    };
 
    inline
    bool isStlString() const {
        return (caster.getType() == typeid(std::string));
    };
 
    inline
    bool isString() const {
        return (isCharArrayString() || isStlString());
    };
 
 
 
    virtual inline
    size_t getElementCount() const {
        return elementCount;
    }
 
 
    inline
    size_t getElementSize() const {
        return caster.getElementSize();
    };
 
 
    virtual inline
    size_t getSize() const {
        return elementCount * caster.getElementSize();
    }
 
 
 
    inline
    Castable & setFill(bool fill=true){
        fillArray = fill;
        return *this;
    }
 
    // Has been protected, even private. Why? Essentially setting a value.
    void clear();
 
    inline
    void reset(){
        caster.unsetType();
        updateSize(0);
        setSeparator(',');
    }
 
 
    std::string getTypeName() const { // todo: support const string &  in Type::call
        if (isCharArrayString()){
            static const std::string s("char-array");
            return s;
        }
        else {
            return Type::call<drain::simpleName>(getType());
        }
    }
 
 
public:
 
 
    template <class T>
    Castable &operator=(const T &x){
        //std::cout << "op= " << x << " -> " << Type::getTypeChar(getType()) << ',' << getElementCount() << std::endl;
        assign(x);
        return *this;
    }
 
    inline
    Castable & operator=(const char *c){
        assignString(c);
        return *this;
    }
 
 
    template <class T>
    Castable & operator=(const T *x){
        throw std::runtime_error("Castable & operator=(const T *x): unsupported");
        return *this;
    }
 
 
    inline
    Castable &operator=(const Castable &c){
        if (&c != this){
            assignCastable(c);
        }
        return *this;
    }
 
 
    /*
    inline
    Castable &operator=(const Variable &c){
        return assignCastable(c);
    }
 
    inline
    Castable &operator=(const Referencer &c){
        return assignCastable(c);
    }
    */
 
    // Special handler for string assignment
    inline
    void assign(const std::string &c){
        assignString(c);
    }
 
 
    inline
    void assign(const char *c){
        assignString(c);
    }
 
    // "NEW"
    inline
    void assign(const Castable &c){
        assignCastable(c);
    }
 
    template <class T>
    inline
    void assign(const T *p){
        if (p == nullptr)
            reset();
        else
            throw std::runtime_error("Castable & assign(const T *p): unsupported");
    }
 
 
    template <class T>
    void assign(const T &x){
        // std::cout << "assign " << x << " -> " << Type::getTypeChar(getType()) << ',' << getElementCount() << std::endl;
        suggestType(typeid(T));
        if (isString()){
            //std::cout << __FUNCTION__ << ':' << x << " -> " << Type::getTypeChar(getType()) << ',' << getElementCount() << '\n';
            assignToString(x);
        }
        else if (typeIsSet()){
            if (fillArray){
                for (size_t i = 0; i<getElementCount(); ++i){
                    caster.put(getPtr(i), x);
                }
            }
            else {
                requestSize(1);
                caster.put(x);
            }
        }
        else {
            throw std::runtime_error(std::string(__FUNCTION__) + ": type is unset");
        }
 
 
    }
 
 
 
    template<typename T>
    // Castable & operator=(std::initializer_list<T> l){
    void assign(std::initializer_list<T> l){
        assignContainer(l);
        //return *this;
    }
 
    template <class T>
    inline
    // Castable &operator=(const std::list<T> & l){
    void assign(const std::list<T> & l){
        assignContainer(l);
        // return *this;
    }
 
    template <class T>
    inline
    // Castable &operator=(const std::vector<T> & v){
    void assign(const std::vector<T> & v){
        assignContainer(v);
        // return *this;
    }
 
    template <class T>
    inline
    // Castable &operator=(const std::set<T> & s){
    void assign(const std::set<T> & s){
        assignContainer(s);
        //return *this;
    }
 
 
    Castable & assignCastable(const Castable &c);
 
 
 
    template <class T>
    inline
    Castable &operator<<(const T &x){
        append(x);
        return *this;
    }
 
 
    /*
     *  Note: if both source and target are strings, does not split it like with Variable::operator=(const char *).
     */
    template <class T>
    inline
    //Castable &operator<<(const T &x){
    void append(const T &x){
        suggestType(typeid(T));
        if (isString()){
            appendToString(x);
        }
        else {
            appendToElementArray(x);
        }
        //return *this;
    }
 
    inline
    // Castable &operator<<
    void append(const char *s){
        //return *this << (std::string(s));
        append(std::string(s));
    }
 
    template <class T>
    inline  
    void append(const std::list<T> & l){
        assignContainer(l, true);
        //return *this;
    }
 
    template <class T>
    inline
    // Castable &operator<<
    void append(const std::vector<T> & v){
        assignContainer(v, true);
    }
 
    template <class T>
    inline  // Castable &operator<<
    void append(const std::set<T> & s){
        assignContainer(s, true);
        // return *this;
    }
 
    // NEW 2025
    inline // protected
    void append(){
    }
 
    template <class T, class ...TT>
    void append(const T &arg, const TT& ...args){
        //Castable::operator<<(x);
        append(arg);
        append(args...);
        //return *this;
    }
 
 
    template <class T>
    inline
    T get(size_t i) const {
        if (i >= elementCount)
            throw std::runtime_error("Castable::get() index overflow");
        return caster.get<T>(getPtr(i));
    }
 
    /*
    template <class T>
    inline
    void setElem(size_t i) const {
        if (i >= elementCount)
            throw std::runtime_error("Castable::get() index overflow");
        return caster.get<T>(getPtr(i));
    }
    */
 
 
 
    inline
    operator std::string() const {
        return toStr();
    }
 
    //  Thanks to Mikael Kilpeläinen.
    template <class T>
    operator T() const {
        if (isCharArrayString()){
            T x;
            std::stringstream sstr;
            sstr << getCharArray();
            sstr >> x;
            return x;
        }
        else
            return caster.get<T>(); //caster.get<T>(ptr);
    }
 
    template <class T, size_t N>
    operator UniTuple<T,N>() const {
        UniTuple<T,N> result;
        result.assignSequence(*this, true);
    }
 
 
    inline
    bool operator==(const Castable &c) const {
        // std::cerr << __FILE__ << __LINE__ << __FUNCTION__ << std::endl;
        //throw std::runtime_error("Castable: operator== not implemented.");
 
        if (!this->typeIsSet()){
            return !c.typeIsSet(); // is "same"... (?)
        }
 
        if (!c.typeIsSet()){
            return false; // could return false for both?
        }
 
        if (this->isString() || c.isString()){ // NOTE: precision loss in rounding numbers
            return (this->toStr() == c.toStr());
        }
 
        if (this->getElementCount() != c.getElementCount()){
            return false;
        }
 
 
        for (size_t i = 0; i<this->getElementCount(); ++i){
            if (! caster.compare(getPtr(i), c.caster, c.getPtr(i))){
                return false;
            }
        }
 
        return true;
    }
 
    inline
    bool operator==(const char * s) const {
        if (isCharArrayString()) // 2021
            return (strcmp(getCharArray(), s) == 0);
        else {
            // Note: caster.get<std::string>() returns only the first element!
            // std::cerr << __FILE__ << __LINE__ << __FUNCTION__ << toStr() << " vs " << caster.get<std::string>() << std::endl;
            return (toStr() == s);
        }
            //return (caster.get<std::string>() == s);
    }
 
 
    inline
    bool operator==(const nullptr_t ptr) const {
        return getType() == typeid(void);
    }
 
    /*
    inline  // 2024
    bool operator==(const std::string & s) const {
        return (caster.get<std::string>() == s);
    }
    */
 
    template <class T>
    bool operator==(const T &x) const {
        if (isCharArrayString()){ // 2024/04
            std::stringstream sstr(getCharArray());
            T c;
            sstr >> c;
            return (c == x);
        }
        else {
            return (caster.get<T>() == x);
        }
    }
 
    template <class T, size_t N>
    bool operator==(const UniTuple<T,N> & x) const {
        if (isString()){ // 2024/04
            // std::cerr << __FILE__ << ':' << __FUNCTION__ << " '" << this->toStr() << "' == '" << x.toStr(',') << "'" << std::endl;
            return (this->toStr() == x.toStr(',')); // consider separator, but this->outputSeparator is null for char array str...
        }
        else if (elementCount == N){
            for (size_t i=0; i<N; ++i){
                if (x[i] != this->get<T>(i)){
                    return false;
                }
            }
            return true;
        }
        else {
            return false;
        }
 
    }
 
 
 
 
    template <class T>
    bool operator!=(const T &x) const {
        return ! this->operator==(x);
    }
 
    bool operator!=(const char *x) const {
        return ! this->operator==(x);
    }
 
 
    // strings?
    template <class T>
    bool operator<(const T &x) const {
        return (caster.get<T>() < x);
    }
 
    template <class T>
    bool operator>(const T &x) const {
        return (caster.get<T>() > x);
    }
 
    // strings?
    template <class T>
    bool operator<=(const T &x) const {
        return (caster.get<T>() <= x);
    }
 
    template <class T>
    bool operator>=(const T &x) const {
        return (caster.get<T>() >= x);
    }
 
 
    inline
    Castable & setSeparator(char c = ','){
        setInputSeparator(c);
        setOutputSeparator(c);
        return *this;
    }
 
 
    inline
    void setInputSeparator(char c = ','){
        inputSeparator = c;
    }
 
 
    inline
    void setOutputSeparator(char c = ','){
        outputSeparator = c;
    }
 
 
    inline
    char getInputSeparator(){
        return inputSeparator;
    }
 
 
    inline
    char getOutputSeparator(){
        return outputSeparator;
    }
 
 
    std::ostream & toStream(std::ostream & ostr = std::cout, char separator='\0') const;
 
    std::istream & fromStream(std::istream & istr);
 
 
    std::string toStr() const;
 
    void typeInfo(std::ostream & ostr) const;
 
    // Writes a bit longer type indentifier and size in bytes, for example "unsigned int(8) for char and "signed int(16) for signed short int."
    virtual
    void info(std::ostream & ostr = std::cout) const;
 
    // void debug(std::ostream & ostr = std::cout) const;
 
 
 
 
    template <class T>
    void toSequence(T & container, char separator = 0) const { // FIX raise
 
        container.clear();
 
        if (isString()){
            if (!separator)
                separator = this->outputSeparator;
            StringTools::split(toStr(), container, separator," \t\n");
        }
        else {
            for (size_t i = 0; i < getElementCount(); ++i) {
                container.insert(container.end(), caster.get<typename T::value_type>(getPtr(i)) );
            }
        }
 
 
    }
 
 
 
    template <class T>
    void toMap(T & map, char separator = 0, char equalSign = '=') const {
 
        map.clear();
 
        if (isString()){
            // This part could be in StringTools?
            typedef std::list<std::string> entryList;
            entryList entries;
            toSequence(entries, separator);
 
            for (entryList::const_iterator it = entries.begin(); it!=entries.end(); ++it){
                //typename T::value_type entry;
                typename T::key_type key;
                typename T::mapped_type data;
                drain::StringTools::split2(*it, key, data, std::string(1, equalSign)); // TRIM?
                map[key] = data;
            }
        }
        else {
            for (size_t i = 0; i < getElementCount(); ++i){
                //typename T::value_type entry;
                typename T::key_type key;
                typename T::mapped_type data;
                std::stringstream sstr;
                sstr << i;
                sstr >> key; // entry.first;
                std::stringstream sstr2;
                //sstr2 << caster.get<typename T::value_type>(getPtr(i)); // weirds
                sstr2 << caster.get<typename T::mapped_type>(getPtr(i)); // weirds
                sstr2 >> data;
                map[key] = data;
            }
        }
 
 
    }
 
 
 
    inline
    char * getPtr(size_t i = 0) {
        return &((char *)caster.ptr)[i*caster.getElementSize()];
    }
 
    inline
    const char * getPtr(size_t i = 0) const {
        return &((const char *)caster.ptr)[i*caster.getElementSize()];
    }
 
 
    void copyFormat(const Castable & c){
        this->elementCount    = c.elementCount;
        this->inputSeparator  = c.inputSeparator;
        this->outputSeparator = c.outputSeparator;
        this->fillArray       = c.fillArray;
    }
 
 
    virtual inline
    bool requestType(const std::type_info & t){
        return (getType() == t);
    }
 
 
    virtual inline
    bool suggestType(const std::type_info & t){
        return (getType() == t);
    }
 
    bool fillArray = false;
 
protected:
 
    virtual
    void updateSize(size_t elems){
        elementCount = elems;
    }
 
protected:
 
    Caster caster;
 
 
 
    template <class F>
    inline // FINAL
    void setType(){
        setType(typeid(F));
    }
 
    virtual inline // virtual?  Variable may need
    void setType(const std::type_info &t){
        setSeparator(','); // ?
        caster.setType(t);
        //elementCount = 1; ?
    }
 
 
    virtual inline
    bool requestSize(size_t elementCount){
        return (getElementCount() == elementCount);
    }
 
 
    template <class F>
    inline
    void setPtr(void *p){
        caster.link(p);
        elementCount = 1;
    }
 
 
    template <class F>
    void setPtr(F &p){
        if ((!std::is_arithmetic<F>::value) && (typeid(F)!=typeid(std::string))){
            throw std::runtime_error(std::string(__FUNCTION__) + ": unsupported type: " + typeid(F).name());
        }
        caster.link(p); // could use setPtr(void *p, const std::type_info &t) ?
        elementCount = 1;
    }
 
    /*
     *  Function of this kind must be available for general (8bit) memory allocators.
     */
    inline
    void setPtr(void *p, const std::type_info &t, size_t count=1){
        //if (t == typeid(void))
        //  throw std::runtime_error(std::string(__FUNCTION__) + ": explicit void type given");
        caster.link(p, t);
        elementCount = count;
    }
 
 
    /*
    template <class F>
    // void setPtr(std::pair<F,F> &p){
        setPtr(&p, typeid(F), 2);
        //caster.link((F*)&v);
        fillArray = true; // if a scalar is assigned, assign to both elements
        //elementCount = 2;
    }
    */
 
 
    template <class F, size_t N>
    void setPtr(UniTuple<F,N> & tuple){
        setPtr(tuple.begin(), typeid(F), N);
        fillArray = true; // (?)  if a scalar is assigned, assign to all elements
    }
 
 
 
 
    void relink(Castable & c);
 
 
    /*
    inline
    void setPtr(const Castable &c){
        //caster.link0((const Caster &)c);
 
        caster.ptr = c.caster.ptr;
        caster.setType(c.getType());
 
        elementCount = c.elementCount; // TODO
        outputSeparator = c.outputSeparator; // ?
    }
 
    inline
    void setPtr(Castable &c){
        caster.link0((Caster &)c);
        // caster.ptr = c.caster.ptr;
        // caster.setType(c.getType());
        elementCount = c.elementCount; // TODO
        outputSeparator = c.outputSeparator; // ?
    }
    */
 
    // IMPORTANT!
    inline
    void castElement(size_t i, const Caster &c, void *p) const {
        c.translate(caster, getPtr(i), p);
    }
 
 
    // Destination type (current type) specific assign operations
 
 
 
 
    template <class T>
    void appendToString(const T & x){
 
        std::stringstream sstr;
 
        // drain::Sprinter::toStream(sstr, *this, drain::Sprinter::plainLayout);
        toStream(sstr);
 
        if (inputSeparator && (getElementCount()>1)){
            sstr << inputSeparator;
        }
        sstr << x;
 
        std::string  s = sstr.str();
 
        suggestType(typeid(std::string));
 
        if (isStlString()){
            caster.put(s);
            //caster.put(ptr, s);
        }
        else if (isCharArrayString()){
            assignToCharArray(s);
        }
        else {
            throw std::runtime_error(std::string(__FUNCTION__) + ": type is not a string: " + typeid(T).name());
        }
    }
 
 
    template <class T>
    void assignToString(const T & x){
 
        /*
        if (x == nullptr){
            //suggestType(typeid(void));
            suggestType(typeid(void));
            //experimental
            return;
        }
        */
 
        suggestType(typeid(std::string));
 
        if (isStlString()){
            caster.put(x);
            //caster.put(ptr, x);
        }
        else if (isCharArrayString()){
            requestSize(0);  // works only for Variable, ok
            clear(); // works always (but if elementCount)
            appendToString(x);
        }
        else {
            throw std::runtime_error(std::string(__FUNCTION__) + ": type is std::string");
        }
    }
 
    void assignToCharArray(const std::string & s);
 
    inline
    void assignToCharArray(const char *s){
        assignToCharArray(std::string(s));
    }
 
 
    template <class T>
    void assignToCharArray(const T & s){
        std::stringstream sstr;
        sstr << s;
        assignToCharArray(sstr.str());
    }
 
 
    inline
    void appendToElementArray(const char *s){
        appendToElementArray(std::string(s));
    }
 
    template <class T>
    void appendToElementArray(const T & s){
 
        suggestType(typeid(T)); // check return code?
        if (!typeIsSet()){
            throw std::runtime_error(std::string(__FUNCTION__) + ": type is unset");
            return;
        }
 
        // Check if now type==string...
        if (isString()){
            throw std::runtime_error(std::string(__FUNCTION__) + ": type is std::string (not implemented yet)");
            //return;
        }
 
        // Extend array.
        requestSize(getElementCount() + 1);
        if (empty()){
            throw std::runtime_error(std::string(__FUNCTION__) + ": still empty after resize request(+1)");
            return;
        }
 
        // TODO: what if non-empty but fixed?
 
        caster.put(getPtr(getElementCount()-1), s);
 
    }
 
 
 
public:
    /* public NEW 2021 (experimental)
     *
     * useful in "stream" definitions:
     * drain::Referencer(range.tuple()).setSeparator(':').setFill().assignString(ftor);
     *
     */
 
 
 
    void assignString(const std::string &s);
 
    // NEW 2024
    template <class T, size_t N>
    inline
    void assign(const UniTuple<T,N> & tuple){
        assignContainer(tuple);
    }
 
    template <class T>
    void assignContainer(const T & v, bool append=false) {
 
        if (!append){
            if (isStlString())
                clear();
            else
                requestSize(0);
        }
 
        suggestType(typeid(typename T::value_type));
        // Note: sequence of strings, will request string type...
 
        if (isString()){
            std::stringstream sstr;
            if (append){
                drain::Sprinter::toStream(sstr, *this, drain::Sprinter::plainLayout);
                //toStream(sstr);  // outputsepp?
                if (inputSeparator)
                    sstr << inputSeparator;
            }
            StringTools::join(v, sstr, inputSeparator); // implement!
            assignToString(sstr.str());
        }
        else if (caster.typeIsSet()){
 
            if (append){
                for (typename T::const_iterator it = v.begin(); it != v.end(); ++it){
                    appendToElementArray(*it);
                }
            }
            else {
                requestSize(v.size());
                typename T::const_iterator it = v.begin();
                typename T::const_iterator itLast = it;
                for (size_t i = 0; i<getElementCount(); ++i){
                    if (it == v.end()){
                        if (fillArray)
                            it = itLast; //v.begin(); WHAT if empty?
                        else
                            return;
                    }
                    else {
                        itLast = it;
                    }
                    caster.put(getPtr(i), *it);
                    ++it;
                }
            }
        }
        else {
            throw std::runtime_error(std::string(__FILE__) + ": type unset, cannot assign");
        }
 
    }
 
 
 
    /* OLD
    inline
    const char * getCharArray() const {
 
        if (!isCharArrayString())
            throw std::runtime_error("getCharArray: type not char array...");
 
        if (empty()){
            static const char * empty = "";
            return empty;
            // throw std::runtime_error("getCharArray: empty array, no even null char");
        }
 
        if (*getPtr(getElementCount()-1) != '\0')
            throw std::runtime_error("getCharArray: no terminating null char");
 
        return getPtr();
 
    }
    */
 
 
    // NEW
 
public:
 
    const char * getCharArray() const;
 
protected:
 
    //  void *ptr;
 
    size_t elementCount;
 
    char inputSeparator;
 
    char outputSeparator;
 
 
};
 
 
 
template <>
std::ostream & Sprinter::toStream(std::ostream & ostr, const drain::Castable & x, const SprinterLayout & layout);
 
 
 
inline
std::ostream & operator<<(std::ostream &ostr, const Castable &c){
    return c.toStream(ostr);
    //return Sprinter::toStream(ostr, c, Sprinter::plainLayout);
}
 
/*  UNDER CONSTR..
inline
std::istream & operator>>(std::istream & istr, Castable &c){
    return c.fromStream(istr);
}
*/
 
template <class T>
inline
T & operator+=(T & x, const Castable &c){
    x += c.get<T>(0);
    return x;
}
 
template <class T>
inline
T & operator-=(T & x, const Castable &c){
    x -= c.get<T>(0);
    return x;
}
 
template <class T>
inline
T & operator*=(T & x, const Castable &c){
    x *= c.get<T>(0);
    return x;
}
 
template <class T>
inline
T & operator/=(T & x, const Castable &c){
    x /= c.get<T>(0);
    return x;
}
 
 
 
template <>
const std::string TypeName<Castable>::name;
 
/*
template <class T, size_t N=2>
template <class T2>
UniTuple<T,N> & UniTuple<T,N>::set(const Castable & t){
    // assignSequence(t, true); // by default LENIENT, or how should it be?
    return *this;
}
*/
 
 
}  // namespace drain
 
 
#endif
 
// Drain