TclObject.hh

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#ifndef TCLOBJECT_HH
#define TCLOBJECT_HH

#include "string_view.hh"
#include "span.hh"
#include "vla.hh"
#include "xxhash.hh"
#include <tcl.h>
#include <algorithm>
#include <initializer_list>
#include <iterator>
#include <cassert>
#include <cstdint>

struct Tcl_Obj;

namespace openmsx {

class Interpreter;

class TclObject
{
        // For STL interface, see below
        struct iterator {
                using value_type        = string_view;
                using reference         = string_view;
                using pointer           = string_view*;
                using difference_type   = ptrdiff_t;
                using iterator_category = std::bidirectional_iterator_tag;

                iterator(const TclObject& obj_, unsigned i_)
                        : obj(&obj_), i(i_) {}

                bool operator==(const iterator& other) const {
                        assert(obj == other.obj);
                        return i == other.i;
                }
                bool operator!=(const iterator& other) const {
                        return !(*this == other);
                }

                string_view operator*() const {
                        return obj->getListIndexUnchecked(i).getString();
                }

                iterator& operator++() {
                        ++i;
                        return *this;
                }
                iterator operator++(int) {
                        iterator result = *this;
                        ++result;
                        return result;
                }
                iterator& operator--() {
                        --i;
                        return *this;
                }
                iterator operator--(int) {
                        iterator result = *this;
                        --result;
                        return result;
                }
        private:
                const TclObject* obj;
                unsigned i;
        };

public:

        TclObject()                                  { init(Tcl_NewObj()); }
        explicit TclObject(Tcl_Obj* o)               { init(o); }
        template<typename T> explicit TclObject(T t) { init(newObj(t)); }
        TclObject(const TclObject&  o)               { init(newObj(o)); }
        TclObject(      TclObject&& o) noexcept      { init(newObj(o)); }

        struct MakeListTag {};
        template<typename... Args>
        TclObject(MakeListTag, Args&&... args) {
                init(newList({newObj(std::forward<Args>(args))...}));
        }

        struct MakeDictTag {};
        template<typename... Args>
        TclObject(MakeDictTag, Args&&... args) {
                init(Tcl_NewDictObj());
                addDictKeyValues(std::forward<Args>(args)...);
        }

        ~TclObject() { Tcl_DecrRefCount(obj); }

        // assignment operators
        TclObject& operator=(const TclObject& other) {
                if (&other != this) {
                        Tcl_DecrRefCount(obj);
                        init(other.obj);
                }
                return *this;
        }
        TclObject& operator=(TclObject&& other) noexcept {
                std::swap(obj, other.obj);
                return *this;
        }
        template<typename T>
        TclObject& operator=(T t) {
                if (Tcl_IsShared(obj)) {
                        Tcl_DecrRefCount(obj);
                        obj = newObj(t);
                        Tcl_IncrRefCount(obj);
                } else {
                        assign(t);
                }
                return *this;
        }

        // get underlying Tcl_Obj
        Tcl_Obj* getTclObject() { return obj; }
        Tcl_Obj* getTclObjectNonConst() const { return const_cast<Tcl_Obj*>(obj); }

        // add elements to a Tcl list
        template<typename T> void addListElement(T t) { addListElement(newObj(t)); }
        template<typename ITER> void addListElements(ITER first, ITER last) {
                addListElementsImpl(first, last,
                                typename std::iterator_traits<ITER>::iterator_category());
        }
        template<typename Range> void addListElements(Range&& range) {
                addListElements(std::begin(range), std::end(range));
        }
        template<typename... Args> void addListElement(Args&&... args) {
                addListElementsImpl({newObj(std::forward<Args>(args))...});
        }

        // add key-value pair(s) to a Tcl dict
        template<typename Key, typename Value>
        void addDictKeyValue(const Key& key, const Value& value) {
                addDictKeyValues({newObj(key), newObj(value)});
        }
        template<typename... Args> void addDictKeyValues(Args&&... args) {
                addDictKeyValues({newObj(std::forward<Args>(args))...});
        }

        // value getters
        string_view getString() const;
        int getInt      (Interpreter& interp) const;
        bool getBoolean (Interpreter& interp) const;
        double getDouble(Interpreter& interp) const;
        span<const uint8_t> getBinary() const;
        unsigned getListLength(Interpreter& interp) const;
        TclObject getListIndex(Interpreter& interp, unsigned index) const;
        TclObject getDictValue(Interpreter& interp, const TclObject& key) const;
        template<typename Key>
        TclObject getDictValue(Interpreter& interp, const Key& key) const {
                return getDictValue(interp, TclObject(key));
        }

        // STL-like interface when interpreting this TclObject as a list of
        // strings. Invalid Tcl lists are silently interpreted as empty lists.
        unsigned size() const { return getListLengthUnchecked(); }
        bool empty() const { return size() == 0; }
        auto begin() const { return iterator(*this, 0); }
        auto end()   const { return iterator(*this, size()); }

        // expressions
        bool evalBool(Interpreter& interp) const;

        TclObject executeCommand(Interpreter& interp, bool compile = false);

        friend bool operator==(const TclObject& x, const TclObject& y) {
                return x.getString() == y.getString();
        }
        friend bool operator==(const TclObject& x, string_view y) {
                return x.getString() == y;
        }
        friend bool operator==(string_view x, const TclObject& y) {
                return x == y.getString();
        }

        friend bool operator!=(const TclObject& x, const TclObject& y) { return !(x == y); }
        friend bool operator!=(const TclObject& x, string_view       y) { return !(x == y); }
        friend bool operator!=(string_view       x, const TclObject& y) { return !(x == y); }

private:
        void init(Tcl_Obj* obj_) noexcept {
                obj = obj_;
                Tcl_IncrRefCount(obj);
        }

        static Tcl_Obj* newObj(string_view s) {
                return Tcl_NewStringObj(s.data(), int(s.size()));
        }
        static Tcl_Obj* newObj(const char* s) {
                return Tcl_NewStringObj(s, int(strlen(s)));
        }
        static Tcl_Obj* newObj(bool b) {
                return Tcl_NewBooleanObj(b);
        }
        static Tcl_Obj* newObj(int i) {
                return Tcl_NewIntObj(i);
        }
        static Tcl_Obj* newObj(unsigned u) {
                return Tcl_NewIntObj(u);
        }
        static Tcl_Obj* newObj(float f) {
                return Tcl_NewDoubleObj(double(f));
        }
        static Tcl_Obj* newObj(double d) {
                return Tcl_NewDoubleObj(d);
        }
        static Tcl_Obj* newObj(span<const uint8_t> buf) {
                return Tcl_NewByteArrayObj(buf.data(), int(buf.size()));
        }
        static Tcl_Obj* newObj(const TclObject& o) {
                return o.obj;
        }
        static Tcl_Obj* newList(std::initializer_list<Tcl_Obj*> l) {
                return Tcl_NewListObj(int(l.size()), l.begin());
        }

        void assign(string_view s) {
                Tcl_SetStringObj(obj, s.data(), int(s.size()));
        }
        void assign(const char* s) {
                Tcl_SetStringObj(obj, s, int(strlen(s)));
        }
        void assign(bool b) {
                Tcl_SetBooleanObj(obj, b);
        }
        void assign(int i) {
                Tcl_SetIntObj(obj, i);
        }
        void assign(unsigned u) {
                Tcl_SetIntObj(obj, u);
        }
        void assign(float f) {
                Tcl_SetDoubleObj(obj, double(f));
        }
        void assign(double d) {
                Tcl_SetDoubleObj(obj, d);
        }
        void assign(span<const uint8_t> b) {
                Tcl_SetByteArrayObj(obj, b.data(), int(b.size()));
        }

        template<typename ITER>
        void addListElementsImpl(ITER first, ITER last, std::input_iterator_tag) {
                for (ITER it = first; it != last; ++it) {
                        addListElement(*it);
                }
        }
        template<typename ITER>
        void addListElementsImpl(ITER first, ITER last, std::random_access_iterator_tag) {
                auto objc = last - first;
                VLA(Tcl_Obj*, objv, objc);
                std::transform(first, last, objv, [](const auto& t) { return newObj(t); });
                addListElementsImpl(objc, objv);
        }

        void addListElement(Tcl_Obj* element);
        void addListElementsImpl(int objc, Tcl_Obj* const* objv);
        void addListElementsImpl(std::initializer_list<Tcl_Obj*> l);
        void addDictKeyValues(std::initializer_list<Tcl_Obj*> keyValuePairs);
        unsigned getListLengthUnchecked() const;
        TclObject getListIndexUnchecked(unsigned index) const;

private:
        Tcl_Obj* obj;
};

// We want to be able to reinterpret_cast a Tcl_Obj* as a TclObject.
static_assert(sizeof(TclObject) == sizeof(Tcl_Obj*), "");

template<typename... Args>
TclObject makeTclList(Args&&... args)
{
        return TclObject(TclObject::MakeListTag{}, std::forward<Args>(args)...);
}

template<typename... Args>
TclObject makeTclDict(Args&&... args)
{
        return TclObject(TclObject::MakeDictTag{}, std::forward<Args>(args)...);
}

struct XXTclHasher {
        uint32_t operator()(string_view str) const {
                return xxhash(str);
        }
        uint32_t operator()(const TclObject& obj) const {
                return xxhash(obj.getString());
        }
};

} // namespace openmsx

#endif