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fix ref_vptr
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@jll63
jll63 committed Feb 2, 2024
1 parent 7c5a320 commit 72372c2
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Showing 2 changed files with 177 additions and 126 deletions.
144 changes: 82 additions & 62 deletions reference.in/vptr.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4,23 +4,20 @@
/***
<sub>/ ->home / ->reference </sub>
entry: yorel::yomm2::policy::vptr
entry: yorel::yomm2::policy::external_vptr
entry: yorel::yomm2::policy::external_vptr_vector
entry: yorel::yomm2::policy::external_vptr_map
headers: yorel/yomm2/core.hpp, yorel/yomm2/keywords.hpp
entry: yorel::yomm2::policy::vptr entry: yorel::yomm2::policy::external_vptr
entry: yorel::yomm2::policy::external_vptr_vector entry:
yorel::yomm2::policy::external_vptr_map headers: yorel/yomm2/core.hpp,
yorel/yomm2/keywords.hpp
---
```
struct vptr;
struct external_vptr;
template<class Policy>
struct external_vptr_vector;
template<class Policy> struct external_vptr_vector;
template<class Policy>
struct external_vptr_map;
template<class Policy> struct external_vptr_map;
```
---
A `vptr` facet is provides a static function that returns a pointer to the
Expand All @@ -46,6 +43,15 @@ facet is optional.
`external_vptr` is a sub-category of `facet`. If present, the runtime calls
its static functions to allow it to initialize its data structures.
## Example
In this example, instances of `Person` and its derived class `Engineer` contain
a pointer to the vtable, initialized by the constructor [^1]. Instances of
`Integer` and `Rational` - both derived from `Number` are allocated in pages
aligned on a 1024 byte boundary. The pointer to the vtable is stored at the
beginning of the page.
***/

//***
Expand All @@ -55,8 +61,33 @@ its static functions to allow it to initialize its data structures.
#else
#include <cstdlib>
#endif

#include <yorel/yomm2/policy.hpp>

// for brevity
using namespace yorel::yomm2;
using namespace policy;

struct Person;
struct Number;

struct vptr_page : virtual default_static_policy::use_facet<vptr> {
template<class QClass>
static auto vptr(QClass& arg) {
using Class = std::remove_const_t<QClass>;
if constexpr (std::is_base_of_v<Number, Class>) {
auto page = reinterpret_cast<std::uintptr_t>(&arg) & ~1023;
return *reinterpret_cast<std::uintptr_t**>(page);
} else if constexpr (std::is_base_of_v<Person, Class>) {
return arg.vptr;
} else {
return default_static_policy::use_facet<policy::vptr>::vptr(arg);
}
}
};

struct custom_policy : default_static_policy::replace<vptr, vptr_page> {};

struct Number {};

struct Integer : Number {
Expand All @@ -76,41 +107,17 @@ struct Rational : Number {
struct Person {
std::uintptr_t* vptr;

Person();

virtual ~Person() {
Person() {
vptr = custom_policy::static_vptr<Person>;
}
};

struct Engineer : Person {
Engineer();
};

struct my_vptr_policy;

#include <yorel/yomm2/policy.hpp>

// for brevity
using namespace yorel::yomm2;
using namespace policy;

struct vptr_page : virtual default_static_policy::use_facet<vptr> {

template<class Class>
static auto vptr(const Class& arg) {
if constexpr (std::is_base_of_v<Number, Class>) {
auto page = reinterpret_cast<std::uintptr_t>(&arg) & ~1023;
return *reinterpret_cast<std::uintptr_t**>(page);
} else if constexpr (std::is_base_of_v<Person, Class>) {
return arg.vptr;
} else {
return default_static_policy::use_facet<policy::vptr>::vptr(arg);
}
Engineer() {
vptr = custom_policy::static_vptr<Engineer>;
}
};

struct my_vptr_policy : default_static_policy::replace<vptr, vptr_page> {};

template<class T>
class Page {
private:
Expand All @@ -128,7 +135,7 @@ class Page {
#endif
);
*reinterpret_cast<std::uintptr_t**>(base) =
my_vptr_policy::static_vptr<T>;
custom_policy::static_vptr<T>;
void* first = base + sizeof(std::uintptr_t*);
size_t space = page_size - sizeof(std::uintptr_t*);
std::align(alignof(T), sizeof(T), first, space);
Expand All @@ -153,15 +160,7 @@ class Page {
}
};

Person::Person() {
vptr = my_vptr_policy::static_vptr<Person>;
}

Engineer::Engineer() {
vptr = my_vptr_policy::static_vptr<Engineer>;
}

#define YOMM2_default_static_policy my_vptr_policy
#define YOMM2_DEFAULT_POLICY custom_policy
#include <yorel/yomm2/keywords.hpp>
#include <yorel/yomm2/runtime.hpp>

Expand All @@ -171,41 +170,62 @@ register_classes(Number, Integer, Rational, Person, Engineer);

declare_method(
void, add,
(virtual_<Person&>, virtual_<const Number&>, virtual_<const Number&>,
(virtual_<const Person&>, virtual_<const Number&>, virtual_<const Number&>,
std::ostream&));

define_method(
void, add, (Person&, const Number& a, const Number& b, std::ostream& os)) {
os << "I don't know how to do this...\n";
void, add,
(const Person&, const Number& a, const Number& b, std::ostream& os)) {
os << "I don't know how to do this...";
}

define_method(
void, add,
(Person&, const Integer& a, const Integer& b, std::ostream& os)) {
os << a.value << " + " << b.value << " = " << a.value + b.value << "\n";
(const Person&, const Integer& a, const Integer& b, std::ostream& os)) {
os << a.value << " + " << b.value << " = " << a.value + b.value;
}

define_method(
void, add,
(Engineer&, const Rational& a, const Rational& b, std::ostream& os)) {
(const Engineer&, const Rational& a, const Rational& b, std::ostream& os)) {
os << a.num << "/" << a.den << " + " << b.num << "/" << b.den << " = "
<< a.num * b.den + a.den * b.num << "/" << a.den * b.den << "\n";
<< a.num * b.den + a.den * b.num << "/" << a.den * b.den;
}

#include <sstream>

BOOST_AUTO_TEST_CASE(ref_vptr_page) {
static_assert(sizeof(Integer) == sizeof(int));
static_assert(sizeof(Rational) == 2 * sizeof(int));
update<my_vptr_policy>();

update<custom_policy>();

Page<Integer> ints;
Number &i_2 = ints.construct(2), &i_3 = ints.construct(3);
const Number &i_2 = ints.construct(2), &i_3 = ints.construct(3);

Page<Rational> rationals;
Number &r_2_3 = rationals.construct(2, 3),
const Number &r_2_3 = rationals.construct(2, 3),
&r_3_4 = rationals.construct(3, 4);
Person&& alice = Engineer();
Person&& bob = Person();
add(bob, i_2, i_3, std::cout);
add(bob, r_2_3, r_3_4, std::cout);
add(alice, r_2_3, r_3_4, std::cout);

const Person& alice = Engineer();
const Person& bob = Person();

std::ostringstream out1, out2, out3;

add(bob, i_2, i_3, out1);
BOOST_TEST(out1.str() == "2 + 3 = 5");

add(bob, r_2_3, r_3_4, out2);
BOOST_TEST(out2.str() == "I don't know how to do this...");

add(alice, r_2_3, r_3_4, out3);
BOOST_TEST(out3.str() == "2/3 + 3/4 = 17/12");
}

//***

/***
[1]: This is similar to the way YOMM11 works.
***/
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