boxed.cpp

/* -----------------------------------------------------------------------------
Copyright 2021 Kevin P. Barry

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
----------------------------------------------------------------------------- */

// Author: Kevin P. Barry [ta0kira@gmail.com]

#include "boxed.hpp"

#include <climits>

#include "category-source.hpp"


#ifdef ZEOLITE_PUBLIC_NAMESPACE
namespace ZEOLITE_PUBLIC_NAMESPACE {
#endif  // ZEOLITE_PUBLIC_NAMESPACE

ReturnTuple DispatchBool(bool value, const ValueFunction& label,
                         const ParamTuple& params, const ValueTuple& args);

ReturnTuple DispatchChar(PrimChar value, const ValueFunction& label,
                         const ParamTuple& params, const ValueTuple& args);

ReturnTuple DispatchInt(PrimInt value, const ValueFunction& label,
                        const ParamTuple& params, const ValueTuple& args);

ReturnTuple DispatchFloat(PrimFloat value, const ValueFunction& label,
                          const ParamTuple& params, const ValueTuple& args);

#ifdef ZEOLITE_PUBLIC_NAMESPACE
}  // namespace ZEOLITE_PUBLIC_NAMESPACE
using namespace ZEOLITE_PUBLIC_NAMESPACE;
#endif  // ZEOLITE_PUBLIC_NAMESPACE


namespace zeolite_internal {

namespace {

void Validate(const std::string& name, const UnionValue& the_union) {
  if (the_union.type_ == UnionValue::Type::BOXED) {
    const auto strong = the_union.value_.as_pointer_->strong_.load();
    const auto weak   = the_union.value_.as_pointer_->weak_.load();
    const TypeValue* const object = the_union.value_.as_pointer_->object_;

    if ((strong == 0 && object) || (weak == 0 && strong > 0)) {
      FAIL() << "Leaked " << the_union.CategoryName() << " " << name << " at "
             << ((void*) the_union.value_.as_pointer_) << " (S: "
             << std::hex << strong << " W: " << weak << ")";
    }

    if ((strong != 0 && !object)) {
      FAIL() << "Invalid counts for freed value " << name << " at "
             << ((void*) the_union.value_.as_pointer_) << " (S: "
             << std::hex << strong << " W: " << weak << ")";
    }
  }
}

}  // namespace

std::string UnionValue::CategoryName() const {
  switch (type_) {
    case UnionValue::Type::EMPTY: return "empty";
    case UnionValue::Type::BOOL:  return "Bool";
    case UnionValue::Type::CHAR:  return "Char";
    case UnionValue::Type::INT:   return "Int";
    case UnionValue::Type::FLOAT: return "Float";
    case UnionValue::Type::BOXED:
      if (!value_.as_pointer_ || !value_.as_pointer_->object_) {
        FAIL() << "Function called on null pointer";
      }
      return value_.as_pointer_->object_->CategoryName();
  }
}

BoxedValue::BoxedValue(const BoxedValue& other)
  : union_(other.union_) {
  switch (union_.type_) {
    case UnionValue::Type::BOXED:
      ++union_.value_.as_pointer_->strong_;
      break;
    default:
      break;
  }
}

BoxedValue& BoxedValue::operator = (const BoxedValue& other) {
  if (&other != this) {
    Cleanup();
    union_ = other.union_;
    switch (union_.type_) {
      case UnionValue::Type::BOXED:
        ++union_.value_.as_pointer_->strong_;
        break;
      default:
        break;
    }
  }
  return *this;
}

BoxedValue::BoxedValue(BoxedValue&& other)
  : union_(other.union_) {
  other.union_.type_  = UnionValue::Type::EMPTY;
  other.union_.value_.as_pointer_ = nullptr;
}

BoxedValue& BoxedValue::operator = (BoxedValue&& other) {
  if (&other != this) {
    Cleanup();
    union_ = other.union_;
    other.union_.type_  = UnionValue::Type::EMPTY;
    other.union_.value_.as_pointer_ = nullptr;
  }
  return *this;
}

BoxedValue::BoxedValue(const WeakValue& other)
  : union_(other.union_) {
  switch (union_.type_) {
    case UnionValue::Type::BOXED:
      while (union_.value_.as_pointer_->lock_.test_and_set(std::memory_order_acquire));
      if (++union_.value_.as_pointer_->strong_ == 1) {
        --union_.value_.as_pointer_->strong_;
        union_.value_.as_pointer_->lock_.clear(std::memory_order_release);
        union_.type_ = UnionValue::Type::EMPTY;
        union_.value_.as_pointer_ = nullptr;
      } else {
        union_.value_.as_pointer_->lock_.clear(std::memory_order_release);
      }
      break;
    default:
      break;
  }
}

BoxedValue::BoxedValue(bool value)
  : union_{ .type_ = UnionValue::Type::BOOL, .value_ = { .as_bool_ = value } } {}

BoxedValue::BoxedValue(PrimChar value)
  : union_{ .type_ = UnionValue::Type::CHAR, .value_ = { .as_char_ = value } } {}

BoxedValue::BoxedValue(PrimInt value)
  : union_{ .type_ = UnionValue::Type::INT, .value_ = { .as_int_ = value } } {}

BoxedValue::BoxedValue(PrimFloat value)
  : union_{ .type_ = UnionValue::Type::FLOAT, .value_ = { .as_float_ = value } } {}

BoxedValue::~BoxedValue() {
  Cleanup();
}

void BoxedValue::Validate(const std::string& name) const {
  zeolite_internal::Validate(name, union_);
}

bool BoxedValue::AsBool() const {
  switch (union_.type_) {
    case UnionValue::Type::BOOL:
      return union_.value_.as_bool_;
    default:
      FAIL() << union_.CategoryName() << " is not a Bool value";
      __builtin_unreachable();
      break;
  }
}

PrimChar BoxedValue::AsChar() const {
  switch (union_.type_) {
    case UnionValue::Type::CHAR:
      return union_.value_.as_char_;
    default:
      FAIL() << union_.CategoryName() << " is not a Char value";
      __builtin_unreachable();
      break;
  }
}

PrimInt BoxedValue::AsInt() const {
  switch (union_.type_) {
    case UnionValue::Type::INT:
      return union_.value_.as_int_;
    default:
      FAIL() << union_.CategoryName() << " is not an Int value";
      __builtin_unreachable();
      break;
  }
}

PrimFloat BoxedValue::AsFloat() const {
  switch (union_.type_) {
    case UnionValue::Type::FLOAT:
      return union_.value_.as_float_;
    default:
      FAIL() << union_.CategoryName() << " is not a Float value";
      __builtin_unreachable();
      break;
  }
}

const PrimString& BoxedValue::AsString() const {
  switch (union_.type_) {
    case UnionValue::Type::BOXED:
      if (!union_.value_.as_pointer_ || !union_.value_.as_pointer_->object_) {
        FAIL() << "Function called on null pointer";
      }
      return union_.value_.as_pointer_->object_->AsString();
    default:
      FAIL() << union_.CategoryName() << " is not a String value";
      __builtin_unreachable();
      break;
  }
}

PrimCharBuffer& BoxedValue::AsCharBuffer() const {
  switch (union_.type_) {
    case UnionValue::Type::BOXED:
      if (!union_.value_.as_pointer_ || !union_.value_.as_pointer_->object_) {
        FAIL() << "Function called on null pointer";
      }
      return union_.value_.as_pointer_->object_->AsCharBuffer();
    default:
      FAIL() << union_.CategoryName() << " is not a CharBuffer value";
      __builtin_unreachable();
      break;
  }
}

// static
bool BoxedValue::Present(const BoxedValue& target) {
  return target.union_.type_ != UnionValue::Type::EMPTY;
}

// static
BoxedValue BoxedValue::Require(const BoxedValue& target) {
  switch (target.union_.type_) {
    case UnionValue::Type::EMPTY:
      FAIL() << "Cannot require empty value";
      __builtin_unreachable();
      break;
    default:
      return target;
  }
}

// static
BoxedValue BoxedValue::Strong(const WeakValue& target) {
  return BoxedValue(target);
}

ReturnTuple BoxedValue::Dispatch(
  const ValueFunction& label, const ParamTuple& params, const ValueTuple& args) const {
  switch (union_.type_) {
    case UnionValue::Type::EMPTY:
      FAIL() << "Function called on empty value";
      __builtin_unreachable();
      break;
    case UnionValue::Type::BOOL:
      return DispatchBool(union_.value_.as_bool_, label, params, args);
    case UnionValue::Type::CHAR:
      return DispatchChar(union_.value_.as_char_, label, params, args);
    case UnionValue::Type::INT:
      return DispatchInt(union_.value_.as_int_, label, params, args);
    case UnionValue::Type::FLOAT:
      return DispatchFloat(union_.value_.as_float_, label, params, args);
    case UnionValue::Type::BOXED:
      if (!union_.value_.as_pointer_ || !union_.value_.as_pointer_->object_) {
        FAIL() << "Function called on null pointer";
      }
      return union_.value_.as_pointer_->object_->Dispatch(label, params, args);
  }
}

void BoxedValue::Cleanup() {
  switch (union_.type_) {
    case UnionValue::Type::BOXED:
      while (union_.value_.as_pointer_->lock_.test_and_set(std::memory_order_acquire));
      if (--union_.value_.as_pointer_->strong_ == 0) {
        TypeValue* const object = union_.value_.as_pointer_->object_;
        union_.value_.as_pointer_->object_ = nullptr;
        union_.value_.as_pointer_->lock_.clear(std::memory_order_release);
        object->~TypeValue();
        if (--union_.value_.as_pointer_->weak_ == 0) {
          // NOTE: as_bytes_ contains object => ~TypeValue() must happen first.
          free(union_.value_.as_bytes_);
        }
      } else {
        union_.value_.as_pointer_->lock_.clear(std::memory_order_release);
      }
      break;
    default:
      break;
  }
  union_.type_  = UnionValue::Type::EMPTY;
  union_.value_.as_pointer_ = nullptr;
}


WeakValue::WeakValue()
  : union_{ .type_ = UnionValue::Type::EMPTY, .value_ = { .as_pointer_ = nullptr } } {}

WeakValue::WeakValue(const WeakValue& other)
  : union_(other.union_) {
  switch (union_.type_) {
    case UnionValue::Type::BOXED:
      ++union_.value_.as_pointer_->weak_;
      break;
    default:
      break;
  }
}

WeakValue& WeakValue::operator = (const WeakValue& other) {
  if (&other != this) {
    Cleanup();
    union_ = other.union_;
    switch (union_.type_) {
      case UnionValue::Type::BOXED:
        ++union_.value_.as_pointer_->weak_;
        break;
      default:
        break;
    }
  }
  return *this;
}

WeakValue::WeakValue(WeakValue&& other)
  : union_(other.union_) {
  other.union_.type_  = UnionValue::Type::EMPTY;
  other.union_.value_.as_pointer_ = nullptr;
}

WeakValue& WeakValue::operator = (WeakValue&& other) {
  if (&other != this) {
    Cleanup();
    union_ = other.union_;
    other.union_.type_  = UnionValue::Type::EMPTY;
    other.union_.value_.as_pointer_ = nullptr;
  }
  return *this;
}

WeakValue::WeakValue(const BoxedValue& other)
  : union_(other.union_) {
  switch (union_.type_) {
    case UnionValue::Type::BOXED:
      ++union_.value_.as_pointer_->weak_;
      break;
    default:
      break;
  }
}

WeakValue& WeakValue::operator = (const BoxedValue& other) {
  Cleanup();
  union_ = other.union_;
  switch (union_.type_) {
    case UnionValue::Type::BOXED:
      ++union_.value_.as_pointer_->weak_;
      break;
    default:
      break;
  }
  return *this;
}

WeakValue::~WeakValue() {
  Cleanup();
}

void WeakValue::Validate(const std::string& name) const {
  zeolite_internal::Validate(name, union_);
}

void WeakValue::Cleanup() {
  switch (union_.type_) {
    case UnionValue::Type::BOXED:
      if (--union_.value_.as_pointer_->weak_ == 0) {
        free(union_.value_.as_bytes_);
      }
      break;
    default:
      break;
  }
  union_.type_  = UnionValue::Type::EMPTY;
  union_.value_.as_pointer_ = nullptr;
}

}  // namespace zeolite_internal