stackvector.h

/*
Copyright 2020 Jacek Piszczek

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.

*/
#pragma once
#include <cstdio>
#include <string>
#include <emul/emulregs.h>
#include <exec/tasks.h>
#include <proto/exec.h>
#include <alloca.h>
#include <functional>

#if defined(DEBUG) && DEBUG
extern "C" { void dprintf(const char *,...); };
#define SVOUT printf 
#else
#define SVOUT(...)
#endif

/* Helper class aiming to streamline creation of temporary vectors for OBArray object iterations 
** in ObjectiveC++ applications, but may have other uses too. The memory for the vector is allocated
** either on stack (if there's enough of it to spare AND the object itself was also allocated
** on stack) or heap. */

template <typename T> class StackVector
{
public:
	/* MUST be inlined or alloca() would fail to survive past this method */
	__attribute__((always_inline)) StackVector(const size_t size, const size_t mustLeaveStackSizeForScope = (16 * 1024), bool callConstructorsDestructors = true)
		: _size(size), _callFree(false), _callConstructorsDestructors(callConstructorsDestructors)
	{
		const size_t needBytes = size * sizeof(T);
		bool onStack = canReserveStack(needBytes, mustLeaveStackSizeForScope) ;

		if (onStack) {
#if defined(DEBUG) && DEBUG
			struct Task *t = FindTask(NULL);
			ULONG usedStack = 0, usedStackAfterAlloca = 0;
			NewGetTaskAttrsA(t, &usedStack, sizeof (usedStack), TASKINFOTYPE_USEDSTACKSIZE, NULL);
			_memory = static_cast<T*>(alloca(needBytes));
			NewGetTaskAttrsA(t, &usedStackAfterAlloca, sizeof (usedStackAfterAlloca), TASKINFOTYPE_USEDSTACKSIZE, NULL);
			SVOUT("%s: allocated on stack %p, alloca using stack? %d stack usage grew by %d\n", __PRETTY_FUNCTION__, _memory, isAllocatedOnStack(), usedStackAfterAlloca - usedStack);
#else
			_memory = static_cast<T*>(alloca(needBytes));
#endif
		}
		else {
			_memory = static_cast<T*>(malloc(needBytes));
			_callFree = true;
			SVOUT("%s: allocated on heap %p\n", __PRETTY_FUNCTION__, _memory);
		}
		
		if (_callConstructorsDestructors && _memory) {
			for (size_t i = 0; i < size; i++) {
				new (&_memory[i]) T ();
			}
		}
	}
	
	StackVector() = delete;
	
	~StackVector()
	{
		if (_callConstructorsDestructors && _memory) {
			for (size_t i = 0; i < _size; i++) {
				(&_memory[i])->~T();
			}
		}

		if (_callFree)
		{
			SVOUT("%s: freeing heap %p..\n", __PRETTY_FUNCTION__, _memory);
			free(_memory);
		}
		else
		{
			SVOUT("%s: memory was alloca'd\n", __PRETTY_FUNCTION__);
		}
	}

	size_t count() const { return _size; }
	bool isValid() const { return _memory != nullptr && _size > 0; }

	// Invalid when called from another thread than the one that constructed the object
	bool isAllocatedOnStack() const { return isStackAddress(FindTask(0), _memory); }

	// Iterates over the vector using a lambda
	void forEach(std::function<void(T& member, size_t index)>&& onEach) {
		if (_memory) {
			for (size_t idx = 0; idx < _size; idx++) {
				onEach(_memory[idx], idx);
			}
		}
	}
	
	void forEach(std::function<void(const T& member, size_t index)>&& onEach) const {
		if (_memory) {
			for (size_t idx = 0; idx < _size; idx++) {
				onEach(_memory[idx], idx);
			}
		}
	}

	void whileEach(std::function<bool(T& member, size_t index)>&& onEach) {
		if (_memory) {
			for (size_t idx = 0; idx < _size; idx++) {
				if (!onEach(_memory[idx], idx))
					break;
			}
		}
	}

	void whileEach(std::function<bool(const T& member, size_t index)>&& onEach) const {
		if (_memory) {
			for (size_t idx = 0; idx < _size; idx++) {
				if (!onEach(_memory[idx], idx))
					break;
			}
		}
	}

	T& operator[](size_t index) {
#ifdef STACKVECTORDEBUG
		if (index >= _size)
		{
			SVOUT("%s: Access at %d outside of size %d\n", __PRETTY_FUNCTION__, index, _size);
		}
#endif
		return _memory[index];
	}
	
	T const & operator[] (size_t index) const {
#ifdef STACKVECTORDEBUG
		if (index >= _size)
		{
			SVOUT("%s: Access at %d outside of size %d\n", __PRETTY_FUNCTION__, index, _size);
		}
#endif
		return _memory[index];
	}

protected:
	bool canReserveStack(const size_t size, const size_t mustLeaveStackSizeForScope) const
	{
		struct Task *t = FindTask(NULL);
		if (isStackAddress(t, const_cast<StackVector<T>*>(this)))
		{
			ULONG usedStack = 0;
			if (0 != NewGetTaskAttrsA(t, &usedStack, sizeof (usedStack), TASKINFOTYPE_USEDSTACKSIZE, NULL))
			{
				struct ETask *e = t->tc_ETask;
				ULONG lower = ULONG(e->PPCSPLower);
				ULONG current = ULONG(e->PPCSPUpper) - usedStack;
			
				SVOUT("%s: 'this' was allocated on stack; lower %p current %p current-size %p\n", __PRETTY_FUNCTION__, lower, current, current - size);
			
				if ((lower + mustLeaveStackSizeForScope) < (current - size))
					return true;
			}
		}

		return false;
	}
	
	bool isStackAddress(struct Task *t, void *address) const
	{
		struct ETask *e = t->tc_ETask;
		SVOUT("%s: lower %p upper %p addr %p \n", __PRETTY_FUNCTION__, e->PPCSPLower, e->PPCSPUpper, address);
		return (address > e->PPCSPLower) && (address < e->PPCSPUpper);
	}
	
	T       *_memory;
	size_t   _size;
	bool     _callFree : 1;
	bool     _callConstructorsDestructors : 1;
};

#ifdef __OBJC__

#import <ob/OBArray.h>
#import <mui/MUIFamily.h>

class IDVector : public StackVector<id>
{
public:
	IDVector(size_t size) : StackVector<id>(size, 32 * 1024, false) { };
};

/*
** GCC doesn't really compile fast enumeration in ObjectiveC++ files, so this can be used to replace it.
** Example:
**  BOOL found = NO;
** 	FastEnumerator<OBString*> objects(stringarray,[&found](OBString* &string, size_t index) {
**    if ([string isEqualToString:@"string we're looking for"]) {
**       found = YES; return false;
**    }
**    return true; // keep going
**  });
*/

template <typename O> class FastEnumerator : protected StackVector<O> 
{
public:
	FastEnumerator(OBArray *arrayToEnumerate, std::function<bool(O& member, size_t index)> && enumCallback) : StackVector<O>([arrayToEnumerate count], 32 * 1024, false) {
		if (StackVector<O>::_memory) {
			[arrayToEnumerate getObjects:StackVector<O>::_memory];
			StackVector<O>::whileEach(std::move(enumCallback));
		}
	};
	FastEnumerator(OBArray *arrayToEnumerate, OBRange && range, std::function<bool(O& member, size_t index)> && enumCallback) : StackVector<O>(range.length, 32 * 1024, false) {
		if (StackVector<O>::_memory) {
			[arrayToEnumerate getObjects:StackVector<O>::_memory inRange:range];
			StackVector<O>::whileEach(std::move(enumCallback));
		}
	};
	FastEnumerator() = delete;
	~FastEnumerator() = default;
};

template <typename O> class FastFamilyEnumerator : protected StackVector<O> 
{
public:
	FastFamilyEnumerator(id<MUIFamily> arrayToEnumerate, std::function<bool(O& member, size_t index)> && enumCallback) : StackVector<O>([arrayToEnumerate count], 32 * 1024, false) {
		if (StackVector<O>::_memory) {
			[arrayToEnumerate getObjects:StackVector<O>::_memory];
			StackVector<O>::whileEach(std::move(enumCallback));
		}
	};
	FastFamilyEnumerator(id<MUIFamily> arrayToEnumerate, OBRange && range, std::function<bool(O& member, size_t index)> && enumCallback) : StackVector<O>(range.length, 32 * 1024, false) {
		if (StackVector<O>::_memory) {
			[arrayToEnumerate getObjects:StackVector<O>::_memory inRange:range];
			StackVector<O>::whileEach(std::move(enumCallback));
		}
	};
	FastFamilyEnumerator() = delete;
	~FastFamilyEnumerator() = default;
};

template <typename O> class FastForEach: protected StackVector<O> 
{
public:
	FastForEach(OBArray *arrayToEnumerate, std::function<void(O& member, size_t index)> && enumCallback) : StackVector<O>([arrayToEnumerate count], 32 * 1024, false) {
		if (StackVector<O>::_memory) {
			[arrayToEnumerate getObjects:StackVector<O>::_memory];
			StackVector<O>::forEach(std::move(enumCallback));
		}
	};
	FastForEach(OBArray *arrayToEnumerate, OBRange && range, std::function<void(O& member, size_t index)> && enumCallback) : StackVector<O>(range.length, 32 * 1024, false) {
		if (StackVector<O>::_memory) {
			[arrayToEnumerate getObjects:StackVector<O>::_memory inRange:range];
			StackVector<O>::forEach(std::move(enumCallback));
		}
	};
	FastForEach() = delete;
	~FastForEach() = default;
};

template <typename O> class FastFamilyForEach : protected StackVector<O> 
{
public:
	FastFamilyForEach(id<MUIFamily> arrayToEnumerate, std::function<void(O& member, size_t index)> && enumCallback) : StackVector<O>([arrayToEnumerate count], 32 * 1024, false) {
		if (StackVector<O>::_memory) {
			[arrayToEnumerate getObjects:StackVector<O>::_memory];
			StackVector<O>::forEach(std::move(enumCallback));
		}
	};
	FastFamilyForEach(id<MUIFamily> arrayToEnumerate, OBRange && range, std::function<void(O& member, size_t index)> && enumCallback) : StackVector<O>(range.length, 32 * 1024, false) {
		if (StackVector<O>::_memory) {
			[arrayToEnumerate getObjects:StackVector<O>::_memory inRange:range];
			StackVector<O>::forEach(std::move(enumCallback));
		}
	};
	FastFamilyForEach() = delete;
	~FastFamilyForEach() = default;
};

#endif