/*
   AngelCode Scripting Library
   Copyright (c) 2012 Andreas Jonsson

   This software is provided 'as-is', without any express or implied
   warranty. In no event will the authors be held liable for any
   damages arising from the use of this software.

   Permission is granted to anyone to use this software for any
   purpose, including commercial applications, and to alter it and
   redistribute it freely, subject to the following restrictions:

   1. The origin of this software must not be misrepresented; you
      must not claim that you wrote the original software. If you use
      this software in a product, an acknowledgment in the product
      documentation would be appreciated but is not required.

   2. Altered source versions must be plainly marked as such, and
      must not be misrepresented as being the original software.

   3. This notice may not be removed or altered from any source
      distribution.

   The original version of this library can be located at:
   http://www.angelcode.com/angelscript/

   Andreas Jonsson
   andreas@angelcode.com
*/


//
// as_symboltable.h
//
//  Created on: Jun 19, 2012
//      Author: Markus Lenger, a.k.a. mlengerx
//
// This class is used for fast symbol lookups while parsing or loading bytecode
//

#ifndef AS_SYMBOLTABLE_H
#define AS_SYMBOLTABLE_H

#include "as_config.h"
#include "as_memory.h"
#include "as_string.h"
#include "as_map.h"
#include "as_datatype.h"


BEGIN_AS_NAMESPACE

// TODO: cleanup: This should be in its own header. It is only here because it is
//                needed for the template and cannot be resolved with a forward declaration
struct asSNameSpace
{
	asCString name;

	// TODO: namespace: A namespace should have access masks. The application should be
	//                  able to restrict specific namespaces from access to specific modules
};




// Interface to avoid nested templates which is not well supported by older compilers, e.g. MSVC6
struct asIFilter
{
	virtual bool operator()(const void*) const = 0;
};




// forward declaration
template<class T>
class asCSymbolTable;




// Iterator that allows iterating in index order
template<class T, class T2 = T>
class asCSymbolTableIterator
{
public:
    T2* operator*() const;
    T2* operator->() const;
    asCSymbolTableIterator<T, T2>& operator++(int);
    asCSymbolTableIterator<T, T2>& operator--(int);
    operator bool() const;
    int GetIndex() const { return m_idx; }

private:
    friend class asCSymbolTable<T>;
    asCSymbolTableIterator<T, T2>(asCSymbolTable<T> *table);

    void Next();
    void Previous();

    asCSymbolTable<T>* m_table;
    unsigned int       m_idx;
};




// Symbol table mapping namespace + name to symbols
template<class T>
class asCSymbolTable
{
public:
    typedef asCSymbolTableIterator<T, T> iterator;
    typedef asCSymbolTableIterator<T, const T> const_iterator;

	asCSymbolTable(unsigned int initialCapacity = 0);

	int      GetFirstIndex(const asSNameSpace *ns, const asCString &name, const asIFilter &comparator) const;
	int      GetFirstIndex(const asSNameSpace *ns, const asCString &name) const;
	int      GetLastIndex() const;

	int      GetIndex(const T*) const;

	T*       GetFirst(const asSNameSpace *ns, const asCString &name, const asIFilter &comparator) const;
	T*       GetFirst(const asSNameSpace *ns, const asCString &name);
	const T* GetFirst(const asSNameSpace *ns, const asCString &name) const;
	T*       Get(unsigned int index);
    const T* Get(unsigned int index) const;
	T*       GetLast();
    const T* GetLast() const;

    const asCArray<unsigned int> &GetIndexes(const asSNameSpace *ns, const asCString &name) const;

	int          Put(T* entry);

	unsigned int GetSize() const;

	void SwapWith(asCSymbolTable<T> &other);

	void Clear();
	bool Erase(unsigned int idx);
	void Allocate(unsigned int elem_cnt, bool keep_data);

	iterator List();
	const_iterator List() const;

private:
	// Don't allow assignment
	asCSymbolTable<T>& operator=(const asCSymbolTable<T> &other) { return *this; }

    friend class asCSymbolTableIterator<T, T>;
    friend class asCSymbolTableIterator<T, const T>;

	void GetKey(const T *entry, asCString &key) const;
	void BuildKey(const asSNameSpace *ns, const asCString &name, asCString &key) const;
	bool CheckIdx(unsigned idx) const;

	asCMap<asCString, asCArray<unsigned int> > m_map;
	asCArray<T*>                               m_entries;
	unsigned int                               m_size;
};




template<class T>
void asCSymbolTable<T>::SwapWith(asCSymbolTable<T> &other)
{
	m_map.SwapWith(other.m_map);
	m_entries.SwapWith(other.m_entries);

	unsigned int tmp = m_size;
	m_size = other.m_size;
	other.m_size = tmp;
}




// Constructor
// initialCapacity gives the number of entries to allocate in advance
template<class T>
asCSymbolTable<T>::asCSymbolTable(unsigned initialCapacity) : m_entries(initialCapacity)
{
	m_size = 0;
}



template<class T>
int asCSymbolTable<T>::GetFirstIndex(
        const asSNameSpace *ns,
        const asCString &name,
        const asIFilter &filter) const
{
	asCString key;
	BuildKey(ns, name, key);

	asSMapNode<asCString, asCArray<unsigned int> > *cursor;
	if( m_map.MoveTo(&cursor, key) )
	{
		const asCArray<unsigned int> &arr = m_map.GetValue(cursor);
		for( unsigned int n = 0; n < arr.GetLength(); n++ )
		{
			T *entry = m_entries[arr[n]];
			if( entry && filter(entry) )
				return arr[n];
		}
	}

	return -1;
}



template<class T>
const asCArray<unsigned int> &asCSymbolTable<T>::GetIndexes(const asSNameSpace *ns, const asCString &name) const
{
	asCString key;
	BuildKey(ns, name, key);

	asSMapNode<asCString, asCArray<unsigned int> > *cursor;
	if( m_map.MoveTo(&cursor, key) )
		return m_map.GetValue(cursor);

	static asCArray<unsigned int> dummy;
	return dummy;
}




template<class T>
T* asCSymbolTable<T>::GetFirst(const asSNameSpace *ns, const asCString &name, const asIFilter &comp) const
{
    int idx = GetFirstIndex(ns, name, comp);
    if (idx != -1) return m_entries[idx];
    return 0;
}




template<class T>
int asCSymbolTable<T>::GetFirstIndex(const asSNameSpace *ns, const asCString &name) const
{
    asCString key;
    BuildKey(ns, name, key);

	asSMapNode<asCString, asCArray<unsigned int> > *cursor;
	if( m_map.MoveTo(&cursor, key) )
        return m_map.GetValue(cursor)[0];

    return -1;
}




// Find the index of a certain symbol
// ATTENTION: this function has linear runtime complexity O(n)!!
template<class T>
int asCSymbolTable<T>::GetIndex(const T* entry) const
{
	for( unsigned int n = 0; n < m_entries.GetLength(); n++ )
		if( m_entries[n] == entry )
			return n;

	return -1;
}






template<class T>
T* asCSymbolTable<T>::Get(unsigned idx)
{
    if( !CheckIdx(idx) )
        return 0;

    return m_entries[idx];
}

template<class T>
const T* asCSymbolTable<T>::Get(unsigned idx) const
{
    return const_cast< asCSymbolTable<T>* >(this)->Get(idx);
}





template<class T>
T* asCSymbolTable<T>::GetFirst(const asSNameSpace *ns, const asCString &name)
{
    int idx = GetFirstIndex(ns, name);
    return Get(idx);
}

template<class T>
const T* asCSymbolTable<T>::GetFirst(const asSNameSpace *ns, const asCString &name) const
{
    return const_cast< asCSymbolTable<T>* >(this)->GetFirst(ns, name);
}





template<class T>
T* asCSymbolTable<T>::GetLast()
{
    return Get(GetLastIndex());
}

template<class T>
const T* asCSymbolTable<T>::GetLast() const
{
    return const_cast< asCSymbolTable<T>* >(this)->GetLast();
}





// Clear the symbol table
// ATTENTION: The contained symbols are not rleased. This is up to the client
template<class T>
void asCSymbolTable<T>::Clear()
{
    m_entries.SetLength(0);
    m_map.EraseAll();
	m_size = 0;
}




// Pre-allocate slots for elemCnt entries
template<class T>
void asCSymbolTable<T>::Allocate(unsigned elemCnt, bool keepData)
{
	asASSERT( elemCnt >= m_entries.GetLength() );
    m_entries.Allocate(elemCnt, keepData);
    if( !keepData )
        m_map.EraseAll();
}



template<class T>
bool asCSymbolTable<T>::Erase(unsigned idx)
{
    if( !CheckIdx(idx) )
    {
        asASSERT(false);
        return false;
    }

    T *entry = m_entries[idx];
    asASSERT(entry);
    if( !entry )
		return false;

	if( idx == m_entries.GetLength() - 1 )
	{
		m_entries.PopLast();

		// TODO: Should remove all trailing empty slots
	}
	else
		m_entries[idx] = 0;
	m_size--;

    asCString key;
    GetKey(entry, key);

	asSMapNode<asCString, asCArray<unsigned int> > *cursor;
	if( m_map.MoveTo(&cursor, key) )
	{
		asCArray<unsigned int> &arr = m_map.GetValue(cursor);
		arr.RemoveValue(idx);
		if( arr.GetLength() == 0 )
			m_map.Erase(cursor);
	}
	else
		asASSERT(false);

	return true;
}




template<class T>
int asCSymbolTable<T>::Put(T *entry)
{
	unsigned int idx = (unsigned int)(m_entries.GetLength());
	asCString key;
	GetKey(entry, key);

	asSMapNode<asCString, asCArray<unsigned int> > *cursor;
	if( m_map.MoveTo(&cursor, key) )
		m_map.GetValue(cursor).PushLast(idx);
	else
	{
		asCArray<unsigned int> arr(1);
		arr.PushLast(idx);
		m_map.Insert(key, arr);
	}

	m_entries.PushLast(entry);
	m_size++;
	return idx;
}



template<class T>
void asCSymbolTable<T>::BuildKey(const asSNameSpace *ns, const asCString &name, asCString &key) const
{
	// TODO: optimize: The key shouldn't be just an asCString. It should keep the
	//                 namespace as a pointer, so it can be compared as pointer.
	//                 Which should be compared first, the namespace or the name? There is likely
	//                 going to be many symbols with the same namespace, so it is probably best to
	//                 compare the name first
    key = ns->name + "::" + name;
}




// Return key for specified symbol (namespace and name are used to generate the key)
template<class T>
void asCSymbolTable<T>::GetKey(const T *entry, asCString &key) const
{
	BuildKey(entry->nameSpace, entry->name, key);
}




template<class T>
unsigned int asCSymbolTable<T>::GetSize() const
{
	return m_size;
}




template<class T>
bool asCSymbolTable<T>::CheckIdx(unsigned int idx) const
{
    return idx < m_entries.GetLength();
}




template<class T>
int asCSymbolTable<T>::GetLastIndex() const
{
    unsigned int idx = (unsigned int)(m_entries.GetLength()) - 1;
	asASSERT( idx == asUINT(-1) || m_entries[idx] );
    return int(idx);
}




template<class T>
asCSymbolTableIterator<T, T> asCSymbolTable<T>::List()
{
    return asCSymbolTableIterator<T, T>(this);
}




template<class T>
typename asCSymbolTable<T>::const_iterator asCSymbolTable<T>::List() const
{
    return asCSymbolTableIterator<T, const T>(const_cast< asCSymbolTable<T> *>(this));
}


/////////////////////////////////////////////////////////////////////////////////////////////////
// Iterator


template<class T, class T2>
asCSymbolTableIterator<T, T2>::asCSymbolTableIterator(asCSymbolTable<T> *table) : m_table(table), m_idx(0)
{
    unsigned int sz = (unsigned int)(m_table->m_entries.GetLength());
    while( m_idx < sz && m_table->m_entries[m_idx] == 0 )
        m_idx++;
}



template<class T, class T2>
T2* asCSymbolTableIterator<T, T2>::operator*() const
{
    asASSERT(m_table->CheckIdx(m_idx));
    return m_table->m_entries[m_idx];
}



template<class T, class T2>
T2* asCSymbolTableIterator<T, T2>::operator->() const
{
    asASSERT(m_table->CheckIdx(m_idx));
    return m_table->m_entries[m_idx];
}



template<class T, class T2>
asCSymbolTableIterator<T, T2>& asCSymbolTableIterator<T, T2>::operator++(int)
{
    Next();
    return *this;
}



// Return true if more elements are following
// ATTENTION: When deleting the object currently pointed to by this iterator this
// method returns false even though there might be more elements in the list
template<class T, class T2>
asCSymbolTableIterator<T, T2>::operator bool() const
{
    return m_idx < m_table->m_entries.GetLength() && m_table->m_entries[m_idx] != 0;
}



template<class T, class T2>
void asCSymbolTableIterator<T, T2>::Next()
{
    unsigned int sz = (unsigned int)(m_table->m_entries.GetLength());
    m_idx++;
    while( m_idx < sz && m_table->m_entries[m_idx] == 0 )
        m_idx++;
}



template<class T, class T2>
void asCSymbolTableIterator<T, T2>::Previous()
{
    // overflow on stepping over first element
    unsigned int sz = (unsigned int)(m_table->m_entries.GetLength());
    m_idx--;
    while( m_idx < sz && m_table->m_entries[m_idx] == 0 )
        m_idx--;
}



template<class T, class T2>
asCSymbolTableIterator<T, T2>& asCSymbolTableIterator<T, T2>::operator--(int)
{
    Previous();
    return *this;
}


END_AS_NAMESPACE

#endif // AS_SYMBOLTABLE_H