/*
 * This file is a part of EZC -- Easy templating in C++ library
 * and is distributed under the BSD 3-Clause licence.
 * Author: Tomasz Sowa <t.sowa@ttmath.org>
 */

/* 
 * Copyright (c) 2007-2021, Tomasz Sowa
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *    
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *    
 *  * Neither the name Tomasz Sowa nor the names of contributors to this
 *    project may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */


#ifndef headerfile_ezc_generator
#define headerfile_ezc_generator

#include "blocks.h"
#include "pattern.h"
#include "functions.h"
#include "objects.h"
#include "outstreams.h"
#include <sstream>
#include <fstream>
#include <vector>
#include "expressionparser.h"


namespace Ezc
{



/*
StreamType
 we use only method write(const wchar_t * str, size_t len) from the stream
*/
template<class StreamType>
class Generator
{
public:

	Generator();
	Generator(const Generator & n);
	Generator & operator=(const Generator & n);
	~Generator();

	void SetPattern(Pattern & pattern);
	void SetBlocks(Blocks & blocks);
	void SetFunctions(Functions<StreamType> & functions);
	void SetObjects(Objects<StreamType> & objects);
	void SetVariables(Vars & variables); // [def] and [let]


	void SetMax(size_t max_items_, size_t max_for_items_);

	// recognizing some special characters in text patterns (item_text in Patterns)
	// \r will be a carriage return (13)
	// \n will be a new line (10)
	// \t will be a tabulator (9)
	// \s will be a space
	// \\ will be one '\'
	// if the second character is different from those shown above the first slash will be printed
	// so "\x" gives "\x"
	// default: false
	void RecognizeSpecialChars(bool spec);

	// trimming white characters (at the beginning and at the end of an item_text)
	// (special char \s if enabled is not treated as a white character here)
	// default: false 
	void TrimWhite(bool trim);

	// skipping new line characters (from the whole string in an item_text)
	// but you can use a new line character written as "\n" (if special chars are turn on)
	// default: false
	void SkipNewLine(bool skip);

	// default: 20
	void SetMaxFilters(size_t new_len);

	// default stack size: 300
	void SetStackSize(size_t new_stack_size);

	// set whether or not we can use cache for functions or blocks
	// true by default
	void CanUseCache(bool can_use_cache);

	// set whether or not we can use variables: [def ...] statement
	// true by default
	void CanUseVars(bool can_use_variables);

	void SetProgramMode(bool program_mode);

	void SetExpressionParser(ExpressionParser * expression_parser);


	// the main methods for generating
	void Generate(StreamType & out);
	void Generate(StreamType & out, OutStreams<StreamType> & out_streams);
	void Generate(OutStreams<StreamType> & out_streams);


	void SetCommentary(const char * com_start,         const char * com_stop);
	void SetCommentary(const std::string & com_start,  const std::string & com_stop);
	void SetCommentary(const wchar_t * com_start,      const wchar_t * com_stop);
	void SetCommentary(const std::wstring & com_start, const std::wstring & com_stop);

private:
	

	struct BlockStack
	{
		std::vector<Var> args;
		StreamType * out_stream;
		bool was_return;
	};

	std::vector<BlockStack> block_stack_tab;
	size_t block_stack_index;
	size_t block_stack_size;

	// current output stream (can be null)
	// at the beginning it is pointing to the main stream (to the StreamType argument passsed to Generate method)
	StreamType * output_stream;

	Pattern    * ppattern;
	Blocks     * pblocks;
	Functions<StreamType> * pfunctions;
	Objects<StreamType> * pobjects;
	Vars       * pvars;

	// pointer to the output streams map (can be null)
	// output stream will be created when [ezc frame "stream_name"] statement is found
	OutStreams<StreamType> * output_frames_streams;

	// temporary error messages
	std::wstring temp_msg;

	bool break_generating;
	size_t current_item;
	size_t max_items;
	size_t max_for_items;
	bool special_chars;
	bool trim_white;
	bool skip_new_line;

	size_t ezc_frames_stack_index;
	size_t ezc_frames_stack_size;

	size_t stack_index;
	size_t stack_size;

	size_t filter_index;
	size_t filter_size;
	// we have to use a pointers table because standard streams such
	// as std::wostringstream are not copyable
	std::vector<StreamType*> filter_tab;
	std::vector<StreamType*> ezc_frame_stack_tab;
	const StreamType empty_stream;

	// temporary streams used in [if..] [for...] or [def ...]
	// or if output_stream is null and an ezc function should be called
	StreamType stream_temp1, stream_temp_define;

	// last result from a user function (FunInfo::res)
	bool last_res;

	// true if this Generator is working now
	bool is_generator_working;

	// true if the Generator is working with [for ...], [if ...] etc.
	bool is_generating_for;
	bool is_generating_if;
	bool is_generating_normal;
	bool is_generating_filter;

	// an empty string for FunInfo objects
	// when there is no any parameters
	const std::wstring empty;

	// a stack for [for] statements
	std::vector<Stack> stack_tab;

	std::wstring commentary_start, commentary_stop;

	bool can_use_vars;
	bool can_find_in_cache;
	bool program_mode;

	ExpressionParser * expression_parser;



	void ResizeStreamStack(std::vector<StreamType*> & stream_tab, size_t stream_tab_max_size);
	void ResizeFilterTab();
	void ResizeStack();
	void ResizeBlockStack();
	void ResizeEzcFrameStack();

	void ClearStreamStack(std::vector<StreamType*> & stream_tab);
	void ClearFilterTab();
	void ClearForStack();
	void ClearBlockStack();
	void ClearEzcFrameTab();

	void ClearStream(StreamType & str);
	void RemoveStackFunData(Stack & sitem);

	bool ConvertToBool(const std::wstring & str);

	template<class CharType>
	CharType ToLower(CharType c);


	bool CheckBlockArgument(int arg_index, Var ** variable);

	bool FindInCache(Item::Function & item_fun,
					 BaseObj<StreamType> ** base_obj,
					 int * method_index,
					 typename Functions<StreamType>::UserFunction ** function,
					 Item ** item_block);

	bool FindInFunctionsAndBlocks(const std::wstring & name,
								  BaseObj<StreamType> ** base_obj,
								  int * method_index,
								  typename Functions<StreamType>::UserFunction ** function,
								  Item ** item_block);
										
	bool FindInVariables(const std::wstring & name,
						 Var ** variable);


	bool Find(Item::Function & item_fun,
			  std::wstring * fun_name,
			  BaseObj<StreamType> ** base_obj,
			  int * method_index,
			  typename Functions<StreamType>::UserFunction ** function,
			  Item ** item_block,
			  Var ** variable);

	void CallFunction(typename Functions<StreamType>::UserFunction * function,
			  FunInfo<StreamType> & info);

	void CallFunction(typename Functions<StreamType>::UserFunction * function,
					  std::vector<Var> & parameters,
					  StreamType & out_stream,
					  const StreamType & in_stream);

	bool CallBlock(Item & item_block,
				   std::vector<Var> & parameters,
				   StreamType & out_stream);


	void CallObject(BaseObj<StreamType> * base_obj, int method_index, FunInfo<StreamType> & info);


	void CallObject(BaseObj<StreamType> * base_obj,
					int method_index,
					std::vector<Var> & parameters,
					StreamType & out_stream,
					const StreamType & in_stream);

	bool CallVariable(Item::Function & item_fun,
					  Var * variable,
					  std::vector<Var> & parameters,
					  StreamType & out_stream,
					  const StreamType & in_stream);

	bool Call(Item::Function & item_fun,
			  std::wstring * fun_name,
			  StreamType & out_stream,
			  bool clear_out_stream,
			  const StreamType & in_stream);

	bool Call(Item::Function & item_fun);

	wchar_t CreateSpecialChar(wchar_t c);
	const wchar_t * PrintSpecialChar(const wchar_t * start, const wchar_t * end);
	void PrintSpecialText(const wchar_t * start, const wchar_t * end);
	void PrintNormalText(const wchar_t * start, const wchar_t * end);
	bool IsWhite(wchar_t c);
	void TrimWhite(const wchar_t *& start, const wchar_t *& end);
	void SkipWhite(const wchar_t *& str);
	size_t StrToSize(const wchar_t * str, const wchar_t ** str_end = 0);


	void CopyTmpStreamToOutputStreams(Item::Function & fun, StreamType & ezc_out_tmp_stream, StreamType & previous_stream);
	void CreateMsg(std::wstring & out, const wchar_t * type, const wchar_t * arg = 0);
	void CreateMsg(StreamType & stream, const wchar_t * type, const wchar_t * arg = 0);
	void CreateMsg(const wchar_t * type, const wchar_t * arg = 0);
	void CreateMsg(const std::wstring & type, const std::wstring & arg);
	void CreateMsg(const std::wstring & type);
	void CreateUnknownMsg(const std::wstring & fun);
	bool LimitAchieved();

	void EvaluateProgramNode(Item & item);

	void MakeTextIf_go(Item & item, bool result);
	void MakeTextIf(Item & item);
	void MakeTextFor(Item & item);
	void MakeItemText(Item & item);
	void MakeTextContainer(Item & item);
	void MakeTextNormal(Item & item);
	void MakeTextDefine(Item & item, Var & var);
	void MakeTextDefine(Item & item);
	void MakeTextDefineIfNotSet(Item & item);
	void MakeTextLet(Item & item, Var & var);
	void MakeTextLet(Item & item);
	void MakeTextLetIfNotSet(Item & item);
	void MakeTextFilter(Item & item);
	void MakeTextEzc(Item & item);
	void MakeTextReturn(Item & item);
	void MakeText(Item & item);
	void MakeEzcFrame(Item & item);

	void Generate();



}; // class Generator






template<class StreamType>
Generator<StreamType>::Generator() : empty_stream()
{
	ppattern      = 0;
	pblocks       = 0;
	pfunctions    = 0;
	pobjects      = 0;
	pvars         = 0;

	max_items     = 50000;
	max_for_items = 5000;
	filter_size   = 20;
	special_chars = false;
	trim_white    = false;
	skip_new_line = false;
	is_generator_working = false;
	stack_size    = 300;
	block_stack_size = 64;
	ezc_frames_stack_size = 16;
	can_find_in_cache = true;
	can_use_vars = true;
	expression_parser = nullptr;
	program_mode = false;
}


template<class StreamType>
Generator<StreamType>::Generator(const Generator<StreamType> & n)
{
	operator=(n);
}



template<class StreamType>
Generator<StreamType> & Generator<StreamType>::operator=(const Generator<StreamType> & n)
{
	ppattern       = n.ppattern;
	pblocks        = n.pblocks;
	pfunctions     = n.pfunctions;
	pobjects       = n.pobjects;
	pvars          = n.pvars;

	max_items      = n.max_items;
	max_for_items  = n.max_for_items;
	special_chars  = n.special_chars;
	trim_white     = n.trim_white;
	skip_new_line  = n.skip_new_line;
	can_find_in_cache = n.can_find_in_cache;
	can_use_vars   = n.can_use_vars;

	// filter, stack and block_stack will be auto resized when calling Generate() method
	filter_size      = n.filter_size;
	stack_size       = n.stack_size;
	block_stack_size = n.block_stack_size;
	ezc_frames_stack_size = n.ezc_frames_stack_size;
	expression_parser    = n.expression_parser;
	program_mode     = n.program_mode;

	// vars doesn't have to be copied

	// don't copy filter tab
	// don't copy stack
	// don't copy ezc_frame_stack_tab
	// don't copy output_stream and output_frames_streams

	// !! CHECK ME
	// may copying should be denied when generator is working?
	// don't copy 'is_generator_working' flag
	is_generator_working = false;

return *this;
}



template<class StreamType>
Generator<StreamType>::~Generator()
{
	ClearFilterTab();
	ClearForStack();
	ClearBlockStack();
	ClearEzcFrameTab();
}


template<class StreamType>
void Generator<StreamType>::SetCommentary(const char * com_start, const char * com_stop)
{
	pt::utf8_to_wide(com_start, commentary_start);
	pt::utf8_to_wide(com_stop,  commentary_stop);
}



template<class StreamType>
void Generator<StreamType>::SetCommentary(const std::string & com_start, const std::string & com_stop)
{
	pt::utf8_to_wide(com_start, commentary_start);
	pt::utf8_to_wide(com_stop,  commentary_stop);
}



template<class StreamType>
void Generator<StreamType>::SetCommentary(const wchar_t * com_start, const wchar_t * com_stop)
{
	commentary_start = com_start;
	commentary_stop  = com_stop;
}



template<class StreamType>
void Generator<StreamType>::SetCommentary(const std::wstring & com_start, const std::wstring & com_stop)
{
	commentary_start = com_start;
	commentary_stop  = com_stop;
}



template<class StreamType>
void Generator<StreamType>::SetPattern(Pattern & pattern)
{
	ppattern = &pattern;
}




template<class StreamType>
void Generator<StreamType>::SetBlocks(Blocks & blocks)
{
	pblocks = &blocks;
}


template<class StreamType>
void Generator<StreamType>::SetFunctions(Functions<StreamType> & functions)
{
	pfunctions = &functions;
}


template<class StreamType>
void Generator<StreamType>::SetObjects(Objects<StreamType> & objects)
{
	pobjects = &objects;
}


template<class StreamType>
void Generator<StreamType>::SetVariables(Vars & variables)
{
	pvars = &variables;
}


template<class StreamType>
void Generator<StreamType>::CanUseCache(bool can_use_cache)
{
	can_find_in_cache = can_use_cache;
}


template<class StreamType>
void Generator<StreamType>::CanUseVars(bool can_use_variables)
{
	can_use_vars = can_use_variables;
}

template<class StreamType>
void Generator<StreamType>::SetProgramMode(bool set_program_mode)
{
	this->program_mode = set_program_mode;
}

template<class StreamType>
void Generator<StreamType>::SetExpressionParser(ExpressionParser * expression_parser)
{
	this->expression_parser = expression_parser;
}




template<class StreamType>
void Generator<StreamType>::ResizeStack()
{
	if( stack_tab.size() != stack_size )
	{
		if( stack_tab.size() > stack_size )
		{
			for(size_t i=stack_size ; i<stack_tab.size() ; ++i)
				RemoveStackFunData(stack_tab[i]);
		}

		stack_tab.resize(stack_size);
	}
}



template<class StreamType>
void Generator<StreamType>::ResizeStreamStack(std::vector<StreamType*> & stream_tab, size_t stream_tab_max_size)
{
	if( stream_tab.size() != stream_tab_max_size )
	{
		if( stream_tab.size() < stream_tab_max_size )
		{
			size_t i = stream_tab.size();
			stream_tab.resize(stream_tab_max_size);

			for( ; i<stream_tab.size() ; ++i)
				stream_tab[i] = new StreamType();
		}
		else
		{
			for(size_t i=stream_tab_max_size ; i<stream_tab.size() ; ++i)
				delete stream_tab[i];
			
			stream_tab.resize(stream_tab_max_size);
		}
	}
}


template<class StreamType>
void Generator<StreamType>::ResizeFilterTab()
{
	ResizeStreamStack(filter_tab, filter_size);
}


template<class StreamType>
void Generator<StreamType>::ResizeEzcFrameStack()
{
	ResizeStreamStack(ezc_frame_stack_tab, ezc_frames_stack_size);
}


template<class StreamType>
void Generator<StreamType>::ResizeBlockStack()
{
	if( block_stack_tab.size() != block_stack_size )
	{
		if( block_stack_tab.size() < block_stack_size )
		{
			size_t i = block_stack_tab.size();
			block_stack_tab.resize(block_stack_size);

			for( ; i<block_stack_tab.size() ; ++i)
				block_stack_tab[i].out_stream = new StreamType();
		}
		else
		{
			for(size_t i=block_stack_size ; i<block_stack_tab.size() ; ++i)
				delete block_stack_tab[i].out_stream;
			
			block_stack_tab.resize(block_stack_size);
		}
	}
}





template<class StreamType>
void Generator<StreamType>::ClearStreamStack(std::vector<StreamType*> & stream_tab)
{
	for(size_t i=0 ; i<stream_tab.size() ; ++i)
		delete stream_tab[i];
	
	stream_tab.clear();
}


template<class StreamType>
void Generator<StreamType>::ClearFilterTab()
{
	ClearStreamStack(filter_tab);
}


template<class StreamType>
void Generator<StreamType>::ClearEzcFrameTab()
{
	ClearStreamStack(ezc_frame_stack_tab);
}


template<class StreamType>
void Generator<StreamType>::ClearBlockStack()
{
	for(size_t i=0 ; i<block_stack_tab.size() ; ++i)
		delete block_stack_tab[i].out_stream;

	block_stack_tab.clear();
}


template<class StreamType>
void Generator<StreamType>::ClearForStack()
{
	for(size_t i=0 ; i<stack_tab.size() ; ++i)
		RemoveStackFunData(stack_tab[i]);
}


template<class StreamType>
void Generator<StreamType>::ClearStream(StreamType & str)
{
	#ifdef EZC_HAS_SPECIAL_STREAM
		str.Clear();
	#else
		str.str(L"");
	#endif
}


template<class StreamType>
void Generator<StreamType>::RemoveStackFunData(Stack & s)
{
	if( s.fun_data && s.auto_remove )
	{
		delete s.fun_data;
		s.fun_data = 0;
	}
}


template<class StreamType>
template<class CharType>
CharType Generator<StreamType>::ToLower(CharType c)
{
	if( c>='A' && c<='Z' )
		return c - 'A' + 'a';

return c;
}


template<class StreamType>
bool Generator<StreamType>::ConvertToBool(const std::wstring & str)
{
	return !str.empty();
}


template<class StreamType>
void Generator<StreamType>::SetMax(size_t max_items_, size_t max_for_items_)
{
	max_items     = max_items_;
	max_for_items = max_for_items_;
}


template<class StreamType>
void Generator<StreamType>::RecognizeSpecialChars(bool spec)
{
	special_chars = spec;
}


template<class StreamType>
void Generator<StreamType>::TrimWhite(bool trim)
{
	trim_white = trim;
}


template<class StreamType>
void Generator<StreamType>::SkipNewLine(bool skip)
{
	skip_new_line = skip;
}


template<class StreamType>
void Generator<StreamType>::SetMaxFilters(size_t new_len)
{
	// the table will be resized when Generate() method is called
	filter_size = new_len;
}


template<class StreamType>
void Generator<StreamType>::SetStackSize(size_t new_stack_size)
{
	// the stack will be resized when Generate() method is called
	stack_size = new_stack_size;
}



template<class StreamType>
void Generator<StreamType>::Generate()
{
	if( is_generator_working )
	{
		CreateMsg(L"generator busy");
		return;
	}

	break_generating = false;
	current_item     = 0;

	// in the case that there something has left on the stack
	// from previous call to Generate()
	// (an exception could have been thrown)
	ClearForStack();

	ResizeFilterTab();
	ResizeStack();
	ResizeBlockStack();
	ResizeEzcFrameStack();
	filter_index = 0;
	stack_index  = 0;
	block_stack_index = 0;

	if( ppattern )
	{
		try
		{
			is_generator_working = true;
			MakeText( ppattern->item_root );
			// !! IMPROVE ME we can print an error message if the stacks are not empty
			// (some [end] statements has been omited)
			is_generator_working = false;
		}
		catch(...)
		{
			is_generator_working = false;
			throw;
		}
	}
}


template<class StreamType>
void Generator<StreamType>::Generate(StreamType & out)
{
	output_stream = &out;
	output_frames_streams = 0;
	Generate();
}



template<class StreamType>
void Generator<StreamType>::Generate(StreamType & out, OutStreams<StreamType> & out_streams)
{
	output_stream = &out;
	output_frames_streams = &out_streams;
	Generate();
}


template<class StreamType>
void Generator<StreamType>::Generate(OutStreams<StreamType> & out_streams)
{
	output_stream = 0;
	output_frames_streams = &out_streams;
	Generate();
}



template<class StreamType>
bool Generator<StreamType>::CheckBlockArgument(int arg_index, Var ** variable)
{
	if( arg_index < 0 )
		return false;

	// it's a numeric function -- an argument to a block e.g.: [1]
	if( block_stack_index > 0 )
	{
		BlockStack & block_stack = block_stack_tab[block_stack_index-1];

		if( size_t(arg_index) < block_stack.args.size() )
		{
			*variable = &block_stack.args[arg_index];
			return true;
		}
	}

	return false;
}



template<class StreamType>
bool Generator<StreamType>::FindInCache(Item::Function & item_fun,
										BaseObj<StreamType> ** base_obj,
										int * method_index,
										typename Functions<StreamType>::UserFunction ** function,
										Item ** item_block)
{
	if( can_find_in_cache )
	{
		if( item_fun.base_obj )
		{
			*base_obj = reinterpret_cast<BaseObj<StreamType> * >(item_fun.base_obj);
			*method_index = item_fun.method_index;
			return true;
		}

		if( item_fun.fun_cache )
		{
			*function = reinterpret_cast<typename Functions<StreamType>::UserFunction*>(item_fun.fun_cache);
			return true;
		}

		if( item_fun.item_block )
		{
			*item_block = item_fun.item_block;
			return true;
		}
	}

return false;
}



template<class StreamType>
bool Generator<StreamType>::FindInFunctionsAndBlocks(const std::wstring & name,
													 BaseObj<StreamType> ** base_obj,
													 int * method_index,
													 typename Functions<StreamType>::UserFunction ** function,
													 Item ** item_block)
{
	if( pobjects )
	{
		typename Objects<StreamType>::Iterator i = pobjects->Find(name, *method_index);

		if( i != pobjects->End() )
		{
			*base_obj = *i;
			return true;
		}
	}

	if( pfunctions )
	{
		typename Functions<StreamType>::Iterator i = pfunctions->Find(name);

		if( i != pfunctions->End() )
		{
			*function = &i->second;
			return true;
		}
	}

	if( pblocks )
	{
		Blocks::Iterator i = pblocks->Find(name);

		if( i != pblocks->End() )
		{
			*item_block = &i->second;
			return true;
		}
	}

return false;
}


template<class StreamType>
bool Generator<StreamType>::FindInVariables(const std::wstring & name,
											Var ** variable)
{
	if( pvars )
	{
		Vars::iterator i = pvars->find(name);

		if( i != pvars->end() )
		{
			*variable = &(i->second);
			return true;
		}
	}

	return false;
}


/*
 * fun_name can be null, it is used only with [let ...] statements
 * and if not null then means: as a funcion name we are not using item_fun.name but fun_name
 */
template<class StreamType>
bool Generator<StreamType>::Find(Item::Function & item_fun,
								 std::wstring * fun_name,
								 BaseObj<StreamType> ** base_obj,
								 int * method_index,
								 typename Functions<StreamType>::UserFunction ** function,
								 Item ** item_block,
								 Var ** variable)
{
	*base_obj = nullptr;
	*method_index = -1;
	*function   = nullptr;
	*item_block = nullptr;
	*variable   = nullptr;

	if( CheckBlockArgument(item_fun.arg, variable) )
		return true;

	if( FindInCache(item_fun, base_obj, method_index, function, item_block) )
		return true;

	if( !fun_name )
		fun_name = &item_fun.name;

	if( FindInFunctionsAndBlocks(*fun_name, base_obj, method_index, function, item_block) )
		return true;

	if( FindInVariables(*fun_name, variable) )
		return true;

	CreateUnknownMsg(*fun_name);

return false;
}



template<class StreamType>
void Generator<StreamType>::CallFunction(typename Functions<StreamType>::UserFunction * function, FunInfo<StreamType> & info)
{
	info.Clear();

	info.is_for      = is_generating_for;
	info.is_if       = is_generating_if;
	info.is_normal   = is_generating_normal;
	info.is_filter   = is_generating_filter;
	info.iter        = info.stack.iter;
	info.stack_tab   = &stack_tab[0];//stack_tab.data();/////////////////////////////////////////////////////////
	info.stack_index = stack_index-1;

	(*function)(info);

	last_res = info.res;
}



template<class StreamType>
void Generator<StreamType>::CallFunction(typename Functions<StreamType>::UserFunction * function,
										 std::vector<Var> & parameters,
										 StreamType & out_stream,
										 const StreamType & in_stream)
{
	if( parameters.empty() )
	{
		FunInfo<StreamType> info(out_stream, parameters, empty, in_stream, stack_tab[stack_index-1], *stack_tab[stack_index-1].item);
		CallFunction(function, info);
	}
	else
	{
		FunInfo<StreamType> info(out_stream, parameters, parameters[0].str, in_stream, stack_tab[stack_index-1], *stack_tab[stack_index-1].item);
		CallFunction(function, info);
	}
}







template<class StreamType>
void Generator<StreamType>::CallObject(BaseObj<StreamType> * base_obj, int method_index, FunInfo<StreamType> & info)
{
	info.Clear();

	info.is_for      = is_generating_for;
	info.is_if       = is_generating_if;
	info.is_normal   = is_generating_normal;
	info.is_filter   = is_generating_filter;
	info.iter        = info.stack.iter;
	info.stack_tab   = &stack_tab[0];//stack_tab.data();/////////////////////////////////////////////////////////
	info.stack_index = stack_index-1;

	base_obj->CallFun(method_index, info);

	last_res = info.res;
}



template<class StreamType>
void Generator<StreamType>::CallObject(BaseObj<StreamType> * base_obj,
										int method_index,
										std::vector<Var> & parameters,
										StreamType & out_stream,
										const StreamType & in_stream)
{
	if( parameters.empty() )
	{
		FunInfo<StreamType> info(out_stream, parameters, empty, in_stream, stack_tab[stack_index-1], *stack_tab[stack_index-1].item);
		CallObject(base_obj, method_index, info);
	}
	else
	{
		FunInfo<StreamType> info(out_stream, parameters, parameters[0].str, in_stream, stack_tab[stack_index-1], *stack_tab[stack_index-1].item);
		CallObject(base_obj, method_index, info);
	}
}



template<class StreamType>
bool Generator<StreamType>::CallBlock(Item & item_block,
									  std::vector<Var> & parameters,
									  StreamType & out_stream)
{
	if( block_stack_index >= block_stack_tab.size() )
	{
		CreateMsg(L"Generator exceeded allowed number of blocks");
		return false;
	}

	StreamType * old_stream = output_stream;
	BlockStack & block_stack = block_stack_tab[block_stack_index];

	block_stack.was_return = false;
	block_stack.args = parameters;

	output_stream = block_stack.out_stream;
	ClearStream(*output_stream);
	block_stack_index += 1;

	MakeText(item_block);

	#ifdef EZC_HAS_SPECIAL_STREAM
		const std::wstring & str = output_stream->Str();
	#else
		const std::wstring & str = output_stream->str();
	#endif

	out_stream.write(str.c_str(), str.size());
	// last_res is set by [return ...] statement or other last evaluated function

	ClearStream(*output_stream);
	output_stream = old_stream;
	block_stack_index -= 1;

return true;
}



template<class StreamType>
bool Generator<StreamType>::CallVariable(Item::Function & item_fun, Var * variable, std::vector<Var> & parameters, StreamType & out_stream, const StreamType & in_stream)
{
	if( variable->is_function )
	{
		return Call(item_fun, &variable->str, out_stream, false, in_stream);
	}
	else
	{
		out_stream << variable->str;
		last_res = variable->res;
		return true;
	}
}


/*
 * fun_name can be null, it is used only with [let ...] statements
 * and if not null then means: as a funcion name we are not using item_fun.name but fun_name
 *
 * return: true if a function, variable or block was found and called (evaluated)
 */
template<class StreamType>
bool Generator<StreamType>::Call(Item::Function & item_fun,
								 std::wstring * fun_name,
								 StreamType & out_stream,
								 bool clear_out_stream,
								 const StreamType & in_stream)
{
BaseObj<StreamType> * base_obj;
int method_index;
typename Functions<StreamType>::UserFunction * fun;
Item * item_block;
Var * variable;
std::vector<Var> parameters;

	if( clear_out_stream )
		ClearStream(out_stream);

	if( !Find(item_fun, fun_name, &base_obj, &method_index, &fun, &item_block, &variable) )
		return false;

	parameters.resize(item_fun.parameters.size());

	for(size_t i=0 ; i<item_fun.parameters.size() ; ++i)
	{
		Item::Function & fun_child = *item_fun.parameters[i];

		if( fun_child.is_function )
		{
			StreamType local_temp_stream;
			Call(fun_child, nullptr, local_temp_stream, true, empty_stream);

			#ifdef EZC_HAS_SPECIAL_STREAM
				parameters[i].str = local_temp_stream.Str();
			#else
				parameters[i].str = local_temp_stream.str();
			#endif

			parameters[i].res = last_res;
		}
		else
		{
			parameters[i].str = fun_child.name;
			parameters[i].res = ConvertToBool(fun_child.name);
		}
	}

	if( base_obj )
		CallObject(base_obj, method_index, parameters, out_stream, in_stream);
	else
	if( fun )
		CallFunction(fun, parameters, out_stream, in_stream);
	else
	if( item_block )
		return CallBlock(*item_block, parameters, out_stream);
	else
	if( variable )
		return CallVariable(item_fun, variable, parameters, out_stream, in_stream);

	return true;
}



// return: true if a function or variable was found and called
template<class StreamType>
bool Generator<StreamType>::Call(Item::Function & item_fun)
{
	return Call(item_fun, nullptr, stream_temp1, true, empty_stream);
}




template<class StreamType>
wchar_t Generator<StreamType>::CreateSpecialChar(wchar_t c)
{
wchar_t res = 0;

	if( c == 'r' )
		res = '\r';
	else
	if( c == 'n' )
		res = '\n';
	else
	if( c == 't' )
		res = '\t';
	else
	if( c == 's' )
		res = ' ';
	else
	if( c == '\\' )
		res = '\\';

return res;
}



// a special character is precedeed by a slash '\'
// if the special character is unknown the first slash is printing
// so "\t" gives one character of code 9
// and "\x" gives "\x" 
template<class StreamType>
const wchar_t * Generator<StreamType>::PrintSpecialChar(const wchar_t * start, const wchar_t * end)
{
wchar_t special = 0;

	if( *start == '\\' && (start+1) != end )
		special = CreateSpecialChar(*(start+1));

	if( special )
	{
		output_stream->write(&special, 1);
		start += 2;
	}
	else
	{
		if( !skip_new_line || *start != 10 )
			output_stream->write(start, 1);

		start += 1;
	}

return start;
}


template<class StreamType>
void Generator<StreamType>::PrintSpecialText(const wchar_t * start, const wchar_t * end)
{
	if( output_stream )
	{
		while( start != end )
		{
			const wchar_t * end2 = start;

			// looking for a first new line character or a special char
			// (for new line only if skip_new_line is true)
			while( end2 != end && *end2 != '\\' && (!skip_new_line || *end2 != 10) )
				end2 += 1;

			// printing the first part of the text
			if( start != end2 )
				output_stream->write(start, end2 - start);

			start = end2;
			
			// skipping one or more new line characters or special chars
			// (new lines only if skip_new_line is true)
			while( start != end && (*start == '\\' || (skip_new_line && *start == 10)) )
				start = PrintSpecialChar(start, end);
		}
	}
}


template<class StreamType>
void Generator<StreamType>::PrintNormalText(const wchar_t * start, const wchar_t * end)
{
	if( output_stream )
	{
		if( skip_new_line )
		{
			while( start != end )
			{
				const wchar_t * end2 = start;

				// looking for a first new line character
				while( end2 != end && *end2 != 10 )
					end2 += 1;

				// printing the first part of the text (until the new line)
				if( start != end2 )
					output_stream->write(start, end2 - start);

				start = end2;
				
				// skipping one or more new line characters
				while( start != end && *start == 10 )
					start += 1;
			}
		}
		else
		{
			if( start != end )
				output_stream->write(start, end - start);
		}
	}
}


template<class StreamType>
bool Generator<StreamType>::IsWhite(wchar_t c)
{
	// 13 (\r) is from a dos file at the end of a line (\r\n)
	// 160 is a non-breaking space

	if( c==' ' || c=='\t' || c==13 || c==160 || c==10 )
		return true;

return false;
}


template<class StreamType>
void Generator<StreamType>::TrimWhite(const wchar_t *& start, const wchar_t *& end)
{
	while( start != end && IsWhite(*start) )
		++start;

	while( start != end && IsWhite(*(end-1)) )
		--end;
}


template<class StreamType>
void Generator<StreamType>::SkipWhite(const wchar_t *& str)
{
	while( IsWhite(*str) )
		str += 1;
}



template<class StreamType>
size_t Generator<StreamType>::StrToSize(const wchar_t * str, const wchar_t ** str_end)
{
size_t res = 0;

	SkipWhite(str);

	// !! IMPROVE ME
	// overflow is not checked

	while( *str>='0' && *str<='9' )
	{
		res *= 10;
		res += *str - '0';
		str += 1;
	}

	SkipWhite(str);

	if( str_end )
		*str_end = str;

return res;
}


template<class StreamType>
void Generator<StreamType>::CopyTmpStreamToOutputStreams(Item::Function & fun, StreamType & ezc_out_tmp_stream, StreamType & previous_stream)
{
	if( output_frames_streams )
	{
		#ifdef EZC_HAS_SPECIAL_STREAM
			const std::wstring & str = ezc_out_tmp_stream.Str();
		#else
			const std::wstring & str = ezc_out_tmp_stream.str();
		#endif

		if( !str.empty() )
		{
			previous_stream.write(str.c_str(), str.size());

			for(size_t s=0 ; s < fun.parameters.size() ; ++s)
			{
				std::wstring & name = fun.parameters[s]->name;
				auto imap = output_frames_streams->streams_map.find(name);

				if( imap == output_frames_streams->streams_map.end() )
				{
					if( output_frames_streams->streams_map.size() < output_frames_streams->streams_tab.size() )
					{
						/* a new stream from the pool (output_stream_tab) is taken */
						StreamType * stream = output_frames_streams->streams_tab[ output_frames_streams->streams_map.size() ];
						output_frames_streams->streams_map.insert(std::make_pair(name, stream));
						ClearStream(*stream);
						stream->write(str.c_str(), str.size());
					}
					else
					{
						CreateMsg(previous_stream, L"limit of output streams in OutStreams<> has been reached");
					}
				}
				else
				{
					StreamType * stream = imap->second;
					stream->write(str.c_str(), str.size());
				}
			}
		}
	}
}



template<class StreamType>
void Generator<StreamType>::CreateMsg(std::wstring & out, const wchar_t * type, const wchar_t * arg)
{
	out = commentary_start;
	out += L"Ezc runtime error: ";
	out += type;

	if( arg )
	{
		out += ' ';
		out += arg;
	}

	out += commentary_stop;
}


template<class StreamType>
void Generator<StreamType>::CreateMsg(StreamType & stream, const wchar_t * type, const wchar_t * arg)
{
	CreateMsg(temp_msg, type, arg);
	stream.write(temp_msg.c_str(), temp_msg.size());
	temp_msg.clear();
}


template<class StreamType>
void Generator<StreamType>::CreateMsg(const wchar_t * type, const wchar_t * arg)
{
	if( output_stream )
		CreateMsg(*output_stream, type, arg);
}



template<class StreamType>
void Generator<StreamType>::CreateMsg(const std::wstring & type, const std::wstring & arg)
{
	CreateMsg(type.c_str(), arg.c_str());
}



template<class StreamType>
void Generator<StreamType>::CreateMsg(const std::wstring & type)
{
	CreateMsg(type.c_str());
}


template<class StreamType>
void Generator<StreamType>::CreateUnknownMsg(const std::wstring & fun)
{
	CreateMsg(L"unknown function", fun.c_str());
}



template<class StreamType>
void Generator<StreamType>::EvaluateProgramNode(Item & item)
{
	if( output_stream )
	{
		if( item.type == Item::item_function )
			*output_stream << " expression: " << item.text;

		if( item.type == Item::item_if )
			*output_stream << " if: " << item.text;

		if( item.type == Item::item_for )
			*output_stream << " for: " << item.text;
	}

	last_res = false;

	if( expression_parser )
	{
		if( expression_parser->Parse(item.text) )
		{
			last_res = expression_parser->LastResultToBool();

			if( output_stream )
			{
				*output_stream << " -> " << expression_parser->LastResult();
			}
		}
		else
		{
			if( output_stream )
			{
				*output_stream << " -> syntax error when evaluating expression: error code: " << (int)expression_parser->LastError();
			}
		}
	}

	if( output_stream )
	{
		*output_stream << "\n";
	}
}



template<class StreamType>
void Generator<StreamType>::MakeItemText(Item & item)
{
const wchar_t * start = item.text.c_str();
const wchar_t * end   = item.text.c_str() + item.text.size();

	if( trim_white )
		TrimWhite(start, end);

	if( special_chars )
		PrintSpecialText(start, end);
	else
		PrintNormalText(start, end);
}


template<class StreamType>
void Generator<StreamType>::MakeTextContainer(Item & item)
{
	std::vector<Item*>::iterator i = item.item_tab.begin();

	for( ; i != item.item_tab.end() && !break_generating ; ++i )
		MakeText(**i);
}



template<class StreamType>
void Generator<StreamType>::MakeTextNormal(Item & item)
{
	is_generating_normal = true;

	if( program_mode )
	{
		EvaluateProgramNode(item);
	}
	else
	{
		if( output_stream )
		{
			Call(item.function, nullptr, *output_stream, false, empty_stream);
		}
		else
		{
			Call(item.function, nullptr, stream_temp1, false, empty_stream);
			ClearStream(stream_temp1);
		}
	}
}



template<class StreamType>
void Generator<StreamType>::MakeTextIf_go(Item & item, bool result)
{
	if( result )
	{
		if( item.item_tab.size() > 0 )
			MakeText( *item.item_tab[0] );
	}
	else
	{
		// second element can be (or not -- it's from [else])
		if( item.item_tab.size() > 1 )
			MakeText( *item.item_tab[1] );
	}
}



template<class StreamType>
void Generator<StreamType>::MakeTextIf(Item & item)
{
	is_generating_if = true;

	if( program_mode )
	{
		EvaluateProgramNode(item);
	}
	else
	{
		if( !Call(item.function) )
			return;
	}

	MakeTextIf_go(item, last_res);
}




template<class StreamType>
void Generator<StreamType>::MakeTextFor(Item & item)
{
	stack_tab[stack_index-1].is_for = true;

	for( ; !break_generating ; stack_tab[stack_index-1].iter += 1 )
	{
		if( stack_tab[stack_index-1].iter >= max_for_items )
		{
			CreateMsg(item.function.name.c_str(),
					  L"function exceeded a limit for a [for] statement");	
			break;
		}

		// is_generating_for will be changed by next call to MakeText()
		// so we should set it in each iterations
		is_generating_for = true;

		if( program_mode )
		{
			EvaluateProgramNode(item);
		}
		else
		{
			Call(item.function, nullptr, stream_temp1, true, empty_stream);
		}

		if( !last_res )
			break;

		if( !item.item_tab.empty() )
			MakeText( *item.item_tab[0] ); // should be only one item
	}
}


template<class StreamType>
void Generator<StreamType>::MakeTextDefine(Item & item, Var & var)
{
	var.str.clear();
	var.res = ConvertToBool(var.str);
	var.is_function = false;

	if( item.function.parameters.empty() )
	{
		return;
	}

	if( item.function.parameters.size() > 1 )
	{
		CreateMsg(L"[def] can have only one parameter");
		return;
	}

	Item::Function & fun = *item.function.parameters[0];

	if( fun.is_function )
	{
		// call function
		if( Call(fun, nullptr, stream_temp_define, true, empty_stream) )
		{
			#ifdef EZC_HAS_SPECIAL_STREAM
				var.str += stream_temp_define.Str();
			#else
				var.str += stream_temp_define.str();
			#endif

			var.res = last_res;
		}
		else
		{
			CreateMsg(L"[def] unknown function/block/variable", item.function.name);
		}
	}
	else
	{
		var.str = fun.name;
		var.res = ConvertToBool(fun.name);
	}
}


template<class StreamType>
void Generator<StreamType>::MakeTextDefine(Item & item)
{
	if( !can_use_vars || !pvars )
	{
		CreateMsg(L"[def] statement not available");
		return;
	}

	Var & var = (*pvars)[item.function.name];
	MakeTextDefine(item, var);
}


template<class StreamType>
void Generator<StreamType>::MakeTextDefineIfNotSet(Item & item)
{
	if( !can_use_vars || !pvars )
	{
		CreateMsg(L"[def?] statement not available");
		return;
	}

	Vars::iterator vi = pvars->find(item.function.name);

	if( vi == pvars->end() )
	{
		Var & var = (*pvars)[item.function.name];
		MakeTextDefine(item, var);
	}
}




template<class StreamType>
void Generator<StreamType>::MakeTextLet(Item & item, Var & var)
{
	var.str.clear();
	var.res = ConvertToBool(var.str);
	var.is_function = true;

	if( item.function.parameters.empty() )
	{
		var.is_function = false;
		return;
	}

	if( item.function.parameters.size() > 1 )
	{
		CreateMsg(L"[let] can have only one parameter");
		return;
	}

	Item::Function & fun = *item.function.parameters[0];
	var.str = fun.name;
	var.is_function = fun.is_function;

	if( !fun.is_function )
	{
		var.res = ConvertToBool(var.str);
	}
}


template<class StreamType>
void Generator<StreamType>::MakeTextLet(Item & item)
{
	if( !can_use_vars || !pvars )
	{
		CreateMsg(L"[let] statement not available");
		return;
	}

	Var & var = (*pvars)[item.function.name];
	MakeTextLet(item, var);
}


template<class StreamType>
void Generator<StreamType>::MakeTextLetIfNotSet(Item & item)
{
	if( !can_use_vars || !pvars )
	{
		CreateMsg(L"[let?] statement not available");
		return;
	}

	Vars::iterator vi = pvars->find(item.function.name);

	if( vi == pvars->end() )
	{
		Var & var = (*pvars)[item.function.name];
		MakeTextLet(item, var);
	}
}



template<class StreamType>
void Generator<StreamType>::MakeTextFilter(Item & item)
{
	if( filter_index >= filter_tab.size() )
	{
		CreateMsg(L"Generator exceeded allowed number of filters");
		return;
	}
	
	StreamType * old_stream = output_stream;
	output_stream = filter_tab[filter_index];
	ClearStream(*output_stream);

	filter_index += 1;

	if( !item.item_tab.empty() )
		MakeText( *item.item_tab[0] ); // should be only one item - item_container

	is_generating_filter = true;

	if( old_stream )
	{
		Call(item.function, nullptr, *old_stream, false, *output_stream);
	}
	else
	{
		Call(item.function, nullptr, stream_temp1, true, *output_stream);
		ClearStream(stream_temp1);
	}

	ClearStream(*output_stream);
	output_stream = old_stream;
	filter_index -= 1;
}





/*
	although we are using a stack for [etc frame] there is no need for the stack now
	because the output is only a one-level map (not nested structure)
	but in the future we can use more complicated class like pt::Space
	and then nested [ezc frame] statements can product a better output
*/
template<class StreamType>
void Generator<StreamType>::MakeEzcFrame(Item & item)
{
std::vector<std::wstring*> output_stream_names;
StreamType * old_stream;
bool stream_added = true;

	if( ezc_frames_stack_index >= ezc_frame_stack_tab.size() )
	{
		CreateMsg(L"Generator exceeded allowed number of [ezc frame] statements");
		return;
	}

	/*
		if we encounter the first ezc frame statement without arguments e.g. [ezc frame] or just [frame]
		then we can simply ignore it
	*/
	if( item.function.parameters.empty() && ezc_frames_stack_index == 0 )
		stream_added = false;

	if( stream_added )
	{
		old_stream = output_stream;
		output_stream = ezc_frame_stack_tab[ezc_frames_stack_index];
		ClearStream(*output_stream);
		ezc_frames_stack_index += 1;
	}

	if( !item.item_tab.empty() )
		MakeText( *item.item_tab[0] ); // should be only one item - item_container

	if( stream_added )
	{
		CopyTmpStreamToOutputStreams(item.function, *output_stream, *old_stream);
		ClearStream(*output_stream);
		output_stream = old_stream;
		ezc_frames_stack_index -= 1;
	}
}



template<class StreamType>
void Generator<StreamType>::MakeTextEzc(Item & item)
{
	if( item.function.name == L"frame" )
		MakeEzcFrame(item);

	// in the future we can use more builtin functions
}


template<class StreamType>
void Generator<StreamType>::MakeTextReturn(Item & item)
{
	last_res = false;

	if( block_stack_index == 0 )
	{
		// the [return] statement is not called from a [block]
		CreateMsg(L"[return] should be called from a [block]");
		return;
	}

	BlockStack & block_stack = block_stack_tab[block_stack_index - 1];
	block_stack.was_return = true;

	if( item.has_function )
	{
		// output stream in [return] statement is ignored (we use only the stream produced by the whole block)
		// this Call() sets last_res which is used later when we return to CallBlock()
		Call(item.function, nullptr, stream_temp1, false, empty_stream);
		ClearStream(stream_temp1);
	}
}




template<class StreamType>
bool Generator<StreamType>::LimitAchieved()
{
	if( break_generating )
		return true;

	if( current_item >= max_items )
	{
		break_generating = true;
		CreateMsg(L"Generator exceeded allowed number of elements");	
		return true;
	}

	if( stack_index >= stack_tab.size() )
	{
		break_generating = true;
		CreateMsg(L"Generator exceeded the stack size");	
		return true;
	}

	if( block_stack_index > 0 )
	{
		BlockStack & block_stack = block_stack_tab[block_stack_index - 1];

		if( block_stack.was_return )
			return true;
	}

return false;
}


template<class StreamType>
void Generator<StreamType>::MakeText(Item & item)
{
	if( LimitAchieved() )
		return;

	current_item         += 1;
	stack_index          += 1;
	is_generating_for    = false;
	is_generating_if     = false;
	is_generating_normal = false;
	is_generating_filter = false;

	stack_tab[stack_index-1].Clear();
	stack_tab[stack_index-1].item = &item;

	if     ( item.type == Item::item_text )				MakeItemText(item);
	else if( item.type == Item::item_container )		MakeTextContainer(item);
	else if( item.type == Item::item_function )			MakeTextNormal(item);
	else if( item.type == Item::item_if )				MakeTextIf(item);
	else if( item.type == Item::item_def )				MakeTextDefine(item);
	else if( item.type == Item::item_def_if_not_set )	MakeTextDefineIfNotSet(item);
	else if( item.type == Item::item_let )				MakeTextLet(item);
	else if( item.type == Item::item_let_if_not_set )	MakeTextLetIfNotSet(item);
	else if( item.type == Item::item_for )				MakeTextFor(item);
	else if( item.type == Item::item_filter )			MakeTextFilter(item);
	else if( item.type == Item::item_ezc )				MakeTextEzc(item);
	else if( item.type == Item::item_return )			MakeTextReturn(item);
	else if( item.type == Item::item_err )
		CreateMsg(L"a wrong directive");

	RemoveStackFunData(stack_tab[stack_index-1]);
	stack_index -=1;
}




} // namespace Ezc


#endif