ezc/src/env.h

/*
 * 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_env
#define headerfile_ezc_env

#include <vector>
#include <map>
#include "item.h"
#include "modelcontainerwrapper.h"
#include "var.h"



namespace Ezc
{



//typedef std::map<std::wstring, Var<StreamType>> Vars;



/*
	a base class for your own function data class
*/
struct FunData
{
	FunData()
	{
	}

	virtual ~FunData()
	{
	}
};



/*
	a generator's stack item
	each statement ([if ...] [for ...] [normal_funcion]) have its own stack item
	iter        - is used only in [for...] - it is the current iteration (start from zero)
	              for other statements it is always zero
	fun_data    - by default this is null pointer, you can set it to a pointer
	              to an object derived from FunData
			      (this have sense only in [for...] statement because in other statements
			      this object would be immediately removed)
	auto_remove - when true it means that object pointing by fun_data and for_name should be automatically
	              removed -- (by using delete fun_data and delete for_name)
	is_for      - true if the item is from [for] statement
	              currently used only in [if-index]
			      (it has to look for the last [for] item)
*/
struct Stack
{
	size_t iter;
	FunData * fun_data;
	bool auto_remove;
	bool is_for;
	const Item * item;


	Stack()
	{
		Clear();
	}

	~Stack()
	{
		if( auto_remove )
		{
			if( fun_data )
			{
				delete fun_data;
				fun_data = 0;
			}
		}
	}

	void Clear()
	{
		iter        = 0;
		fun_data    = 0;
		auto_remove = true;
		is_for      = false;
		item        = 0;
	}
};


template<class StreamType>
struct Env
{
	// an alias to res.stream
	StreamType & out;

	// result
	Var<StreamType> & res;

	// table of parameters
	// the table can be empty
	std::vector<Var<StreamType>> & params;

	// the first parameter
	// you can always use it even if there are not any parameters (params is empty)
	// in such a way the reference points to an empty string
	//const std::wstring & par;

	// an input stream used in [filter] statement
	// and when methods/functions are chained
	Var<StreamType> & in;

	// indicates that this function is from [for ...] statement
	bool is_for;

	// indicates that this function is from [if ...] statement
	bool is_if;

	// indicates that this function is from [if-def ...] statement
	bool is_if_def;

	// indicates that this function is from [if-not-def ...] statement
	bool is_if_not_def;

	// indicates that this funcion is a normal statement e.g.: [funcion_name]
	bool is_normal;

	// indicates that this function is from a filter statement [filter ...]
	bool is_filter;

	// a pointer to the stack
	Stack * stack_tab;

	// current stack item
	size_t stack_index;

	// a stack's item from generator's stack
	// each function has a new stack item
	// on this stack you have iter (description below) and fun_data pointer
	// you can assign to it your own object derived from FunData
	// 'stack' is a reference to stack_tab[stack_index]
	Stack & stack;

	// the same as stack.iter (this is mainly for backward compatibility)
	// it indicates the number of a current iteration for the [for] statement (the first iteration is 0)
	// for other statements than [for] this is always zero
	size_t iter;

	//
	const Item & item;



	Env(Var<StreamType> & result,
		std::vector<Var<StreamType>> & pars,
		Var<StreamType> & input_stream,
		Stack & s,
		const Item & item_) : out(result.stream), res(result), params(pars), in(input_stream), stack(s), item(item_)
	{
		clear();
	}


	void clear()
	{
		is_for				= false;
		is_if				= false;
		is_if_def			= false;
		is_if_not_def		= false;
		is_normal			= false;
		is_filter			= false;
		iter				= 0;
		stack_tab			= nullptr;
		stack_index			= 0;
	}


};




} // namespace Ezc


#endif