dlg_stream_input.h

本工具提供一个词法分析器和语法分析器的集成开发环境

/************************************************************/
/*															*/
/*		Predefined char stream: Input from (c++) stream.	*/
/*															*/
/* By Hubert Holin ([e-mail]), 1998.		*/
/*															*/
/* This is completely free stuff, do whatever you want with	*/
/* it (but then, I will take no responsability for whatever	*/
/* may happen if you do either... caveat emptor!).			*/
/*															*/
/************************************************************/

#ifndef _DLG_STREAM_INPUT_H
#define _DLG_STREAM_INPUT_H

#include PCCTS_ISTREAM_H

PCCTS_NAMESPACE_STD

#ifndef DLGX_H
#include "DLexerBase.h"
#endif


// NOTES:	The semantics of the copy constructor
//			and the affectation operator may be unwaranted...
//			and the stream may not be reset.
//
//			It would have been so much nicer for nextChar()
//			to throw (of for the DLGInputStream to change status)
//			upon hiting EOF than to return an "int"...

template	<
				class E,
				class T = ::std::char_traits<E>
			>
class DLG_stream_input : public DLGInputStream
{
public:
	
						DLG_stream_input(::std::basic_istream<E,T> * p_input_stream)
	:	input(p_input_stream)
	{
		// nothing to do!
	};
	
						DLG_stream_input(const DLG_stream_input & a_recopier)
	:	input(a_recopier.input)
	{
		// nothing to do!
	};
	
	virtual				~DLG_stream_input()
	{
		this->purge();	// bloody templarized lookup...
	};
	
	DLG_stream_input	operator = (const DLG_stream_input & a_affecter)
	{
		if (this != &a_affecter)
		{
			input = a_affecter.input;
		}

		return(*this);
	};
	
	virtual int			nextChar()
	{
		E	extracted_stuff;
		
		input->get(extracted_stuff);
		
		if	(*input)
		{
			return(int(extracted_stuff));
		}
		else
		{
			return(EOF);
		}
	};
	
protected:
	
	::std::basic_istream<E,T> *	input;
	
private:
	
	void	purge()
	{
		// nothing to do!
	};
};

#endif /* _DLG_STREAM_INPUT_H */