// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; tab-width: 8 -*-
//
// lower_tri.h: Rcpp R/C++ interface class library -- lower.tri
//
// Copyright (C) 2010 - 2011 Dirk Eddelbuettel and Romain Francois
//
// This file is part of Rcpp.
//
// Rcpp is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
//
// Rcpp is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Rcpp.  If not, see <http://www.gnu.org/licenses/>.

#ifndef Rcpp__sugar__lower_tri_h
#define Rcpp__sugar__lower_tri_h

namespace Rcpp{
namespace sugar{

template <int RTYPE, bool LHS_NA, typename LHS_T>
class LowerTri : public VectorBase<
	LGLSXP ,
	false ,
	LowerTri<RTYPE,LHS_NA,LHS_T>
> {
public:
	typedef Rcpp::MatrixBase<RTYPE,LHS_NA,LHS_T> LHS_TYPE ;

	LowerTri( const LHS_TYPE& lhs, bool diag) :
		nr( lhs.nrow() ), nc( lhs.ncol() ),
		getter( diag ? (&LowerTri::get_diag_true) : (&LowerTri::get_diag_false) ){}

	// inline int operator[]( int index ) const {
	// 	int i = Rcpp::internal::get_line( index, nr ) ;
	// 	int j = Rcpp::internal::get_column( index, nr, i ) ;
	// 	return get(i,j) ;
	// }
	inline int operator()( int i, int j ) const {
		return get(i,j) ;
	}

	inline R_xlen_t size() const { return static_cast<R_xlen_t>(nr) * nc ; }
	inline int nrow() const { return nr; }
	inline int ncol() const { return nc; }

private:
	int nr, nc ;
	typedef bool (LowerTri::*Method)(int,int) ;

	Method getter ;
	inline bool get_diag_true( int i, int j ){
		return i <= j ;
	}
	inline bool get_diag_false( int i, int j ){
		return i < j ;
	}
	inline bool get( int i, int j){
		return (this->*getter)(i, j ) ;
	}

} ;

} // sugar

template <int RTYPE, bool LHS_NA, typename LHS_T>
inline sugar::LowerTri<RTYPE,LHS_NA,LHS_T>
lower_tri( const Rcpp::MatrixBase<RTYPE,LHS_NA,LHS_T>& lhs, bool diag = false){
	return sugar::LowerTri<RTYPE,LHS_NA,LHS_T>( lhs, diag ) ;
}

} // Rcpp

#endif
