The R Project SVN R

/*
 *  R : A Computer Langage for Statistical Data Analysis
 *  Copyright (C) 1995, 1996  Robert Gentleman and Ross Ihaka
 *
 *  This program 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.
 *
 *  This program 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 this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "Defn.h"

/*-----------------------*/
/* Basic List Constructs */
/*-----------------------*/

/* cons - return a dotted pair with the given car and cdr */
SEXP cons(SEXP car, SEXP cdr)
{
    SEXP e;
    PROTECT(car);
    PROTECT(cdr);
    e = allocSExp(LISTSXP);
    UNPROTECT(2);
    CAR(e) = car;
    SETCDR(e, cdr);
#ifdef oldmem
    TAG(e) = R_NilValue;
#endif
    return e;
}

SEXP list1(SEXP s)
{
    return CONS(s, R_NilValue);
}

SEXP list2(SEXP s, SEXP t)
{
    PROTECT(s);
    s = CONS(s, list1(t));
    UNPROTECT(1);
    return s;
}

SEXP list3(SEXP s, SEXP t, SEXP u)
{
    PROTECT(s);
    s = CONS(s, list2(t, u));
    UNPROTECT(1);
    return s;
}

SEXP list4(SEXP s, SEXP t, SEXP u, SEXP v)
{
    PROTECT(s);
    s = CONS(s, list3(t, u, v));
    UNPROTECT(1);
    return s;
}

/* listAppend - Destructive list append */
/* See also ``append'' */
SEXP listAppend(SEXP s, SEXP t)
{
    SEXP r;
    if (s == R_NilValue)
        return t;
    r = s;
    while (CDR(r) != R_NilValue)
        r = CDR(r);
    SETCDR(r, t);
    return s;
}


/*--------------------------------*/
/* Language based list constructs */
/*--------------------------------*/

/* lcons - return a (language) dotted pair with the given car and cdr */
SEXP lcons(SEXP car, SEXP cdr)
{
    SEXP e;
    PROTECT(car);
    PROTECT(cdr);
    e = allocSExp(LANGSXP);
    UNPROTECT(2);
    CAR(e) = car;
    SETCDR(e, cdr);
    TAG(e) = R_NilValue;
    return e;
}

SEXP lang1(SEXP s)
{
    return LCONS(s, R_NilValue);
}

SEXP lang2(SEXP s, SEXP t)
{
    PROTECT(s);
    s = LCONS(s, list1(t));
    UNPROTECT(1);
    return s;
}

SEXP lang3(SEXP s, SEXP t, SEXP u)
{
    PROTECT(s);
    s = LCONS(s, list2(t, u));
    UNPROTECT(1);
    return s;
}

SEXP lang4(SEXP s, SEXP t, SEXP u, SEXP v)
{
    PROTECT(s);
    s = LCONS(s, list3(t, u, v));
    UNPROTECT(1);
    return s;
}