422 lines
10 KiB
C
422 lines
10 KiB
C
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/*************************************************************************
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* *
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* YAP Prolog *
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* *
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* Yap Prolog was developed at NCCUP - Universidade do Porto *
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* *
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* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
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* *
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**************************************************************************
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* *
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* File: sort.c *
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* Last rev: *
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* mods: *
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* comments: sorting in Prolog *
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* *
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*************************************************************************/
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/* for the moment, follow Prolog's traditional mergesort */
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#include "Yap.h"
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#include "Yatom.h"
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#include "Heap.h"
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#ifndef NULL
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#define NULL (void *)0
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#endif
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/* fill in the even or the odd elements */
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#define M_EVEN 0
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#define M_ODD 1
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STATIC_PROTO(Int build_new_list, (CELL *, Term));
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STATIC_PROTO(void simple_mergesort, (CELL *, Int, int));
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STATIC_PROTO(Int compact_mergesort, (CELL *, Int, int));
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STATIC_PROTO(int key_mergesort, (CELL *, Int, int, Functor));
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STATIC_PROTO(void adjust_vector, (CELL *, Int));
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STATIC_PROTO(Int p_sort, (void));
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STATIC_PROTO(Int p_msort, (void));
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STATIC_PROTO(Int p_ksort, (void));
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/* copy to a new list of terms */
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static Int
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build_new_list(CELL *pt, Term t)
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{
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Int out = 0;
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if (IsVarTerm(t))
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return(-1);
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if (t == TermNil)
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return(0);
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restart:
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while (IsPairTerm(t)) {
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out++;
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pt[0] = HeadOfTerm(t);
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t = TailOfTerm(t);
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if (IsVarTerm(t))
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return(-1);
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if (t == TermNil) {
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return(out);
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}
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pt += 2;
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if (pt > ASP - 4096) {
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if (!gc(2, ENV, P)) {
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Error(SYSTEM_ERROR, TermNil, "YAP could not grow stack in sort/2");
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return(FALSE);
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}
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t = Deref(ARG1);
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pt = H;
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out = 0;
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goto restart;
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}
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}
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return(-1);
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}
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/* copy to a new list of terms */
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static
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void simple_mergesort(CELL *pt, Int size, int my_p)
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{
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if (size > 2) {
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Int half_size = size / 2;
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CELL *pt_left, *pt_right, *end_pt, *end_pt_left;
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int left_p, right_p;
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pt_right = pt + half_size*2;
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left_p = my_p^1;
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right_p = my_p;
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simple_mergesort(pt, half_size, left_p);
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simple_mergesort(pt_right, size-half_size, right_p);
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/* now implement a simple merge routine */
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/* pointer to after the end of the list */
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end_pt = pt + 2*size;
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/* pointer to the element after the last element to the left */
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end_pt_left = pt+half_size*2;
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/* where is left list */
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pt_left = pt+left_p;
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/* where is right list */
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pt_right += right_p;
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/* where is new list */
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pt += my_p;
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/* while there are elements in the left or right vector do compares */
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while (pt_left < end_pt_left && pt_right < end_pt) {
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/* if the element to the left is larger than the one to the right */
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if (compare_terms(pt_left[0], pt_right[0]) <= 0) {
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/* copy the one to the left */
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pt[0] = pt_left[0];
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/* and avance the two pointers */
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pt += 2;
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pt_left += 2;
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} else {
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/* otherwise, copy the one to the right */
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pt[0] = pt_right[0];
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pt += 2;
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pt_right += 2;
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}
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}
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/* if any elements were left in the left vector just copy them */
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while (pt_left < end_pt_left) {
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pt[0] = pt_left[0];
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pt += 2;
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pt_left += 2;
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}
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/* if any elements were left in the right vector
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and they are in the wrong place, just copy them */
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if (my_p != right_p) {
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while(pt_right < end_pt) {
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pt[0] = pt_right[0];
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pt += 2;
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pt_right += 2;
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}
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}
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} else {
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if (size > 1 && (compare_terms(pt[0],pt[2]) > 0)) {
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CELL t = pt[2];
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pt[2+my_p] = pt[0];
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pt[my_p] = t;
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} else if (my_p) {
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pt[1] = pt[0];
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if (size > 1)
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pt[3] = pt[2];
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}
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}
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}
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/* copy to a new list of terms */
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static
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int key_mergesort(CELL *pt, Int size, int my_p, Functor FuncDMinus)
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{
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if (size > 2) {
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Int half_size = size / 2;
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CELL *pt_left, *pt_right, *end_pt, *end_pt_left;
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int left_p, right_p;
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pt_right = pt + half_size*2;
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left_p = my_p^1;
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right_p = my_p;
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if (!key_mergesort(pt, half_size, left_p, FuncDMinus))
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return(FALSE);
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if (!key_mergesort(pt_right, size-half_size, right_p, FuncDMinus))
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return(FALSE);
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/* now implement a simple merge routine */
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/* pointer to after the end of the list */
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end_pt = pt + 2*size;
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/* pointer to the element after the last element to the left */
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end_pt_left = pt+half_size*2;
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/* where is left list */
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pt_left = pt+left_p;
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/* where is right list */
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pt_right += right_p;
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/* where is new list */
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pt += my_p;
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/* while there are elements in the left or right vector do compares */
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while (pt_left < end_pt_left && pt_right < end_pt) {
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/* if the element to the left is larger than the one to the right */
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Term t0 = pt_left[0] , t1 = pt_right[0];
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if (IsVarTerm(t0) || !IsApplTerm(t0) || FunctorOfTerm(t0) != FuncDMinus)
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return(FALSE);
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t0 = ArgOfTerm(1,t0);
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if (IsVarTerm(t1) || !IsApplTerm(t1) || FunctorOfTerm(t1) != FuncDMinus)
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return(FALSE);
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t1 = ArgOfTerm(1,t1);
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if (compare_terms(t0, t1) <= 0) {
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/* copy the one to the left */
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pt[0] = pt_left[0];
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/* and avance the two pointers */
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pt += 2;
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pt_left += 2;
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} else {
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/* otherwise, copy the one to the right */
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pt[0] = pt_right[0];
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pt += 2;
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pt_right += 2;
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}
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}
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/* if any elements were left in the left vector just copy them */
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while (pt_left < end_pt_left) {
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pt[0] = pt_left[0];
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pt += 2;
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pt_left += 2;
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}
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/* if any elements were left in the right vector
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and they are in the wrong place, just copy them */
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if (my_p != right_p) {
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while(pt_right < end_pt) {
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pt[0] = pt_right[0];
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pt += 2;
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pt_right += 2;
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}
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}
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} else {
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if (size > 1) {
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Term t0 = pt[0], t1 = pt[2];
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if (IsVarTerm(t0) || !IsApplTerm(t0) || FunctorOfTerm(t0) != FuncDMinus)
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return(FALSE);
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t0 = ArgOfTerm(1,t0);
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if (IsVarTerm(t1) || !IsApplTerm(t1) || FunctorOfTerm(t1) != FuncDMinus)
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return(FALSE);
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t1 = ArgOfTerm(1,t1);
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if (compare_terms(t0,t1) > 0) {
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CELL t = pt[2];
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pt[2+my_p] = pt[0];
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pt[my_p] = t;
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} else if (my_p) {
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pt[1] = pt[0];
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pt[3] = pt[2];
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}
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} else {
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if (my_p)
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pt[1] = pt[0];
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}
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}
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return(TRUE);
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}
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/* copy to a new list of terms and compress duplicates */
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static
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Int compact_mergesort(CELL *pt, Int size, int my_p)
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{
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if (size > 2) {
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Int half_size = size / 2;
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CELL *pt_left, *pt_right, *end_pt_right, *end_pt_left;
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int left_p, right_p;
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Int lsize, rsize;
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pt_right = pt + half_size*2;
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left_p = my_p^1;
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right_p = my_p;
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lsize = compact_mergesort(pt, half_size, left_p);
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rsize = compact_mergesort(pt_right, size-half_size, right_p);
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/* now implement a simple merge routine */
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/* where is left list */
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pt_left = pt+left_p;
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/* pointer to the element after the last element to the left */
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end_pt_left = pt+2*lsize;
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/* where is right list */
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pt_right += right_p;
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/* pointer to after the end of the list */
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end_pt_right = pt_right + 2*rsize;
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/* where is new list */
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pt += my_p;
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size = 0;
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/* while there are elements in the left or right vector do compares */
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while (pt_left < end_pt_left && pt_right < end_pt_right) {
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/* if the element to the left is larger than the one to the right */
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Int cmp = compare_terms(pt_left[0], pt_right[0]);
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if (cmp < 0) {
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/* copy the one to the left */
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pt[0] = pt_left[0];
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/* and avance the two pointers */
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pt += 2;
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size ++;
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pt_left += 2;
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} else if (cmp == 0) {
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/* otherwise, just skip one of them, anyone */
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pt_left += 2;
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} else {
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/* otherwise, copy the one to the right */
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pt[0] = pt_right[0];
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pt += 2;
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pt_right += 2;
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size++;
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}
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}
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/* if any elements were left in the left vector just copy them */
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while (pt_left < end_pt_left) {
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pt[0] = pt_left[0];
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pt += 2;
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pt_left += 2;
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size++;
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}
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/* if any elements were left in the right vector
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and they are in the wrong place, just copy them */
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while(pt_right < end_pt_right) {
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pt[0] = pt_right[0];
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pt += 2;
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pt_right += 2;
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size++;
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}
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return(size);
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} else if (size == 2) {
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Int cmp = compare_terms(pt[0],pt[2]);
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if (cmp > 0) {
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/* swap */
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CELL t = pt[2];
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pt[2+my_p] = pt[0];
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pt[my_p] = t;
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return(2);
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} else if (cmp == 0) {
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if (my_p)
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pt[1] = pt[0];
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return(1);
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} else {
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if (my_p) {
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pt[1] = pt[0];
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pt[3] = pt[2];
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}
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return(2);
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}
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} else {
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/* size = 1 */
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if (my_p)
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pt[1] = pt[0];
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return(1);
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}
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}
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static void
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adjust_vector(CELL *pt, Int size)
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{
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/* the elements are where they should be */
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CELL *ptf = pt + 2*(size-1);
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pt ++;
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while (pt < ptf) {
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pt[0] = AbsPair(pt+1);
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pt += 2;
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}
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/* close the list */
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pt[0] = TermNil;
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}
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static Int
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p_sort(void)
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{
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/* use the heap to build a new list */
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CELL *pt = H;
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Term out;
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/* list size */
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Int size;
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size = build_new_list(pt, Deref(ARG1));
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if (size < 0)
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return(FALSE);
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if (size < 2)
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return(unify(ARG1, ARG2));
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pt = H; /* because of possible garbage collection */
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/* make sure no one writes on our temp data structure */
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H += size*2;
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/* reserve the necessary space */
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size = compact_mergesort(pt, size, M_EVEN);
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/* reajust space */
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H = pt+size*2;
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adjust_vector(pt, size);
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out = AbsPair(pt);
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return(unify(out, ARG2));
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}
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static Int
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p_msort(void)
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{
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/* use the heap to build a new list */
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CELL *pt = H;
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Term out;
|
||
|
|
/* list size */
|
||
|
|
Int size;
|
||
|
|
size = build_new_list(pt, Deref(ARG1));
|
||
|
|
if (size < 0)
|
||
|
|
return(FALSE);
|
||
|
|
if (size < 2)
|
||
|
|
return(unify(ARG1, ARG2));
|
||
|
|
pt = H; /* because of possible garbage collection */
|
||
|
|
/* reserve the necessary space */
|
||
|
|
H += size*2;
|
||
|
|
simple_mergesort(pt, size, M_EVEN);
|
||
|
|
adjust_vector(pt, size);
|
||
|
|
out = AbsPair(pt);
|
||
|
|
return(unify(out, ARG2));
|
||
|
|
}
|
||
|
|
|
||
|
|
static Int
|
||
|
|
p_ksort(void)
|
||
|
|
{
|
||
|
|
/* use the heap to build a new list */
|
||
|
|
CELL *pt = H;
|
||
|
|
Term out;
|
||
|
|
/* list size */
|
||
|
|
Int size;
|
||
|
|
size = build_new_list(pt, Deref(ARG1));
|
||
|
|
if (size < 0)
|
||
|
|
return(FALSE);
|
||
|
|
if (size < 2)
|
||
|
|
return(unify(ARG1, ARG2));
|
||
|
|
/* reserve the necessary space */
|
||
|
|
pt = H; /* because of possible garbage collection */
|
||
|
|
H += size*2;
|
||
|
|
if (!key_mergesort(pt, size, M_EVEN, MkFunctor(AtomMinus,2)))
|
||
|
|
return(FALSE);
|
||
|
|
adjust_vector(pt, size);
|
||
|
|
out = AbsPair(pt);
|
||
|
|
return(unify(out, ARG2));
|
||
|
|
}
|
||
|
|
|
||
|
|
void
|
||
|
|
InitSortPreds(void)
|
||
|
|
{
|
||
|
|
InitCPred("$sort", 2, p_sort, 0);
|
||
|
|
InitCPred("$msort", 2, p_msort, 0);
|
||
|
|
InitCPred("$keysort", 2, p_ksort, 0);
|
||
|
|
}
|