ltree_op.c

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/*
 * op function for ltree
 * Teodor Sigaev <teodor@stack.net>
 * contrib/ltree/ltree_op.c
 */
#include "postgres.h"
 
#include <ctype.h>
 
#include "common/hashfn.h"
#include "ltree.h"
#include "utils/builtins.h"
#include "utils/selfuncs.h"
#include "varatt.h"
 
PG_MODULE_MAGIC_EXT(
                    .name = "ltree",
                    .version = PG_VERSION
);
 
/* compare functions */
PG_FUNCTION_INFO_V1(ltree_cmp);
PG_FUNCTION_INFO_V1(ltree_lt);
PG_FUNCTION_INFO_V1(ltree_le);
PG_FUNCTION_INFO_V1(ltree_eq);
PG_FUNCTION_INFO_V1(ltree_ne);
PG_FUNCTION_INFO_V1(ltree_ge);
PG_FUNCTION_INFO_V1(ltree_gt);
PG_FUNCTION_INFO_V1(hash_ltree);
PG_FUNCTION_INFO_V1(hash_ltree_extended);
PG_FUNCTION_INFO_V1(nlevel);
PG_FUNCTION_INFO_V1(ltree_isparent);
PG_FUNCTION_INFO_V1(ltree_risparent);
PG_FUNCTION_INFO_V1(subltree);
PG_FUNCTION_INFO_V1(subpath);
PG_FUNCTION_INFO_V1(ltree_index);
PG_FUNCTION_INFO_V1(ltree_addltree);
PG_FUNCTION_INFO_V1(ltree_addtext);
PG_FUNCTION_INFO_V1(ltree_textadd);
PG_FUNCTION_INFO_V1(lca);
PG_FUNCTION_INFO_V1(ltree2text);
PG_FUNCTION_INFO_V1(text2ltree);
PG_FUNCTION_INFO_V1(ltreeparentsel);
 
/*
 * btree-comparison function.
 */
int
ltree_compare(const ltree *a, const ltree *b)
{
    ltree_level *al = LTREE_FIRST(a);
    ltree_level *bl = LTREE_FIRST(b);
    int         an = a->numlevel;
    int         bn = b->numlevel;
 
    while (an > 0 && bn > 0)
    {
        int         res;
 
        res = memcmp(al->name, bl->name, Min(al->len, bl->len));
        if (res == 0)
        {
            if (al->len != bl->len)
                return (int) al->len - (int) bl->len;
        }
        else
            return res;
 
        an--;
        bn--;
        al = LEVEL_NEXT(al);
        bl = LEVEL_NEXT(bl);
    }
 
    return a->numlevel - b->numlevel;
}
 
/*
 * Returns a "distance" between a and b.  If a < b, the distance is negative,
 * consistent with the ltree_compare() ordering.
 */
float
ltree_compare_distance(const ltree *a, const ltree *b)
{
    ltree_level *al = LTREE_FIRST(a);
    ltree_level *bl = LTREE_FIRST(b);
    int         an = a->numlevel;
    int         bn = b->numlevel;
 
    while (an > 0 && bn > 0)
    {
        int         res;
 
        res = memcmp(al->name, bl->name, Min(al->len, bl->len));
        if (res == 0)
        {
            if (al->len != bl->len)
                return (float) (al->len - bl->len) * 10.0 * (an + 1);
        }
        else
        {
            if (res < 0)
                return -1.0 * 10.0 * (an + 1);
            else
                return 1.0 * 10.0 * (an + 1);
        }
 
        an--;
        bn--;
        al = LEVEL_NEXT(al);
        bl = LEVEL_NEXT(bl);
    }
 
    return ((float) (a->numlevel - b->numlevel)) * 10.0 * (an + 1);
}
 
#define RUNCMP                      \
ltree *a = PG_GETARG_LTREE_P(0);    \
ltree *b = PG_GETARG_LTREE_P(1);    \
int res = ltree_compare(a,b);       \
PG_FREE_IF_COPY(a,0);               \
PG_FREE_IF_COPY(b,1)
 
Datum
ltree_cmp(PG_FUNCTION_ARGS)
{
    RUNCMP;
    PG_RETURN_INT32(res);
}
 
Datum
ltree_lt(PG_FUNCTION_ARGS)
{
    RUNCMP;
    PG_RETURN_BOOL(res < 0);
}
 
Datum
ltree_le(PG_FUNCTION_ARGS)
{
    RUNCMP;
    PG_RETURN_BOOL(res <= 0);
}
 
Datum
ltree_eq(PG_FUNCTION_ARGS)
{
    RUNCMP;
    PG_RETURN_BOOL(res == 0);
}
 
Datum
ltree_ge(PG_FUNCTION_ARGS)
{
    RUNCMP;
    PG_RETURN_BOOL(res >= 0);
}
 
Datum
ltree_gt(PG_FUNCTION_ARGS)
{
    RUNCMP;
    PG_RETURN_BOOL(res > 0);
}
 
Datum
ltree_ne(PG_FUNCTION_ARGS)
{
    RUNCMP;
    PG_RETURN_BOOL(res != 0);
}
 
/* Compute a hash for the ltree */
Datum
hash_ltree(PG_FUNCTION_ARGS)
{
    ltree      *a = PG_GETARG_LTREE_P(0);
    uint32      result = 1;
    int         an = a->numlevel;
    ltree_level *al = LTREE_FIRST(a);
 
    while (an > 0)
    {
        uint32      levelHash = DatumGetUInt32(hash_any((unsigned char *) al->name, al->len));
 
        /*
         * Combine hash values of successive elements by multiplying the
         * current value by 31 and adding on the new element's hash value.
         *
         * This method is borrowed from hash_array(), which see for further
         * commentary.
         */
        result = (result << 5) - result + levelHash;
 
        an--;
        al = LEVEL_NEXT(al);
    }
 
    PG_FREE_IF_COPY(a, 0);
    PG_RETURN_UINT32(result);
}
 
/* Compute an extended hash for the ltree */
Datum
hash_ltree_extended(PG_FUNCTION_ARGS)
{
    ltree      *a = PG_GETARG_LTREE_P(0);
    const uint64 seed = PG_GETARG_INT64(1);
    uint64      result = 1;
    int         an = a->numlevel;
    ltree_level *al = LTREE_FIRST(a);
 
    /*
     * If the path has length zero, return 1 + seed to ensure that the low 32
     * bits of the result match hash_ltree when the seed is 0, as required by
     * the hash index support functions, but to also return a different value
     * when there is a seed.
     */
    if (an == 0)
    {
        PG_FREE_IF_COPY(a, 0);
        PG_RETURN_UINT64(result + seed);
    }
 
    while (an > 0)
    {
        uint64      levelHash = DatumGetUInt64(hash_any_extended((unsigned char *) al->name, al->len, seed));
 
        result = (result << 5) - result + levelHash;
 
        an--;
        al = LEVEL_NEXT(al);
    }
 
    PG_FREE_IF_COPY(a, 0);
    PG_RETURN_UINT64(result);
}
 
Datum
nlevel(PG_FUNCTION_ARGS)
{
    ltree      *a = PG_GETARG_LTREE_P(0);
    int         res = a->numlevel;
 
    PG_FREE_IF_COPY(a, 0);
    PG_RETURN_INT32(res);
}
 
bool
inner_isparent(const ltree *c, const ltree *p)
{
    ltree_level *cl = LTREE_FIRST(c);
    ltree_level *pl = LTREE_FIRST(p);
    int         pn = p->numlevel;
 
    if (pn > c->numlevel)
        return false;
 
    while (pn > 0)
    {
        if (cl->len != pl->len)
            return false;
        if (memcmp(cl->name, pl->name, cl->len) != 0)
            return false;
 
        pn--;
        cl = LEVEL_NEXT(cl);
        pl = LEVEL_NEXT(pl);
    }
    return true;
}
 
Datum
ltree_isparent(PG_FUNCTION_ARGS)
{
    ltree      *c = PG_GETARG_LTREE_P(1);
    ltree      *p = PG_GETARG_LTREE_P(0);
    bool        res = inner_isparent(c, p);
 
    PG_FREE_IF_COPY(c, 1);
    PG_FREE_IF_COPY(p, 0);
    PG_RETURN_BOOL(res);
}
 
Datum
ltree_risparent(PG_FUNCTION_ARGS)
{
    ltree      *c = PG_GETARG_LTREE_P(0);
    ltree      *p = PG_GETARG_LTREE_P(1);
    bool        res = inner_isparent(c, p);
 
    PG_FREE_IF_COPY(c, 0);
    PG_FREE_IF_COPY(p, 1);
    PG_RETURN_BOOL(res);
}
 
 
static ltree *
inner_subltree(ltree *t, int32 startpos, int32 endpos)
{
    char       *start = NULL,
               *end = NULL;
    ltree_level *ptr = LTREE_FIRST(t);
    ltree      *res;
    int         i;
 
    if (startpos < 0 || endpos < 0 || startpos >= t->numlevel || startpos > endpos)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("invalid positions")));
 
    if (endpos > t->numlevel)
        endpos = t->numlevel;
 
    start = end = (char *) ptr;
    for (i = 0; i < endpos; i++)
    {
        if (i == startpos)
            start = (char *) ptr;
        if (i == endpos - 1)
        {
            end = (char *) LEVEL_NEXT(ptr);
            break;
        }
        ptr = LEVEL_NEXT(ptr);
    }
 
    res = (ltree *) palloc0(LTREE_HDRSIZE + (end - start));
    SET_VARSIZE(res, LTREE_HDRSIZE + (end - start));
    res->numlevel = endpos - startpos;
 
    memcpy(LTREE_FIRST(res), start, end - start);
 
    return res;
}
 
Datum
subltree(PG_FUNCTION_ARGS)
{
    ltree      *t = PG_GETARG_LTREE_P(0);
    ltree      *res = inner_subltree(t, PG_GETARG_INT32(1), PG_GETARG_INT32(2));
 
    PG_FREE_IF_COPY(t, 0);
    PG_RETURN_POINTER(res);
}
 
Datum
subpath(PG_FUNCTION_ARGS)
{
    ltree      *t = PG_GETARG_LTREE_P(0);
    int32       start = PG_GETARG_INT32(1);
    int32       len = (fcinfo->nargs == 3) ? PG_GETARG_INT32(2) : 0;
    int32       end;
    ltree      *res;
 
    if (start < 0)
        start = t->numlevel + start;
 
    if (len < 0)
        end = t->numlevel + len;
    else if (len == 0)
        end = (fcinfo->nargs == 3) ? start : LTREE_MAX_LEVELS;
    else
        end = start + len;
 
    res = inner_subltree(t, start, end);
 
    PG_FREE_IF_COPY(t, 0);
    PG_RETURN_POINTER(res);
}
 
static ltree *
ltree_concat(ltree *a, ltree *b)
{
    ltree      *r;
    int         numlevel = (int) a->numlevel + b->numlevel;
 
    if (numlevel > LTREE_MAX_LEVELS)
        ereport(ERROR,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("number of ltree levels (%d) exceeds the maximum allowed (%d)",
                        numlevel, LTREE_MAX_LEVELS)));
 
    r = (ltree *) palloc0(VARSIZE(a) + VARSIZE(b) - LTREE_HDRSIZE);
    SET_VARSIZE(r, VARSIZE(a) + VARSIZE(b) - LTREE_HDRSIZE);
    r->numlevel = (uint16) numlevel;
 
    memcpy(LTREE_FIRST(r), LTREE_FIRST(a), VARSIZE(a) - LTREE_HDRSIZE);
    memcpy(((char *) LTREE_FIRST(r)) + VARSIZE(a) - LTREE_HDRSIZE,
           LTREE_FIRST(b),
           VARSIZE(b) - LTREE_HDRSIZE);
    return r;
}
 
Datum
ltree_addltree(PG_FUNCTION_ARGS)
{
    ltree      *a = PG_GETARG_LTREE_P(0);
    ltree      *b = PG_GETARG_LTREE_P(1);
    ltree      *r;
 
    r = ltree_concat(a, b);
    PG_FREE_IF_COPY(a, 0);
    PG_FREE_IF_COPY(b, 1);
    PG_RETURN_POINTER(r);
}
 
Datum
ltree_addtext(PG_FUNCTION_ARGS)
{
    ltree      *a = PG_GETARG_LTREE_P(0);
    text       *b = PG_GETARG_TEXT_PP(1);
    char       *s;
    ltree      *r,
               *tmp;
 
    s = text_to_cstring(b);
 
    tmp = (ltree *) DatumGetPointer(DirectFunctionCall1(ltree_in,
                                                        PointerGetDatum(s)));
 
    pfree(s);
 
    r = ltree_concat(a, tmp);
 
    pfree(tmp);
 
    PG_FREE_IF_COPY(a, 0);
    PG_FREE_IF_COPY(b, 1);
    PG_RETURN_POINTER(r);
}
 
Datum
ltree_index(PG_FUNCTION_ARGS)
{
    ltree      *a = PG_GETARG_LTREE_P(0);
    ltree      *b = PG_GETARG_LTREE_P(1);
    int         start = (fcinfo->nargs == 3) ? PG_GETARG_INT32(2) : 0;
    int         i,
                j;
    ltree_level *startptr,
               *aptr,
               *bptr;
    bool        found = false;
 
    if (start < 0)
    {
        if (-start >= a->numlevel)
            start = 0;
        else
            start = (int) (a->numlevel) + start;
    }
 
    if (a->numlevel - start < b->numlevel || a->numlevel == 0 || b->numlevel == 0)
    {
        PG_FREE_IF_COPY(a, 0);
        PG_FREE_IF_COPY(b, 1);
        PG_RETURN_INT32(-1);
    }
 
    startptr = LTREE_FIRST(a);
    for (i = 0; i <= a->numlevel - b->numlevel; i++)
    {
        if (i >= start)
        {
            aptr = startptr;
            bptr = LTREE_FIRST(b);
            for (j = 0; j < b->numlevel; j++)
            {
                if (!(aptr->len == bptr->len && memcmp(aptr->name, bptr->name, aptr->len) == 0))
                    break;
                aptr = LEVEL_NEXT(aptr);
                bptr = LEVEL_NEXT(bptr);
            }
 
            if (j == b->numlevel)
            {
                found = true;
                break;
            }
        }
        startptr = LEVEL_NEXT(startptr);
    }
 
    if (!found)
        i = -1;
 
    PG_FREE_IF_COPY(a, 0);
    PG_FREE_IF_COPY(b, 1);
    PG_RETURN_INT32(i);
}
 
Datum
ltree_textadd(PG_FUNCTION_ARGS)
{
    ltree      *a = PG_GETARG_LTREE_P(1);
    text       *b = PG_GETARG_TEXT_PP(0);
    char       *s;
    ltree      *r,
               *tmp;
 
    s = text_to_cstring(b);
 
    tmp = (ltree *) DatumGetPointer(DirectFunctionCall1(ltree_in,
                                                        PointerGetDatum(s)));
 
    pfree(s);
 
    r = ltree_concat(tmp, a);
 
    pfree(tmp);
 
    PG_FREE_IF_COPY(a, 1);
    PG_FREE_IF_COPY(b, 0);
    PG_RETURN_POINTER(r);
}
 
/*
 * Common code for variants of lca(), find longest common ancestor of inputs
 *
 * Returns NULL if there is no common ancestor, ie, the longest common
 * prefix is empty.
 */
ltree *
lca_inner(ltree **a, int len)
{
    int         tmp,
                num,
                i,
                reslen;
    ltree     **ptr;
    ltree_level *l1,
               *l2;
    ltree      *res;
 
    if (len <= 0)
        return NULL;            /* no inputs? */
    if ((*a)->numlevel == 0)
        return NULL;            /* any empty input means NULL result */
 
    /* num is the length of the longest common ancestor so far */
    num = (*a)->numlevel - 1;
 
    /* Compare each additional input to *a */
    ptr = a + 1;
    while (ptr - a < len)
    {
        if ((*ptr)->numlevel == 0)
            return NULL;
        else if ((*ptr)->numlevel == 1)
            num = 0;
        else
        {
            l1 = LTREE_FIRST(*a);
            l2 = LTREE_FIRST(*ptr);
            tmp = Min(num, (*ptr)->numlevel - 1);
            num = 0;
            for (i = 0; i < tmp; i++)
            {
                if (l1->len == l2->len &&
                    memcmp(l1->name, l2->name, l1->len) == 0)
                    num = i + 1;
                else
                    break;
                l1 = LEVEL_NEXT(l1);
                l2 = LEVEL_NEXT(l2);
            }
        }
        ptr++;
    }
 
    /* Now compute size of result ... */
    reslen = LTREE_HDRSIZE;
    l1 = LTREE_FIRST(*a);
    for (i = 0; i < num; i++)
    {
        reslen += MAXALIGN(l1->len + LEVEL_HDRSIZE);
        l1 = LEVEL_NEXT(l1);
    }
 
    /* ... and construct it by copying from *a */
    res = (ltree *) palloc0(reslen);
    SET_VARSIZE(res, reslen);
    res->numlevel = num;
 
    l1 = LTREE_FIRST(*a);
    l2 = LTREE_FIRST(res);
 
    for (i = 0; i < num; i++)
    {
        memcpy(l2, l1, MAXALIGN(l1->len + LEVEL_HDRSIZE));
        l1 = LEVEL_NEXT(l1);
        l2 = LEVEL_NEXT(l2);
    }
 
    return res;
}
 
Datum
lca(PG_FUNCTION_ARGS)
{
    int         i;
    ltree     **a,
               *res;
 
    a = palloc_array(ltree *, fcinfo->nargs);
    for (i = 0; i < fcinfo->nargs; i++)
        a[i] = PG_GETARG_LTREE_P(i);
    res = lca_inner(a, (int) fcinfo->nargs);
    for (i = 0; i < fcinfo->nargs; i++)
        PG_FREE_IF_COPY(a[i], i);
    pfree(a);
 
    if (res)
        PG_RETURN_POINTER(res);
    else
        PG_RETURN_NULL();
}
 
Datum
text2ltree(PG_FUNCTION_ARGS)
{
    text       *in = PG_GETARG_TEXT_PP(0);
    char       *s;
    ltree      *out;
 
    s = text_to_cstring(in);
 
    out = (ltree *) DatumGetPointer(DirectFunctionCall1(ltree_in,
                                                        PointerGetDatum(s)));
    pfree(s);
    PG_FREE_IF_COPY(in, 0);
    PG_RETURN_POINTER(out);
}
 
 
Datum
ltree2text(PG_FUNCTION_ARGS)
{
    ltree      *in = PG_GETARG_LTREE_P(0);
    char       *ptr;
    int         i;
    ltree_level *curlevel;
    text       *out;
 
    out = (text *) palloc(VARSIZE(in) + VARHDRSZ);
    ptr = VARDATA(out);
    curlevel = LTREE_FIRST(in);
    for (i = 0; i < in->numlevel; i++)
    {
        if (i != 0)
        {
            *ptr = '.';
            ptr++;
        }
        memcpy(ptr, curlevel->name, curlevel->len);
        ptr += curlevel->len;
        curlevel = LEVEL_NEXT(curlevel);
    }
 
    SET_VARSIZE(out, ptr - ((char *) out));
    PG_FREE_IF_COPY(in, 0);
 
    PG_RETURN_POINTER(out);
}
 
 
/*
 *  ltreeparentsel - Selectivity of parent relationship for ltree data types.
 *
 * This function is not used anymore, if the ltree extension has been
 * updated to 1.2 or later.
 */
Datum
ltreeparentsel(PG_FUNCTION_ARGS)
{
    PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0);
    Oid         operator = PG_GETARG_OID(1);
    List       *args = (List *) PG_GETARG_POINTER(2);
    int         varRelid = PG_GETARG_INT32(3);
    double      selec;
 
    /* Use generic restriction selectivity logic, with default 0.001. */
    selec = generic_restriction_selectivity(root, operator, InvalidOid,
                                            args, varRelid,
                                            0.001);
 
    PG_RETURN_FLOAT8((float8) selec);
}