LWGEOM_dump()

Datum LWGEOM_dump

(

PG_FUNCTION_ARGS

)

Definition at line 70 of file lwgeom_dump.c.

{
        GSERIALIZED *pglwgeom;
        LWCOLLECTION *lwcoll;
        LWGEOM *lwgeom;
        FuncCallContext *funcctx;
        GEOMDUMPSTATE *state;
        GEOMDUMPNODE *node;
        TupleDesc tupdesc;
        HeapTuple tuple;
        AttInMetadata *attinmeta;
        MemoryContext oldcontext, newcontext;
        Datum result;
        char address[256];
        char *ptr;
        int i;
        char *values[2];
 
        if (SRF_IS_FIRSTCALL())
        {
                funcctx = SRF_FIRSTCALL_INIT();
                newcontext = funcctx->multi_call_memory_ctx;
 
                oldcontext = MemoryContextSwitchTo(newcontext);
 
                pglwgeom = PG_GETARG_GSERIALIZED_P_COPY(0);
                lwgeom = lwgeom_from_gserialized(pglwgeom);
 
                /* Create function state */
                state = lwalloc(sizeof(GEOMDUMPSTATE));
                state->root = lwgeom;
                state->stacklen=0;
 
                if ( lwgeom_is_collection(lwgeom) )
                {
                        /*
                         * Push a GEOMDUMPNODE on the state stack
                         */
                        node = lwalloc(sizeof(GEOMDUMPNODE));
                        node->idx=0;
                        node->geom = lwgeom;
                        PUSH(state, node);
                }
 
                funcctx->user_fctx = state;
 
                /*
                 * Build a tuple description for an
                 * geometry_dump tuple
                 */
                get_call_result_type(fcinfo, 0, &tupdesc);
                BlessTupleDesc(tupdesc);
 
                /*
                 * generate attribute metadata needed later to produce
                 * tuples from raw C strings
                 */
                attinmeta = TupleDescGetAttInMetadata(tupdesc);
                funcctx->attinmeta = attinmeta;
 
                MemoryContextSwitchTo(oldcontext);
        }
 
        /* stuff done on every call of the function */
        funcctx = SRF_PERCALL_SETUP();
        newcontext = funcctx->multi_call_memory_ctx;
 
        /* get state */
        state = funcctx->user_fctx;
 
        /* Handled simple geometries */
        if ( ! state->root ) SRF_RETURN_DONE(funcctx);
        /* Return nothing for empties */
        if ( lwgeom_is_empty(state->root) ) SRF_RETURN_DONE(funcctx);
        if ( ! lwgeom_is_collection(state->root) )
        {
                values[0] = "{}";
                values[1] = lwgeom_to_hexwkb(state->root, WKB_EXTENDED, 0);
                tuple = BuildTupleFromCStrings(funcctx->attinmeta, values);
                result = HeapTupleGetDatum(tuple);
 
                state->root = NULL;
                SRF_RETURN_NEXT(funcctx, result);
        }
 
        while (1)
        {
                node = LAST(state);
                lwcoll = (LWCOLLECTION*)node->geom;
 
                if ( node->idx < lwcoll->ngeoms )
                {
                        lwgeom = lwcoll->geoms[node->idx];
                        if ( ! lwgeom_is_collection(lwgeom) )
                        {
                                /* write address of current geom */
                                ptr=address;
                                *ptr++='{';
                                for (i=0; i<state->stacklen; i++)
                                {
                                        if ( i ) ptr += sprintf(ptr, ",");
                                        ptr += sprintf(ptr, "%d", state->stack[i]->idx+1);
                                }
                                *ptr++='}';
                                *ptr='\0';
 
                                break;
                        }
 
                        /*
                         * It's a collection, increment index
                         * of current node, push a new one on the
                         * stack
                         */
 
                        oldcontext = MemoryContextSwitchTo(newcontext);
 
                        node = lwalloc(sizeof(GEOMDUMPNODE));
                        node->idx=0;
                        node->geom = lwgeom;
                        PUSH(state, node);
 
                        MemoryContextSwitchTo(oldcontext);
 
                        continue;
                }
 
                if ( ! POP(state) ) SRF_RETURN_DONE(funcctx);
                LAST(state)->idx++;
        }
 
        lwgeom->srid = state->root->srid;
 
        values[0] = address;
        values[1] = lwgeom_to_hexwkb(lwgeom, WKB_EXTENDED, 0);
        tuple = BuildTupleFromCStrings(funcctx->attinmeta, values);
        result = TupleGetDatum(funcctx->slot, tuple);
        node->idx++;
        SRF_RETURN_NEXT(funcctx, result);
}

References GEOMDUMPNODE_T::geom, LWCOLLECTION::geoms, GEOMDUMPNODE_T::idx, LAST, lwalloc(), lwgeom_from_gserialized(), lwgeom_is_collection(), lwgeom_is_empty(), lwgeom_to_hexwkb(), LWCOLLECTION::ngeoms, POP, PUSH, GEOMDUMPSTATE::root, LWGEOM::srid, GEOMDUMPSTATE::stack, GEOMDUMPSTATE::stacklen, and WKB_EXTENDED.

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