vector/Vlib/read.c

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/*!
   \file lib/vector/Vlib/read.c

   \brief Vector library - read features

   Higher level functions for reading/writing/manipulating vectors.

   (C) 2001-2009, 2011-2013 by the GRASS Development Team

   This program is free software under the GNU General Public License
   (>=v2). Read the file COPYING that comes with GRASS for details.

   \author Original author CERL, probably Dave Gerdes or Mike Higgins.
   \author Update to GRASS 5.7 Radim Blazek and David D. Gray.
   \author Update to GRASS 7 Martin Landa <landa.martin gmail.com>
 */

#include <sys/types.h>
#include <grass/vector.h>
#include <grass/glocale.h>

static int read_dummy()
{
    G_warning("Vect_read_line() %s",
              _("for this format/level not supported"));
    return -1;
}

#if !defined HAVE_OGR || !defined HAVE_POSTGRES
static int format()
{
    G_fatal_error(_("Requested format is not compiled in this version"));
    return 0;
}
#endif

static int (*Read_next_line_array[][3]) () = {
    {
        read_dummy, V1_read_next_line_nat, V2_read_next_line_nat}
#ifdef HAVE_OGR
    , {
        read_dummy, V1_read_next_line_ogr, V2_read_next_line_ogr}
    , {
        read_dummy, V1_read_next_line_ogr, V2_read_next_line_ogr}
#else
    , {
        read_dummy, format, format}
    , {
        read_dummy, format, format}
#endif
#ifdef HAVE_POSTGRES
    , {
        read_dummy, V1_read_next_line_pg, V2_read_next_line_pg}
#else
    , {
        read_dummy, format, format}
#endif
};

static int (*Read_line_array[]) () = {
    V2_read_line_nat
#ifdef HAVE_OGR
    , V2_read_line_sfa
    , V2_read_line_sfa
#else
    , format
    , format
#endif
#ifdef HAVE_POSTGRES
    , V2_read_line_pg
#else
    , format
#endif
};

    
/*!
  \brief Get line id for sequential reading.

  This function returns id of feature which has been read by calling
  Vect_read_next_line().

  \param Map pointer to Map_info struct

  \return feature id
  \return -1 on error
*/
int Vect_get_next_line_id(const struct Map_info *Map)
{
    G_debug(3, "Vect_get_next_line()");

    if (!VECT_OPEN(Map)) {
        G_warning(_("Vector map is not open for reading"));
        return -1;
    }
    
    return Map->next_line - 1;
}

/*!
   \brief Read next vector feature

   This function implements sequential access, constraints are
   reflected, see Vect_set_constraint_region(),
   Vect_set_constraint_type(), or Vect_set_constraint_field() for
   details.
     
   Use Vect_rewind() to reset reading. Topological level is not
   required.

   A warning is printed on failure.
   
   \param Map pointer Map_info struct
   \param[out] line_p feature geometry (pointer to line_pnts struct)
   \param[out] line_c feature categories (pointer to line_cats struct)

   \return feature type (GV_POINT, GV_LINE, ...)
   \return -1 on error
   \return -2 nothing to read
 */
int Vect_read_next_line(const struct Map_info *Map,
                        struct line_pnts *line_p, struct line_cats *line_c)
{
    int ret;
    
    G_debug(3, "Vect_read_next_line(): next_line = %d", Map->next_line);

    if (!VECT_OPEN(Map)) {
        G_warning(_("Vector map is not open for reading"));
        return -1;
    }
    
    ret = (*Read_next_line_array[Map->format][Map->level]) (Map, line_p,
                                                            line_c);
    if (ret == -1)
        G_warning(_("Unable to read feature %d from vector map <%s>"),
                  Map->next_line, Vect_get_full_name(Map));
    
    return ret;
}

/*!
   \brief Read vector feature (topological level required)

   This function implements random access. Constraits are ignored.

   Note: Topology must be built at level >= GV_BUILD_BASE

   A warning is printed on failure.
   
   \param Map pointer to vector map
   \param[out] line_p feature geometry (pointer to line_pnts struct)
   \param[out] line_c feature categories (pointer to line_cats struct)
   \param line feature id (starts at 1)
   
   \return feature type
   \return -1 on failure
   \return -2 nothing to read   
 */
int Vect_read_line(const struct Map_info *Map,
                   struct line_pnts *line_p, struct line_cats *line_c, int line)
{
    int ret;
    
    G_debug(3, "Vect_read_line(): line = %d", line);

    if (!VECT_OPEN(Map)) {
        G_warning(_("Vector map is not open for reading"));
        return -1;
    }
    
    if (line < 1 || line > Map->plus.n_lines) {
        G_warning(_("Attempt to access feature with invalid id (%d)"), line);
        return -1;
    }
    
    ret = (*Read_line_array[Map->format]) (Map, line_p, line_c, line);

    if (ret == -1)
        G_warning(_("Unable to read feature %d from vector map <%s>"),
                  line, Vect_get_full_name(Map));
    
    return ret;
}

/*!
  \brief Check if feature is alive or dead (topological level required)
  
  Note: Topology must be built at level >= GV_BUILD_BASE

  \param Map pointer to Map_info structure
  \param line feature id
  
  \return 1 feature alive
  \return 0 feature is dead or index is out of range
 */
int Vect_line_alive(const struct Map_info *Map, int line)
{
    if (line < 1 || line > Map->plus.n_lines) {
        G_warning(_("Line index is out of range"));
        return 0;
    }

    if (Map->plus.Line[line] != NULL)
        return 1;
    
    return 0;
}

/*!
  \brief Check if node is alive or dead (topological level required)
  
  Note: Topology must be built at level >= GV_BUILD_BASE

  \param Map pointer to Map_info structure
  \param node node id
  
  \return 1 node alive
  \return 0 node is dead or index is out of range
 */
int Vect_node_alive(const struct Map_info *Map, int node)
{
    if (node < 1 || node > Map->plus.n_nodes) {
        G_warning(_("Node index is out of range"));
        return 0;
    }

    if (Map->plus.Node[node] != NULL)
        return 1;

    return 0;
}

/*!
  \brief Check if area is alive or dead (topological level required)
  
  Note: Topology must be built at level >= GV_BUILD_AREAS

  \param Map pointer to Map_info structure
  \param area area id
  
  \return 1 area alive
  \return 0 area is dead or index is out of range
*/
int Vect_area_alive(const struct Map_info *Map, int area)
{
    if (area < 1 || area > Map->plus.n_areas) {
        G_warning(_("Area index is out of range"));
        return 0;
    }
    
    if (Map->plus.Area[area] != NULL)
        return 1;

    return 0;
}

/*!
  \brief Check if isle is alive or dead (topological level required)

  Note: Topology must be built at level >= GV_BUILD_AREAS
  
  \param Map pointer to Map_info structure
  \param isle isle id
  
  \return 1 isle alive
  \return 0 isle is dead or index is out of range
*/
int Vect_isle_alive(const struct Map_info *Map, int isle)
{
    if (isle < 1 || isle > Map->plus.n_isles) {
        G_warning(_("Isle index is out of range"));
        return 0;
    }

    if (Map->plus.Isle[isle] != NULL)
        return 1;

    return 0;
}

/*!
  \brief Get feature offset (topological level required)
  
  Note: Topology must be built at level >= GV_BUILD_BASE
  
  Used for Vect_restore_line().
  
  \param Map pointer to Map_info structure
  \param line feature id

  \return feature offset
  \return -1 on error
*/
off_t Vect_get_line_offset(const struct Map_info *Map, int line)
{
    if (line < 1 || line > Map->plus.n_lines) {
        return -1;
    }
    
    if (Map->plus.Line[line] != NULL) {
        return Map->plus.Line[line]->offset;
    }
    
    return -1;
}