/* glpapi15.c (basic graph and network routines) */

/***********************************************************************

*  This code is part of GLPK (GNU Linear Programming Kit).

*

*  Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,

*  2009, 2010 Andrew Makhorin, Department for Applied Informatics,

*  Moscow Aviation Institute, Moscow, Russia. All rights reserved.

*  E-mail: <mao@gnu.org>.

*

*  GLPK 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 3 of the License, or

*  (at your option) any later version.

*

*  GLPK 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 GLPK. If not, see <http://www.gnu.org/licenses/>.

***********************************************************************/

#include "glpapi.h"

/* CAUTION: DO NOT CHANGE THE LIMITS BELOW */

#define NV_MAX 100000000 /* = 100*10^6 */

/* maximal number of vertices in the graph */

#define NA_MAX 500000000 /* = 500*10^6 */

/* maximal number of arcs in the graph */

/***********************************************************************

*  NAME

*

*  glp_create_graph - create graph

*

*  SYNOPSIS

*

*  glp_graph *glp_create_graph(int v_size, int a_size);

*

*  DESCRIPTION

*

*  The routine creates a new graph, which initially is empty, i.e. has

*  no vertices and arcs.

*

*  The parameter v_size specifies the size of data associated with each

*  vertex of the graph (0 to 256 bytes).

*

*  The parameter a_size specifies the size of data associated with each

*  arc of the graph (0 to 256 bytes).

*

*  RETURNS

*

*  The routine returns a pointer to the graph created. */

static void create_graph(glp_graph *G, int v_size, int a_size)

{     G->pool = dmp_create_pool();

      G->name = NULL;

      G->nv_max = 50;

      G->nv = G->na = 0;

      G->v = xcalloc(1+G->nv_max, sizeof(glp_vertex *));

      G->index = NULL;

      G->v_size = v_size;

      G->a_size = a_size;

      return;

}

glp_graph *glp_create_graph(int v_size, int a_size)

{     glp_graph *G;

      if (!(0 <= v_size && v_size <= 256))

         xerror("glp_create_graph: v_size = %d; invalid size of vertex "

            "data\n", v_size);

      if (!(0 <= a_size && a_size <= 256))

         xerror("glp_create_graph: a_size = %d; invalid size of arc dat"

            "a\n", a_size);

      G = xmalloc(sizeof(glp_graph));

      create_graph(G, v_size, a_size);

      return G;

}

/***********************************************************************

*  NAME

*

*  glp_set_graph_name - assign (change) graph name

*

*  SYNOPSIS

*

*  void glp_set_graph_name(glp_graph *G, const char *name);

*

*  DESCRIPTION

*

*  The routine glp_set_graph_name assigns a symbolic name specified by

*  the character string name (1 to 255 chars) to the graph.

*

*  If the parameter name is NULL or an empty string, the routine erases

*  the existing symbolic name of the graph. */

void glp_set_graph_name(glp_graph *G, const char *name)

{     if (G->name != NULL)

      {  dmp_free_atom(G->pool, G->name, strlen(G->name)+1);

         G->name = NULL;

      }

      if (!(name == NULL || name[0] == '\0'))

      {  int j;

         for (j = 0; name[j] != '\0'; j++)

         {  if (j == 256)

               xerror("glp_set_graph_name: graph name too long\n");

            if (iscntrl((unsigned char)name[j]))

               xerror("glp_set_graph_name: graph name contains invalid "

                  "character(s)\n");

         }

         G->name = dmp_get_atom(G->pool, strlen(name)+1);

         strcpy(G->name, name);

      }

      return;

}

/***********************************************************************

*  NAME

*

*  glp_add_vertices - add new vertices to graph

*

*  SYNOPSIS

*

*  int glp_add_vertices(glp_graph *G, int nadd);

*

*  DESCRIPTION

*

*  The routine glp_add_vertices adds nadd vertices to the specified

*  graph. New vertices are always added to the end of the vertex list,

*  so ordinal numbers of existing vertices remain unchanged.

*

*  Being added each new vertex is isolated (has no incident arcs).

*

*  RETURNS

*

*  The routine glp_add_vertices returns an ordinal number of the first

*  new vertex added to the graph. */

int glp_add_vertices(glp_graph *G, int nadd)

{     int i, nv_new;

      if (nadd < 1)

         xerror("glp_add_vertices: nadd = %d; invalid number of vertice"

            "s\n", nadd);

      if (nadd > NV_MAX - G->nv)

         xerror("glp_add_vertices: nadd = %d; too many vertices\n",

            nadd);

      /* determine new number of vertices */

      nv_new = G->nv + nadd;

      /* increase the room, if necessary */

      if (G->nv_max < nv_new)

      {  glp_vertex **save = G->v;

         while (G->nv_max < nv_new)

         {  G->nv_max += G->nv_max;

            xassert(G->nv_max > 0);

         }

         G->v = xcalloc(1+G->nv_max, sizeof(glp_vertex *));

         memcpy(&G->v[1], &save[1], G->nv * sizeof(glp_vertex *));

         xfree(save);

      }

      /* add new vertices to the end of the vertex list */

      for (i = G->nv+1; i <= nv_new; i++)

      {  glp_vertex *v;

         G->v[i] = v = dmp_get_atom(G->pool, sizeof(glp_vertex));

         v->i = i;

         v->name = NULL;

         v->entry = NULL;

         if (G->v_size == 0)

            v->data = NULL;

         else

         {  v->data = dmp_get_atom(G->pool, G->v_size);

            memset(v->data, 0, G->v_size);

         }

         v->temp = NULL;

         v->in = v->out = NULL;

      }

      /* set new number of vertices */

      G->nv = nv_new;

      /* return the ordinal number of the first vertex added */

      return nv_new - nadd + 1;

}

/**********************************************************************/

void glp_set_vertex_name(glp_graph *G, int i, const char *name)

{     /* assign (change) vertex name */

      glp_vertex *v;

      if (!(1 <= i && i <= G->nv))

         xerror("glp_set_vertex_name: i = %d; vertex number out of rang"

            "e\n", i);

      v = G->v[i];

      if (v->name != NULL)

      {  if (v->entry != NULL)

         {  xassert(G->index != NULL);

            avl_delete_node(G->index, v->entry);

            v->entry = NULL;

         }

         dmp_free_atom(G->pool, v->name, strlen(v->name)+1);

         v->name = NULL;

      }

      if (!(name == NULL || name[0] == '\0'))

      {  int k;

         for (k = 0; name[k] != '\0'; k++)

         {  if (k == 256)

               xerror("glp_set_vertex_name: i = %d; vertex name too lon"

                  "g\n", i);

            if (iscntrl((unsigned char)name[k]))

               xerror("glp_set_vertex_name: i = %d; vertex name contain"

                  "s invalid character(s)\n", i);

         }

         v->name = dmp_get_atom(G->pool, strlen(name)+1);

         strcpy(v->name, name);

         if (G->index != NULL)

         {  xassert(v->entry == NULL);

            v->entry = avl_insert_node(G->index, v->name);

            avl_set_node_link(v->entry, v);

         }

      }

      return;

}

/***********************************************************************

*  NAME

*

*  glp_add_arc - add new arc to graph

*

*  SYNOPSIS

*

*  glp_arc *glp_add_arc(glp_graph *G, int i, int j);

*

*  DESCRIPTION

*

*  The routine glp_add_arc adds a new arc to the specified graph.

*

*  The parameters i and j specify the ordinal numbers of, resp., tail

*  and head vertices of the arc. Note that self-loops and multiple arcs

*  are allowed.

*

*  RETURNS

*

*  The routine glp_add_arc returns a pointer to the arc added. */

glp_arc *glp_add_arc(glp_graph *G, int i, int j)

{     glp_arc *a;

      if (!(1 <= i && i <= G->nv))

         xerror("glp_add_arc: i = %d; tail vertex number out of range\n"

            , i);

      if (!(1 <= j && j <= G->nv))

         xerror("glp_add_arc: j = %d; head vertex number out of range\n"

            , j);

      if (G->na == NA_MAX)

         xerror("glp_add_arc: too many arcs\n");

      a = dmp_get_atom(G->pool, sizeof(glp_arc));

      a->tail = G->v[i];

      a->head = G->v[j];

      if (G->a_size == 0)

         a->data = NULL;

      else

      {  a->data = dmp_get_atom(G->pool, G->a_size);

         memset(a->data, 0, G->a_size);

      }

      a->temp = NULL;

      a->t_prev = NULL;

      a->t_next = G->v[i]->out;

      if (a->t_next != NULL) a->t_next->t_prev = a;

      a->h_prev = NULL;

      a->h_next = G->v[j]->in;

      if (a->h_next != NULL) a->h_next->h_prev = a;

      G->v[i]->out = G->v[j]->in = a;

      G->na++;

      return a;

}

/***********************************************************************

*  NAME

*

*  glp_del_vertices - delete vertices from graph

*

*  SYNOPSIS

*

*  void glp_del_vertices(glp_graph *G, int ndel, const int num[]);

*

*  DESCRIPTION

*

*  The routine glp_del_vertices deletes vertices along with all

*  incident arcs from the specified graph. Ordinal numbers of vertices

*  to be deleted should be placed in locations num[1], ..., num[ndel],

*  ndel > 0.

*

*  Note that deleting vertices involves changing ordinal numbers of

*  other vertices remaining in the graph. New ordinal numbers of the

*  remaining vertices are assigned under the assumption that the

*  original order of vertices is not changed. */

void glp_del_vertices(glp_graph *G, int ndel, const int num[])

{     glp_vertex *v;

      int i, k, nv_new;

      /* scan the list of vertices to be deleted */

      if (!(1 <= ndel && ndel <= G->nv))

         xerror("glp_del_vertices: ndel = %d; invalid number of vertice"

            "s\n", ndel);

      for (k = 1; k <= ndel; k++)

      {  /* take the number of vertex to be deleted */

         i = num[k];

         /* obtain pointer to i-th vertex */

         if (!(1 <= i && i <= G->nv))

            xerror("glp_del_vertices: num[%d] = %d; vertex number out o"

               "f range\n", k, i);

         v = G->v[i];

         /* check that the vertex is not marked yet */

         if (v->i == 0)

            xerror("glp_del_vertices: num[%d] = %d; duplicate vertex nu"

               "mbers not allowed\n", k, i);

         /* erase symbolic name assigned to the vertex */

         glp_set_vertex_name(G, i, NULL);

         xassert(v->name == NULL);

         xassert(v->entry == NULL);

         /* free vertex data, if allocated */

         if (v->data != NULL)

            dmp_free_atom(G->pool, v->data, G->v_size);

         /* delete all incoming arcs */

         while (v->in != NULL)

            glp_del_arc(G, v->in);

         /* delete all outgoing arcs */

         while (v->out != NULL)

            glp_del_arc(G, v->out);

         /* mark the vertex to be deleted */

         v->i = 0;

      }

      /* delete all marked vertices from the vertex list */

      nv_new = 0;

      for (i = 1; i <= G->nv; i++)

      {  /* obtain pointer to i-th vertex */

         v = G->v[i];

         /* check if the vertex is marked */

         if (v->i == 0)

         {  /* it is marked, delete it */

            dmp_free_atom(G->pool, v, sizeof(glp_vertex));

         }

         else

         {  /* it is not marked, keep it */

            v->i = ++nv_new;

            G->v[v->i] = v;

         }

      }

      /* set new number of vertices in the graph */

      G->nv = nv_new;

      return;

}

/***********************************************************************

*  NAME

*

*  glp_del_arc - delete arc from graph

*

*  SYNOPSIS

*

*  void glp_del_arc(glp_graph *G, glp_arc *a);

*

*  DESCRIPTION

*

*  The routine glp_del_arc deletes an arc from the specified graph.

*  The arc to be deleted must exist. */

void glp_del_arc(glp_graph *G, glp_arc *a)

{     /* some sanity checks */

      xassert(G->na > 0);

      xassert(1 <= a->tail->i && a->tail->i <= G->nv);

      xassert(a->tail == G->v[a->tail->i]);

      xassert(1 <= a->head->i && a->head->i <= G->nv);

      xassert(a->head == G->v[a->head->i]);

      /* remove the arc from the list of incoming arcs */

      if (a->h_prev == NULL)

         a->head->in = a->h_next;

      else

         a->h_prev->h_next = a->h_next;

      if (a->h_next == NULL)

         ;

      else

         a->h_next->h_prev = a->h_prev;

      /* remove the arc from the list of outgoing arcs */

      if (a->t_prev == NULL)

         a->tail->out = a->t_next;

      else

         a->t_prev->t_next = a->t_next;

      if (a->t_next == NULL)

         ;

      else

         a->t_next->t_prev = a->t_prev;

      /* free arc data, if allocated */

      if (a->data != NULL)

         dmp_free_atom(G->pool, a->data, G->a_size);

      /* delete the arc from the graph */

      dmp_free_atom(G->pool, a, sizeof(glp_arc));

      G->na--;

      return;

}

/***********************************************************************

*  NAME

*

*  glp_erase_graph - erase graph content

*

*  SYNOPSIS

*

*  void glp_erase_graph(glp_graph *G, int v_size, int a_size);

*

*  DESCRIPTION

*

*  The routine glp_erase_graph erases the content of the specified

*  graph. The effect of this operation is the same as if the graph

*  would be deleted with the routine glp_delete_graph and then created

*  anew with the routine glp_create_graph, with exception that the

*  handle (pointer) to the graph remains valid. */

static void delete_graph(glp_graph *G)

{     dmp_delete_pool(G->pool);

      xfree(G->v);

      if (G->index != NULL) avl_delete_tree(G->index);

      return;

}

void glp_erase_graph(glp_graph *G, int v_size, int a_size)

{     if (!(0 <= v_size && v_size <= 256))

         xerror("glp_erase_graph: v_size = %d; invalid size of vertex d"

            "ata\n", v_size);

      if (!(0 <= a_size && a_size <= 256))

         xerror("glp_erase_graph: a_size = %d; invalid size of arc data"

            "\n", a_size);

      delete_graph(G);

      create_graph(G, v_size, a_size);

      return;

}

/***********************************************************************

*  NAME

*

*  glp_delete_graph - delete graph

*

*  SYNOPSIS

*

*  void glp_delete_graph(glp_graph *G);

*

*  DESCRIPTION

*

*  The routine glp_delete_graph deletes the specified graph and frees

*  all the memory allocated to this program object. */

void glp_delete_graph(glp_graph *G)

{     delete_graph(G);

      xfree(G);

      return;

}

/**********************************************************************/

void glp_create_v_index(glp_graph *G)

{     /* create vertex name index */

      glp_vertex *v;

      int i;

      if (G->index == NULL)

      {  G->index = avl_create_tree(avl_strcmp, NULL);

         for (i = 1; i <= G->nv; i++)

         {  v = G->v[i];

            xassert(v->entry == NULL);

            if (v->name != NULL)

            {  v->entry = avl_insert_node(G->index, v->name);

               avl_set_node_link(v->entry, v);

            }

         }

      }

      return;

}

int glp_find_vertex(glp_graph *G, const char *name)

{     /* find vertex by its name */

      AVLNODE *node;

      int i = 0;

      if (G->index == NULL)

         xerror("glp_find_vertex: vertex name index does not exist\n");

      if (!(name == NULL || name[0] == '\0' || strlen(name) > 255))

      {  node = avl_find_node(G->index, name);

         if (node != NULL)

            i = ((glp_vertex *)avl_get_node_link(node))->i;

      }

      return i;

}

void glp_delete_v_index(glp_graph *G)

{     /* delete vertex name index */

      int i;

      if (G->index != NULL)

      {  avl_delete_tree(G->index), G->index = NULL;

         for (i = 1; i <= G->nv; i++) G->v[i]->entry = NULL;

      }

      return;

}

/***********************************************************************

*  NAME

*

*  glp_read_graph - read graph from plain text file

*

*  SYNOPSIS

*

*  int glp_read_graph(glp_graph *G, const char *fname);

*

*  DESCRIPTION

*

*  The routine glp_read_graph reads a graph from a plain text file.

*

*  RETURNS

*

*  If the operation was successful, the routine returns zero. Otherwise

*  it prints an error message and returns non-zero. */

int glp_read_graph(glp_graph *G, const char *fname)

{     glp_data *data;

      jmp_buf jump;

      int nv, na, i, j, k, ret;

      glp_erase_graph(G, G->v_size, G->a_size);

      xprintf("Reading graph from `%s'...\n", fname);

      data = glp_sdf_open_file(fname);

      if (data == NULL)

      {  ret = 1;

         goto done;

      }

      if (setjmp(jump))

      {  ret = 1;

         goto done;

      }

      glp_sdf_set_jump(data, jump);

      nv = glp_sdf_read_int(data);

      if (nv < 0)

         glp_sdf_error(data, "invalid number of vertices\n");

      na = glp_sdf_read_int(data);

      if (na < 0)

         glp_sdf_error(data, "invalid number of arcs\n");

      xprintf("Graph has %d vert%s and %d arc%s\n",

         nv, nv == 1 ? "ex" : "ices", na, na == 1 ? "" : "s");

      if (nv > 0) glp_add_vertices(G, nv);

      for (k = 1; k <= na; k++)

      {  i = glp_sdf_read_int(data);

         if (!(1 <= i && i <= nv))

            glp_sdf_error(data, "tail vertex number out of range\n");

         j = glp_sdf_read_int(data);

         if (!(1 <= j && j <= nv))

            glp_sdf_error(data, "head vertex number out of range\n");

         glp_add_arc(G, i, j);

      }

      xprintf("%d lines were read\n", glp_sdf_line(data));

      ret = 0;

done: if (data != NULL) glp_sdf_close_file(data);

      return ret;

}

/***********************************************************************

*  NAME

*

*  glp_write_graph - write graph to plain text file

*

*  SYNOPSIS

*

*  int glp_write_graph(glp_graph *G, const char *fname).

*

*  DESCRIPTION

*

*  The routine glp_write_graph writes the specified graph to a plain

*  text file.

*

*  RETURNS

*

*  If the operation was successful, the routine returns zero. Otherwise

*  it prints an error message and returns non-zero. */

int glp_write_graph(glp_graph *G, const char *fname)

{     XFILE *fp;

      glp_vertex *v;

      glp_arc *a;

      int i, count, ret;

      xprintf("Writing graph to `%s'...\n", fname);

      fp = xfopen(fname, "w"), count = 0;

      if (fp == NULL)

      {  xprintf("Unable to create `%s' - %s\n", fname, xerrmsg());

         ret = 1;

         goto done;

      }

      xfprintf(fp, "%d %d\n", G->nv, G->na), count++;

      for (i = 1; i <= G->nv; i++)

      {  v = G->v[i];

         for (a = v->out; a != NULL; a = a->t_next)

            xfprintf(fp, "%d %d\n", a->tail->i, a->head->i), count++;

      }

      xfflush(fp);

      if (xferror(fp))

      {  xprintf("Write error on `%s' - %s\n", fname, xerrmsg());

         ret = 1;

         goto done;

      }

      xprintf("%d lines were written\n", count);

      ret = 0;

done: if (fp != NULL) xfclose(fp);

      return ret;

}

/* eof */