#include "pl-incl.h"

typedef struct
{
  term_t	varnames;		/* Report variables+names */  
  IOSTREAM *stream;
  int		has_exception;		/* exception is raised */

  term_t	exception;		/* raised exception */
} read_data, *ReadData;

static void
init_read_data(ReadData _PL_rd, IOSTREAM *in ARG_LD)
{ 
  _PL_rd->varnames = 0;
  _PL_rd->stream = in;
  _PL_rd->has_exception = 0;
  _PL_rd->exception = 0;
}

static void
free_read_data(ReadData _PL_rd)
{ 
}

static int 
read_term(term_t t, ReadData rd ARG_LD)
{
  return Yap_read_term(t, rd->stream, rd->varnames);
}


		 /*******************************
		 *	   TERM <->ATOM		*
		 *******************************/

static int
atom_to_term(term_t atom, term_t term, term_t bindings)
{ GET_LD
  PL_chars_t txt;

  if ( !bindings && PL_is_variable(atom) ) /* term_to_atom(+, -) */
  { char buf[1024];
    size_t bufsize = sizeof(buf);
    int rval;
    char *s = buf;
    IOSTREAM *stream;
    PL_chars_t txt;

    stream = Sopenmem(&s, &bufsize, "w");
    stream->encoding = ENC_UTF8;
    PL_write_term(stream, term, 1200, PL_WRT_QUOTED);
    Sflush(stream);

    txt.text.t = s;
    txt.length = bufsize;
    txt.storage = PL_CHARS_HEAP;
    txt.encoding = ENC_UTF8;
    txt.canonical = FALSE;
    rval = PL_unify_text(atom, 0, &txt, PL_ATOM);

    Sclose(stream);
    if ( s != buf )
      Sfree(s);

    return rval;
  }

  if ( PL_get_text(atom, &txt, CVT_ALL|CVT_EXCEPTION) )
  { GET_LD
    read_data rd;
    int rval;
    IOSTREAM *stream;
    source_location oldsrc = LD->read_source;

    stream = Sopen_text(&txt, "r");

    init_read_data(&rd, stream PASS_LD);
    if ( bindings && (PL_is_variable(bindings) || PL_is_list(bindings)) )
      rd.varnames = bindings;
    else if ( bindings )
      return PL_error(NULL, 0, NULL, ERR_TYPE, ATOM_list, bindings);

    if ( !(rval = read_term(term, &rd PASS_LD)) && rd.has_exception )
      rval = PL_raise_exception(rd.exception);
    free_read_data(&rd);
    Sclose(stream);
    LD->read_source = oldsrc;

    return rval;
  }

  fail;
}


static
PRED_IMPL("atom_to_term", 3, atom_to_term, 0)
{ return atom_to_term(A1, A2, A3);
}


static
PRED_IMPL("term_to_atom", 2, term_to_atom, 0)
{ return atom_to_term(A2, A1, 0);
}


int
PL_chars_to_term(const char *s, term_t t)
{ GET_LD
  read_data rd;
  int rval;
  IOSTREAM *stream = Sopen_string(NULL, (char *)s, -1, "r");
  source_location oldsrc = LD->read_source;

  init_read_data(&rd, stream PASS_LD);
  PL_put_variable(t);
  if ( !(rval = read_term(t, &rd PASS_LD)) && rd.has_exception )
    PL_put_term(t, rd.exception);
  free_read_data(&rd);
  Sclose(stream);
  LD->read_source = oldsrc;

  return rval;
}

		 /*******************************
		 *      PUBLISH PREDICATES	*
		 *******************************/

BeginPredDefs(read)
  PRED_DEF("atom_to_term", 3, atom_to_term, 0)
  PRED_DEF("term_to_atom", 2, term_to_atom, 0)
EndPredDefs