xref: /src/external/lgpl3/gmp/dist/demos/expr/exprfa.c

/* mpf expression evaluation

Copyright 2000, 2001, 2002, 2004 Free Software Foundation, Inc.

This file is part of the GNU MP Library.

The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at your
option) any later version.

The GNU MP Library 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 Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */


/* Future: Bitwise "&", "|" and "&" could be done, if desired.  Not sure
   those functions would be much value though.  */


#include <ctype.h>
#include <stdio.h>
#include <string.h>

#include "gmp.h"
#include "expr-impl.h"


/* Change this to "#define TRACE(x) x" to get some traces. */
#define TRACE(x)


static size_t
e_mpf_number (mpf_ptr res, __gmp_const char *e, size_t elen, int base)
{
  char    *edup;
  size_t  i, ret, extra=0;
  int     mant_base, exp_base;
  void    *(*allocate_func) (size_t);
  void    (*free_func) (void *, size_t);

  TRACE (printf ("mpf_number base=%d \"%.*s\"\n", base, (int) elen, e));

  /* mpf_set_str doesn't currently accept 0x for hex in base==0, so do it
     here instead.  FIXME: Would prefer to let mpf_set_str handle this.  */
  if (base == 0 && elen >= 2 && e[0] == '0' && (e[1] == 'x' || e[1] == 'X'))
    {
      base = 16;
      extra = 2;
      e += extra;
      elen -= extra;
    }

  if (base == 0)
    mant_base = 10;
  else if (base < 0)
    mant_base = -base;
  else
    mant_base = base;

  /* exponent in decimal if base is negative */
  if (base < 0)
    exp_base = 10;
  else if (base == 0)
    exp_base = 10;
  else
    exp_base = base;

#define IS_EXPONENT(c) \
  (c == '@' || (base <= 10 && base >= -10 && (e[i] == 'e' || e[i] == 'E')))

  i = 0;
  for (;;)
    {
      if (i >= elen)
        goto parsed;
      if (e[i] == '.')
        break;
      if (IS_EXPONENT (e[i]))
        goto exponent;
      if (! isasciidigit_in_base (e[i], mant_base))
        goto parsed;
      i++;
    }

  /* fraction */
  i++;
  for (;;)
    {
      if (i >= elen)
        goto parsed;
      if (IS_EXPONENT (e[i]))
        goto exponent;
      if (! isasciidigit_in_base (e[i], mant_base))
        goto parsed;
      i++;
    }

 exponent:
  i++;
  if (i >= elen)
    goto parsed;
  if (e[i] == '-')
    i++;
  for (;;)
    {
      if (i >= elen)
        goto parsed;
      if (! isasciidigit_in_base (e[i], exp_base))
        break;
      i++;
    }

 parsed:
  TRACE (printf ("  parsed i=%u \"%.*s\"\n", i, (int) i, e));

  mp_get_memory_functions (&allocate_func, NULL, &free_func);
  edup = (*allocate_func) (i+1);
  memcpy (edup, e, i);
  edup[i] = '\0';

  if (mpf_set_str (res, edup, base) == 0)
    ret = i + extra;
  else
    ret = 0;

  (*free_func) (edup, i+1);
  return ret;
}

static int
e_mpf_ulong_p (mpf_srcptr f)
{
  return mpf_integer_p (f) && mpf_fits_ulong_p (f);
}

/* Don't want to change the precision of w, can only do an actual swap when
   w and x have the same precision.  */
static void
e_mpf_set_or_swap (mpf_ptr w, mpf_ptr x)
{
  if (mpf_get_prec (w) == mpf_get_prec (x))
    mpf_swap (w, x);
  else
    mpf_set (w, x);
}


int
mpf_expr_a (__gmp_const struct mpexpr_operator_t *table,
            mpf_ptr res, int base, unsigned long prec,
            __gmp_const char *e, size_t elen,
            mpf_srcptr var[26])
{
  struct mpexpr_parse_t  p;

  p.table = table;
  p.res = (mpX_ptr) res;
  p.base = base;
  p.prec = prec;
  p.e = e;
  p.elen = elen;
  p.var = (mpX_srcptr *) var;

  p.mpX_clear       = (mpexpr_fun_one_t)      mpf_clear;
  p.mpX_ulong_p     = (mpexpr_fun_i_unary_t)  e_mpf_ulong_p;
  p.mpX_get_ui      = (mpexpr_fun_get_ui_t)   mpf_get_ui;
  p.mpX_init        = (mpexpr_fun_unary_ui_t) mpf_init2;
  p.mpX_number      = (mpexpr_fun_number_t)   e_mpf_number;
  p.mpX_set         = (mpexpr_fun_unary_t)    mpf_set;
  p.mpX_set_or_swap = (mpexpr_fun_unary_t)    e_mpf_set_or_swap;
  p.mpX_set_si      = (mpexpr_fun_set_si_t)   mpf_set_si;
  p.mpX_swap        = (mpexpr_fun_swap_t)     mpf_swap;

  return mpexpr_evaluate (&p);
}