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Make the Lisp reader and string-to-float more consistent.

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* data.c (atof): Remove decl; no longer used or needed.
(Fstring_to_number): Use new string_to_float function, to be
consistent with how the Lisp reader treats infinities and NaNs.
Do not assume that floating-point numbers represent EMACS_INT
without losing information; this is not true on most 64-bit hosts.
Avoid double-rounding errors, by insisting on integers when
parsing non-base-10 numbers, as the documentation specifies.
Report integer overflow instead of silently converting to
integers.
* lisp.h (string_to_float): New decl, replacing ...
(isfloat_string): Remove.
* lread.c (read1): Do not accept +. and -. as integers; this
appears to have been a coding error.  Similarly, do not accept
strings like +-1e0 as floating point numbers.  Do not report
overflow for some integer overflows and not others; instead,
report them all.  Break out the floating-point parsing into a new
function string_to_float, so that Fstring_to_number parses
floating point numbers consistently with the Lisp reader.
(string_to_float): New function, replacing isfloat_string.
This function checks for valid syntax and produces the resulting
Lisp float number too.
This commit is contained in:
Paul Eggert 2011-04-19 23:24:51 -07:00
parent 602ea69dc7
commit 8b9587d73b
4 changed files with 106 additions and 112 deletions
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25
src/ChangeLog
View file

@ -1,3 +1,28 @@
2011-04-20 Paul Eggert <eggert@cs.ucla.edu>
Make the Lisp reader and string-to-float more consistent.
* data.c (atof): Remove decl; no longer used or needed.
(Fstring_to_number): Use new string_to_float function, to be
consistent with how the Lisp reader treats infinities and NaNs.
Do not assume that floating-point numbers represent EMACS_INT
without losing information; this is not true on most 64-bit hosts.
Avoid double-rounding errors, by insisting on integers when
parsing non-base-10 numbers, as the documentation specifies.
Report integer overflow instead of silently converting to
integers.
* lisp.h (string_to_float): New decl, replacing ...
(isfloat_string): Remove.
* lread.c (read1): Do not accept +. and -. as integers; this
appears to have been a coding error. Similarly, do not accept
strings like +-1e0 as floating point numbers. Do not report
overflow for some integer overflows and not others; instead,
report them all. Break out the floating-point parsing into a new
function string_to_float, so that Fstring_to_number parses
floating point numbers consistently with the Lisp reader.
(string_to_float): New function, replacing isfloat_string.
This function checks for valid syntax and produces the resulting
Lisp float number too.
2011-04-19 Eli Zaretskii <eliz@gnu.org>
* syntax.h (SETUP_SYNTAX_TABLE_FOR_OBJECT): Fix setting of

42
src/data.c
View file

@ -48,10 +48,6 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
#include <math.h>
#if !defined (atof)
extern double atof (const char *);
#endif /* !atof */
Lisp_Object Qnil, Qt, Qquote, Qlambda, Qunbound;
static Lisp_Object Qsubr;
Lisp_Object Qerror_conditions, Qerror_message, Qtop_level;
@ -2415,8 +2411,7 @@ If the base used is not 10, STRING is always parsed as integer. */)
{
register char *p;
register int b;
int sign = 1;
Lisp_Object val;
EMACS_INT n;
CHECK_STRING (string);
@ -2430,38 +2425,23 @@ If the base used is not 10, STRING is always parsed as integer. */)
xsignal1 (Qargs_out_of_range, base);
}
/* Skip any whitespace at the front of the number. Some versions of
atoi do this anyway, so we might as well make Emacs lisp consistent. */
/* Skip any whitespace at the front of the number. Typically strtol does
this anyway, so we might as well be consistent. */
p = SSDATA (string);
while (*p == ' ' || *p == '\t')
p++;
if (*p == '-')
if (b == 10)
{
sign = -1;
p++;
}
else if (*p == '+')
p++;
if (isfloat_string (p, 1) && b == 10)
val = make_float (sign * atof (p));
else
{
double v = 0;
while (1)
{
int digit = digit_to_number (*p++, b);
if (digit < 0)
break;
v = v * b + digit;
}
val = make_fixnum_or_float (sign * v);
Lisp_Object val = string_to_float (p, 1);
if (FLOATP (val))
return val;
}
return val;
n = strtol (p, NULL, b);
if (FIXNUM_OVERFLOW_P (n))
xsignal (Qoverflow_error, list1 (string));
return make_number (n);
}

2
src/lisp.h
View file

@ -2782,7 +2782,7 @@ extern Lisp_Object oblookup (Lisp_Object, const char *, EMACS_INT, EMACS_INT);
} while (0)
extern int openp (Lisp_Object, Lisp_Object, Lisp_Object,
Lisp_Object *, Lisp_Object);
extern int isfloat_string (const char *, int);
Lisp_Object string_to_float (char const *, int);
extern void map_obarray (Lisp_Object, void (*) (Lisp_Object, Lisp_Object),
Lisp_Object);
extern void dir_warning (const char *, Lisp_Object);

149
src/lread.c
View file

@ -3006,85 +3006,32 @@ read1 (register Lisp_Object readcharfun, int *pch, int first_in_list)
if (!quoted && !uninterned_symbol)
{
register char *p1;
Lisp_Object result;
p1 = read_buffer;
if (*p1 == '+' || *p1 == '-') p1++;
/* Is it an integer? */
if (p1 != p)
if ('0' <= *p1 && *p1 <= '9')
{
while (p1 != p && (c = *p1) >= '0' && c <= '9') p1++;
do
p1++;
while ('0' <= *p1 && *p1 <= '9');
/* Integers can have trailing decimal points. */
if (p1 > read_buffer && p1 < p && *p1 == '.') p1++;
p1 += (*p1 == '.');
if (p1 == p)
/* It is an integer. */
{
if (p1[-1] == '.')
p1[-1] = '\0';
{
/* EMACS_INT n = atol (read_buffer); */
char *endptr = NULL;
EMACS_INT n = (errno = 0,
strtol (read_buffer, &endptr, 10));
if (errno == ERANGE && endptr)
{
Lisp_Object args
= Fcons (make_string (read_buffer,
endptr - read_buffer),
Qnil);
xsignal (Qoverflow_error, args);
}
return make_fixnum_or_float (n);
}
/* It is an integer. */
EMACS_INT n = strtol (read_buffer, NULL, 10);
if (FIXNUM_OVERFLOW_P (n))
xsignal (Qoverflow_error,
list1 (build_string (read_buffer)));
return make_number (n);
}
}
if (isfloat_string (read_buffer, 0))
{
/* Compute NaN and infinities using 0.0 in a variable,
to cope with compilers that think they are smarter
than we are. */
double zero = 0.0;
double value;
/* Negate the value ourselves. This treats 0, NaNs,
and infinity properly on IEEE floating point hosts,
and works around a common bug where atof ("-0.0")
drops the sign. */
int negative = read_buffer[0] == '-';
/* The only way p[-1] can be 'F' or 'N', after isfloat_string
returns 1, is if the input ends in e+INF or e+NaN. */
switch (p[-1])
{
case 'F':
value = 1.0 / zero;
break;
case 'N':
value = zero / zero;
/* If that made a "negative" NaN, negate it. */
{
int i;
union { double d; char c[sizeof (double)]; } u_data, u_minus_zero;
u_data.d = value;
u_minus_zero.d = - 0.0;
for (i = 0; i < sizeof (double); i++)
if (u_data.c[i] & u_minus_zero.c[i])
{
value = - value;
break;
}
}
/* Now VALUE is a positive NaN. */
break;
default:
value = atof (read_buffer + negative);
break;
}
return make_float (negative ? - value : value);
}
result = string_to_float (read_buffer, 0);
if (FLOATP (result))
return result;
}
{
Lisp_Object name, result;
@ -3242,20 +3189,40 @@ substitute_in_interval (INTERVAL interval, Lisp_Object arg)
}
/* Return the length of the floating-point number that is the prefix of CP, or
zero if there is none. */
#define LEAD_INT 1
#define DOT_CHAR 2
#define TRAIL_INT 4
#define E_CHAR 8
#define EXP_INT 16
int
isfloat_string (const char *cp, int ignore_trailing)
/* Convert CP to a floating point number. Return a non-float value if CP does
not have valid floating point syntax. If IGNORE_TRAILING is nonzero,
consider just the longest prefix of CP that has valid floating point
syntax. */
Lisp_Object
string_to_float (char const *cp, int ignore_trailing)
{
int state;
const char *start = cp;
/* Compute NaN and infinities using a variable, to cope with compilers that
think they are smarter than we are. */
double zero = 0;
/* Negate the value ourselves. This treats 0, NaNs, and infinity properly on
IEEE floating point hosts, and works around a formerly-common bug where
atof ("-0.0") drops the sign. */
int negative = *cp == '-';
double value = 0;
state = 0;
if (*cp == '+' || *cp == '-')
if (negative || *cp == '+')
cp++;
if (*cp >= '0' && *cp <= '9')
@ -3295,21 +3262,43 @@ isfloat_string (const char *cp, int ignore_trailing)
{
state |= EXP_INT;
cp += 3;
value = 1.0 / zero;
}
else if (cp[-1] == '+' && cp[0] == 'N' && cp[1] == 'a' && cp[2] == 'N')
{
state |= EXP_INT;
cp += 3;
value = zero / zero;
/* If that made a "negative" NaN, negate it. */
{
int i;
union { double d; char c[sizeof (double)]; } u_data, u_minus_zero;
u_data.d = value;
u_minus_zero.d = - 0.0;
for (i = 0; i < sizeof (double); i++)
if (u_data.c[i] & u_minus_zero.c[i])
{
value = - value;
break;
}
}
/* Now VALUE is a positive NaN. */
}
return ((ignore_trailing
|| *cp == 0 || *cp == ' ' || *cp == '\t' || *cp == '\n'
|| *cp == '\r' || *cp == '\f')
&& (state == (LEAD_INT|DOT_CHAR|TRAIL_INT)
|| state == (DOT_CHAR|TRAIL_INT)
|| state == (LEAD_INT|E_CHAR|EXP_INT)
|| state == (LEAD_INT|DOT_CHAR|TRAIL_INT|E_CHAR|EXP_INT)
|| state == (DOT_CHAR|TRAIL_INT|E_CHAR|EXP_INT)));
if (! (state == (LEAD_INT|DOT_CHAR|TRAIL_INT)
|| state == (DOT_CHAR|TRAIL_INT)
|| state == (LEAD_INT|E_CHAR|EXP_INT)
|| state == (LEAD_INT|DOT_CHAR|TRAIL_INT|E_CHAR|EXP_INT)
|| state == (DOT_CHAR|TRAIL_INT|E_CHAR|EXP_INT)))
return make_number (0); /* Any non-float value will do. */
if (! value)
value = atof (start + negative);
if (negative)
value = - value;
return make_float (value);
}