From 8b9587d73b579fb2fdd0eaaa1ed5fd608653e522 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Tue, 19 Apr 2011 23:24:51 -0700 Subject: [PATCH] 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. --- src/ChangeLog | 25 +++++++++ src/data.c | 42 ++++---------- src/lisp.h | 2 +- src/lread.c | 149 +++++++++++++++++++++++--------------------------- 4 files changed, 106 insertions(+), 112 deletions(-) diff --git a/src/ChangeLog b/src/ChangeLog index 4a675cc96c6..c232c242fd7 100644 --- a/src/ChangeLog +++ b/src/ChangeLog @@ -1,3 +1,28 @@ +2011-04-20 Paul Eggert + + 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 * syntax.h (SETUP_SYNTAX_TABLE_FOR_OBJECT): Fix setting of diff --git a/src/data.c b/src/data.c index c9250a67bf0..c3ee3e39939 100644 --- a/src/data.c +++ b/src/data.c @@ -48,10 +48,6 @@ along with GNU Emacs. If not, see . */ #include -#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 == '-') - { - sign = -1; - p++; - } - else if (*p == '+') - p++; - - if (isfloat_string (p, 1) && b == 10) - val = make_float (sign * atof (p)); - else + if (b == 10) { - 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); } diff --git a/src/lisp.h b/src/lisp.h index 581835dd32b..6080007c780 100644 --- a/src/lisp.h +++ b/src/lisp.h @@ -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); diff --git a/src/lread.c b/src/lread.c index d32f0b6a7e2..776d4ced7f2 100644 --- a/src/lread.c +++ b/src/lread.c @@ -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); } -- 2.39.2