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Fix lexing of numbers with trailing decimal point and exponent

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Numbers with a trailing dot and an exponent were incorrectly read as
integers (with the exponent ignored) instead of the floats they should
be.  For example, 1.e6 was read as the integer 1, not 1000000.0 as
every sane person would agree was meant. (Bug#48678)

Numbers with a trailing dot but no exponent are still read as
integers.

* src/lread.c (string_to_number): Fix float lexing.
* test/src/lread-tests.el (lread-float): Add test.
* doc/lispref/numbers.texi (Float Basics): Clarify syntax.
This commit is contained in:
Mattias Engdegård 2021-05-20 18:26:15 +02:00
parent 40d2970f43
commit de45864cf7
3 changed files with 74 additions and 6 deletions
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3
doc/lispref/numbers.texi
View file

@ -237,7 +237,8 @@ precede the number and its exponent. For example, @samp{1500.0},
@samp{+15e2}, @samp{15.0e+2}, @samp{+1500000e-3}, and @samp{.15e4} are
five ways of writing a floating-point number whose value is 1500.
They are all equivalent. Like Common Lisp, Emacs Lisp requires at
least one digit after any decimal point in a floating-point number;
least one digit after a decimal point in a floating-point number that
does not have an exponent;
@samp{1500.} is an integer, not a floating-point number.
Emacs Lisp treats @code{-0.0} as numerically equal to ordinary zero

10
src/lread.c
View file

@ -3938,8 +3938,7 @@ string_to_number (char const *string, int base, ptrdiff_t *plen)
bool signedp = negative | positive;
cp += signedp;
enum { INTOVERFLOW = 1, LEAD_INT = 2, DOT_CHAR = 4, TRAIL_INT = 8,
E_EXP = 16 };
enum { INTOVERFLOW = 1, LEAD_INT = 2, TRAIL_INT = 4, E_EXP = 16 };
int state = 0;
int leading_digit = digit_to_number (*cp, base);
uintmax_t n = leading_digit;
@ -3959,7 +3958,6 @@ string_to_number (char const *string, int base, ptrdiff_t *plen)
char const *after_digits = cp;
if (*cp == '.')
{
state |= DOT_CHAR;
cp++;
}
@ -4008,8 +4006,10 @@ string_to_number (char const *string, int base, ptrdiff_t *plen)
cp = ecp;
}
float_syntax = ((state & (DOT_CHAR|TRAIL_INT)) == (DOT_CHAR|TRAIL_INT)
|| (state & ~INTOVERFLOW) == (LEAD_INT|E_EXP));
/* A float has digits after the dot or an exponent.
This excludes numbers like "1." which are lexed as integers. */
float_syntax = ((state & TRAIL_INT)
|| ((state & LEAD_INT) && (state & E_EXP)));
}
if (plen)

67
test/src/lread-tests.el
View file

@ -196,4 +196,71 @@ literals (Bug#20852)."
(should-error (read-event "foo: "))
(should-error (read-char-exclusive "foo: "))))
(ert-deftest lread-float ()
(should (equal (read "13") 13))
(should (equal (read "+13") 13))
(should (equal (read "-13") -13))
(should (equal (read "13.") 13))
(should (equal (read "+13.") 13))
(should (equal (read "-13.") -13))
(should (equal (read "13.25") 13.25))
(should (equal (read "+13.25") 13.25))
(should (equal (read "-13.25") -13.25))
(should (equal (read ".25") 0.25))
(should (equal (read "+.25") 0.25))
(should (equal (read "-.25") -0.25))
(should (equal (read "13e4") 130000.0))
(should (equal (read "+13e4") 130000.0))
(should (equal (read "-13e4") -130000.0))
(should (equal (read "13e+4") 130000.0))
(should (equal (read "+13e+4") 130000.0))
(should (equal (read "-13e+4") -130000.0))
(should (equal (read "625e-4") 0.0625))
(should (equal (read "+625e-4") 0.0625))
(should (equal (read "-625e-4") -0.0625))
(should (equal (read "1.25e2") 125.0))
(should (equal (read "+1.25e2") 125.0))
(should (equal (read "-1.25e2") -125.0))
(should (equal (read "1.25e+2") 125.0))
(should (equal (read "+1.25e+2") 125.0))
(should (equal (read "-1.25e+2") -125.0))
(should (equal (read "1.25e-1") 0.125))
(should (equal (read "+1.25e-1") 0.125))
(should (equal (read "-1.25e-1") -0.125))
(should (equal (read "4.e3") 4000.0))
(should (equal (read "+4.e3") 4000.0))
(should (equal (read "-4.e3") -4000.0))
(should (equal (read "4.e+3") 4000.0))
(should (equal (read "+4.e+3") 4000.0))
(should (equal (read "-4.e+3") -4000.0))
(should (equal (read "5.e-1") 0.5))
(should (equal (read "+5.e-1") 0.5))
(should (equal (read "-5.e-1") -0.5))
(should (equal (read "0") 0))
(should (equal (read "+0") 0))
(should (equal (read "-0") 0))
(should (equal (read "0.") 0))
(should (equal (read "+0.") 0))
(should (equal (read "-0.") 0))
(should (equal (read "0.0") 0.0))
(should (equal (read "+0.0") 0.0))
(should (equal (read "-0.0") -0.0))
(should (equal (read "0e5") 0.0))
(should (equal (read "+0e5") 0.0))
(should (equal (read "-0e5") -0.0))
(should (equal (read "0e-5") 0.0))
(should (equal (read "+0e-5") 0.0))
(should (equal (read "-0e-5") -0.0))
(should (equal (read ".0e-5") 0.0))
(should (equal (read "+.0e-5") 0.0))
(should (equal (read "-.0e-5") -0.0))
(should (equal (read "0.0e-5") 0.0))
(should (equal (read "+0.0e-5") 0.0))
(should (equal (read "-0.0e-5") -0.0))
(should (equal (read "0.e-5") 0.0))
(should (equal (read "+0.e-5") 0.0))
(should (equal (read "-0.e-5") -0.0))
)
;;; lread-tests.el ends here