Mark H Weaver <mhw@HIDDEN>
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From: Mark H Weaver <mhw@HIDDEN>
To: Ian Price <ianprice90@HIDDEN>
Subject: Re: bug#18295: Radix points in non-decimal numbers
References: <87egwc6eaa.fsf@HIDDEN>
Date: Wed, 01 Oct 2014 01:19:39 -0400
In-Reply-To: <87egwc6eaa.fsf@HIDDEN> (Ian Price's message of "Tue, 19 Aug
2014 10:04:45 +0100")
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--=-=-=
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Hi Ian,
Ian Price <ianprice90@HIDDEN> writes:
> Occasionally it is handy to use a radix point in bases other than
> decimal. i.e. 1.1 in binary is 1.5 decimal.
I agree that this would be nice.
Here's a preliminary patch to implement it, against stable-2.0. It
works, but is not yet ready to push. It needs tests, but more
importantly I'm undecided on how best to limit the exponents. The
numbers are represented exactly until just before returning from
string->number, so very large exponents could exhaust the available
memory. Of course, a large integer can already exhaust the memory, but
that's less likely to happen by accident when exponents are not
involved. Also, if they _are_ converted to inexact at the end (which
happens unless #e is given), large exponents will become infinite or
zero, which is not as nice as an error message, although I think we
already fail to do this in some cases.
One easy solution would be to prohibit exponents unless radix == 10.
Thoughts?
If you want to work more on this, we could be co-authors of the commit.
I should probably focus on other things for a while.
Best,
Mark
--=-=-=
Content-Type: text/x-patch
Content-Disposition: inline;
filename=0001-PRELIMINARY-string-number-Support-digits-after-point.patch
Content-Description: [PATCH] PRELIMINARY string->number: Support digits
after point for non-decimals
From 9ed731c917d4dd9d73258d96e401da5a06bef77a Mon Sep 17 00:00:00 2001
From: Mark H Weaver <mhw@HIDDEN>
Date: Mon, 29 Sep 2014 01:26:50 -0400
Subject: [PATCH] PRELIMINARY string->number: Support digits after point for
non-decimals.
NOTE: This limits the radix to 36. Previously, we would accept
bogosities such as:
(string->number "{" 37) => 36
(string->number "|" 38) => 37
TODO: Generalize code that places reasonable limits on exponents when
using non-decimal radices. (search for XXX in the patch)
TODO: Add tests.
TODO: Split into multiple commits (use scm_t_wchar, avoid the word
"decimal" except where base 10 is assumed, doc fixes, limit to
radix <= 36, support digits after point for non-decimals)
---
doc/ref/api-data.texi | 6 +--
libguile/numbers.c | 94 +++++++++++++++++++++----------------------
test-suite/tests/numbers.test | 6 +--
3 files changed, 53 insertions(+), 53 deletions(-)
diff --git a/doc/ref/api-data.texi b/doc/ref/api-data.texi
index acdf9ca..e5880d2 100644
--- a/doc/ref/api-data.texi
+++ b/doc/ref/api-data.texi
@@ -1,7 +1,7 @@
@c -*-texinfo-*-
@c This is part of the GNU Guile Reference Manual.
-@c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004, 2006, 2007,
-@c 2008, 2009, 2010, 2011, 2012, 2013, 2014 Free Software Foundation, Inc.
+@c Copyright (C) 1996, 1997, 2000-2004, 2006-2014
+@c Free Software Foundation, Inc.
@c See the file guile.texi for copying conditions.
@node Simple Data Types
@@ -1098,7 +1098,7 @@ inexact, a radix of 10 will be used.
@deffnx {C Function} scm_string_to_number (string, radix)
Return a number of the maximally precise representation
expressed by the given @var{string}. @var{radix} must be an
-exact integer, either 2, 8, 10, or 16. If supplied, @var{radix}
+exact integer between 2 and 36. If supplied, @var{radix}
is a default radix that may be overridden by an explicit radix
prefix in @var{string} (e.g.@: "#o177"). If @var{radix} is not
supplied, then the default radix is 10. If string is not a
diff --git a/libguile/numbers.c b/libguile/numbers.c
index c197eee..4748b51 100644
--- a/libguile/numbers.c
+++ b/libguile/numbers.c
@@ -1,6 +1,4 @@
-/* Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
- * 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013,
- * 2014 Free Software Foundation, Inc.
+/* Copyright (C) 1995-2014 Free Software Foundation, Inc.
*
* Portions Copyright 1990, 1991, 1992, 1993 by AT&T Bell Laboratories
* and Bellcore. See scm_divide.
@@ -5806,7 +5804,7 @@ enum t_exactness {NO_EXACTNESS, INEXACT, EXACT};
/* Caller is responsible for checking that the return value is in range
for the given radix, which should be <= 36. */
static unsigned int
-char_decimal_value (scm_t_uint32 c)
+char_digit_value (scm_t_wchar c)
{
/* uc_decimal_value returns -1 on error. When cast to an unsigned int,
that's certainly above any valid decimal, so we take advantage of
@@ -5818,8 +5816,8 @@ char_decimal_value (scm_t_uint32 c)
if (d >= 10U)
{
c = uc_tolower (c);
- if (c >= (scm_t_uint32) 'a')
- d = c - (scm_t_uint32)'a' + 10U;
+ if (c >= (scm_t_wchar)'a')
+ d = c - (scm_t_wchar)'a' + 10U;
}
return d;
}
@@ -5837,14 +5835,14 @@ mem2uinteger (SCM mem, unsigned int *p_idx,
scm_t_bits add = 0;
unsigned int digit_value;
SCM result;
- char c;
+ scm_t_wchar c;
size_t len = scm_i_string_length (mem);
if (idx == len)
return SCM_BOOL_F;
c = scm_i_string_ref (mem, idx);
- digit_value = char_decimal_value (c);
+ digit_value = char_digit_value (c);
if (digit_value >= radix)
return SCM_BOOL_F;
@@ -5862,9 +5860,9 @@ mem2uinteger (SCM mem, unsigned int *p_idx,
break;
else
{
- digit_value = char_decimal_value (c);
- /* This check catches non-decimals in addition to out-of-range
- decimals. */
+ digit_value = char_digit_value (c);
+ /* This check catches non-digits in addition to out-of-range
+ digits. */
if (digit_value >= radix)
break;
}
@@ -5899,18 +5897,17 @@ mem2uinteger (SCM mem, unsigned int *p_idx,
}
-/* R5RS, section 7.1.1, lexical structure of numbers: <decimal 10>. Only
- * covers the parts of the rules that start at a potential point. The value
- * of the digits up to the point have been parsed by the caller and are given
- * in variable result. The content of *p_exactness indicates, whether a hash
- * has already been seen in the digits before the point.
+/* R5RS, section 7.1.1, lexical structure of numbers: <decimal 10>. We
+ * generalize this to support radices other than 10. Only covers the
+ * parts of the rules that start at a potential point. The value of the
+ * digits up to the point have been parsed by the caller and are given
+ * in variable result. The content of *p_exactness indicates, whether a
+ * hash has already been seen in the digits before the point.
*/
-#define DIGIT2UINT(d) (uc_numeric_value(d).numerator)
-
static SCM
-mem2decimal_from_point (SCM result, SCM mem,
- unsigned int *p_idx, enum t_exactness *p_exactness)
+mem2real_from_point (SCM result, SCM mem, unsigned int *p_idx,
+ unsigned int radix, enum t_exactness *p_exactness)
{
unsigned int idx = *p_idx;
enum t_exactness x = *p_exactness;
@@ -5930,13 +5927,12 @@ mem2decimal_from_point (SCM result, SCM mem,
while (idx != len)
{
scm_t_wchar c = scm_i_string_ref (mem, idx);
- if (uc_is_property_decimal_digit ((scm_t_uint32) c))
+ digit_value = char_digit_value (c);
+ if (digit_value < radix)
{
- if (x == INEXACT)
- return SCM_BOOL_F;
- else
- digit_value = DIGIT2UINT (c);
- }
+ if (x == INEXACT)
+ return SCM_BOOL_F;
+ }
else if (c == '#')
{
x = INEXACT;
@@ -5946,20 +5942,20 @@ mem2decimal_from_point (SCM result, SCM mem,
break;
idx++;
- if (SCM_MOST_POSITIVE_FIXNUM / 10 < shift)
+ if (SCM_MOST_POSITIVE_FIXNUM / radix < shift)
{
big_shift = scm_product (big_shift, SCM_I_MAKINUM (shift));
result = scm_product (result, SCM_I_MAKINUM (shift));
if (add > 0)
result = scm_sum (result, SCM_I_MAKINUM (add));
- shift = 10;
+ shift = radix;
add = digit_value;
}
else
{
- shift = shift * 10;
- add = add * 10 + digit_value;
+ shift = shift * radix;
+ add = add * radix + digit_value;
}
};
@@ -5981,6 +5977,7 @@ mem2decimal_from_point (SCM result, SCM mem,
int sign = 1;
unsigned int start;
scm_t_wchar c;
+ unsigned int digit_value;
int exponent;
SCM e;
@@ -6020,24 +6017,29 @@ mem2decimal_from_point (SCM result, SCM mem,
else
sign = 1;
- if (!uc_is_property_decimal_digit ((scm_t_uint32) c))
+ digit_value = char_digit_value (c);
+ if (digit_value >= radix)
return SCM_BOOL_F;
idx++;
- exponent = DIGIT2UINT (c);
+ exponent = digit_value;
while (idx != len)
{
scm_t_wchar c = scm_i_string_ref (mem, idx);
- if (uc_is_property_decimal_digit ((scm_t_uint32) c))
+ digit_value = char_digit_value (c);
+ if (digit_value < radix)
{
idx++;
+ /* XXX FIXME: This logic is not sufficient for
+ non-decimal numbers */
if (exponent <= SCM_MAXEXP)
- exponent = exponent * 10 + DIGIT2UINT (c);
+ exponent = exponent * radix + digit_value;
}
else
break;
}
+ /* XXX FIXME: This logic is not sufficient for non-decimal numbers */
if (exponent > ((sign == 1) ? SCM_MAXEXP : SCM_MAXEXP + DBL_DIG + 1))
{
size_t exp_len = idx - start;
@@ -6046,7 +6048,7 @@ mem2decimal_from_point (SCM result, SCM mem,
scm_out_of_range ("string->number", exp_num);
}
- e = scm_integer_expt (SCM_I_MAKINUM (10), SCM_I_MAKINUM (exponent));
+ e = scm_integer_expt (SCM_I_MAKINUM (radix), SCM_I_MAKINUM (exponent));
if (sign == 1)
result = scm_product (result, e);
else
@@ -6138,15 +6140,14 @@ mem2ureal (SCM mem, unsigned int *p_idx,
if (scm_i_string_ref (mem, idx) == '.')
{
- if (radix != 10)
- return SCM_BOOL_F;
- else if (idx + 1 == len)
+ if (idx + 1 == len)
return SCM_BOOL_F;
- else if (!uc_is_property_decimal_digit ((scm_t_uint32) scm_i_string_ref (mem, idx+1)))
+ else if (char_digit_value (scm_i_string_ref (mem, idx+1))
+ >= radix)
return SCM_BOOL_F;
else
- result = mem2decimal_from_point (SCM_INUM0, mem,
- p_idx, &implicit_x);
+ result = mem2real_from_point (SCM_INUM0, mem, p_idx,
+ radix, &implicit_x);
}
else
{
@@ -6173,14 +6174,13 @@ mem2ureal (SCM mem, unsigned int *p_idx,
/* both are int/big here, I assume */
result = scm_i_make_ratio (uinteger, divisor);
}
- else if (radix == 10)
+ else
{
- result = mem2decimal_from_point (uinteger, mem, &idx, &implicit_x);
+ result = mem2real_from_point (uinteger, mem, &idx,
+ radix, &implicit_x);
if (scm_is_false (result))
return SCM_BOOL_F;
}
- else
- result = uinteger;
*p_idx = idx;
}
@@ -6436,7 +6436,7 @@ SCM_DEFINE (scm_string_to_number, "string->number", 1, 1, 0,
(SCM string, SCM radix),
"Return a number of the maximally precise representation\n"
"expressed by the given @var{string}. @var{radix} must be an\n"
- "exact integer, either 2, 8, 10, or 16. If supplied, @var{radix}\n"
+ "exact integer between 2 and 36. If supplied, @var{radix}\n"
"is a default radix that may be overridden by an explicit radix\n"
"prefix in @var{string} (e.g. \"#o177\"). If @var{radix} is not\n"
"supplied, then the default radix is 10. If string is not a\n"
@@ -6451,7 +6451,7 @@ SCM_DEFINE (scm_string_to_number, "string->number", 1, 1, 0,
if (SCM_UNBNDP (radix))
base = 10;
else
- base = scm_to_unsigned_integer (radix, 2, INT_MAX);
+ base = scm_to_unsigned_integer (radix, 2, 36);
answer = scm_i_string_to_number (string, base);
scm_remember_upto_here_1 (string);
diff --git a/test-suite/tests/numbers.test b/test-suite/tests/numbers.test
index 847f939..0acc3db 100644
--- a/test-suite/tests/numbers.test
+++ b/test-suite/tests/numbers.test
@@ -1,6 +1,6 @@
;;;; numbers.test --- tests guile's numbers -*- scheme -*-
-;;;; Copyright (C) 2000, 2001, 2003, 2004, 2005, 2006, 2009, 2010, 2011,
-;;;; 2012, 2013 Free Software Foundation, Inc.
+;;;; Copyright (C) 2000, 2001, 2003-2006, 2009-2014
+;;;; Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
@@ -1575,7 +1575,7 @@
(for-each (lambda (x) (if (string->number x) (throw 'fail)))
'("" "q" "1q" "6+7iq" "8+9q" "10+11" "13+" "18@19q" "20@q" "23@"
"+25iq" "26i" "-q" "-iq" "i" "5#.0" "8/" "10#11" ".#" "."
- "#o.2" "3.4q" "15.16e17q" "18.19e+q" ".q" ".17#18" "10q" "#b2"
+ "3.4q" "15.16e17q" "18.19e+q" ".q" ".17#18" "10q" "#b2"
"#b3" "#b4" "#b5" "#b6" "#b7" "#b8" "#b9" "#ba" "#bb" "#bc"
"#bd" "#be" "#bf" "#q" "#b#b1" "#o#o1" "#d#d1" "#x#x1" "#e#e1"
"#i#i1" "12@12+0i" "3/0" "0/0" "4+3/0i" "4/0-3i" "2+0/0i"
--
1.8.4
--=-=-=--
bug-guile@HIDDEN:bug#18295; Package guile.
Full text available.ludo@HIDDEN (Ludovic Courtès)
to control <at> debbugs.gnu.org.
Full text available.Received: (at submit) by debbugs.gnu.org; 19 Aug 2014 09:05:33 +0000 From debbugs-submit-bounces <at> debbugs.gnu.org Tue Aug 19 05:05:33 2014 Received: from localhost ([127.0.0.1]:47096 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.80) (envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>) id 1XJfMD-00007z-6f for submit <at> debbugs.gnu.org; Tue, 19 Aug 2014 05:05:33 -0400 Received: from eggs.gnu.org ([208.118.235.92]:37363) by debbugs.gnu.org with esmtp (Exim 4.80) (envelope-from <guile-bugs@HIDDEN>) id 1XJfMA-00007l-Lf for submit <at> debbugs.gnu.org; Tue, 19 Aug 2014 05:05:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from <guile-bugs@HIDDEN>) id 1XJfLz-000616-BJ for submit <at> debbugs.gnu.org; Tue, 19 Aug 2014 05:05:25 -0400 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on eggs.gnu.org X-Spam-Level: X-Spam-Status: No, score=0.8 required=5.0 tests=BAYES_50,FREEMAIL_FROM autolearn=disabled version=3.3.2 Received: from lists.gnu.org ([2001:4830:134:3::11]:51355) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from <guile-bugs@HIDDEN>) id 1XJfLz-000612-8h for submit <at> debbugs.gnu.org; Tue, 19 Aug 2014 05:05:19 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39038) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from <guile-bugs@HIDDEN>) id 1XJfLt-0001Gs-N5 for bug-guile@HIDDEN; Tue, 19 Aug 2014 05:05:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from <guile-bugs@HIDDEN>) id 1XJfLo-0005yf-6a for bug-guile@HIDDEN; Tue, 19 Aug 2014 05:05:13 -0400 Received: from plane.gmane.org ([80.91.229.3]:58344) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from <guile-bugs@HIDDEN>) id 1XJfLo-0005x2-18 for bug-guile@HIDDEN; Tue, 19 Aug 2014 05:05:08 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from <guile-bugs@HIDDEN>) id 1XJfLc-00014S-V5 for bug-guile@HIDDEN; Tue, 19 Aug 2014 11:04:56 +0200 Received: from host109-153-29-205.range109-153.btcentralplus.com ([109.153.29.205]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for <bug-guile@HIDDEN>; Tue, 19 Aug 2014 11:04:56 +0200 Received: from ianprice90 by host109-153-29-205.range109-153.btcentralplus.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for <bug-guile@HIDDEN>; Tue, 19 Aug 2014 11:04:56 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: bug-guile@HIDDEN From: Ian Price <ianprice90@HIDDEN> Subject: Radix points in non-decimal numbers Date: Tue, 19 Aug 2014 10:04:45 +0100 Lines: 26 Message-ID: <87egwc6eaa.fsf@HIDDEN> Mime-Version: 1.0 Content-Type: text/plain X-Complaints-To: usenet@HIDDEN X-Gmane-NNTP-Posting-Host: host109-153-29-205.range109-153.btcentralplus.com User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) Cancel-Lock: sha1:REXvvaCycnnQbiByiVt3OD4fRpw= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2001:4830:134:3::11 X-Spam-Score: -4.1 (----) X-Debbugs-Envelope-To: submit X-BeenThere: debbugs-submit <at> debbugs.gnu.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: <debbugs-submit.debbugs.gnu.org> List-Unsubscribe: <http://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe> List-Archive: <http://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/> List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org> List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help> List-Subscribe: <http://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe> Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org> X-Spam-Score: -4.1 (----) Severity : wishlist Occasionally it is handy to use a radix point in bases other than decimal. i.e. 1.1 in binary is 1.5 decimal. In Guile (stable-2.0), at the moment, this gives an error. scheme@(guile-user)> #b1.1 While reading expression: ERROR: In procedure scm_lreadr: #<unknown port>:1:6: unknown # object We already support this in the output of string->number scheme@(guile-user)> (number->string 1.5 2) $1 = "1.1" Obviously this is not required by either the R5RS (and presumably the R7RS) or the R6RS, which special case the point for decimals only, however, Racket does let you do this. -- Ian Price -- shift-reset.com "Programming is like pinball. The reward for doing it well is the opportunity to do it again" - from "The Wizardy Compiled"
Ian Price <ianprice90@HIDDEN>:bug-guile@HIDDEN.
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