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author | Mark H Weaver <mhw@netris.org> | 2014-04-18 15:04:12 -0400 |
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committer | Mark H Weaver <mhw@netris.org> | 2014-06-01 19:19:40 -0400 |
commit | a5186f506f69ef8a8accd234ca434efd13f302c9 (patch) | |
tree | 7ebaceaf19c1e738ebf3b504c7af4b5567010872 | |
parent | 12c6a47773041ff5d0a3553421d2f358d9e479a9 (diff) | |
download | guile-a5186f506f69ef8a8accd234ca434efd13f302c9.tar.gz |
SRFI-1 'length+' raises an error unless passed a proper or circular list.
Fixes <http://bugs.gnu.org/17296>.
* libguile/srfi-1.c (scm_srfi1_length_plus): Rewrite to raise an error
unless passed a proper or circular list, based on code from
'scm_ilength'.
* test-suite/tests/srfi-1.test (length+): Add tests.
-rw-r--r-- | libguile/srfi-1.c | 32 | ||||
-rw-r--r-- | test-suite/tests/srfi-1.test | 6 |
2 files changed, 33 insertions, 5 deletions
diff --git a/libguile/srfi-1.c b/libguile/srfi-1.c index 54c7e2aa3..fcbf80694 100644 --- a/libguile/srfi-1.c +++ b/libguile/srfi-1.c @@ -1,7 +1,7 @@ /* srfi-1.c --- SRFI-1 procedures for Guile * - * Copyright (C) 1995, 1996, 1997, 2000, 2001, 2002, 2003, 2005, 2006, - * 2008, 2009, 2010, 2011 Free Software Foundation, Inc. + * Copyright (C) 1995-1997, 2000-2003, 2005, 2006, 2008-2011, + * 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 License @@ -614,8 +614,32 @@ SCM_DEFINE (scm_srfi1_length_plus, "length+", 1, 0, 0, "circular.") #define FUNC_NAME s_scm_srfi1_length_plus { - long len = scm_ilength (lst); - return (len >= 0 ? SCM_I_MAKINUM (len) : SCM_BOOL_F); + size_t i = 0; + SCM tortoise = lst; + SCM hare = lst; + + do + { + if (SCM_NULL_OR_NIL_P (hare)) + return scm_from_size_t (i); + if (!scm_is_pair (hare)) + scm_wrong_type_arg_msg (FUNC_NAME, 1, lst, "proper or circular list"); + hare = SCM_CDR (hare); + i++; + if (SCM_NULL_OR_NIL_P (hare)) + return scm_from_size_t (i); + if (!scm_is_pair (hare)) + scm_wrong_type_arg_msg (FUNC_NAME, 1, lst, "proper or circular list"); + hare = SCM_CDR (hare); + i++; + /* For every two steps the hare takes, the tortoise takes one. */ + tortoise = SCM_CDR(tortoise); + } + while (!scm_is_eq (hare, tortoise)); + + /* If the tortoise ever catches the hare, then the list must contain + a cycle. */ + return SCM_BOOL_F; } #undef FUNC_NAME diff --git a/test-suite/tests/srfi-1.test b/test-suite/tests/srfi-1.test index d40f8e1c2..bce0e86da 100644 --- a/test-suite/tests/srfi-1.test +++ b/test-suite/tests/srfi-1.test @@ -1,6 +1,6 @@ ;;;; srfi-1.test --- Test suite for Guile's SRFI-1 functions. -*- scheme -*- ;;;; -;;;; Copyright 2003, 2004, 2005, 2006, 2008, 2009, 2010, 2011 Free Software Foundation, Inc. +;;;; Copyright 2003-2006, 2008-2011, 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 @@ -1329,6 +1329,10 @@ (length+)) (pass-if-exception "too many args" exception:wrong-num-args (length+ 123 456)) + (pass-if-exception "not a pair" exception:wrong-type-arg + (length+ 'x)) + (pass-if-exception "improper list" exception:wrong-type-arg + (length+ '(x y . z))) (pass-if (= 0 (length+ '()))) (pass-if (= 1 (length+ '(x)))) (pass-if (= 2 (length+ '(x y)))) |