description of sort ...
* doc/lispref/sequences.texi (Sequence Functions): ... and generalize
it for sequences. Add an example.
* src/fns.c (Fsort): Use more natural Qsequencep error.
* test/automated/fns-tests.el (fns-tests-sort): Minor style rewrite.
+2014-08-29 Dmitry Antipov <dmantipov@yandex.ru>
+
+ * lists.texi (Functions that Rearrange Lists): Remove
+ description of sort ...
+ * sequences.texi (Sequence Functions): ... and generalize
+ it for sequences. Add an example.
+
2014-08-28 Eli Zaretskii <eliz@gnu.org>
* display.texi (Bidirectional Display): Update the Emacs's class
@end smallexample
@end defun
-@defun sort list predicate
-@cindex stable sort
-@cindex sorting lists
-This function sorts @var{list} stably, though destructively, and
-returns the sorted list. It compares elements using @var{predicate}. A
-stable sort is one in which elements with equal sort keys maintain their
-relative order before and after the sort. Stability is important when
-successive sorts are used to order elements according to different
-criteria.
-
-The argument @var{predicate} must be a function that accepts two
-arguments. It is called with two elements of @var{list}. To get an
-increasing order sort, the @var{predicate} should return non-@code{nil} if the
-first element is ``less than'' the second, or @code{nil} if not.
-
-The comparison function @var{predicate} must give reliable results for
-any given pair of arguments, at least within a single call to
-@code{sort}. It must be @dfn{antisymmetric}; that is, if @var{a} is
-less than @var{b}, @var{b} must not be less than @var{a}. It must be
-@dfn{transitive}---that is, if @var{a} is less than @var{b}, and @var{b}
-is less than @var{c}, then @var{a} must be less than @var{c}. If you
-use a comparison function which does not meet these requirements, the
-result of @code{sort} is unpredictable.
-
-The destructive aspect of @code{sort} is that it rearranges the cons
-cells forming @var{list} by changing @sc{cdr}s. A nondestructive sort
-function would create new cons cells to store the elements in their
-sorted order. If you wish to make a sorted copy without destroying the
-original, copy it first with @code{copy-sequence} and then sort.
-
-Sorting does not change the @sc{car}s of the cons cells in @var{list};
-the cons cell that originally contained the element @code{a} in
-@var{list} still has @code{a} in its @sc{car} after sorting, but it now
-appears in a different position in the list due to the change of
-@sc{cdr}s. For example:
-
-@example
-@group
-(setq nums '(1 3 2 6 5 4 0))
- @result{} (1 3 2 6 5 4 0)
-@end group
-@group
-(sort nums '<)
- @result{} (0 1 2 3 4 5 6)
-@end group
-@group
-nums
- @result{} (1 2 3 4 5 6)
-@end group
-@end example
-
-@noindent
-@strong{Warning}: Note that the list in @code{nums} no longer contains
-0; this is the same cons cell that it was before, but it is no longer
-the first one in the list. Don't assume a variable that formerly held
-the argument now holds the entire sorted list! Instead, save the result
-of @code{sort} and use that. Most often we store the result back into
-the variable that held the original list:
-
-@example
-(setq nums (sort nums '<))
-@end example
-
-@xref{Sorting}, for more functions that perform sorting.
-See @code{documentation} in @ref{Accessing Documentation}, for a
-useful example of @code{sort}.
-@end defun
-
@node Sets And Lists
@section Using Lists as Sets
@cindex lists as sets
@end defun
+@defun sort sequence predicate
+@cindex stable sort
+@cindex sorting lists
+@cindex sorting vectors
+This function sorts @var{sequence} stably. Note that this function doesn't work
+for all sequences; it may be used only for lists and vectors. If @var{sequence}
+is a list, it is modified destructively. This functions returns the sorted
+@var{sequence} and compares elements using @var{predicate}. A stable sort is
+one in which elements with equal sort keys maintain their relative order before
+and after the sort. Stability is important when successive sorts are used to
+order elements according to different criteria.
+
+The argument @var{predicate} must be a function that accepts two
+arguments. It is called with two elements of @var{sequence}. To get an
+increasing order sort, the @var{predicate} should return non-@code{nil} if the
+first element is ``less than'' the second, or @code{nil} if not.
+
+The comparison function @var{predicate} must give reliable results for
+any given pair of arguments, at least within a single call to
+@code{sort}. It must be @dfn{antisymmetric}; that is, if @var{a} is
+less than @var{b}, @var{b} must not be less than @var{a}. It must be
+@dfn{transitive}---that is, if @var{a} is less than @var{b}, and @var{b}
+is less than @var{c}, then @var{a} must be less than @var{c}. If you
+use a comparison function which does not meet these requirements, the
+result of @code{sort} is unpredictable.
+
+The destructive aspect of @code{sort} for lists is that it rearranges the
+cons cells forming @var{sequence} by changing @sc{cdr}s. A nondestructive
+sort function would create new cons cells to store the elements in their
+sorted order. If you wish to make a sorted copy without destroying the
+original, copy it first with @code{copy-sequence} and then sort.
+
+Sorting does not change the @sc{car}s of the cons cells in @var{sequence};
+the cons cell that originally contained the element @code{a} in
+@var{sequence} still has @code{a} in its @sc{car} after sorting, but it now
+appears in a different position in the list due to the change of
+@sc{cdr}s. For example:
+
+@example
+@group
+(setq nums '(1 3 2 6 5 4 0))
+ @result{} (1 3 2 6 5 4 0)
+@end group
+@group
+(sort nums '<)
+ @result{} (0 1 2 3 4 5 6)
+@end group
+@group
+nums
+ @result{} (1 2 3 4 5 6)
+@end group
+@end example
+
+@noindent
+@strong{Warning}: Note that the list in @code{nums} no longer contains
+0; this is the same cons cell that it was before, but it is no longer
+the first one in the list. Don't assume a variable that formerly held
+the argument now holds the entire sorted list! Instead, save the result
+of @code{sort} and use that. Most often we store the result back into
+the variable that held the original list:
+
+@example
+(setq nums (sort nums '<))
+@end example
+
+For the better understanding of what stable sort is, consider the following
+vector example. After sorting, all items whose @code{car} is 8 are grouped
+at the beginning of @code{vector}, but their relative order is preserved.
+All items whose @code{car} is 9 are grouped at the end of @code{vector},
+but their relative order is also preserved:
+
+@example
+@group
+(setq
+ vector
+ (vector '(8 . "xxx") '(9 . "aaa") '(8 . "bbb") '(9 . "zzz")
+ '(9 . "ppp") '(8 . "ttt") '(8 . "eee") '(9 . "fff")))
+ @result{} [(8 . "xxx") (9 . "aaa") (8 . "bbb") (9 . "zzz")
+ (9 . "ppp") (8 . "ttt") (8 . "eee") (9 . "fff")]
+@end group
+@group
+(sort vector (lambda (x y) (< (car x) (car y))))
+ @result{} [(8 . "xxx") (8 . "bbb") (8 . "ttt") (8 . "eee")
+ (9 . "aaa") (9 . "zzz") (9 . "ppp") (9 . "fff")]
+@end group
+@end example
+
+@xref{Sorting}, for more functions that perform sorting.
+See @code{documentation} in @ref{Accessing Documentation}, for a
+useful example of @code{sort}.
+@end defun
+
@node Arrays
@section Arrays
@cindex array
else if (VECTORP (seq))
seq = sort_vector (seq, predicate);
else if (!NILP (seq))
- wrong_type_argument (Qarrayp, seq);
+ wrong_type_argument (Qsequencep, seq);
return seq;
}
(should (equal
(sort
(vector
- (cons 8 "xxx") (cons 9 "aaa") (cons 8 "bbb") (cons 9 "zzz")
- (cons 9 "ppp") (cons 8 "ttt") (cons 8 "eee") (cons 9 "fff"))
+ '(8 . "xxx") '(9 . "aaa") '(8 . "bbb") '(9 . "zzz")
+ '(9 . "ppp") '(8 . "ttt") '(8 . "eee") '(9 . "fff"))
(lambda (x y) (< (car x) (car y))))
[(8 . "xxx") (8 . "bbb") (8 . "ttt") (8 . "eee")
(9 . "aaa") (9 . "zzz") (9 . "ppp") (9 . "fff")])))
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