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These functions search for elements or subsequences in a sequence.
(See also cl-member
and cl-assoc
; see Lists.)
This function searches seq for an element matching item. If it finds a match, it returns the matching element. Otherwise, it returns
nil
. It returns the leftmost match, unless:from-end
is true, in which case it returns the rightmost match. The:start
and:end
arguments may be used to limit the range of elements that are searched.
This function is like
cl-find
, except that it returns the integer position in the sequence of the matching item rather than the item itself. The position is relative to the start of the sequence as a whole, even if:start
is non-zero. The function returnsnil
if no matching element was found.
This function returns the number of elements of seq which match item. The result is always a nonnegative integer.
The cl-find-if
, cl-find-if-not
, cl-position-if
,
cl-position-if-not
, cl-count-if
, and cl-count-if-not
functions are defined similarly.
This function compares the specified parts of seq1 and seq2. If they are the same length and the corresponding elements match (according to
:test
,:test-not
, and:key
), the function returnsnil
. If there is a mismatch, the function returns the index (relative to seq1) of the first mismatching element. This will be the leftmost pair of elements that do not match, or the position at which the shorter of the two otherwise-matching sequences runs out.If
:from-end
is true, then the elements are compared from right to left starting at(1-
end1)
and(1-
end2)
. If the sequences differ, then one plus the index of the rightmost difference (relative to seq1) is returned.An interesting example is
(cl-mismatch str1 str2 :key 'upcase)
, which compares two strings case-insensitively.
This function searches seq2 for a subsequence that matches seq1 (or part of it specified by
:start1
and:end1
). Only matches that fall entirely within the region defined by:start2
and:end2
will be considered. The return value is the index of the leftmost element of the leftmost match, relative to the start of seq2, ornil
if no matches were found. If:from-end
is true, the function finds the rightmost matching subsequence.