--- /dev/null
+;;; seq.el --- Sequence manipulation functions -*- lexical-binding: t -*-
+
+;; Copyright (C) 2014-2015 Free Software Foundation, Inc.
+
+;; Author: Nicolas Petton <nicolasNOSPAMpetton.fr>
+;; Keywords: sequences
+;; Version: 1.4
+;; Package: seq
+
+;; Maintainer: emacs-develNOSPAMgnu.org
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Sequence-manipulation functions that complement basic functions
+;; provided by subr.el.
+;;
+;; All functions are prefixed with "seq-".
+;;
+;; All provided functions work on lists, strings and vectors.
+;;
+;; Functions taking a predicate or iterating over a sequence using a
+;; function as argument take the function as their first argument and
+;; the sequence as their second argument. All other functions take
+;; the sequence as their first argument.
+;;
+;; All functions are tested in test/automated/seq-tests.el
+
+;;; Code:
+
+(defmacro seq-doseq (spec &rest body)
+ "Loop over a sequence.
+Similar to `dolist' but can be applied lists, strings and vectors.
+
+Evaluate BODY with VAR bound to each element of SEQ, in turn.
+Then evaluate RESULT to get return value, default nil.
+
+\(fn (VAR SEQ [RESULT]) BODY...)"
+ (declare (indent 1) (debug ((symbolp form &optional form) body)))
+ (let ((is-list (make-symbol "is-list"))
+ (seq (make-symbol "seq"))
+ (index (make-symbol "index")))
+ `(let* ((,seq ,(cadr spec))
+ (,is-list (listp ,seq))
+ (,index (if ,is-list ,seq 0)))
+ (while (if ,is-list
+ (consp ,index)
+ (< ,index (seq-length ,seq)))
+ (let ((,(car spec) (if ,is-list
+ (car ,index)
+ (seq-elt ,seq ,index))))
+ ,@body
+ (setq ,index (if ,is-list
+ (cdr ,index)
+ (+ ,index 1)))))
+ ,@(if (cddr spec)
+ `((setq ,(car spec) nil) ,@(cddr spec))))))
+
+(defun seq-drop (seq n)
+ "Return a subsequence of SEQ without its first N elements.
+The result is a sequence of the same type as SEQ.
+
+If N is a negative integer or zero, SEQ is returned."
+ (if (<= n 0)
+ seq
+ (if (listp seq)
+ (seq--drop-list seq n)
+ (let ((length (seq-length seq)))
+ (seq-subseq seq (min n length) length)))))
+
+(defun seq-take (seq n)
+ "Return a subsequence of SEQ with its first N elements.
+The result is a sequence of the same type as SEQ.
+
+If N is a negative integer or zero, an empty sequence is
+returned."
+ (if (listp seq)
+ (seq--take-list seq n)
+ (seq-subseq seq 0 (min (max n 0) (seq-length seq)))))
+
+(defun seq-drop-while (pred seq)
+ "Return a sequence from the first element for which (PRED element) is nil in SEQ.
+The result is a sequence of the same type as SEQ."
+ (if (listp seq)
+ (seq--drop-while-list pred seq)
+ (seq-drop seq (seq--count-successive pred seq))))
+
+(defun seq-take-while (pred seq)
+ "Return the successive elements for which (PRED element) is non-nil in SEQ.
+The result is a sequence of the same type as SEQ."
+ (if (listp seq)
+ (seq--take-while-list pred seq)
+ (seq-take seq (seq--count-successive pred seq))))
+
+(defun seq-filter (pred seq)
+ "Return a list of all the elements for which (PRED element) is non-nil in SEQ."
+ (let ((exclude (make-symbol "exclude")))
+ (delq exclude (seq-map (lambda (elt)
+ (if (funcall pred elt)
+ elt
+ exclude))
+ seq))))
+
+(defun seq-remove (pred seq)
+ "Return a list of all the elements for which (PRED element) is nil in SEQ."
+ (seq-filter (lambda (elt) (not (funcall pred elt)))
+ seq))
+
+(defun seq-reduce (function seq initial-value)
+ "Reduce the function FUNCTION across SEQ, starting with INITIAL-VALUE.
+
+Return the result of calling FUNCTION with INITIAL-VALUE and the
+first element of SEQ, then calling FUNCTION with that result and
+the second element of SEQ, then with that result and the third
+element of SEQ, etc.
+
+If SEQ is empty, return INITIAL-VALUE and FUNCTION is not called."
+ (if (seq-empty-p seq)
+ initial-value
+ (let ((acc initial-value))
+ (seq-doseq (elt seq)
+ (setq acc (funcall function acc elt)))
+ acc)))
+
+(defun seq-some-p (pred seq)
+ "Return any element for which (PRED element) is non-nil in SEQ, nil otherwise."
+ (catch 'seq--break
+ (seq-doseq (elt seq)
+ (when (funcall pred elt)
+ (throw 'seq--break elt)))
+ nil))
+
+(defun seq-every-p (pred seq)
+ "Return non-nil if (PRED element) is non-nil for all elements of the sequence SEQ."
+ (catch 'seq--break
+ (seq-doseq (elt seq)
+ (or (funcall pred elt)
+ (throw 'seq--break nil)))
+ t))
+
+(defun seq-count (pred seq)
+ "Return the number of elements for which (PRED element) is non-nil in SEQ."
+ (let ((count 0))
+ (seq-doseq (elt seq)
+ (when (funcall pred elt)
+ (setq count (+ 1 count))))
+ count))
+
+(defun seq-empty-p (seq)
+ "Return non-nil if the sequence SEQ is empty, nil otherwise."
+ (if (listp seq)
+ (null seq)
+ (= 0 (seq-length seq))))
+
+(defun seq-sort (pred seq)
+ "Return a sorted sequence comparing using PRED the elements of SEQ.
+The result is a sequence of the same type as SEQ."
+ (if (listp seq)
+ (sort (seq-copy seq) pred)
+ (let ((result (seq-sort pred (append seq nil))))
+ (seq-into result (type-of seq)))))
+
+(defun seq-contains-p (seq elt &optional testfn)
+ "Return the first element in SEQ that equals to ELT.
+Equality is defined by TESTFN if non-nil or by `equal' if nil."
+ (seq-some-p (lambda (e)
+ (funcall (or testfn #'equal) elt e))
+ seq))
+
+(defun seq-uniq (seq &optional testfn)
+ "Return a list of the elements of SEQ with duplicates removed.
+TESTFN is used to compare elements, or `equal' if TESTFN is nil."
+ (let ((result '()))
+ (seq-doseq (elt seq)
+ (unless (seq-contains-p result elt testfn)
+ (setq result (cons elt result))))
+ (nreverse result)))
+
+(defun seq-subseq (seq start &optional end)
+ "Return the subsequence of SEQ from START to END.
+If END is omitted, it defaults to the length of the sequence.
+If START or END is negative, it counts from the end."
+ (cond ((or (stringp seq) (vectorp seq)) (substring seq start end))
+ ((listp seq)
+ (let (len (errtext (format "Bad bounding indices: %s, %s" start end)))
+ (and end (< end 0) (setq end (+ end (setq len (seq-length seq)))))
+ (if (< start 0) (setq start (+ start (or len (setq len (seq-length seq))))))
+ (when (> start 0)
+ (setq seq (nthcdr (1- start) seq))
+ (or seq (error "%s" errtext))
+ (setq seq (cdr seq)))
+ (if end
+ (let ((res nil))
+ (while (and (>= (setq end (1- end)) start) seq)
+ (push (pop seq) res))
+ (or (= (1+ end) start) (error "%s" errtext))
+ (nreverse res))
+ (seq-copy seq))))
+ (t (error "Unsupported sequence: %s" seq))))
+
+(defun seq-concatenate (type &rest seqs)
+ "Concatenate, into a sequence of type TYPE, the sequences SEQS.
+TYPE must be one of following symbols: vector, string or list.
+
+\n(fn TYPE SEQUENCE...)"
+ (pcase type
+ (`vector (apply #'vconcat seqs))
+ (`string (apply #'concat seqs))
+ (`list (apply #'append (append seqs '(nil))))
+ (t (error "Not a sequence type name: %s" type))))
+
+(defun seq-mapcat (function seq &optional type)
+ "Concatenate the result of applying FUNCTION to each element of SEQ.
+The result is a sequence of type TYPE, or a list if TYPE is nil."
+ (apply #'seq-concatenate (or type 'list)
+ (seq-map function seq)))
+
+(defun seq-partition (seq n)
+ "Return a list of the elements of SEQ grouped into sub-sequences of length N.
+The last sequence may contain less than N elements. If N is a
+negative integer or 0, nil is returned."
+ (unless (< n 1)
+ (let ((result '()))
+ (while (not (seq-empty-p seq))
+ (push (seq-take seq n) result)
+ (setq seq (seq-drop seq n)))
+ (nreverse result))))
+
+(defun seq-intersection (seq1 seq2 &optional testfn)
+ "Return a list of the elements that appear in both SEQ1 and SEQ2.
+Equality is defined by TESTFN if non-nil or by `equal' if nil."
+ (seq-reduce (lambda (acc elt)
+ (if (seq-contains-p seq2 elt testfn)
+ (cons elt acc)
+ acc))
+ (seq-reverse seq1)
+ '()))
+
+(defun seq-difference (seq1 seq2 &optional testfn)
+ "Return a list of th elements that appear in SEQ1 but not in SEQ2.
+Equality is defined by TESTFN if non-nil or by `equal' if nil."
+ (seq-reduce (lambda (acc elt)
+ (if (not (seq-contains-p seq2 elt testfn))
+ (cons elt acc)
+ acc))
+ (seq-reverse seq1)
+ '()))
+
+(defun seq-group-by (function seq)
+ "Apply FUNCTION to each element of SEQ.
+Separate the elements of SEQ into an alist using the results as
+keys. Keys are compared using `equal'."
+ (seq-reduce
+ (lambda (acc elt)
+ (let* ((key (funcall function elt))
+ (cell (assoc key acc)))
+ (if cell
+ (setcdr cell (push elt (cdr cell)))
+ (push (list key elt) acc))
+ acc))
+ (seq-reverse seq)
+ nil))
+
+(defalias 'seq-reverse
+ (if (ignore-errors (reverse [1 2]))
+ #'reverse
+ (lambda (seq)
+ "Return the reversed copy of list, vector, or string SEQ.
+See also the function `nreverse', which is used more often."
+ (let ((result '()))
+ (seq-map (lambda (elt) (push elt result))
+ seq)
+ (if (listp seq)
+ result
+ (seq-into result (type-of seq)))))))
+
+(defun seq-into (seq type)
+ "Convert the sequence SEQ into a sequence of type TYPE.
+TYPE can be one of the following symbols: vector, string or list."
+ (pcase type
+ (`vector (vconcat seq))
+ (`string (concat seq))
+ (`list (append seq nil))
+ (t (error "Not a sequence type name: %s" type))))
+
+(defun seq--drop-list (list n)
+ "Return a list from LIST without its first N elements.
+This is an optimization for lists in `seq-drop'."
+ (while (and list (> n 0))
+ (setq list (cdr list)
+ n (1- n)))
+ list)
+
+(defun seq--take-list (list n)
+ "Return a list from LIST made of its first N elements.
+This is an optimization for lists in `seq-take'."
+ (let ((result '()))
+ (while (and list (> n 0))
+ (setq n (1- n))
+ (push (pop list) result))
+ (nreverse result)))
+
+(defun seq--drop-while-list (pred list)
+ "Return a list from the first element for which (PRED element) is nil in LIST.
+This is an optimization for lists in `seq-drop-while'."
+ (while (and list (funcall pred (car list)))
+ (setq list (cdr list)))
+ list)
+
+(defun seq--take-while-list (pred list)
+ "Return the successive elements for which (PRED element) is non-nil in LIST.
+This is an optimization for lists in `seq-take-while'."
+ (let ((result '()))
+ (while (and list (funcall pred (car list)))
+ (push (pop list) result))
+ (nreverse result)))
+
+(defun seq--count-successive (pred seq)
+ "Return the number of successive elements for which (PRED element) is non-nil in SEQ."
+ (let ((n 0)
+ (len (seq-length seq)))
+ (while (and (< n len)
+ (funcall pred (seq-elt seq n)))
+ (setq n (+ 1 n)))
+ n))
+
+(defun seq--activate-font-lock-keywords ()
+ "Activate font-lock keywords for some symbols defined in seq."
+ (font-lock-add-keywords 'emacs-lisp-mode
+ '("\\<seq-doseq\\>")))
+
+(defalias 'seq-copy #'copy-sequence)
+(defalias 'seq-elt #'elt)
+(defalias 'seq-length #'length)
+(defalias 'seq-do #'mapc)
+(defalias 'seq-each #'seq-do)
+(defalias 'seq-map #'mapcar)
+
+(add-to-list 'emacs-lisp-mode-hook #'seq--activate-font-lock-keywords)
+
+;;;; ChangeLog:
+
+;; 2015-04-15 Nicolas Petton <nicolasNOSPAMpetton.fr>
+;;
+;; seq.el update
+;;
+;; * packages/seq/seq.el: Update seq.el to version 1.4
+;; * packages/seq/tests/seq-tests.el: Update seq.el to version 1.4
+;;
+;; 2015-03-25 Nicolas Petton <nicolasNOSPAMpetton.fr>
+;;
+;; Rephrases a comment in seq.el about the order of the arguments
+;;
+;; * packages/seq/seq.el: Better comment about the order of the arguments
+;;
+;; 2015-03-09 Nicolas Petton <nicolasNOSPAMpetton.fr>
+;;
+;; Update seq.el to version 1.3
+;;
+;; * packages/seq/seq.el: update to version 1.3
+;; * packages/seq/tests/seq-tests.el: update to version 1.3
+;;
+;; 2015-02-11 Nicolas Petton <nicolasNOSPAMpetton.fr>
+;;
+;; Update seq.el to version 1.2
+;;
+;; * package/seq/seq.el: Update to version 1.2
+;; * packages/seq/tests/seq-tests.el: Update to version 1.2
+;;
+;; 2015-02-09 Nicolas Petton <nicolasNOSPAMpetton.fr>
+;;
+;; Update seq.el to version 1.1.1
+;;
+;; * package/seq/seq.el: Update to version 1.1.1
+;; * packages/seq/tests/seq-tests.el: Update to version 1.1.1
+;;
+;; 2015-02-06 Nicolas Petton <nicolasNOSPAMpetton.fr>
+;;
+;; Update seq.el to version 1.1
+;;
+;; * packages/seq/seq.el: Update to version 1.1
+;; * packages/seq/tests/seq-tests.el: Update to version 1.1
+;;
+;; 2015-01-14 Nicolas Petton <nicolasNOSPAMpetton.fr>
+;;
+;; packages/seq: New package
+;;
+
+
+(provide 'seq)
+;;; seq.el ends here
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