;; Author: Nicolas Petton <nicolas@petton.fr>
;; Keywords: sequences
-;; Version: 1.3
+;; Version: 1.7
;; Package: seq
;; Maintainer: emacs-devel@gnu.org
;;
;; All provided functions work on lists, strings and vectors.
;;
-;; Functions taking a predicate or a function iterating over the
-;; sequence as argument take the function as their first argument and
+;; 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.
;;
(defmacro seq-doseq (spec &rest body)
"Loop over a sequence.
-Similar to `dolist' but can be applied lists, strings and vectors.
+Similar to `dolist' but can be applied to 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...)"
+\(fn (VAR SEQ) BODY...)"
(declare (indent 1) (debug ((symbolp form &optional form) body)))
- (let ((is-list (make-symbol "is-list"))
+ (let ((length (make-symbol "length"))
(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))))))
+ (,length (if (listp ,seq) nil (seq-length ,seq)))
+ (,index (if ,length 0 ,seq)))
+ (while (if ,length
+ (< ,index ,length)
+ (consp ,index))
+ (let ((,(car spec) (if ,length
+ (prog1 (seq-elt ,seq ,index)
+ (setq ,index (+ ,index 1)))
+ (pop ,index))))
+ ,@body)))))
+
+(if (fboundp 'pcase-defmacro)
+ ;; Implementation of `seq-let' based on a `pcase'
+ ;; pattern. Requires Emacs>=25.1.
+ (progn
+ (pcase-defmacro seq (&rest args)
+ "pcase pattern matching sequence elements.
+Matches if the object is a sequence (list, string or vector), and
+binds each element of ARGS to the corresponding element of the
+sequence."
+ `(and (pred seq-p)
+ ,@(seq--make-pcase-bindings args)))
+
+ (defmacro seq-let (args seq &rest body)
+ "Bind the variables in ARGS to the elements of SEQ then evaluate BODY.
+
+ARGS can also include the `&rest' marker followed by a variable
+name to be bound to the rest of SEQ."
+ (declare (indent 2) (debug t))
+ `(pcase-let ((,(seq--make-pcase-patterns args) ,seq))
+ ,@body)))
+
+ ;; Implementation of `seq-let' compatible with Emacs<25.1.
+ (defmacro seq-let (args seq &rest body)
+ "Bind the variables in ARGS to the elements of SEQ then evaluate BODY.
+
+ARGS can also include the `&rest' marker followed by a variable
+name to be bound to the rest of SEQ."
+ (declare (indent 2) (debug t))
+ (let ((seq-var (make-symbol "seq")))
+ `(let* ((,seq-var ,seq)
+ ,@(seq--make-bindings args seq-var))
+ ,@body))))
(defun seq-drop (seq n)
"Return a subsequence of SEQ without its first N elements.
(`vector (apply #'vconcat seqs))
(`string (apply #'concat seqs))
(`list (apply #'append (append seqs '(nil))))
- (t (error "Not a sequence type name: %s" type))))
+ (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.
(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
(`vector (vconcat seq))
(`string (concat seq))
(`list (append seq nil))
- (t (error "Not a sequence type name: %s" type))))
+ (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.
(setq n (+ 1 n)))
n))
+(defun seq--make-pcase-bindings (args)
+ "Return a list of bindings of the variables in ARGS to the elements of a sequence."
+ (let ((bindings '())
+ (index 0)
+ (rest-marker nil))
+ (seq-doseq (name args)
+ (unless rest-marker
+ (pcase name
+ (`&rest
+ (progn (push `(app (pcase--flip seq-drop ,index)
+ ,(seq--elt-safe args (1+ index)))
+ bindings)
+ (setq rest-marker t)))
+ (t
+ (push `(app (pcase--flip seq--elt-safe ,index) ,name) bindings))))
+ (setq index (1+ index)))
+ bindings))
+
+(defun seq--make-pcase-patterns (args)
+ "Return a list of `(seq ...)' pcase patterns from the argument list ARGS."
+ (cons 'seq
+ (seq-map (lambda (elt)
+ (if (seq-p elt)
+ (seq--make-pcase-patterns elt)
+ elt))
+ args)))
+
+;; Helper function for the Backward-compatible version of `seq-let'
+;; for Emacs<25.1.
+(defun seq--make-bindings (args seq &optional bindings)
+ "Return a list of bindings of the variables in ARGS to the elements of a sequence.
+if BINDINGS is non-nil, append new bindings to it, and return
+BINDINGS."
+ (let ((index 0)
+ (rest-marker nil))
+ (seq-doseq (name args)
+ (unless rest-marker
+ (pcase name
+ ((pred seq-p)
+ (setq bindings (seq--make-bindings (seq--elt-safe args index)
+ `(seq--elt-safe ,seq ,index)
+ bindings)))
+ (`&rest
+ (progn (push `(,(seq--elt-safe args (1+ index))
+ (seq-drop ,seq ,index))
+ bindings)
+ (setq rest-marker t)))
+ (t
+ (push `(,name (seq--elt-safe ,seq ,index)) bindings))))
+ (setq index (1+ index)))
+ bindings))
+
+(defun seq--elt-safe (seq n)
+ "Return element of SEQ at the index N.
+If no element is found, return nil."
+ (when (or (listp seq)
+ (and (sequencep seq)
+ (> (seq-length seq) n)))
+ (seq-elt seq 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\\>" "\\<seq-let\\>")))
+
(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)
+(defalias 'seq-p #'sequencep)
+
+(unless (fboundp 'elisp--font-lock-flush-elisp-buffers)
+ ;; In Emacsā„25, (via elisp--font-lock-flush-elisp-buffers and a few others)
+ ;; we automatically highlight macros.
+ (add-hook 'emacs-lisp-mode-hook #'seq--activate-font-lock-keywords))
(provide 'seq)
;;; seq.el ends here