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[Emacs-diffs] master 4ac426a: Merge branch 'seq-let'
From: |
Nicolas Petton |
Subject: |
[Emacs-diffs] master 4ac426a: Merge branch 'seq-let' |
Date: |
Tue, 05 May 2015 20:11:35 +0000 |
branch: master
commit 4ac426a1b90912ea947d46a57b6fcbbbf7586da1
Merge: 0508aa2 8cb4b4f
Author: Nicolas Petton <address@hidden>
Commit: Nicolas Petton <address@hidden>
Merge branch 'seq-let'
---
doc/lispref/sequences.texi | 38 +++++++++++++++++++++++++++++++++-
lisp/emacs-lisp/seq.el | 48 +++++++++++++++++++++++++++++++++++++++++-
test/automated/seq-tests.el | 21 ++++++++++++++++++
3 files changed, 104 insertions(+), 3 deletions(-)
diff --git a/doc/lispref/sequences.texi b/doc/lispref/sequences.texi
index b48fae4..1166ef8 100644
--- a/doc/lispref/sequences.texi
+++ b/doc/lispref/sequences.texi
@@ -413,7 +413,7 @@ but their relative order is also preserved:
(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}.
@@ -797,6 +797,42 @@ vector or string (@pxref{Iteration} for more information
about the
@code{dolist} macro). This is primarily useful for side-effects.
@end defmac
address@hidden seq-let arguments sequense address@hidden
address@hidden sequence destructuring
+ This macro binds the variables in defined in the sequence
address@hidden to the elements of the sequence @var{sequence}.
address@hidden can itself include sequences allowing for nested
+destructuring.
+
+The @var{arguments} sequence can also include the `&rest' marker
+followed by a variable name to be bound to the rest of
address@hidden
+
address@hidden
address@hidden
+(seq-let [first second] [1 2 3 4]
+ (list first second))
address@hidden (1 2)
address@hidden group
address@hidden
+(seq-let (_ a _ b) '(1 2 3 4)
+ (list a b))
address@hidden (2 4)
address@hidden group
address@hidden
+(seq-let [a [b [c]]] [1 [2 [3]]]
+ (list a b c))
address@hidden (1 2 3)
address@hidden group
address@hidden
+(seq-let [a b &rest others] [1 2 3 4]
+ others)
address@hidden group
address@hidden [3 4]
address@hidden example
address@hidden defmac
+
+
@node Arrays
@section Arrays
@cindex array
diff --git a/lisp/emacs-lisp/seq.el b/lisp/emacs-lisp/seq.el
index 456debf..f1633ce 100644
--- a/lisp/emacs-lisp/seq.el
+++ b/lisp/emacs-lisp/seq.el
@@ -4,7 +4,7 @@
;; Author: Nicolas Petton <address@hidden>
;; Keywords: sequences
-;; Version: 1.5
+;; Version: 1.6
;; Package: seq
;; Maintainer: address@hidden
@@ -40,6 +40,11 @@
;;
;; All functions are tested in test/automated/seq-tests.el
+;;; TODO:
+
+;; - Add a pcase macro named using `pcase-defmacro' that `seq-let'
+;; - could wrap.
+
;;; Code:
(defmacro seq-doseq (spec &rest body)
@@ -65,6 +70,14 @@ Evaluate BODY with VAR bound to each element of SEQ, in turn.
(pop ,index))))
,@body)))))
+(defmacro seq-let (args seq &rest body)
+ "Bind the variables in ARGS to the elements of SEQ then evaluate BODY."
+ (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.
The result is a sequence of the same type as SEQ.
@@ -336,7 +349,38 @@ This is an optimization for lists in `seq-take-while'."
(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-doseq\\>" "\\<seq-let\\>")))
+
+(defun seq--make-bindings (args seq &optional bindings)
+ "Return a list of bindings of the variables in ARGS to the elements of SEQ.
+if BINDINGS is non-nil, append new bindings to it, and
+return BINDINGS."
+ (let ((index 0)
+ (rest-bound nil))
+ (seq-doseq (name args)
+ (unless rest-bound
+ (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-bound 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)))
(defalias 'seq-copy #'copy-sequence)
(defalias 'seq-elt #'elt)
diff --git a/test/automated/seq-tests.el b/test/automated/seq-tests.el
index 7f6e06c..ab46eb8 100644
--- a/test/automated/seq-tests.el
+++ b/test/automated/seq-tests.el
@@ -276,5 +276,26 @@ Evaluate BODY for each created sequence.
(v2 [2 4 6]))
(should (seq-empty-p (seq-difference v1 v2)))))
+(ert-deftest test-seq-let ()
+ (with-test-sequences (seq '(1 2 3 4))
+ (seq-let (a b c d e) seq
+ (should (= a 1))
+ (should (= b 2))
+ (should (= c 3))
+ (should (= d 4))
+ (should (null e)))
+ (seq-let (a b &rest others) seq
+ (should (= a 1))
+ (should (= b 2))
+ (should (same-contents-p others (seq-drop seq 2)))))
+ (let ((seq '(1 (2 (3 (4))))))
+ (seq-let (_ (_ (_ (a)))) seq
+ (should (= a 4))))
+ (let (seq)
+ (seq-let (a b c) seq
+ (should (null a))
+ (should (null b))
+ (should (null c)))))
+
(provide 'seq-tests)
;;; seq-tests.el ends here