New if-let, when-let, thread-first and thread-last macros.

* lisp/emacs-lisp/subr-x.el
(internal--listify, internal--check-binding)
(internal--build-binding-value-form, internal--build-binding)
(internal--build-bindings): New functions.
(internal--thread-argument, thread-first, thread-last)
(if-let, when-let): New macros.

* test/automated/subr-x-tests.el
(subr-x-test-if-let-single-binding-expansion)
(subr-x-test-if-let-single-symbol-expansion)
(subr-x-test-if-let-nil-related-expansion)
(subr-x-test-if-let-malformed-binding, subr-x-test-if-let-true)
(subr-x-test-if-let-false, subr-x-test-if-let-bound-references)
(subr-x-test-if-let-and-lazyness-is-preserved)
(subr-x-test-when-let-body-expansion)
(subr-x-test-when-let-single-binding-expansion)
(subr-x-test-when-let-single-symbol-expansion)
(subr-x-test-when-let-nil-related-expansion)
(subr-x-test-when-let-malformed-binding)
(subr-x-test-when-let-true, subr-x-test-when-let-false)
(subr-x-test-when-let-bound-references)
(subr-x-test-when-let-and-lazyness-is-preserved)
(subr-x-test-thread-first-no-forms)
(subr-x-test-thread-first-function-names-are-threaded)
(subr-x-test-thread-first-expansion)
(subr-x-test-thread-last-no-forms)
(subr-x-test-thread-last-function-names-are-threaded)
(subr-x-test-thread-last-expansion): New tests.

2 files changed, 550 insertions, 0 deletions

diff --git a/test/ChangeLog b/test/ChangeLog
index 9b0f3ab1b04..34807205e0f 100644
--- a/test/ChangeLog
+++ b/test/ChangeLog
@@ -1,3 +1,27 @@
+2014-06-30  Fabián Ezequiel Gallina  <fgallina@gnu.org>
+
+        * automated/subr-x-tests.el
+        (subr-x-test-if-let-single-binding-expansion)
+        (subr-x-test-if-let-single-symbol-expansion)
+        (subr-x-test-if-let-nil-related-expansion)
+        (subr-x-test-if-let-malformed-binding, subr-x-test-if-let-true)
+        (subr-x-test-if-let-false, subr-x-test-if-let-bound-references)
+        (subr-x-test-if-let-and-lazyness-is-preserved)
+        (subr-x-test-when-let-body-expansion)
+        (subr-x-test-when-let-single-binding-expansion)
+        (subr-x-test-when-let-single-symbol-expansion)
+        (subr-x-test-when-let-nil-related-expansion)
+        (subr-x-test-when-let-malformed-binding)
+        (subr-x-test-when-let-true, subr-x-test-when-let-false)
+        (subr-x-test-when-let-bound-references)
+        (subr-x-test-when-let-and-lazyness-is-preserved)
+        (subr-x-test-thread-first-no-forms)
+        (subr-x-test-thread-first-function-names-are-threaded)
+        (subr-x-test-thread-first-expansion)
+        (subr-x-test-thread-last-no-forms)
+        (subr-x-test-thread-last-function-names-are-threaded)
+        (subr-x-test-thread-last-expansion): New tests.
+
 2014-06-29  Michael Albinus  <michael.albinus@gmx.de>
 
         * automated/tramp-tests.el (tramp--instrument-test-case):
diff --git a/test/automated/subr-x-tests.el b/test/automated/subr-x-tests.el
new file mode 100644
index 00000000000..cb4d3686bb2
--- /dev/null
+++ b/test/automated/subr-x-tests.el
@@ -0,0 +1,526 @@
+;;; subr-x-tests.el --- Testing the extended lisp routines
+
+;; Copyright (C) 2011-2014 Free Software Foundation, Inc.
+
+;; Author: Fabián E. Gallina <fgallina@gnu.org>
+;; Keywords:
+
+;; This program 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.
+
+;; This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;;
+
+;;; Code:
+
+(require 'ert)
+(require 'subr-x)
+
+
+;; if-let tests
+
+(ert-deftest subr-x-test-if-let-single-binding-expansion ()
+  "Test single bindings are expanded properly."
+  (should (equal
+           (macroexpand
+            '(if-let (a 1)
+                 (- a)
+               "no"))
+           '(let* ((a (and t 1)))
+              (if a
+                  (- a)
+                "no"))))
+  (should (equal
+           (macroexpand
+            '(if-let (a)
+                 (- a)
+               "no"))
+           '(let* ((a (and t nil)))
+              (if a
+                  (- a)
+                "no")))))
+
+(ert-deftest subr-x-test-if-let-single-symbol-expansion ()
+  "Test single symbol bindings are expanded properly."
+  (should (equal
+           (macroexpand
+            '(if-let (a)
+                 (- a)
+               "no"))
+           '(let* ((a (and t nil)))
+              (if a
+                  (- a)
+                "no"))))
+  (should (equal
+           (macroexpand
+            '(if-let (a b c)
+                 (- a)
+               "no"))
+           '(let* ((a (and t nil))
+                   (b (and a nil))
+                   (c (and b nil)))
+              (if c
+                  (- a)
+                "no"))))
+  (should (equal
+           (macroexpand
+            '(if-let (a (b 2) c)
+                 (- a)
+               "no"))
+           '(let* ((a (and t nil))
+                   (b (and a 2))
+                   (c (and b nil)))
+              (if c
+                  (- a)
+                "no")))))
+
+(ert-deftest subr-x-test-if-let-nil-related-expansion ()
+  "Test nil is processed properly."
+  (should (equal
+           (macroexpand
+            '(if-let (nil)
+                 (- a)
+               "no"))
+           '(let* ((nil (and t nil)))
+              (if nil
+                  (- a)
+                "no"))))
+  (should (equal
+           (macroexpand
+            '(if-let ((nil))
+                 (- a)
+               "no"))
+           '(let* ((nil (and t nil)))
+              (if nil
+                  (- a)
+                "no"))))
+  (should (equal
+           (macroexpand
+            '(if-let ((a 1) (nil) (b 2))
+                 (- a)
+               "no"))
+           '(let* ((a (and t 1))
+                   (nil (and a nil))
+                   (b (and nil 2)))
+              (if b
+                  (- a)
+                "no"))))
+  (should (equal
+           (macroexpand
+            '(if-let ((a 1) nil (b 2))
+                 (- a)
+               "no"))
+           '(let* ((a (and t 1))
+                   (nil (and a nil))
+                   (b (and nil 2)))
+              (if b
+                  (- a)
+                "no")))))
+
+(ert-deftest subr-x-test-if-let-malformed-binding ()
+  "Test malformed bindings trigger errors."
+  (should-error (macroexpand
+                 '(if-let (_ (a 1 1) (b 2) (c 3) d)
+                      (- a)
+                    "no"))
+                :type 'error)
+  (should-error (macroexpand
+                 '(if-let (_ (a 1) (b 2 2) (c 3) d)
+                      (- a)
+                    "no"))
+                :type 'error)
+  (should-error (macroexpand
+                 '(if-let (_ (a 1) (b 2) (c 3 3) d)
+                      (- a)
+                    "no"))
+                :type 'error)
+  (should-error (macroexpand
+                 '(if-let ((a 1 1))
+                      (- a)
+                    "no"))
+                :type 'error))
+
+(ert-deftest subr-x-test-if-let-true ()
+  "Test `if-let' with truthy bindings."
+  (should (equal
+           (if-let (a 1)
+               a
+             "no")
+           1))
+  (should (equal
+           (if-let ((a 1) (b 2) (c 3))
+               (list a b c)
+             "no")
+           (list 1 2 3))))
+
+(ert-deftest subr-x-test-if-let-false ()
+  "Test `if-let' with falsey bindings."
+  (should (equal
+           (if-let (a nil)
+               (list a b c)
+             "no")
+           "no"))
+  (should (equal
+           (if-let ((a nil) (b 2) (c 3))
+               (list a b c)
+             "no")
+           "no"))
+  (should (equal
+           (if-let ((a 1) (b nil) (c 3))
+               (list a b c)
+             "no")
+           "no"))
+  (should (equal
+           (if-let ((a 1) (b 2) (c nil))
+               (list a b c)
+             "no")
+           "no"))
+  (should (equal
+           (if-let (z (a 1) (b 2) (c 3))
+               (list a b c)
+             "no")
+           "no"))
+  (should (equal
+           (if-let ((a 1) (b 2) (c 3) d)
+               (list a b c)
+             "no")
+           "no")))
+
+(ert-deftest subr-x-test-if-let-bound-references ()
+  "Test `if-let' bindings can refer to already bound symbols."
+  (should (equal
+           (if-let ((a (1+ 0)) (b (1+ a)) (c (1+ b)))
+               (list a b c)
+             "no")
+           (list 1 2 3))))
+
+(ert-deftest subr-x-test-if-let-and-lazyness-is-preserved ()
+  "Test `if-let' respects `and' lazyness."
+  (let (a-called b-called c-called)
+    (should (equal
+             (if-let ((a nil)
+                      (b (setq b-called t))
+                      (c (setq c-called t)))
+                 "yes"
+               (list a-called b-called c-called))
+             (list nil nil nil))))
+  (let (a-called b-called c-called)
+    (should (equal
+             (if-let ((a (setq a-called t))
+                      (b nil)
+                      (c (setq c-called t)))
+                 "yes"
+               (list a-called b-called c-called))
+             (list t nil nil))))
+  (let (a-called b-called c-called)
+    (should (equal
+             (if-let ((a (setq a-called t))
+                      (b (setq b-called t))
+                      (c nil)
+                      (d (setq c-called t)))
+                 "yes"
+               (list a-called b-called c-called))
+             (list t t nil)))))
+
+
+;; when-let tests
+
+(ert-deftest subr-x-test-when-let-body-expansion ()
+  "Test body allows for multiple sexps wrapping with progn."
+  (should (equal
+           (macroexpand
+            '(when-let (a 1)
+               (message "opposite")
+               (- a)))
+           '(let* ((a (and t 1)))
+              (if a
+                  (progn
+                    (message "opposite")
+                    (- a)))))))
+
+(ert-deftest subr-x-test-when-let-single-binding-expansion ()
+  "Test single bindings are expanded properly."
+  (should (equal
+           (macroexpand
+            '(when-let (a 1)
+               (- a)))
+           '(let* ((a (and t 1)))
+              (if a
+                  (- a)))))
+  (should (equal
+           (macroexpand
+            '(when-let (a)
+               (- a)))
+           '(let* ((a (and t nil)))
+              (if a
+                  (- a))))))
+
+(ert-deftest subr-x-test-when-let-single-symbol-expansion ()
+  "Test single symbol bindings are expanded properly."
+  (should (equal
+           (macroexpand
+            '(when-let (a)
+               (- a)))
+           '(let* ((a (and t nil)))
+              (if a
+                  (- a)))))
+  (should (equal
+           (macroexpand
+            '(when-let (a b c)
+               (- a)))
+           '(let* ((a (and t nil))
+                   (b (and a nil))
+                   (c (and b nil)))
+              (if c
+                  (- a)))))
+  (should (equal
+           (macroexpand
+            '(when-let (a (b 2) c)
+               (- a)))
+           '(let* ((a (and t nil))
+                   (b (and a 2))
+                   (c (and b nil)))
+              (if c
+                  (- a))))))
+
+(ert-deftest subr-x-test-when-let-nil-related-expansion ()
+  "Test nil is processed properly."
+  (should (equal
+           (macroexpand
+            '(when-let (nil)
+               (- a)))
+           '(let* ((nil (and t nil)))
+              (if nil
+                  (- a)))))
+  (should (equal
+           (macroexpand
+            '(when-let ((nil))
+               (- a)))
+           '(let* ((nil (and t nil)))
+              (if nil
+                  (- a)))))
+  (should (equal
+           (macroexpand
+            '(when-let ((a 1) (nil) (b 2))
+               (- a)))
+           '(let* ((a (and t 1))
+                   (nil (and a nil))
+                   (b (and nil 2)))
+              (if b
+                  (- a)))))
+  (should (equal
+           (macroexpand
+            '(when-let ((a 1) nil (b 2))
+               (- a)))
+           '(let* ((a (and t 1))
+                   (nil (and a nil))
+                   (b (and nil 2)))
+              (if b
+                  (- a))))))
+
+(ert-deftest subr-x-test-when-let-malformed-binding ()
+  "Test malformed bindings trigger errors."
+  (should-error (macroexpand
+                 '(when-let (_ (a 1 1) (b 2) (c 3) d)
+                    (- a)))
+                :type 'error)
+  (should-error (macroexpand
+                 '(when-let (_ (a 1) (b 2 2) (c 3) d)
+                    (- a)))
+                :type 'error)
+  (should-error (macroexpand
+                 '(when-let (_ (a 1) (b 2) (c 3 3) d)
+                    (- a)))
+                :type 'error)
+  (should-error (macroexpand
+                 '(when-let ((a 1 1))
+                    (- a)))
+                :type 'error))
+
+(ert-deftest subr-x-test-when-let-true ()
+  "Test `when-let' with truthy bindings."
+  (should (equal
+           (when-let (a 1)
+             a)
+           1))
+  (should (equal
+           (when-let ((a 1) (b 2) (c 3))
+             (list a b c))
+           (list 1 2 3))))
+
+(ert-deftest subr-x-test-when-let-false ()
+  "Test `when-let' with falsey bindings."
+  (should (equal
+           (when-let (a nil)
+             (list a b c)
+             "no")
+           nil))
+  (should (equal
+           (when-let ((a nil) (b 2) (c 3))
+             (list a b c)
+             "no")
+           nil))
+  (should (equal
+           (when-let ((a 1) (b nil) (c 3))
+             (list a b c)
+             "no")
+           nil))
+  (should (equal
+           (when-let ((a 1) (b 2) (c nil))
+             (list a b c)
+             "no")
+           nil))
+  (should (equal
+           (when-let (z (a 1) (b 2) (c 3))
+             (list a b c)
+             "no")
+           nil))
+  (should (equal
+           (when-let ((a 1) (b 2) (c 3) d)
+             (list a b c)
+             "no")
+           nil)))
+
+(ert-deftest subr-x-test-when-let-bound-references ()
+  "Test `when-let' bindings can refer to already bound symbols."
+  (should (equal
+           (when-let ((a (1+ 0)) (b (1+ a)) (c (1+ b)))
+             (list a b c))
+           (list 1 2 3))))
+
+(ert-deftest subr-x-test-when-let-and-lazyness-is-preserved ()
+  "Test `when-let' respects `and' lazyness."
+  (let (a-called b-called c-called)
+    (should (equal
+             (progn
+               (when-let ((a nil)
+                          (b (setq b-called t))
+                          (c (setq c-called t)))
+                 "yes")
+               (list a-called b-called c-called))
+             (list nil nil nil))))
+  (let (a-called b-called c-called)
+    (should (equal
+             (progn
+               (when-let ((a (setq a-called t))
+                          (b nil)
+                          (c (setq c-called t)))
+                 "yes")
+               (list a-called b-called c-called))
+             (list t nil nil))))
+  (let (a-called b-called c-called)
+    (should (equal
+             (progn
+               (when-let ((a (setq a-called t))
+                          (b (setq b-called t))
+                          (c nil)
+                          (d (setq c-called t)))
+                 "yes")
+               (list a-called b-called c-called))
+             (list t t nil)))))
+
+
+;; Thread first tests
+
+(ert-deftest subr-x-test-thread-first-no-forms ()
+  "Test `thread-first' with no forms expands to the first form."
+  (should (equal (macroexpand '(thread-first 5)) 5))
+  (should (equal (macroexpand '(thread-first (+ 1 2))) '(+ 1 2))))
+
+(ert-deftest subr-x-test-thread-first-function-names-are-threaded ()
+  "Test `thread-first' wraps single function names."
+  (should (equal (macroexpand
+                  '(thread-first 5
+                     -))
+                 '(- 5)))
+  (should (equal (macroexpand
+                  '(thread-first (+ 1 2)
+                     -))
+                 '(- (+ 1 2)))))
+
+(ert-deftest subr-x-test-thread-first-expansion ()
+  "Test `thread-first' expands correctly."
+  (should (equal
+           (macroexpand '(thread-first
+                             5
+                           (+ 20)
+                           (/ 25)
+                           -
+                           (+ 40)))
+           '(+ (- (/ (+ 5 20) 25)) 40))))
+
+(ert-deftest subr-x-test-thread-first-examples ()
+  "Test several `thread-first' examples."
+  (should (equal (thread-first (+ 40 2)) 42))
+  (should (equal (thread-first
+                     5
+                   (+ 20)
+                   (/ 25)
+                   -
+                   (+ 40)) 39))
+  (should (equal (thread-first
+                     "this-is-a-string"
+                   (split-string "-")
+                   (nbutlast 2)
+                   (append (list "good")))
+                 (list "this" "is" "good"))))
+
+;; Thread last tests
+
+(ert-deftest subr-x-test-thread-last-no-forms ()
+  "Test `thread-last' with no forms expands to the first form."
+  (should (equal (macroexpand '(thread-last 5)) 5))
+  (should (equal (macroexpand '(thread-last (+ 1 2))) '(+ 1 2))))
+
+(ert-deftest subr-x-test-thread-last-function-names-are-threaded ()
+  "Test `thread-last' wraps single function names."
+  (should (equal (macroexpand
+                  '(thread-last 5
+                     -))
+                 '(- 5)))
+  (should (equal (macroexpand
+                  '(thread-last (+ 1 2)
+                     -))
+                 '(- (+ 1 2)))))
+
+(ert-deftest subr-x-test-thread-last-expansion ()
+  "Test `thread-last' expands correctly."
+  (should (equal
+           (macroexpand '(thread-last
+                             5
+                           (+ 20)
+                           (/ 25)
+                           -
+                           (+ 40)))
+           '(+ 40 (- (/ 25 (+ 20 5)))))))
+
+(ert-deftest subr-x-test-thread-last-examples ()
+  "Test several `thread-last' examples."
+  (should (equal (thread-last (+ 40 2)) 42))
+  (should (equal (thread-last
+                     5
+                   (+ 20)
+                   (/ 25)
+                   -
+                   (+ 40)) 39))
+  (should (equal (thread-last
+                     (list 1 -2 3 -4 5)
+                   (mapcar #'abs)
+                   (cl-reduce #'+)
+                   (format "abs sum is: %s"))
+                 "abs sum is: 15")))
+
+
+(provide 'subr-x-tests)
+;;; subr-x-tests.el ends here