From: Fabián Ezequiel Gallina Date: Mon, 30 Jun 2014 04:11:43 +0000 (-0300) Subject: New if-let, when-let, thread-first and thread-last macros. X-Git-Tag: emacs-25.0.90~2636^2~74^2~8 X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=c08f8be29f4f6d107da5cc38d614519df7a6ab11;p=emacs.git 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. --- diff --git a/etc/NEWS b/etc/NEWS index 1fc4a218d76..85f996f8486 100644 --- a/etc/NEWS +++ b/etc/NEWS @@ -178,6 +178,14 @@ permissions set to temporary values (e.g., for creating private files). ** Functions `rmail-delete-forward' and `rmail-delete-backward' take an optional repeat-count argument. +--- +** New macros `if-let' and `when-let' allow defining bindings and to + execute code depending whether all values are a true. + +--- +** New macros `thread-first' and `thread-last' allow threading a form + as the first or last argument of subsequent forms. + * Changes in Emacs 24.5 on Non-Free Operating Systems diff --git a/lisp/ChangeLog b/lisp/ChangeLog index 3e9e6f3ee27..56e53ee673c 100644 --- a/lisp/ChangeLog +++ b/lisp/ChangeLog @@ -1,3 +1,14 @@ +2014-06-30 Fabián Ezequiel Gallina + + New if-let, when-let, thread-first and thread-last macros. + + * 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. + 2014-06-30 Grégoire Jadi * net/rcirc.el (rcirc-buffer-process): Restore previous diff --git a/lisp/emacs-lisp/subr-x.el b/lisp/emacs-lisp/subr-x.el index 505a556b65f..60cd7b8995b 100644 --- a/lisp/emacs-lisp/subr-x.el +++ b/lisp/emacs-lisp/subr-x.el @@ -32,6 +32,113 @@ ;;; Code: +(require 'pcase) + + +(defmacro internal--thread-argument (first? &rest forms) + "Internal implementation for `thread-first' and `thread-last'. +When Argument FIRST? is non-nil argument is threaded first, else +last. FORMS are the expressions to be threaded." + (pcase forms + (`(,x (,f . ,args) . ,rest) + `(internal--thread-argument + ,first? ,(if first? `(,f ,x ,@args) `(,f ,@args ,x)) ,@rest)) + (`(,x ,f . ,rest) `(internal--thread-argument ,first? (,f ,x) ,@rest)) + (_ (car forms)))) + +(defmacro thread-first (&rest forms) + "Thread FORMS elements as the first argument of their succesor. +Example: + (thread-first + 5 + (+ 20) + (/ 25) + - + (+ 40)) +Is equivalent to: + (+ (- (/ (+ 5 20) 25)) 40) +Note how the single `-' got converted into a list before +threading." + (declare (indent 1) + (debug (form &rest [&or symbolp (sexp &rest form)]))) + `(internal--thread-argument t ,@forms)) + +(defmacro thread-last (&rest forms) + "Thread FORMS elements as the last argument of their succesor. +Example: + (thread-last + 5 + (+ 20) + (/ 25) + - + (+ 40)) +Is equivalent to: + (+ 40 (- (/ 25 (+ 20 5)))) +Note how the single `-' got converted into a list before +threading." + (declare (indent 1) (debug thread-first)) + `(internal--thread-argument nil ,@forms)) + +(defsubst internal--listify (elt) + "Wrap ELT in a list if it is not one." + (if (not (listp elt)) + (list elt) + elt)) + +(defsubst internal--check-binding (binding) + "Check BINDING is properly formed." + (when (> (length binding) 2) + (signal + 'error + (cons "`let' bindings can have only one value-form" binding))) + binding) + +(defsubst internal--build-binding-value-form (binding prev-var) + "Build the conditional value form for BINDING using PREV-VAR." + `(,(car binding) (and ,prev-var ,(cadr binding)))) + +(defun internal--build-binding (binding prev-var) + "Check and build a single BINDING with PREV-VAR." + (thread-first + binding + internal--listify + internal--check-binding + (internal--build-binding-value-form prev-var))) + +(defun internal--build-bindings (bindings) + "Check and build conditional value forms for BINDINGS." + (let ((prev-var t)) + (mapcar (lambda (binding) + (let ((binding (internal--build-binding binding prev-var))) + (setq prev-var (car binding)) + binding)) + bindings))) + +(defmacro if-let (bindings then &rest else) + "Process BINDINGS and if all values are non-nil eval THEN, else ELSE. +Argument BINDINGS is a list of tuples whose car is a symbol to be +bound and (optionally) used in THEN, and its cadr is a sexp to be +evaled to set symbol's value. In the special case you only want +to bind a single value, BINDINGS can just be a plain tuple." + (declare (indent 2) (debug ((&rest (symbolp form)) form body))) + (when (and (<= (length bindings) 2) + (not (listp (car bindings)))) + ;; Adjust the single binding case + (setq bindings (list bindings))) + `(let* ,(internal--build-bindings bindings) + (if ,(car (internal--listify (car (last bindings)))) + ,then + ,@else))) + +(defmacro when-let (bindings &rest body) + "Process BINDINGS and if all values are non-nil eval BODY. +Argument BINDINGS is a list of tuples whose car is a symbol to be +bound and (optionally) used in BODY, and its cadr is a sexp to be +evaled to set symbol's value. In the special case you only want +to bind a single value, BINDINGS can just be a plain tuple." + (declare (indent 1) (debug if-let)) + (list 'if-let bindings (macroexp-progn body))) + (defsubst hash-table-keys (hash-table) "Return a list of keys in HASH-TABLE." (let ((keys '())) 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 + + * 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 * 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 +;; 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 . + +;;; 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