From: Artur Malabarba Date: Wed, 17 Jun 2015 14:38:46 +0000 (+0100) Subject: * lisp/let-alist.el: move to lisp/emacs-lisp/let-alist.el X-Git-Tag: emacs-25.0.90~1720 X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=02617f15075177cd5a390dd13bd3fc6b49e08fad;p=emacs.git * lisp/let-alist.el: move to lisp/emacs-lisp/let-alist.el --- diff --git a/lisp/emacs-lisp/let-alist.el b/lisp/emacs-lisp/let-alist.el new file mode 100644 index 00000000000..ca7a904a087 --- /dev/null +++ b/lisp/emacs-lisp/let-alist.el @@ -0,0 +1,142 @@ +;;; let-alist.el --- Easily let-bind values of an assoc-list by their names -*- lexical-binding: t; -*- + +;; Copyright (C) 2014-2015 Free Software Foundation, Inc. + +;; Author: Artur Malabarba +;; Maintainer: Artur Malabarba +;; Version: 1.0.4 +;; Keywords: extensions lisp +;; Prefix: let-alist +;; Separator: - + +;; 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 . + +;;; Commentary: + +;; This package offers a single macro, `let-alist'. This macro takes a +;; first argument (whose value must be an alist) and a body. +;; +;; The macro expands to a let form containing body, where each dotted +;; symbol inside body is let-bound to their cdrs in the alist. Dotted +;; symbol is any symbol starting with a `.'. Only those present in +;; the body are let-bound and this search is done at compile time. +;; +;; For instance, the following code +;; +;; (let-alist alist +;; (if (and .title .body) +;; .body +;; .site +;; .site.contents)) +;; +;; essentially expands to +;; +;; (let ((.title (cdr (assq 'title alist))) +;; (.body (cdr (assq 'body alist))) +;; (.site (cdr (assq 'site alist))) +;; (.site.contents (cdr (assq 'contents (cdr (assq 'site alist)))))) +;; (if (and .title .body) +;; .body +;; .site +;; .site.contents)) +;; +;; If you nest `let-alist' invocations, the inner one can't access +;; the variables of the outer one. You can, however, access alists +;; inside the original alist by using dots inside the symbol, as +;; displayed in the example above by the `.site.contents'. +;; +;;; Code: + + +(defun let-alist--deep-dot-search (data) + "Return alist of symbols inside DATA that start with a `.'. +Perform a deep search and return an alist where each car is the +symbol, and each cdr is the same symbol without the `.'." + (cond + ((symbolp data) + (let ((name (symbol-name data))) + (when (string-match "\\`\\." name) + ;; Return the cons cell inside a list, so it can be appended + ;; with other results in the clause below. + (list (cons data (intern (replace-match "" nil nil name))))))) + ((not (consp data)) nil) + (t (append (let-alist--deep-dot-search (car data)) + (let-alist--deep-dot-search (cdr data)))))) + +(defun let-alist--access-sexp (symbol variable) + "Return a sexp used to access SYMBOL inside VARIABLE." + (let* ((clean (let-alist--remove-dot symbol)) + (name (symbol-name clean))) + (if (string-match "\\`\\." name) + clean + (let-alist--list-to-sexp + (mapcar #'intern (nreverse (split-string name "\\."))) + variable)))) + +(defun let-alist--list-to-sexp (list var) + "Turn symbols LIST into recursive calls to `cdr' `assq' on VAR." + `(cdr (assq ',(car list) + ,(if (cdr list) (let-alist--list-to-sexp (cdr list) var) + var)))) + +(defun let-alist--remove-dot (symbol) + "Return SYMBOL, sans an initial dot." + (let ((name (symbol-name symbol))) + (if (string-match "\\`\\." name) + (intern (replace-match "" nil nil name)) + symbol))) + + +;;; The actual macro. +;;;###autoload +(defmacro let-alist (alist &rest body) + "Let-bind dotted symbols to their cdrs in ALIST and execute BODY. +Dotted symbol is any symbol starting with a `.'. Only those present +in BODY are let-bound and this search is done at compile time. + +For instance, the following code + + (let-alist alist + (if (and .title .body) + .body + .site + .site.contents)) + +essentially expands to + + (let ((.title (cdr (assq 'title alist))) + (.body (cdr (assq 'body alist))) + (.site (cdr (assq 'site alist))) + (.site.contents (cdr (assq 'contents (cdr (assq 'site alist)))))) + (if (and .title .body) + .body + .site + .site.contents)) + +If you nest `let-alist' invocations, the inner one can't access +the variables of the outer one. You can, however, access alists +inside the original alist by using dots inside the symbol, as +displayed in the example above." + (declare (indent 1) (debug t)) + (let ((var (make-symbol "alist"))) + `(let ((,var ,alist)) + (let ,(mapcar (lambda (x) `(,(car x) ,(let-alist--access-sexp (car x) var))) + (delete-dups (let-alist--deep-dot-search body))) + ,@body)))) + +(provide 'let-alist) + +;;; let-alist.el ends here diff --git a/lisp/let-alist.el b/lisp/let-alist.el deleted file mode 100644 index ca7a904a087..00000000000 --- a/lisp/let-alist.el +++ /dev/null @@ -1,142 +0,0 @@ -;;; let-alist.el --- Easily let-bind values of an assoc-list by their names -*- lexical-binding: t; -*- - -;; Copyright (C) 2014-2015 Free Software Foundation, Inc. - -;; Author: Artur Malabarba -;; Maintainer: Artur Malabarba -;; Version: 1.0.4 -;; Keywords: extensions lisp -;; Prefix: let-alist -;; Separator: - - -;; 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 . - -;;; Commentary: - -;; This package offers a single macro, `let-alist'. This macro takes a -;; first argument (whose value must be an alist) and a body. -;; -;; The macro expands to a let form containing body, where each dotted -;; symbol inside body is let-bound to their cdrs in the alist. Dotted -;; symbol is any symbol starting with a `.'. Only those present in -;; the body are let-bound and this search is done at compile time. -;; -;; For instance, the following code -;; -;; (let-alist alist -;; (if (and .title .body) -;; .body -;; .site -;; .site.contents)) -;; -;; essentially expands to -;; -;; (let ((.title (cdr (assq 'title alist))) -;; (.body (cdr (assq 'body alist))) -;; (.site (cdr (assq 'site alist))) -;; (.site.contents (cdr (assq 'contents (cdr (assq 'site alist)))))) -;; (if (and .title .body) -;; .body -;; .site -;; .site.contents)) -;; -;; If you nest `let-alist' invocations, the inner one can't access -;; the variables of the outer one. You can, however, access alists -;; inside the original alist by using dots inside the symbol, as -;; displayed in the example above by the `.site.contents'. -;; -;;; Code: - - -(defun let-alist--deep-dot-search (data) - "Return alist of symbols inside DATA that start with a `.'. -Perform a deep search and return an alist where each car is the -symbol, and each cdr is the same symbol without the `.'." - (cond - ((symbolp data) - (let ((name (symbol-name data))) - (when (string-match "\\`\\." name) - ;; Return the cons cell inside a list, so it can be appended - ;; with other results in the clause below. - (list (cons data (intern (replace-match "" nil nil name))))))) - ((not (consp data)) nil) - (t (append (let-alist--deep-dot-search (car data)) - (let-alist--deep-dot-search (cdr data)))))) - -(defun let-alist--access-sexp (symbol variable) - "Return a sexp used to access SYMBOL inside VARIABLE." - (let* ((clean (let-alist--remove-dot symbol)) - (name (symbol-name clean))) - (if (string-match "\\`\\." name) - clean - (let-alist--list-to-sexp - (mapcar #'intern (nreverse (split-string name "\\."))) - variable)))) - -(defun let-alist--list-to-sexp (list var) - "Turn symbols LIST into recursive calls to `cdr' `assq' on VAR." - `(cdr (assq ',(car list) - ,(if (cdr list) (let-alist--list-to-sexp (cdr list) var) - var)))) - -(defun let-alist--remove-dot (symbol) - "Return SYMBOL, sans an initial dot." - (let ((name (symbol-name symbol))) - (if (string-match "\\`\\." name) - (intern (replace-match "" nil nil name)) - symbol))) - - -;;; The actual macro. -;;;###autoload -(defmacro let-alist (alist &rest body) - "Let-bind dotted symbols to their cdrs in ALIST and execute BODY. -Dotted symbol is any symbol starting with a `.'. Only those present -in BODY are let-bound and this search is done at compile time. - -For instance, the following code - - (let-alist alist - (if (and .title .body) - .body - .site - .site.contents)) - -essentially expands to - - (let ((.title (cdr (assq 'title alist))) - (.body (cdr (assq 'body alist))) - (.site (cdr (assq 'site alist))) - (.site.contents (cdr (assq 'contents (cdr (assq 'site alist)))))) - (if (and .title .body) - .body - .site - .site.contents)) - -If you nest `let-alist' invocations, the inner one can't access -the variables of the outer one. You can, however, access alists -inside the original alist by using dots inside the symbol, as -displayed in the example above." - (declare (indent 1) (debug t)) - (let ((var (make-symbol "alist"))) - `(let ((,var ,alist)) - (let ,(mapcar (lambda (x) `(,(car x) ,(let-alist--access-sexp (car x) var))) - (delete-dups (let-alist--deep-dot-search body))) - ,@body)))) - -(provide 'let-alist) - -;;; let-alist.el ends here