[COMMIT] Import Edward O'Connor's json.el

Ted, this makes your json.el more easily available to XEmacs users. Included is a tweak to have it better work on non-Mule XEmacs invocations. APPROVE COMMIT NOTE: This patch has been committed. SUPERSEDES 17793.19077.50295.840813(a)parhasard.net xemacs-packages/net-utils/ChangeLog addition: 2006-12-29 Aidan Kehoe <kehoea(a)parhasard.net&gt; * json.el: Imported from http://edward.oconnor.cx/elisp/json.el. * json.el (json-unicode-setup): New. This function checks what Unicode support is available in the current emacs, and initialises json-encode-char0 and json-decode-char0 (intended to be workalikes for encode-char and decode-char) as appropriate. In 21.4, the function is re-evaluated after un-decode (the entry point for Mule-UCS) is loaded. XEmacs Packages source patch: Diff command: cvs -q diff -Nu Files affected: xemacs-packages/net-utils/json.el =================================================================== RCS Index: xemacs-packages/net-utils/json.el =================================================================== RCS file: json.el diff -N json.el --- /dev/null Fri Dec 29 20:42:50 2006 +++ json.el Fri Dec 29 20:42:16 2006 ＠＠ -0,0 +1,556 ＠＠ +;;; json.el --- JavaScript Object Notation parser / generator + +;; Copyright (C) 2006 Edward O'Connor <ted(a)oconnor.cx&gt; + +;; Author: Edward O'Connor <ted(a)oconnor.cx&gt; +;; Keywords: convenience + +;; This file is NOT part of GNU Emacs. + +;; This 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 2, or (at your option) any later +;; version. + +;; This file 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 Emacs; see the file COPYING, or type `C-h C-c'. If not, +;; write to the Free Software Foundation at this address: + +;; Free Software Foundation +;; 51 Franklin Street, Fifth Floor +;; Boston, MA 02110-1301 +;; USA + +;;; Commentary: + +;; This is a library for parsing and generating JSON (JavaScript Object +;; Notation). + +;; Learn all about JSON here: <URL:http://json.org/>;. + +;; The user-serviceable entry points for the parser are the functions +;; `json-read' and `json-read-from-string'. The encoder has a single +;; entry point, `json-encode'. + +;; Since there are several natural representations of key-value pair +;; mappings in elisp (alist, plist, hash-table), `json-read' allows you +;; to specify which you'd prefer (see `json-object-type' and +;; `json-array-type'). + +;; Similarly, since `false' and `null' are distinct in JSON, you can +;; distinguish them by binding `json-false' and `json-null' as desired. + +;; The latest version of json.el can be found here: + +;; <URL:http://edward.oconnor.cx/elisp/json.el> + +;;; History: + +;; 2006-03-11 - Initial version. +;; 2006-03-13 - Added JSON generation in addition to parsing. Various +;; other cleanups, bugfixes, and improvements. + +;;; Code: + +(eval-when-compile (require 'cl)) + +;; Parameters + +(defvar json-object-type 'alist + "Type to convert JSON objects to. +Must be one of `alist', `plist', or `hash-table'. Consider let-binding +this around your call to `json-read' instead of `setq'ing it.") + +(defvar json-array-type 'vector + "Type to convert JSON arrays to. +Must be one of `vector' or `list'. Consider let-binding this around +your call to `json-read' instead of `setq'ing it.") + +(defvar json-key-type nil + "Type to convert JSON keys to. +Must be one of `string', `symbol', `keyword', or nil. + +If nil, `json-read' will guess the type based on the value of +`json-object-type': + + If `json-object-type' is: nil will be interpreted as: + `hash-table' `string' + `alist' `symbol' + `plist' `keyword' + +Note that values other than `string' might behave strangely for +Sufficiently Weird keys. Consider let-binding this around your call to +`json-read' instead of `setq'ing it.") + +(defvar json-false :json-false + "Value to use when reading JSON `false'. +If this has the same value as `json-read-null-value', you might not be +able to tell the difference between `false' and `null'. Consider let- +binding this around your call to `json-read' instead of `setq'ing it.") + +(defvar json-null nil + "Value to use when reading JSON `null'. +If this has the same value as `json-read-false-value', you might not be +able to tell the difference between `false' and `null'. Consider let- +binding this around your call to `json-read' instead of `setq'ing it.") + + + +;;; Utilities + +(defun json-join (strings separator) + "Join STRINGS with SEPARATOR." + (mapconcat 'identity strings separator)) + +(defun json-alist-p (list) + "Non-null iff LIST is an alist." + (or (null list) + (and (consp (car list)) + (json-alist-p (cdr list))))) + +(defun json-plist-p (list) + "Non-null iff LIST is a plist." + (or (null list) + (and (keywordp (car list)) + (consp (cdr list)) + (json-plist-p (cddr list))))) + +;; Reader utilities + +(defsubst json-advance (&optional n) + "Skip past the following N characters." + (unless n (setq n 1)) + (let ((goal (+ (point) n))) + (goto-char goal) + (when (< (point) goal) + (signal 'end-of-file nil)))) + +(defsubst json-peek () + "Return the character at point." + (let ((char (char-after (point)))) + (or char :json-eof))) + +(defsubst json-pop () + "Advance past the character at point, returning it." + (let ((char (json-peek))) + (if (eq char :json-eof) + (signal 'end-of-file nil) + (json-advance) + char))) + +(defun json-skip-whitespace () + "Skip past the whitespace at point." + (while (looking-at "[\t\r\n\f\b ]") + (goto-char (match-end 0)))) + + + +;; Error conditions + +(put 'json-error 'error-message "Unknown JSON error") +(put 'json-error 'error-conditions '(json-error error)) + +(put 'json-readtable-error 'error-message "JSON readtable error") +(put 'json-readtable-error 'error-conditions + '(json-readtable-error json-error error)) + +(put 'json-unknown-keyword 'error-message "Unrecognized keyword") +(put 'json-unknown-keyword 'error-conditions + '(json-unknown-keyword json-error error)) + +(put 'json-number-format 'error-message "Invalid number format") +(put 'json-number-format 'error-conditions + '(json-number-format json-error error)) + +(put 'json-string-escape 'error-message "Bad unicode escape") +(put 'json-string-escape 'error-conditions + '(json-string-escape json-error error)) + +(put 'json-string-format 'error-message "Bad string format") +(put 'json-string-format 'error-conditions + '(json-string-format json-error error)) + +(put 'json-object-format 'error-message "Bad JSON object") +(put 'json-object-format 'error-conditions + '(json-object-format json-error error)) + + + +;;; Keywords + +(defvar json-keywords '("true" "false" "null") + "List of JSON keywords.") + +;; Keyword parsing + +(defun json-read-keyword (keyword) + "Read a JSON keyword at point. +KEYWORD is the keyword expected." + (unless (member keyword json-keywords) + (signal 'json-unknown-keyword (list keyword))) + (mapc (lambda (char) + (unless (char-equal char (json-peek)) + (signal 'json-unknown-keyword + (list (save-excursion + (backward-word 1) + (word-at-point))))) + (json-advance)) + keyword) + (unless (looking-at "\\(\\s-\\|[],}]\\|$\\)") + (signal 'json-unknown-keyword + (list (save-excursion + (backward-word 1) + (word-at-point))))) + (cond ((string-equal keyword "true") t) + ((string-equal keyword "false") json-false) + ((string-equal keyword "null") json-null))) + +;; Keyword encoding + +(defun json-encode-keyword (keyword) + "Encode KEYWORD as a JSON value." + (cond ((eq keyword t) "true") + ((eq keyword json-false) "false") + ((eq keyword json-null) "null"))) + +;;; Numbers + +;; Number parsing + +(defun json-read-number () + "Read the JSON number following point." + (if (char-equal (json-peek) ?-) + (progn + (json-advance) + (- 0 (json-read-number))) + (if (looking-at "[0-9]+\\([.][0-9]+\\)?\\([eE][+-]?[0-9]+\\)?") + (progn + (goto-char (match-end 0)) + (string-to-number (match-string 0))) + (signal 'json-number-format (list (point)))))) + +;; Number encoding + +(defun json-encode-number (number) + "Return a JSON representation of NUMBER." + (format "%s" number)) + +;;; Strings + +(defvar json-special-chars + '((?\" . ?\") + (?\\ . ?\\) + (?/ . ?/) + (?b . ?\b) + (?f . ?\f) + (?n . ?\n) + (?r . ?\r) + (?t . ?\t)) + "Characters which are escaped in JSON, with their elisp counterparts.") + +;; String parsing + +(defun json-read-escaped-char () + "Read the JSON string escaped character at point." + ;; Skip over the '\' + (json-advance) + (let* ((char (json-pop)) + (special (assq char json-special-chars))) + (cond + (special (cdr special)) + ((not (eq char ?u)) char) + ((looking-at "[0-9A-Fa-f][0-9A-Fa-f][0-9A-Fa-f][0-9A-Fa-f]") + (let ((hex (match-string 0))) + (json-advance 4) + (json-decode-char0 'ucs (string-to-number hex 16)))) + (t + (signal 'json-string-escape (list (point))))))) + +(defun json-read-string () + "Read the JSON string at point." + (unless (char-equal (json-peek) ?\") + (signal 'json-string-format (list "doesn't start with '\"'!"))) + ;; Skip over the '"' + (json-advance) + (let ((characters '()) + (char (json-peek))) + (while (not (char-equal char ?\")) + (push (if (char-equal char ?\\) + (json-read-escaped-char) + (json-pop)) + characters) + (setq char (json-peek))) + ;; Skip over the '"' + (json-advance) + (if characters + (apply 'string (nreverse characters)) + ""))) + +;; String encoding + +(defun json-unicode-setup () + "Determine what Unicode code-point support this emacs has. " + (if (and (fboundp 'encode-char) (fboundp 'decode-char)) + (progn + (defalias 'json-encode-char0 'encode-char) + (defalias 'json-decode-char0 'decode-char)) + (defun json-decode-char0 (quote-ucs code &optional restriction) + (assert (eq quote-ucs 'ucs) t + "Sorry, decode-char doesn't yet support anything but the UCS. ") + (assert (< code 255) t + "Sorry, no support for Unicode code points above 255") + (if (fboundp 'decode-coding-string) + (car (append (decode-coding-string (format "%c" code) + 'iso-8859-1) nil)) + (int-to-char code))) + (defun json-encode-char0 (char quote-ucs &optional restriction) + (assert (eq quote-ucs 'ucs) t + "Sorry, encode-char doesn't yet support anything but the UCS. ") + (assert (if (featurep 'mule) + (memq (char-charset char) '(ascii latin-iso8859-1 control-1)) + t) t + "Sorry, no support for Unicode code points above 255") + (if (fboundp 'encode-coding-string) + (car (append (encode-coding-string (format "%c" char) + 'iso-8859-1) nil)) + (char-to-int char))))) + +(json-unicode-setup) + +(unless (featurep 'un-define) + (eval-after-load "un-define" '(progn (load "mucs") (json-unicode-setup)))) + +(defun json-encode-char (char) + "Encode CHAR as a JSON string." + (setq char (json-encode-char0 char 'ucs)) + (let ((control-char (car (rassoc char json-special-chars)))) + (cond + ;; Special JSON character (\n, \r, etc.) + (control-char + (format "\\%c" control-char)) + ;; ASCIIish printable character + ((and (> char 31) (< char 161)) + (format "%c" char)) + ;; Fallback: UCS code point in \uNNNN form + (t + (format "\\u%04x" char))))) + +(defun json-encode-string (string) + "Return a JSON representation of STRING." + (format "\"%s\"" (mapconcat 'json-encode-char string ""))) + +;;; JSON Objects + +(defun json-new-object () + "Create a new Elisp object corresponding to a JSON object. +Please see the documentation of `json-object-type'." + (cond ((eq json-object-type 'hash-table) + (make-hash-table :test 'equal)) + (t + (list)))) + +(defun json-add-to-object (object key value) + "Add a new KEY -> VALUE association to OBJECT. +Returns the updated object, which you should save, e.g.: + (setq obj (json-add-to-object obj \"foo\" \"bar\")) +Please see the documentation of `json-object-type' and `json-key-type'." + (let ((json-key-type + (if (eq json-key-type nil) + (cdr (assq json-object-type '((hash-table . string) + (alist . symbol) + (plist . keyword)))) + json-key-type))) + (setq key + (cond ((eq json-key-type 'string) + key) + ((eq json-key-type 'symbol) + (intern key)) + ((eq json-key-type 'keyword) + (intern (concat ":" key))))) + (cond ((eq json-object-type 'hash-table) + (puthash key value object) + object) + ((eq json-object-type 'alist) + (cons (cons key value) object)) + ((eq json-object-type 'plist) + (cons key (cons value object)))))) + +;; JSON object parsing + +(defun json-read-object () + "Read the JSON object at point." + ;; Skip over the "{" + (json-advance) + (json-skip-whitespace) + ;; read key/value pairs until "}" + (let ((elements (json-new-object)) + key value) + (while (not (char-equal (json-peek) ?})) + (json-skip-whitespace) + (setq key (json-read-string)) + (json-skip-whitespace) + (if (char-equal (json-peek) ?:) + (json-advance) + (signal 'json-object-format (list ":" (json-peek)))) + (setq value (json-read)) + (setq elements (json-add-to-object elements key value)) + (json-skip-whitespace) + (unless (char-equal (json-peek) ?}) + (if (char-equal (json-peek) ?,) + (json-advance) + (signal 'json-object-format (list "," (json-peek)))))) + ;; Skip over the "}" + (json-advance) + elements)) + +;; Hash table encoding + +(defun json-encode-hash-table (hash-table) + "Return a JSON representation of HASH-TABLE." + (format "{%s}" + (json-join + (let (r) + (maphash + (lambda (k v) + (push (format "%s:%s" + (json-encode k) + (json-encode v)) + r)) + hash-table) + r) + ", "))) + +;; List encoding (including alists and plists) + +(defun json-encode-alist (alist) + "Return a JSON representation of ALIST." + (format "{%s}" + (json-join (mapcar (lambda (cons) + (format "%s:%s" + (json-encode (car cons)) + (json-encode (cdr cons)))) + alist) + ", "))) + +(defun json-encode-plist (plist) + "Return a JSON representation of PLIST." + (let (result) + (while plist + (push (concat (json-encode (car plist)) + ":" + (json-encode (cadr plist))) + result) + (setq plist (cddr plist))) + (concat "{" (json-join (nreverse result) ", ") "}"))) + +(defun json-encode-list (list) + "Return a JSON representation of LIST. +Tries to DWIM: simple lists become JSON arrays, while alists and plists +become JSON objects." + (cond ((null list) "null") + ((json-alist-p list) (json-encode-alist list)) + ((json-plist-p list) (json-encode-plist list)) + ((listp list) (json-encode-array list)) + (t + (signal 'json-error (list list))))) + +;;; Arrays + +;; Array parsing + +(defun json-read-array () + "Read the JSON array at point." + ;; Skip over the "[" + (json-advance) + (json-skip-whitespace) + ;; read values until "]" + (let (elements) + (while (not (char-equal (json-peek) ?\])) + (push (json-read) elements) + (json-skip-whitespace) + (unless (char-equal (json-peek) ?\]) + (if (char-equal (json-peek) ?,) + (json-advance) + (signal 'json-error (list 'bleah))))) + ;; Skip over the "]" + (json-advance) + (apply json-array-type (nreverse elements)))) + +;; Array encoding + +(defun json-encode-array (array) + "Return a JSON representation of ARRAY." + (concat "[" (mapconcat 'json-encode array ", ") "]")) + + + +;;; JSON reader. + +(defvar json-readtable + (let ((table + '((?t json-read-keyword "true") + (?f json-read-keyword "false") + (?n json-read-keyword "null") + (?{ json-read-object) + (?\[ json-read-array) + (?\" json-read-string)))) + (mapc (lambda (char) + (push (list char 'json-read-number) table)) + '(?- ?0 ?1 ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9)) + table) + "Readtable for JSON reader.") + +(defun json-read () + "Parse and return the JSON object following point. +Advances point just past JSON object." + (json-skip-whitespace) + (let ((char (json-peek))) + (if (not (eq char :json-eof)) + (let ((record (cdr (assq char json-readtable)))) + (if (functionp (car record)) + (apply (car record) (cdr record)) + (signal 'json-readtable-error record))) + (signal 'end-of-file nil)))) + +;; Syntactic sugar for the reader + +(defun json-read-from-string (string) + "Read the JSON object contained in STRING and return it." + (with-temp-buffer + (insert string) + (goto-char (point-min)) + (json-read))) + +(defun json-read-file (file) + "Read the first JSON object contained in FILE and return it." + (with-temp-buffer + (insert-file file) + (goto-char (point-min)) + (json-read))) + + + +;;; JSON encoder + +(defun json-encode (object) + "Return a JSON representation of OBJECT as a string." + (cond ((memq object (list t json-null json-false)) + (json-encode-keyword object)) + ((stringp object) (json-encode-string object)) + ((keywordp object) (json-encode-string + (substring (symbol-name object) 1))) + ((symbolp object) (json-encode-string + (symbol-name object))) + ((numberp object) (json-encode-number object)) + ((arrayp object) (json-encode-array object)) + ((hash-table-p object) (json-encode-hash-table object)) + ((listp object) (json-encode-list object)) + (t (signal 'json-error (list object))))) + +(provide 'json) +;;; json.el ends here -- When I was in the scouts, the leader told me to pitch a tent. I couldn't find any pitch, so I used creosote. _______________________________________________ XEmacs-Patches mailing list XEmacs-Patches(a)xemacs.org http://calypso.tux.org/cgi-bin/mailman/listinfo/xemacs-patches