bug#679: marked as done (23.0.60; Function json-read-number does not handle complete Javascript spec)

[don@donarmstrong.com (Emacs bug Tracking System)]

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Your message dated Thu, 28 Aug 2008 16:22:08 -0400
with message-id <87sksoc2kv.fsf@cyd.mit.edu>
and subject line Re: 23.0.60; Function json-read-number does not handle complete Javascript spec
has caused the Emacs bug report #679,
regarding 23.0.60; Function json-read-number does not handle complete Javascript spec
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
message is talking about, this may indicate a serious mail system
misconfiguration somewhere. Please contact don@donarmstrong.com
immediately.)


-- 
679: http://emacsbugs.donarmstrong.com/cgi-bin/bugreport.cgi?bug=679
Emacs Bug Tracking System
Contact don@donarmstrong.com with problems

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From: sand@blarg.net
To: emacs-pretest-bug@gnu.org
Cc: rfrancoise@debian.org
Subject: 23.0.60; Function json-read-number does not handle complete Javascript spec
Date: 9 Aug 2008 07:05:28 -0000
Message-ID: <20080809070528.26869.qmail@priss.frightenedpiglet.com>

----

In json.el, the 'json-read-number' function is intended to read the
textual representation of Javascript numbers.

(defun json-read-number ()
  "Read the JSON number following point.
N.B.: Only numbers which can fit in Emacs Lisp's native number
representation will be parsed correctly."
  (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))))))

The Javascript spec
(http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Guide:Literals#Floating-Point_Literals)
says the following about floating-point numbers:

| A floating-point literal can have the following parts:
| 
|     * A decimal integer which can be signed (preceded by "+" or "-"),
|     * A decimal point ("."),
|     * A fraction (another decimal number),
|     * An exponent. 
| 
| The exponent part is an "e" or "E" followed by an integer, which can
| be signed (preceded by "+" or "-"). A floating-point literal must have
| at least one digit and either a decimal point or "e" (or "E"). 

This means that

  1.

is a valid floating point-literal per the spec, but the regular
expression above does not match the complete text---the regular
expression requires digits after the decimal point.  This ends up
matched as a simple integer, leaving the decimal point in the input
stream and causing a later syntax error.  Similarly

  .1

is a valid floating point-literal illegal that Emacs rejects, because
the regular expression requires digits before the decimal point.
Testing with the error console in Firefox confirms that the two
examples above are valid syntax.

The parser function needs to be fixed to handle the complete syntax.

----


In GNU Emacs 23.0.60.1 (i486-pc-linux-gnu, GTK+ Version 2.12.11)
 of 2008-07-27 on elegiac, modified by Debian
 (emacs-snapshot package, version 1:20080727-1)
Windowing system distributor `The X.Org Foundation', version 11.0.10402000
configured using `configure  '--build' 'i486-linux-gnu' '--host' 'i486-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' '--localstatedir=/var' '--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-pop=yes' '--enable-locallisppath=/etc/emacs-snapshot:/etc/emacs:/usr/local/share/emacs/23.0.60/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/23.0.60/site-lisp:/usr/share/emacs/site-lisp' '--with-x=yes' '--with-x-toolkit=gtk' 'build_alias=i486-linux-gnu' 'host_alias=i486-linux-gnu' 'CFLAGS=-DDEBIAN -DSITELOAD_PURESIZE_EXTRA=5000 -g -O2' 'LDFLAGS=-g -Wl,--as-needed' 'CPPFLAGS=''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: POSIX
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t

Major mode: VM

Minor modes in effect:
  shell-dirtrack-mode: t
  auto-image-file-mode: t
  show-paren-mode: t
  icomplete-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  global-auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t



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From: Chong Yidong <cyd@stupidchicken.com>
To: "Edward O'Connor" <hober0@gmail.com>
Cc: 679-done@emacsbugs.donarmstrong.com
Subject: Re: 23.0.60; Function json-read-number does not handle complete Javascript spec
Date: Thu, 28 Aug 2008 16:22:08 -0400
Message-ID: <87sksoc2kv.fsf@cyd.mit.edu>

> I've attached a modified version, which disallows octal & hexadecimal.

Checked in, thanks.