emacs: Fix bug in resynchronizing after a JSON parse error

[notmuch] / emacs / notmuch-lib.el

;; notmuch-lib.el --- common variables, functions and function declarations
;;
;; Copyright © Carl Worth
;;
;; This file is part of Notmuch.
;;
;; Notmuch 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.
;;
;; Notmuch 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 Notmuch.  If not, see <http://www.gnu.org/licenses/>.
;;
;; Authors: Carl Worth <cworth@cworth.org>

;; This is an part of an emacs-based interface to the notmuch mail system.

(require 'mm-view)
(require 'mm-decode)
(require 'json)
(require 'cl)

(defvar notmuch-command "notmuch"
  "Command to run the notmuch binary.")

(defgroup notmuch nil
  "Notmuch mail reader for Emacs."
  :group 'mail)

(defgroup notmuch-hello nil
  "Overview of saved searches, tags, etc."
  :group 'notmuch)

(defgroup notmuch-search nil
  "Searching and sorting mail."
  :group 'notmuch)

(defgroup notmuch-show nil
  "Showing messages and threads."
  :group 'notmuch)

(defgroup notmuch-send nil
  "Sending messages from Notmuch."
  :group 'notmuch)

(custom-add-to-group 'notmuch-send 'message 'custom-group)

(defgroup notmuch-crypto nil
  "Processing and display of cryptographic MIME parts."
  :group 'notmuch)

(defgroup notmuch-hooks nil
  "Running custom code on well-defined occasions."
  :group 'notmuch)

(defgroup notmuch-external nil
  "Running external commands from within Notmuch."
  :group 'notmuch)

(defgroup notmuch-faces nil
  "Graphical attributes for displaying text"
  :group 'notmuch)

(defcustom notmuch-search-oldest-first t
  "Show the oldest mail first when searching."
  :type 'boolean
  :group 'notmuch-search)

;;

(defvar notmuch-search-history nil
  "Variable to store notmuch searches history.")

(defcustom notmuch-saved-searches '(("inbox" . "tag:inbox")
                                    ("unread" . "tag:unread"))
  "A list of saved searches to display."
  :type '(alist :key-type string :value-type string)
  :group 'notmuch-hello)

(defcustom notmuch-archive-tags '("-inbox")
  "List of tag changes to apply to a message or a thread when it is archived.

Tags starting with \"+\" (or not starting with either \"+\" or
\"-\") in the list will be added, and tags starting with \"-\"
will be removed from the message or thread being archived.

For example, if you wanted to remove an \"inbox\" tag and add an
\"archived\" tag, you would set:
    (\"-inbox\" \"+archived\")"
  :type '(repeat string)
  :group 'notmuch-search
  :group 'notmuch-show)

(defun notmuch-version ()
  "Return a string with the notmuch version number."
  (let ((long-string
         ;; Trim off the trailing newline.
         (substring (shell-command-to-string
                     (concat notmuch-command " --version"))
                    0 -1)))
    (if (string-match "^notmuch\\( version\\)? \\(.*\\)$"
                      long-string)
        (match-string 2 long-string)
      "unknown")))

(defun notmuch-config-get (item)
  "Return a value from the notmuch configuration."
  ;; Trim off the trailing newline
  (substring (shell-command-to-string
              (concat notmuch-command " config get " item))
              0 -1))

(defun notmuch-database-path ()
  "Return the database.path value from the notmuch configuration."
  (notmuch-config-get "database.path"))

(defun notmuch-user-name ()
  "Return the user.name value from the notmuch configuration."
  (notmuch-config-get "user.name"))

(defun notmuch-user-primary-email ()
  "Return the user.primary_email value from the notmuch configuration."
  (notmuch-config-get "user.primary_email"))

(defun notmuch-user-other-email ()
  "Return the user.other_email value (as a list) from the notmuch configuration."
  (split-string (notmuch-config-get "user.other_email") "\n"))

(defun notmuch-kill-this-buffer ()
  "Kill the current buffer."
  (interactive)
  (kill-buffer (current-buffer)))

(defun notmuch-prettify-subject (subject)
  ;; This function is used by `notmuch-search-process-filter' which
  ;; requires that we not disrupt its' matching state.
  (save-match-data
    (if (and subject
             (string-match "^[ \t]*$" subject))
        "[No Subject]"
      subject)))

(defun notmuch-escape-boolean-term (term)
  "Escape a boolean term for use in a query.

The caller is responsible for prepending the term prefix and a
colon.  This performs minimal escaping in order to produce
user-friendly queries."

  (save-match-data
    (if (or (equal term "")
            (string-match "[ ()]\\|^\"" term))
        ;; Requires escaping
        (concat "\"" (replace-regexp-in-string "\"" "\"\"" term t t) "\"")
      term)))

(defun notmuch-id-to-query (id)
  "Return a query that matches the message with id ID."
  (concat "id:" (notmuch-escape-boolean-term id)))

;;

(defun notmuch-common-do-stash (text)
  "Common function to stash text in kill ring, and display in minibuffer."
  (if text
      (progn
        (kill-new text)
        (message "Stashed: %s" text))
    ;; There is nothing to stash so stash an empty string so the user
    ;; doesn't accidentally paste something else somewhere.
    (kill-new "")
    (message "Nothing to stash!")))

;;

(defun notmuch-remove-if-not (predicate list)
  "Return a copy of LIST with all items not satisfying PREDICATE removed."
  (let (out)
    (while list
      (when (funcall predicate (car list))
        (push (car list) out))
      (setq list (cdr list)))
    (nreverse out)))

;; This lets us avoid compiling these replacement functions when emacs
;; is sufficiently new enough to supply them alone. We do the macro
;; treatment rather than just wrapping our defun calls in a when form
;; specifically so that the compiler never sees the code on new emacs,
;; (since the code is triggering warnings that we don't know how to get
;; rid of.
;;
;; A more clever macro here would accept a condition and a list of forms.
(defmacro compile-on-emacs-prior-to-23 (form)
  "Conditionally evaluate form only on emacs < emacs-23."
  (list 'when (< emacs-major-version 23)
        form))

(defun notmuch-split-content-type (content-type)
  "Split content/type into 'content' and 'type'"
  (split-string content-type "/"))

(defun notmuch-match-content-type (t1 t2)
  "Return t if t1 and t2 are matching content types, taking wildcards into account"
  (let ((st1 (notmuch-split-content-type t1))
        (st2 (notmuch-split-content-type t2)))
    (if (or (string= (cadr st1) "*")
            (string= (cadr st2) "*"))
        ;; Comparison of content types should be case insensitive.
        (string= (downcase (car st1)) (downcase (car st2)))
      (string= (downcase t1) (downcase t2)))))

(defvar notmuch-multipart/alternative-discouraged
  '(
    ;; Avoid HTML parts.
    "text/html"
    ;; multipart/related usually contain a text/html part and some associated graphics.
    "multipart/related"
    ))

(defun notmuch-multipart/alternative-choose (types)
  "Return a list of preferred types from the given list of types"
  ;; Based on `mm-preferred-alternative-precedence'.
  (let ((seq types))
    (dolist (pref (reverse notmuch-multipart/alternative-discouraged))
      (dolist (elem (copy-sequence seq))
        (when (string-match pref elem)
          (setq seq (nconc (delete elem seq) (list elem))))))
    seq))

(defun notmuch-parts-filter-by-type (parts type)
  "Given a list of message parts, return a list containing the ones matching
the given type."
  (remove-if-not
   (lambda (part) (notmuch-match-content-type (plist-get part :content-type) type))
   parts))

;; Helper for parts which are generally not included in the default
;; JSON output.
(defun notmuch-get-bodypart-internal (query part-number process-crypto)
  (let ((args '("show" "--format=raw"))
        (part-arg (format "--part=%s" part-number)))
    (setq args (append args (list part-arg)))
    (if process-crypto
        (setq args (append args '("--decrypt"))))
    (setq args (append args (list query)))
    (with-temp-buffer
      (let ((coding-system-for-read 'no-conversion))
        (progn
          (apply 'call-process (append (list notmuch-command nil (list t nil) nil) args))
          (buffer-string))))))

(defun notmuch-get-bodypart-content (msg part nth process-crypto)
  (or (plist-get part :content)
      (notmuch-get-bodypart-internal (notmuch-id-to-query (plist-get msg :id)) nth process-crypto)))

;; Workaround: The call to `mm-display-part' below triggers a bug in
;; Emacs 24 if it attempts to use the shr renderer to display an HTML
;; part with images in it (demonstrated in 24.1 and 24.2 on Debian and
;; Fedora 17, though unreproducable in other configurations).
;; `mm-shr' references the variable `gnus-inhibit-images' without
;; first loading gnus-art, which defines it, resulting in a
;; void-variable error.  Hence, we advise `mm-shr' to ensure gnus-art
;; is loaded.
(if (>= emacs-major-version 24)
    (defadvice mm-shr (before load-gnus-arts activate)
      (require 'gnus-art nil t)
      (ad-disable-advice 'mm-shr 'before 'load-gnus-arts)))

(defun notmuch-mm-display-part-inline (msg part nth content-type process-crypto)
  "Use the mm-decode/mm-view functions to display a part in the
current buffer, if possible."
  (let ((display-buffer (current-buffer)))
    (with-temp-buffer
      ;; In case there is :content, the content string is already converted
      ;; into emacs internal format. `gnus-decoded' is a fake charset,
      ;; which means no further decoding (to be done by mm- functions).
      (let* ((charset (if (plist-member part :content)
                          'gnus-decoded
                        (plist-get part :content-charset)))
             (handle (mm-make-handle (current-buffer) `(,content-type (charset . ,charset)))))
        ;; If the user wants the part inlined, insert the content and
        ;; test whether we are able to inline it (which includes both
        ;; capability and suitability tests).
        (when (mm-inlined-p handle)
          (insert (notmuch-get-bodypart-content msg part nth process-crypto))
          (when (mm-inlinable-p handle)
            (set-buffer display-buffer)
            (mm-display-part handle)
            t))))))

;; Converts a plist of headers to an alist of headers. The input plist should
;; have symbols of the form :Header as keys, and the resulting alist will have
;; symbols of the form 'Header as keys.
(defun notmuch-headers-plist-to-alist (plist)
  (loop for (key value . rest) on plist by #'cddr
        collect (cons (intern (substring (symbol-name key) 1)) value)))

(defun notmuch-combine-face-text-property (start end face)
  "Combine FACE into the 'face text property between START and END.

This function combines FACE with any existing faces between START
and END.  Attributes specified by FACE take precedence over
existing attributes.  FACE must be a face name (a symbol or
string), a property list of face attributes, or a list of these."

  (let ((pos start))
    (while (< pos end)
      (let ((cur (get-text-property pos 'face))
            (next (next-single-property-change pos 'face nil end)))
        (put-text-property pos next 'face (cons face cur))
        (setq pos next)))))

;; Compatibility functions for versions of emacs before emacs 23.
;;
;; Both functions here were copied from emacs 23 with the following copyright:
;;
;; Copyright (C) 1985, 1986, 1992, 1994, 1995, 1999, 2000, 2001, 2002, 2003,
;;   2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
;;
;; and under the GPL version 3 (or later) exactly as notmuch itself.
(compile-on-emacs-prior-to-23
 (defun apply-partially (fun &rest args)
   "Return a function that is a partial application of FUN to ARGS.
ARGS is a list of the first N arguments to pass to FUN.
The result is a new function which does the same as FUN, except that
the first N arguments are fixed at the values with which this function
was called."
   (lexical-let ((fun fun) (args1 args))
     (lambda (&rest args2) (apply fun (append args1 args2))))))

(compile-on-emacs-prior-to-23
 (defun mouse-event-p (object)
   "Return non-nil if OBJECT is a mouse click event."
   (memq (event-basic-type object) '(mouse-1 mouse-2 mouse-3 mouse-movement))))

;; This variable is used only buffer local, but it needs to be
;; declared globally first to avoid compiler warnings.
(defvar notmuch-show-process-crypto nil)
(make-variable-buffer-local 'notmuch-show-process-crypto)

;; Incremental JSON parsing

;; These two variables are internal variables to the parsing
;; routines. They are always used buffer local but need to be declared
;; globally to avoid compiler warnings.

(defvar notmuch-json-parser nil
  "Internal incremental JSON parser object: local to the buffer being parsed.")

(defvar notmuch-json-state nil
  "State of the internal JSON parser: local to the buffer being parsed.")

(defun notmuch-json-create-parser (buffer)
  "Return a streaming JSON parser that consumes input from BUFFER.

This parser is designed to read streaming JSON whose structure is
known to the caller.  Like a typical JSON parsing interface, it
provides a function to read a complete JSON value from the input.
However, it extends this with an additional function that
requires the next value in the input to be a compound value and
descends into it, allowing its elements to be read one at a time
or further descended into.  Both functions can return 'retry to
indicate that not enough input is available.

The parser always consumes input from BUFFER's point.  Hence, the
caller is allowed to delete and data before point and may
resynchronize after an error by moving point."

  (list buffer
        ;; Terminator stack: a stack of characters that indicate the
        ;; end of the compound values enclosing point
        '()
        ;; Next: One of
        ;; * 'expect-value if the next token must be a value, but a
        ;;   value has not yet been reached
        ;; * 'value if point is at the beginning of a value
        ;; * 'expect-comma if the next token must be a comma
        'expect-value
        ;; Allow terminator: non-nil if the next token may be a
        ;; terminator
        nil
        ;; Partial parse position: If state is 'value, a marker for
        ;; the position of the partial parser or nil if no partial
        ;; parsing has happened yet
        nil
        ;; Partial parse state: If state is 'value, the current
        ;; `parse-partial-sexp' state
        nil))

(defmacro notmuch-json-buffer (jp) `(first ,jp))
(defmacro notmuch-json-term-stack (jp) `(second ,jp))
(defmacro notmuch-json-next (jp) `(third ,jp))
(defmacro notmuch-json-allow-term (jp) `(fourth ,jp))
(defmacro notmuch-json-partial-pos (jp) `(fifth ,jp))
(defmacro notmuch-json-partial-state (jp) `(sixth ,jp))

(defvar notmuch-json-syntax-table
  (let ((table (make-syntax-table)))
    ;; The standard syntax table is what we need except that "." needs
    ;; to have word syntax instead of punctuation syntax.
    (modify-syntax-entry ?. "w" table)
    table)
  "Syntax table used for incremental JSON parsing.")

(defun notmuch-json-scan-to-value (jp)
  ;; Helper function that consumes separators, terminators, and
  ;; whitespace from point.  Returns nil if it successfully reached
  ;; the beginning of a value, 'end if it consumed a terminator, or
  ;; 'retry if not enough input was available to reach a value.  Upon
  ;; nil return, (notmuch-json-next jp) is always 'value.

  (if (eq (notmuch-json-next jp) 'value)
      ;; We're already at a value
      nil
    ;; Drive the state toward 'expect-value
    (skip-chars-forward " \t\r\n")
    (or (when (eobp) 'retry)
        ;; Test for the terminator for the current compound
        (when (and (notmuch-json-allow-term jp)
                   (eq (char-after) (car (notmuch-json-term-stack jp))))
          ;; Consume it and expect a comma or terminator next
          (forward-char)
          (setf (notmuch-json-term-stack jp) (cdr (notmuch-json-term-stack jp))
                (notmuch-json-next jp) 'expect-comma
                (notmuch-json-allow-term jp) t)
          'end)
        ;; Test for a separator
        (when (eq (notmuch-json-next jp) 'expect-comma)
          (when (/= (char-after) ?,)
            (signal 'json-readtable-error (list "expected ','")))
          ;; Consume it, switch to 'expect-value, and disallow a
          ;; terminator
          (forward-char)
          (skip-chars-forward " \t\r\n")
          (setf (notmuch-json-next jp) 'expect-value
                (notmuch-json-allow-term jp) nil)
          ;; We moved point, so test for eobp again and fall through
          ;; to the next test if there's more input
          (when (eobp) 'retry))
        ;; Next must be 'expect-value and we know this isn't
        ;; whitespace, EOB, or a terminator, so point must be on a
        ;; value
        (progn
          (assert (eq (notmuch-json-next jp) 'expect-value))
          (setf (notmuch-json-next jp) 'value)
          nil))))

(defun notmuch-json-begin-compound (jp)
  "Parse the beginning of a compound value and traverse inside it.

Returns 'retry if there is insufficient input to parse the
beginning of the compound.  If this is able to parse the
beginning of a compound, it moves point past the token that opens
the compound and returns t.  Later calls to `notmuch-json-read'
will return the compound's elements.

Entering JSON objects is currently unimplemented."

  (with-current-buffer (notmuch-json-buffer jp)
    ;; Disallow terminators
    (setf (notmuch-json-allow-term jp) nil)
    ;; Save "next" so we can restore it if there's a syntax error
    (let ((saved-next (notmuch-json-next jp)))
      (or (notmuch-json-scan-to-value jp)
          (if (/= (char-after) ?\[)
              (progn
                (setf (notmuch-json-next jp) saved-next)
                (signal 'json-readtable-error (list "expected '['")))
            (forward-char)
            (push ?\] (notmuch-json-term-stack jp))
            ;; Expect a value or terminator next
            (setf (notmuch-json-next jp) 'expect-value
                  (notmuch-json-allow-term jp) t)
            t)))))

(defun notmuch-json-read (jp)
  "Parse the value at point in JP's buffer.

Returns 'retry if there is insufficient input to parse a complete
JSON value (though it may still move point over separators or
whitespace).  If the parser is currently inside a compound value
and the next token ends the list or object, this moves point just
past the terminator and returns 'end.  Otherwise, this moves
point to just past the end of the value and returns the value."

  (with-current-buffer (notmuch-json-buffer jp)
    (or
     ;; Get to a value state
     (notmuch-json-scan-to-value jp)

     ;; Can we parse a complete value?
     (let ((complete
            (if (looking-at "[-+0-9tfn]")
                ;; This is a number or a keyword, so the partial
                ;; parser isn't going to help us because a truncated
                ;; number or keyword looks like a complete symbol to
                ;; it.  Look for something that clearly ends it.
                (save-excursion
                  (skip-chars-forward "^]},: \t\r\n")
                  (not (eobp)))

              ;; We're looking at a string, object, or array, which we
              ;; can partial parse.  If we just reached the value, set
              ;; up the partial parser.
              (when (null (notmuch-json-partial-state jp))
                (setf (notmuch-json-partial-pos jp) (point-marker)))

              ;; Extend the partial parse until we either reach EOB or
              ;; get the whole value
              (save-excursion
                (let ((pstate
                       (with-syntax-table notmuch-json-syntax-table
                         (parse-partial-sexp
                          (notmuch-json-partial-pos jp) (point-max) 0 nil
                          (notmuch-json-partial-state jp)))))
                  ;; A complete value is available if we've reached
                  ;; depth 0 or less and encountered a complete
                  ;; subexpression.
                  (if (and (<= (first pstate) 0) (third pstate))
                      t
                    ;; Not complete.  Update the partial parser state
                    (setf (notmuch-json-partial-pos jp) (point-marker)
                          (notmuch-json-partial-state jp) pstate)
                    nil))))))

       (if (not complete)
           'retry
         ;; We have a value.  Reset the partial parse state and expect
         ;; a comma or terminator after the value.
         (setf (notmuch-json-next jp) 'expect-comma
               (notmuch-json-allow-term jp) t
               (notmuch-json-partial-pos jp) nil
               (notmuch-json-partial-state jp) nil)
         ;; Parse the value
         (let ((json-object-type 'plist)
               (json-array-type 'list)
               (json-false nil))
           (json-read)))))))

(defun notmuch-json-eof (jp)
  "Signal a json-error if there is more data in JP's buffer.

Moves point to the beginning of any trailing data or to the end
of the buffer if there is only trailing whitespace."

  (with-current-buffer (notmuch-json-buffer jp)
    (skip-chars-forward " \t\r\n")
    (unless (eobp)
      (signal 'json-error (list "Trailing garbage following JSON data")))))

(defun notmuch-json-parse-partial-list (result-function error-function results-buf)
  "Parse a partial JSON list from current buffer.

This function consumes a JSON list from the current buffer,
applying RESULT-FUNCTION in buffer RESULT-BUFFER to each complete
value in the list.  It operates incrementally and should be
called whenever the buffer has been extended with additional
data.

If there is a syntax error, this will attempt to resynchronize
with the input and will apply ERROR-FUNCTION in buffer
RESULT-BUFFER to any input that was skipped.

It sets up all the needed internal variables: the caller just
needs to call it with point in the same place that the parser
left it."
  (let (done)
    (unless (local-variable-p 'notmuch-json-parser)
      (set (make-local-variable 'notmuch-json-parser)
           (notmuch-json-create-parser (current-buffer)))
      (set (make-local-variable 'notmuch-json-state) 'begin))
    (while (not done)
      (condition-case nil
          (case notmuch-json-state
                ((begin)
                 ;; Enter the results list
                 (if (eq (notmuch-json-begin-compound
                          notmuch-json-parser) 'retry)
                     (setq done t)
                   (setq notmuch-json-state 'result)))
                ((result)
                 ;; Parse a result
                 (let ((result (notmuch-json-read notmuch-json-parser)))
                   (case result
                         ((retry) (setq done t))
                         ((end) (setq notmuch-json-state 'end))
                         (otherwise (with-current-buffer results-buf
                                      (funcall result-function result))))))
                ((end)
                 ;; Any trailing data is unexpected
                 (notmuch-json-eof notmuch-json-parser)
                 (setq done t)))
        (json-error
         ;; Do our best to resynchronize and ensure forward
         ;; progress
         (let ((bad (buffer-substring (line-beginning-position)
                                      (line-end-position))))
           (forward-line)
           (with-current-buffer results-buf
             (funcall error-function "%s" bad))))))
    ;; Clear out what we've parsed
    (delete-region (point-min) (point))))




(provide 'notmuch-lib)

;; Local Variables:
;; byte-compile-warnings: (not cl-functions)
;; End: