;;; hideif.el --- hides selected code within ifdef  -*- lexical-binding:t -*-

;; Copyright (C) 1988, 1994, 2001-2025 Free Software Foundation, Inc.

;; Author: Brian Marick
;;	Daniel LaLiberte <liberte@holonexus.org>
;; Maintainer: Luke Lee <luke.yx.lee@gmail.com>
;; Keywords: c, outlines

;; 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 <https://www.gnu.org/licenses/>.

;;; Commentary:

;; To initialize, toggle the hide-ifdef minor mode with
;;
;; M-x hide-ifdef-mode
;;
;; This will set up key bindings and call hide-ifdef-mode-hook if it
;; has a value.  To explicitly hide ifdefs using a buffer-local
;; define list (default empty), type
;;
;; M-x hide-ifdefs  or C-c @ h
;;
;; Hide-ifdef suppresses the display of code that the preprocessor wouldn't
;; pass through.  Support complete C/C++ expression and precedence.
;; It will automatically scan for new #define symbols and macros on the way
;; parsing.
;;
;; The hidden code is marked by ellipses (...).  Be
;; cautious when editing near ellipses, since the hidden text is
;; still in the buffer, and you can move the point into it and modify
;; text unawares.
;; You can make your buffer read-only while hide-ifdef-hiding by setting
;; hide-ifdef-read-only to a non-nil value.  You can toggle this
;; variable with hide-ifdef-toggle-read-only (C-c @ C-q).
;;
;; You can undo the effect of hide-ifdefs by typing
;;
;; M-x show-ifdefs  or C-c @ s
;;
;; Use M-x hide-ifdef-define (C-c @ d) to define a symbol.
;; Use M-x hide-ifdef-undef (C-c @ u) to undefine a symbol.
;;
;; If you define or undefine a symbol while hide-ifdef-mode is in effect,
;; the display will be updated.  The global define list hide-ifdef-env
;; is affected accordingly.  You can save changes to this globally define
;; list with hide-ifdef-set-define-alist.  This adds entries to
;; hide-ifdef-define-alist.
;;
;; If you have defined a hide-ifdef-mode-hook, you can set
;; up a list of symbols that may be used by hide-ifdefs as in the
;; following example:
;;
;; (add-hook 'hide-ifdef-mode-hook
;;      (lambda ()
;;	 (unless hide-ifdef-define-alist
;;	   (setq hide-ifdef-define-alist
;;		'((list1 (ONE . 1) (TWO . 2))
;;		  (list2 (TWO . 2) (THREE . 3)))))
;;	 (hide-ifdef-use-define-alist 'list2))) ; use list2 by default
;;
;; Currently recursive #include is not yet supported, a quick and reliable
;; way is to let the compiler generates all the #include-d defined macros
;; into a file, then open it in Emacs with hide-ifdefs (C-c @ h).
;; Take gcc and hello.c for example, hello.c #include-s <stdio.h>:
;;
;;   $ gcc -dM -E hello.c -o hello.hh
;;
;; Then, open hello.hh and perform hide-ifdefs.
;;
;; You can call hide-ifdef-use-define-alist (C-c @ U) at any time to specify
;; another list to use.
;;
;; To cause ifdefs to be hidden as soon as hide-ifdef-mode is called,
;; set hide-ifdef-initially to non-nil.
;;
;; If you set hide-ifdef-lines to t, hide-ifdefs hides all the #ifdef lines.
;; In the absence of highlighting, that might be a bad idea.  If you set
;; hide-ifdef-lines to nil (the default), the surrounding preprocessor
;; lines will be displayed.  That can be confusing in its own
;; right.  Other variations on display are possible, but not much
;; better.
;;
;; You can explicitly hide or show individual ifdef blocks irrespective
;; of the define list by using hide-ifdef-block and show-ifdef-block.
;;
;; You can move the point between ifdefs with forward-ifdef, backward-ifdef,
;; up-ifdef, down-ifdef, next-ifdef, and previous-ifdef.
;;
;; If you have minor-mode-alist in your mode line (the default) two labels
;; may appear.  "Ifdef" will appear when hide-ifdef-mode is active.  "Hiding"
;; will appear when text may be hidden ("hide-ifdef-hiding" is non-nil).
;;
;; Written by Brian Marick, at Gould, Computer Systems Division, Urbana IL.
;; Extensively modified by Daniel LaLiberte (while at Gould).
;;
;; Extensively modified by Luke Lee in 2013 to support complete C expression
;; evaluation and argumented macro expansion; C++11, C++14, C++17, GCC
;; extension literals and gcc/clang matching behaviors are supported in 2021.
;; Various floating point types and operations are also supported but the
;; actual precision is limited by the Emacs internal floating representation,
;; which is the C data type "double" or IEEE binary64 format.
;; C99 and GNU style variadic arguments support is completed in 2022/E.

;;; Code:

(require 'cc-mode)
(require 'cl-lib)

(defgroup hide-ifdef nil
  "Hide selected code within `ifdef'."
  :group 'c)

(defcustom hide-ifdef-initially nil
  "Non-nil means call `hide-ifdefs' when Hide-Ifdef mode is first activated."
  :type 'boolean)

(defcustom hide-ifdef-read-only nil
  "Set to non-nil if you want buffer to be read-only while hiding text."
  :type 'boolean)

(defcustom hide-ifdef-lines nil
  "Non-nil means hide the #ifX, #else, and #endif lines."
  :type 'boolean)

(defcustom hide-ifdef-shadow nil
  "Non-nil means shadow text instead of hiding it."
  :type 'boolean
  :version "23.1")

(defface hide-ifdef-shadow '((t (:inherit shadow)))
  "Face for shadowing ifdef blocks."
  :version "23.1")

(defcustom hide-ifdef-exclude-define-regexp nil
  "Ignore #define names if those names match this exclusion pattern."
  :type '(choice (const nil) string)
  :version "25.1")

(define-obsolete-variable-alias 'hide-ifdef-expand-reinclusion-protection
  'hide-ifdef-expand-reinclusion-guard "28.1")

(defcustom hide-ifdef-expand-reinclusion-guard t
  "Non-nil means don't hide an entire header file enclosed by #ifndef...#endif.
Most C/C++ headers are usually wrapped with ifdefs to prevent re-inclusion:

  ----- beginning of file -----
  #ifndef _XXX_HEADER_FILE_INCLUDED_
  #define _XXX_HEADER_FILE_INCLUDED_
     xxx
     xxx
     xxx...
  #endif
  ----- end of file -----

The first time we visit such a file, _XXX_HEADER_FILE_INCLUDED_ is
undefined, and so nothing is hidden.  The next time we visit it, everything will
be hidden.

This behavior is generally undesirable.  If this option is non-nil, the
outermost #if is always visible."
  :type 'boolean
  :version "25.1")

(defcustom hide-ifdef-header-regexp
  "\\.h\\(h\\|xx\\|pp\\|\\+\\+\\)?\\'"
  "C/C++ header file name patterns to determine if current buffer is a header.
Effective only if `hide-ifdef-expand-reinclusion-guard' is t."
  :type 'regexp
  :version "25.1")

(defvar-keymap hide-ifdef-mode-submap
  :doc "Keymap used by `hide-ifdef-mode' under `hide-ifdef-mode-prefix-key'."
  ;; Set up the submap that goes after the prefix key.
  "d"   #'hide-ifdef-define
  "u"   #'hide-ifdef-undef
  "D"   #'hide-ifdef-set-define-alist
  "U"   #'hide-ifdef-use-define-alist
  "h"   #'hide-ifdefs
  "s"   #'show-ifdefs
  "C-d" #'hide-ifdef-block
  "C-s" #'show-ifdef-block
  "e"   #'hif-evaluate-macro
  "C"   #'hif-clear-all-ifdef-defined
  "C-q" #'hide-ifdef-toggle-read-only
  "C-w" #'hide-ifdef-toggle-shadowing
  "<remap> <read-only-mode>" #'hide-ifdef-toggle-outside-read-only)

(defcustom hide-ifdef-mode-prefix-key "\C-c@"
  "Prefix key for all Hide-Ifdef mode commands."
  :type 'key-sequence
  :version "27.1")

(defcustom hide-ifdef-verbose nil
  "Show some defining symbols on hiding for a visible feedback."
  :type 'boolean
  :version "28.1")

(defcustom hide-ifdef-evalulate-enter-hook nil
  "Hook function to be called when entering `hif-evaluate-macro'."
  :type 'hook
  :version "28.1")

(defcustom hide-ifdef-evalulate-leave-hook nil
  "Hook function to be called when leaving `hif-evaluate-macro'."
  :type 'hook
  :version "28.1")

(defvar hide-ifdef-mode-map
  ;; Set up the mode's main map, which leads via the prefix key to the submap.
  (let ((map (make-sparse-keymap)))
    (define-key map hide-ifdef-mode-prefix-key hide-ifdef-mode-submap)
    map)
  "Keymap used with `hide-ifdef-mode'.")

(easy-menu-define hide-ifdef-mode-menu hide-ifdef-mode-map
  "Menu for `hide-ifdef-mode'."
  '("Hide-Ifdef"
    ["Hide some ifdefs" hide-ifdefs
     :help "Hide the contents of some #ifdefs"]
    ["Show all ifdefs" show-ifdefs
     :help "Cancel the effects of `hide-ifdef': show the contents of all #ifdefs"]
    ["Hide ifdef block" hide-ifdef-block
     :help "Hide the ifdef block (true or false part) enclosing or before the cursor"]
    ["Show ifdef block" show-ifdef-block
     :help "Show the ifdef block (true or false part) enclosing or before the cursor"]
    ["Define a variable..." hide-ifdef-define
     :help "Define a VAR so that #ifdef VAR would be included"]
    ["Undefine a variable..." hide-ifdef-undef
     :help "Undefine a VAR so that #ifdef VAR would not be included"]
    ["Define an alist..." hide-ifdef-set-define-alist
     :help "Set the association for NAME to `hide-ifdef-env'"]
    ["Use an alist..." hide-ifdef-use-define-alist
     :help "Set `hide-ifdef-env' to the define list specified by NAME"]
    ["Toggle read only" hide-ifdef-toggle-read-only
     :style toggle :selected hide-ifdef-read-only
     :help "Buffer should be read-only while hiding text"]
    ["Toggle shadowing" hide-ifdef-toggle-shadowing
     :style toggle :selected hide-ifdef-shadow
     :help "Text should be shadowed instead of hidden"]))

(defvar hide-ifdef-hiding nil
  "Non-nil when text may be hidden.")

(or (assq 'hide-ifdef-hiding minor-mode-alist)
    (setq minor-mode-alist
          (cons '(hide-ifdef-hiding " Hiding")
                minor-mode-alist)))

;; Fix c-mode syntax table so we can recognize whole symbols.
(defvar hide-ifdef-syntax-table
  (let ((st (copy-syntax-table c-mode-syntax-table)))
    (modify-syntax-entry ?_ "w" st)
    (modify-syntax-entry ?& "." st)
    (modify-syntax-entry ?\| "." st)
    st)
  "Syntax table used for tokenizing #if expressions.")

(defvar hide-ifdef-env nil
  "An alist of defined symbols and their values.")

(defvar hide-ifdef-env-backup nil
  "This variable is a backup of the previously cleared `hide-ifdef-env'.
This backup prevents any accidental clearance of `hide-ifdef-env' by
`hif-clear-all-ifdef-defined'.")

(defvar hif-outside-read-only nil
  "Internal variable.  Saves the value of `buffer-read-only' while hiding.")

;;;###autoload
(define-minor-mode hide-ifdef-mode
  "Toggle features to hide/show #ifdef blocks (Hide-Ifdef mode).

Hide-Ifdef mode is a buffer-local minor mode for use with C and
C-like major modes.  When enabled, code within #ifdef constructs
that the C preprocessor would eliminate may be hidden from view.
Several variables affect how the hiding is done:

`hide-ifdef-env'
        An association list of defined and undefined symbols for the
        current project.  Initially, the global value of `hide-ifdef-env'
        is used.  This variable was a buffer-local variable, which limits
        hideif to parse only one C/C++ file at a time.  We've extended
        hideif to support parsing a C/C++ project containing multiple C/C++
        source files opened simultaneously in different buffers.  Therefore
        `hide-ifdef-env' can no longer be buffer local but must be global.

`hide-ifdef-define-alist'
        An association list of defined symbol lists.
        Use `hide-ifdef-set-define-alist' to save the current `hide-ifdef-env'
        and `hide-ifdef-use-define-alist' to set the current `hide-ifdef-env'
        from one of the lists in `hide-ifdef-define-alist'.

`hide-ifdef-lines'
        Set to non-nil to not show #if, #ifdef, #ifndef, #else, and
        #endif lines when hiding.

`hide-ifdef-initially'
        Indicates whether `hide-ifdefs' should be called when Hide-Ifdef mode
        is activated.

`hide-ifdef-read-only'
        Set to non-nil if you want to make buffers read only while hiding.
        After `show-ifdefs', read-only status is restored to previous value.

\\{hide-ifdef-mode-map}"
  :group 'hide-ifdef :lighter " Ifdef"
  (if hide-ifdef-mode
      (progn
        ;; inherit global values

        ;; `hide-ifdef-env' is now a global variable.
        ;; We can still simulate the behavior of older hideif versions (i.e.
        ;; `hide-ifdef-env' being buffer local) by clearing this variable
        ;; (C-c @ C) every time before hiding current buffer.
;;      (setq-local hide-ifdef-env
;;           (default-value 'hide-ifdef-env))
        (setq hide-ifdef-env (default-value 'hide-ifdef-env))
        ;; Some C/C++ headers might have other ways to prevent reinclusion and
        ;; thus would like `hide-ifdef-expand-reinclusion-guard' to be nil.
        (setq-local hide-ifdef-expand-reinclusion-guard
                    (default-value 'hide-ifdef-expand-reinclusion-guard))
        (setq-local hide-ifdef-hiding
                    (default-value 'hide-ifdef-hiding))
        (setq-local hif-outside-read-only buffer-read-only)
        (setq-local line-move-ignore-invisible t)
        (add-hook 'change-major-mode-hook
                  (lambda () (hide-ifdef-mode -1)) nil t)

        (add-to-invisibility-spec '(hide-ifdef . t))

        (if hide-ifdef-initially
            (hide-ifdefs)
          (show-ifdefs)))
    ;; else end hide-ifdef-mode
    (kill-local-variable 'line-move-ignore-invisible)
    (remove-from-invisibility-spec '(hide-ifdef . t))
    (when hide-ifdef-hiding
      (show-ifdefs))))

(defun hif-clear-all-ifdef-defined ()
  "Clears all symbols defined in `hide-ifdef-env'.
It will backup this variable to `hide-ifdef-env-backup' before clearing to
prevent accidental clearance.
When prefixed, it swaps current symbols with the backup ones."
  (interactive)
  (if current-prefix-arg
      (if hide-ifdef-env-backup
          (when (y-or-n-p (format
                           "Restore all %d #defined symbols just cleared? "
                           (length hide-ifdef-env-backup)))
            (let ((tmp hide-ifdef-env-backup))
              (setq hide-ifdef-env hide-ifdef-env-backup)
              (setq hide-ifdef-env-backup tmp))
            (message "Backup symbols restored."))
        (message "No backup symbol to restore."))
    (when (y-or-n-p (format "Clear all %d #defined symbols? "
                            (length hide-ifdef-env)))
      (if hide-ifdef-env ;; backup only if not empty
          (setq hide-ifdef-env-backup hide-ifdef-env))
      (setq hide-ifdef-env nil)
      (message "All defined symbols cleared." ))))

(defun hif-show-all (&optional start end)
  "Show all of the text in the current buffer.
If there is a marked region from START to END it only shows the symbols within."
  (interactive
   (if (use-region-p)
       (list (region-beginning) (region-end))
     (list (point-min) (point-max))))
  (hif-show-ifdef-region
   (or start (point-min)) (or end (point-max))))

;; By putting this on after-revert-hook, we arrange that it only
;; does anything when revert-buffer avoids turning off the mode.
;; (That can happen in VC.)
(defun hif-after-revert-function ()
  (and hide-ifdef-mode hide-ifdef-hiding
       (hide-ifdefs nil nil t)))
(add-hook 'after-revert-hook #'hif-after-revert-function)

(defun hif-end-of-line ()
  "Find the end-point of line concatenation."
  (end-of-line)
  (while (progn (skip-chars-backward " \t" (line-beginning-position))
                (= ?\\ (char-before)))
    (end-of-line 2)))

(defun hif-merge-ifdef-region (start end)
  "Merge nearby ifdef regions to form a bigger overlay.
The region is defined by START and END.  This will decrease the number of
overlays created."
  ;; Generally there is no need to call itself recursively since there should
  ;; originally exists no un-merged regions; however, if a part of the file is
  ;; hidden with `hide-ifdef-lines' equals to nil while another part with 't,
  ;; this case happens.
  ;; TODO: Should we merge? or just create a container overlay? -- this can
  ;; prevent `show-ifdefs' expanding too many hidden contents since there
  ;; is only a big overlay exists there without any smaller overlays.
  (save-restriction
    (widen) ; Otherwise `point-min' and `point-max' will be restricted and thus
                                        ; fail to find neighbor overlays
    (let ((begovrs (overlays-in
                    (max (- start 2) (point-min))
                    (max (- start 1) (point-min))))
          (endovrs (overlays-in
                    (min (+ end 1) (point-max))
                    (min (+ end 2) (point-max))))
          (ob nil)
          (oe nil)
          b e)
      ;; Merge overlays before START
      (dolist (o begovrs)
        (when (overlay-get o 'hide-ifdef)
          (setq b (min start (overlay-start o))
                e (max end (overlay-end o)))
          (move-overlay o b e)
          (hif-merge-ifdef-region b e)
          (setq ob o)))
      ;; Merge overlays after END
      (dolist (o endovrs)
        (when (overlay-get o 'hide-ifdef)
          (setq b (min start (overlay-start o))
                e (max end (overlay-end o)))
          (move-overlay o b e)
          (hif-merge-ifdef-region b e)
          (setf oe o)))
      ;; If both START and END merging happens, merge into bigger one
      (when (and ob oe)
        (let ((b (min (overlay-start ob) (overlay-start oe)))
              (e (max (overlay-end ob) (overlay-end oe))))
          (delete-overlay oe)
          (move-overlay ob b e)
          (hif-merge-ifdef-region b e)))
      (or ob oe))))

(defun hide-ifdef-region-internal (start end)
  (unless (hif-merge-ifdef-region start end)
  (let ((o (make-overlay start end)))
    (overlay-put o 'hide-ifdef t)
    (if hide-ifdef-shadow
        (overlay-put o 'face 'hide-ifdef-shadow)
        (overlay-put o 'invisible 'hide-ifdef)))))

(defun hide-ifdef-region (start end)
  "START is the start of a #if, #elif, or #else form.  END is the ending part.
Everything including these lines is made invisible."
  (save-excursion
    (goto-char start) (hif-end-of-line) (setq start (point))
    (goto-char end) (hif-end-of-line) (setq end (point))
    (hide-ifdef-region-internal start end)))

(defun hif-show-ifdef-region (start end)
  "Everything between START and END is made visible."
  (let ((onum (length (overlays-in start end))))
    (remove-overlays start end 'hide-ifdef t)
    (/= onum (length (overlays-in start end)))))


;;===%%SF%% evaluation (Start)  ===

(defun hif-eval (form)
  "Evaluate hideif internal representation."
  (let ((val (eval form t)))
    (if (stringp val)
        (or (get-text-property 0 'hif-value val)
            val)
      val)))

;; It is not useful to set this to anything but `eval'.
;; In fact, the variable might as well be eliminated.
(defvar hide-ifdef-evaluator #'hif-eval
  "The function to use to evaluate a form.
The evaluator is given a canonical form and returns t if text under
that form should be displayed.")

(defvar hif-undefined-symbol nil
  "...is by default considered to be false.")


(defun hif-set-var (var value)
  "Prepend (VAR VALUE) pair to `hide-ifdef-env'."
  (setq hide-ifdef-env (cons (cons var value) hide-ifdef-env)))

(defconst hif-predefine-alist
  '((__LINE__         . hif-__LINE__)
    (__FILE__         . hif-__FILE__)
    (__COUNTER__      . hif-__COUNTER__)
    (__cplusplus      . hif-__cplusplus)
    (__DATE__         . hif-__DATE__)
    (__TIME__         . hif-__TIME__)
    (__STDC__         . hif-__STDC__)
    (__STDC_VERSION__ . hif-__STDC_VERSION__)
    (__STDC_HOST__    . hif-__STDC_HOST__)
    (__BASE_FILE__    . hif-__FILE__)))

(declare-function semantic-c-hideif-lookup  "semantic/bovine/c" (var))
(declare-function semantic-c-hideif-defined "semantic/bovine/c" (var))

(defun hif-lookup (var)
  (or (when (bound-and-true-p semantic-c-takeover-hideif)
        (semantic-c-hideif-lookup var))
      (let ((val (assq var hide-ifdef-env)))
        (if val
            (cdr val)
          (if (setq val (assq var hif-predefine-alist))
              (funcall (cdr val))
            hif-undefined-symbol)))))

(defun hif-defined (var)
  (let (def)
    (cond
     ((bound-and-true-p semantic-c-takeover-hideif)
      (semantic-c-hideif-defined var))
     ;; Here we can't use hif-lookup as an empty definition like `#define EMPTY'
     ;; is considered defined but is evaluated as nil.
     ((assq var hide-ifdef-env) 1)
     ((and (setq def (assq var hif-predefine-alist))
           (funcall (cdr def))) 1)
     (t 0))))

;;===%%SF%% evaluation (End)  ===



;;===%%SF%% parsing (Start)  ===
;;;  The code that understands what ifs and ifdef in files look like.

(defconst hif-cpp-prefix      "\\(^\\|\r\\)?[ \t]*#[ \t]*")
(defconst hif-ifxdef-regexp   (concat hif-cpp-prefix "if\\(n\\)?def"))
(defconst hif-ifndef-regexp   (concat hif-cpp-prefix "ifndef"))
(defvar hif-ifx-regexp      (concat hif-cpp-prefix "if\\((\\|\\(n?def\\)?[ \t]+\\)"))
(defconst hif-elif-regexp     (concat hif-cpp-prefix "elif"))
(defconst hif-else-regexp     (concat hif-cpp-prefix "else"))
(defconst hif-endif-regexp    (concat hif-cpp-prefix "endif"))
(defconst hif-ifx-else-endif-regexp
  (concat hif-ifx-regexp "\\|" hif-elif-regexp "\\|" hif-else-regexp "\\|"
          hif-endif-regexp))
(defconst hif-macro-expr-prefix-regexp
  (concat hif-cpp-prefix "\\(if(\\|if\\(n?def\\)?[ \t]+\\|elif\\|define[ \t]+\\)"))

(defconst hif-line-concat     "\\\\[ \t]*[\n\r]")
;; If `hif-white-regexp' is modified, `hif-tokenize' might need to be modified
;; accordingly.
(defconst hif-white-regexp    (concat "\\(?:[ \t]\\|/\\*.*?\\*/"
                                      "\\|\\(?:" hif-line-concat "\\)\\)*"))
(defconst hif-define-regexp   (concat hif-cpp-prefix "\\(define\\|undef\\)"))
(defconst hif-id-regexp       (concat "[[:alpha:]_][[:alnum:]_]*"))
(defconst hif-etc-regexp      "\\.\\.\\.")
(defconst hif-macroref-regexp
  (concat hif-white-regexp "\\(" hif-id-regexp "\\)"
          "\\("
          "(" hif-white-regexp
          "\\(" hif-id-regexp "\\)?" hif-white-regexp
          "\\(" "," hif-white-regexp hif-id-regexp hif-white-regexp "\\)*"
          "\\(" "," hif-white-regexp "\\)?" "\\(" hif-etc-regexp "\\)?" hif-white-regexp
          ")"
          "\\)?" ))

;; The point here is *NOT* to do "syntax error checking" for C(++) compiler, but
;; to parse and recognize *already valid* numeric literals.  Therefore we don't
;; need to worry if number like "0x12'" is invalid, leave it to the compiler.
;; Otherwise, the runtime performance of hideif would be poor.
;;
;; GCC fixed-point literal extension:
;;
;; ‘ullk’ or ‘ULLK’ for unsigned long long _Accum and _Sat unsigned long long _Accum
;; ‘ullr’ or ‘ULLR’ for unsigned long long _Fract and _Sat unsigned long long _Fract
;;
;; ‘llk’ or ‘LLK’ for long long _Accum and _Sat long long _Accum
;; ‘llr’ or ‘LLR’ for long long _Fract and _Sat long long _Fract
;; ‘uhk’ or ‘UHK’ for unsigned short _Accum and _Sat unsigned short _Accum
;; ‘ulk’ or ‘ULK’ for unsigned long _Accum and _Sat unsigned long _Accum
;; ‘uhr’ or ‘UHR’ for unsigned short _Fract and _Sat unsigned short _Fract
;; ‘ulr’ or ‘ULR’ for unsigned long _Fract and _Sat unsigned long _Fract
;;
;; ‘lk’ or ‘LK’ for long _Accum and _Sat long _Accum
;; ‘lr’ or ‘LR’ for long _Fract and _Sat long _Fract
;; ‘uk’ or ‘UK’ for unsigned _Accum and _Sat unsigned _Accum
;; ‘ur’ or ‘UR’ for unsigned _Fract and _Sat unsigned _Fract
;; ‘hk’ or ‘HK’ for short _Accum and _Sat short _Accum
;; ‘hr’ or ‘HR’ for short _Fract and _Sat short _Fract
;;
;; ‘r’ or ‘R’ for _Fract and _Sat _Fract
;; ‘k’ or ‘K’ for _Accum and _Sat _Accum

;; C++14 also include '0b' for binary and "'" as separator
(defconst hif-numtype-suffix-regexp
  ;;  "\\(ll[uU]\\|LL[uU]\\|[uU]?ll\\|[uU]?LL\\|[lL][uU]\\|[uU][lL]\\|[uUlLfF]\\)"
  (concat
   "\\(\\(ll[uU]\\|LL[uU]\\|[uU]?ll\\|[uU]?LL\\|[lL][uU]\\|[uU][lL]\\|"
   "[uU][hH]\\)[kKrR]?\\|" ; GCC fixed-point extension
   "[dD][dDfFlL]\\|"       ; GCC floating-point extension
   "[uUlLfF]\\)"))
(defconst hif-bin-regexp
  (concat "[+-]?0[bB]\\([01']+\\)"
          hif-numtype-suffix-regexp "?"))
(defconst hif-hex-regexp
  (concat "[+-]?0[xX]\\([[:xdigit:]']+\\)"
          hif-numtype-suffix-regexp "?"))
(defconst hif-oct-regexp
  (concat "[+-]?0[0-7']+"
          hif-numtype-suffix-regexp "?"))
(defconst hif-dec-regexp
  (concat "[+-]?\\(0\\|[1-9][0-9']*\\)"
          hif-numtype-suffix-regexp "?"))

(defconst hif-decfloat-regexp
  ;; `hif-string-to-decfloat' relies on the number and ordering of parentheses
  (concat
   "\\(?:"
   "\\([+-]?[0-9]+\\)\\([eE][+-]?[0-9]+\\)?[dD]?[fFlL]?"
   "\\|\\([+-]?[0-9]+\\)\\.\\([eE][+-]?[0-9]+\\)?[dD]?[dDfFlL]?"
   "\\|\\([+-]?[0-9]*\\.[0-9]+\\)\\([eE][+-]?[0-9]+\\)?[dD]?[dDfFlL]?"
   "\\)"))

;; C++17 hexadecimal floating point literal
(defconst hif-hexfloat-regexp
  ;; `hif-string-to-hexfloat' relies on the ordering of regexp groupings
  (concat
   "[+-]?\\(?:"
   "0[xX]\\([[:xdigit:]']+\\)[pP]\\([+-]?[0-9']+\\)[fFlL]?"
   "\\|"
   "0[xX]\\([[:xdigit:]']+\\)\\.[pP]\\([+-]?[0-9']+\\)[fFlL]?"
   "\\|"
   "0[xX]\\([[:xdigit:]']*\\)\\.\\([[:xdigit:]']+\\)[pP]\\([+-]?[0-9']+\\)[fFlL]?"
   "\\)"))

;; Store the current token and the whole token list during parsing.
;; Bound dynamically.
(defvar hif-token)
(defvar hif-token-list)

(defconst hif-token-alist
  '(("||"  . hif-or)
    ("&&"  . hif-and)
    ("|"   . hif-logior)
    ("^"   . hif-logxor)
    ("&"   . hif-logand)
    ("<<"  . hif-shiftleft)
    (">>"  . hif-shiftright)
    ("=="  . hif-equal)
    ;; Note: we include tokens like `=' which aren't supported by CPP's
    ;; expression syntax, because they are still relevant for the tokenizer,
    ;; especially in conjunction with ##.
    ("="   . hif-assign)
    ("!="  . hif-notequal)
    ("##"  . hif-token-concat)
    ("!"   . hif-not)
    ("~"   . hif-lognot)
    ("("   . hif-lparen)
    (")"   . hif-rparen)
    (">"   . hif-greater)
    ("<"   . hif-less)
    (">="  . hif-greater-equal)
    ("<="  . hif-less-equal)
    ("+"   . hif-plus)
    ("-"   . hif-minus)
    ("*"   . hif-multiply)
    ("/"   . hif-divide)
    ("%"   . hif-modulo)
    ("?"   . hif-conditional)
    (":"   . hif-colon)
    (","   . hif-comma)
    ("#"   . hif-stringify)
    ("..." . hif-etc)
    ("defined" . hif-defined)))

(defconst hif-valid-token-list (mapcar #'cdr hif-token-alist))

(defconst hif-token-regexp
  ;; The ordering of regexp grouping is crucial to `hif-strtok'
  (concat
   ;; hex/binary:
   "\\([+-]?0[xXbB]\\([[:xdigit:]']+\\)?\\.?\\([[:xdigit:]']+\\)?\\([pP]\\([+-]?[0-9]+\\)\\)?"
   hif-numtype-suffix-regexp "?\\)"
   ;; decimal/octal:
   "\\|\\(\\([+-]?[0-9']+\\(\\.[0-9']*\\)?\\)\\([eE][+-]?[0-9]+\\)?"
   hif-numtype-suffix-regexp "?\\)"
   "\\|" (regexp-opt (mapcar #'car hif-token-alist) t)
   "\\|\\(\\w+\\)"))

;; C++11 Unicode string literals (L"" u8"" u"" U"" R"" LR"" u8R"" uR"")
(defconst hif-unicode-prefix-regexp  "\\(?:u8R?\\|[uUL]R?\\|R\\)")
(defconst hif-string-literal-regexp
  (concat hif-unicode-prefix-regexp "?"
          "\\(\"\\(?:[^\"\\]\\|\\\\.\\)*\"\\)"))

;; matching and conversion

(defun hif-full-match (regexp string)
  "A full REGEXP match of STRING instead of partially match."
  (string-match (concat "\\`" regexp "\\'") string))

(defun hif-is-number (string)
  "Check if STRING is a valid C(++) numeric literal."
  (or (hif-full-match hif-dec-regexp string)
      (hif-full-match hif-hex-regexp string)
      (hif-full-match hif-oct-regexp string)
      (hif-full-match hif-bin-regexp string)))

(defun hif-is-float (string)
  "Check if STRING is a valid C(++) floating point literal."
  (or (hif-full-match hif-decfloat-regexp string)
      (hif-full-match hif-hexfloat-regexp string)))

(defun hif-delete-char-in-string (char string)
  "Delete CHAR in STRING inplace."
  (let ((i (length string))
        (s nil))
    (while (> i 0)
      (setq i (1- i))
      (unless (eq (aref string i) char)
        (setq s (cons (aref string i) s))))
    (concat s)))

(defun hif-string-to-decfloat (string &optional fix exp)
  "Convert a C(++) decimal floating formatted string into float.
Assuming we've just regexp-matched with `hif-decfloat-regexp' and it matched.
if REMATCH is t, do a rematch."
  ;; In elisp `(string-to-number "01.e2")' will return 1 instead of the expected
  ;; 100.0; therefore we need to write our own.
  ;; This function relies on the regexp groups of `hif-hexfloat-regexp'
  (if (or fix exp)
      (setq fix (hif-delete-char-in-string ?' fix)
            exp (hif-delete-char-in-string ?' exp))
    ;; rematch
    (setq string (hif-delete-char-in-string ?' string))
    (hif-full-match hif-decfloat-regexp string)
    (setq fix (or (match-string 1 string)
                  (match-string 3 string)
                  (match-string 5 string))
          exp (or (match-string 2 string)
                  (match-string 4 string)
                  (match-string 6 string))))
  (setq fix (string-to-number fix)
        exp (if (zerop (length exp)) ;; nil or ""
                0 (string-to-number (substring-no-properties exp 1))))
  (* fix (expt 10 exp)))

(defun hif-string-to-hexfloat (string &optional int fra exp)
  "Convert a C++17 hex float formatted string into float.
Assuming we've just regexp-matched with `hif-hexfloat-regexp' and it matched.
if REMATCH is t, do a rematch."
  ;; This function relies on the regexp groups of `hif-hexfloat-regexp'
  (let ((negate (if (eq ?- (aref string 0)) -1.0 1.0)))
    (if (or int fra exp)
        (setq int (hif-delete-char-in-string ?' int)
              fra (hif-delete-char-in-string ?' fra)
              exp (hif-delete-char-in-string ?' exp))
      (setq string (hif-delete-char-in-string ?' string))
      (hif-full-match hif-hexfloat-regexp string)
      (setq int (or (match-string 1 string)
                    (match-string 3 string)
                    (match-string 5 string))
            fra (or (match-string 2 string)
                    (match-string 4 string)
                    (match-string 6 string))
            exp (match-string 7 string)))
    (setq int (if (zerop (length int)) ;; nil or ""
                  0 (string-to-number int 16))
          fra (if (zerop (length fra))
                  0 (/ (string-to-number fra 16)
                       (expt 16.0 (length fra))))
          exp (if (zerop (length exp))
                  0 (string-to-number exp)))
    (* negate (+ int fra) (expt 2.0 exp))))

(defun hif-string-to-number (string &optional base)
  "Like `string-to-number', but it understands C(++) literals."
  (setq string (hif-delete-char-in-string ?' string))
  (string-to-number string base))

;; The dynamic binding variable `hif-simple-token-only' is shared only by
;; `hif-tokenize' and `hif-find-define'. The purpose is to prevent `hif-tokenize'
;; from returning one more value to indicate a simple token is scanned. This help
;; speeding up macro evaluation on those very simple cases like integers or
;; literals.
;; Check the long comments before `hif-find-define' for more details. [lukelee]
(defvar hif-simple-token-only)

(defsubst hif-is-white (c)
  (memq c '(?  ?\t ?\n ?\r)))

(defun hif-strtok (string &optional rematch)
  "Convert STRING into a hideif mode internal token.
Assuming we've just performed a `hif-token-regexp' lookup."
  ;; This function relies on the regexp groups of `hif-token-regexp'
  ;; New hideif internal number representation: a text string with `hif-value'
  ;; property to keep its value. Strings without `hif-value' property is a
  ;; normal C(++) string.  This is mainly for stringification.  The original
  ;; implementation only keep the value thus a C++ number like octal 01234
  ;; will become "668" after being stringified instead of the expected "01234".
  (let (bufstr m1 m3 m5 m6 m8 neg ch val dec)
    (when rematch
      (string-match hif-token-regexp string)
      (setq bufstr string))

    (cond

     ;; decimal/octal
     ((match-string 8 bufstr)
      (setq m6 (match-string 9 bufstr))
      (setq val
            (if (or (setq m8 (match-string 11 bufstr))
                    (match-string 10 bufstr)) ;; floating
                ;; TODO: do we need to add 'hif-type property for
                ;; type-checking, but this will slow things down
                (hif-string-to-decfloat string m6 m8)
              (setq ch (aref string 0))
              (hif-string-to-number
               string
               ;; octal begin with `0'
               (if (and (> (length string) 1)
                        (or (eq ch ?0)
                            ;; -0... or +0...
                            (and (memq ch '(?- ?+))
                                 (eq (aref string 1) ?0))))
                   8 (setq dec 10)))))
      ;; Decimal integer without sign and extension is identical to its
      ;; string form, make it as simple as possible
      (if (and dec
               (null (match-string 12 bufstr)) ;; no extension like 'UL'
               (not (memq ch '(?- ?+))))
          val
        (add-text-properties 0 1 (list 'hif-value val) string)
        string))

     ;; hex/binary
     ((match-string 1 bufstr)
      (setq m3 (match-string 3 bufstr))
      (add-text-properties
       0 1
       (list 'hif-value
             (if (or (setq m5 (match-string 5 bufstr))
                     m3)
                 (hif-string-to-hexfloat
                  string
                  (match-string 2 bufstr) m3 m5) ;; hexfloat
               (setq neg (if (eq (aref string 0) ?-) -1 1))
               (* neg
                  (hif-string-to-number
                   ;; (5-(-1))/2=3; (5-1)/2=2
                   (substring-no-properties string (ash (- 5 neg) -1))
                   ;; (3-(-1))/2=2; (3-1)/2=1
                   (if (or (eq (setq ch (aref string (ash (- 3 neg) -1))) ?x)
                           (eq ch ?X)) ;; hex
                       16 2)))))
       string) string)

     ;; operator
     ((setq m1 (match-string 14 bufstr))
      (cdr (assoc m1 hif-token-alist #'string-equal)))

     (t
      (setq hif-simple-token-only nil)
      (hif--intern-safe string)))))

(defun hif-backward-comment (&optional start end)
  "If we're currently within a C(++) comment, skip them backwards."
  ;; Ignore trailing white spaces after comment
  (setq end (or end (point)))
  (while (and (> (1- end) 1)
              (hif-is-white (char-after (1- end))))
     (cl-decf end))
  (let ((p0 end)
        p cmt ce ws we ;; ce:comment start, ws:white start, we whilte end
        cmtlist) ;; pair of (start.end) of comments
    (setq start (or start (progn (beginning-of-line) (point)))
          p start)
    (while (< (1+ p) end)
      (if (char-equal ?/ (char-after p)) ; /
          (if (char-equal ?/ (char-after (1+ p))) ; //
              (progn
                ;; merge whites immediately ahead
                (setq ce (if (and we (= (1- p) we)) ws p))
                ;; scan for end of line
                (while (and (< (cl-incf p) end)
                            (not (char-equal ?\n (char-after p)))
                            (not (char-equal ?\r (char-after p)))))
                ;; Merge with previous comment if immediately followed
                (push (cons (if (and cmtlist
                                     (= (cdr (car cmtlist)) ce))
                                (car (pop cmtlist)) ;; extend previous comment
                              ce)
                            p)
                      cmtlist))
            (when (char-equal ?* (char-after (1+ p))) ; /*
              ;; merge whites immediately ahead
              (setq ce (if (and we (= (1- p) we)) ws p))
              ;; Check if it immediately follows previous /*...*/ comment;
              ;; if yes, extend and merge into previous comment
              (setq cmt (if (and cmtlist
                                 (= (cdr (car cmtlist)) ce))
                            (car (pop cmtlist)) ;; extend previous comment
                          ce))
              (setq p (+ 2 p))
              ;; Scanning for `*/'
              (catch 'break
                (while (< (1+ p) end)
                  (if (not (and (char-equal ?* (char-after p))
                                (char-equal ?/ (char-after (1+ p)))))
                      (cl-incf p)
                    ;; found `*/', mark end pos
                    (push (cons cmt (1+ (setq p (1+ p)))) cmtlist)
                    (throw 'break nil)))
                ;; (1+ p) >= end
                (push (cons cmt end) cmtlist))))
        ;; Trace most recent continuous white spaces before a comment
        (if (char-equal ?  (char-after p))
            (if (and ws (= we (1- p))) ;; continued
                (setq we p)
              (setq ws p
                    we p))
          (setq ws nil
                we nil)))
      (cl-incf p))
    ;; Goto beginning of the last comment, if we're within
    (setq cmt (car cmtlist)) ;; last cmt
    (setq cmt (if (and cmt
                       (>= p0 (car cmt))
                       (<= p0 (cdr cmt)))
                  (car cmt) ;; beginning of the last comment
                p0))
    ;; Ignore leading whites ahead of comment
    (while (and (> (1- cmt) 1)
                (hif-is-white (char-after (1- cmt))))
       (cl-decf cmt))
    (goto-char cmt)))

(defun hif-tokenize (start end)
  "Separate string between START and END into a list of tokens."
  (let ((token-list nil)
        ;; Similar to `hif-white-regexp' but keep the spaces if there are
        (white-regexp (concat "\\(?:"
                              "\\([ \t]+\\)\\|/\\*.*?\\*/"
                              "\\|\\(?:" hif-line-concat "\\)"
                              "\\)*"))
        token)
    (setq hif-simple-token-only t)
    (with-syntax-table hide-ifdef-syntax-table
      (save-excursion
        (save-restriction
          ;; Narrow down to the focusing region so that the ending white spaces
          ;; of that line will not be treated as a white, as `looking-at' won't
          ;; look outside the restriction; otherwise it will note the last token
          ;; or string as one with an `hif-space' property.
          (setq end (hif-backward-comment start end))
          (narrow-to-region start end)
          (goto-char start)
          (while (progn (forward-comment (point-max)) (< (point) end))
            ;; (message "expr-start = %d" expr-start) (sit-for 1)
            (cond
             ((looking-at "\\\\\n")
              (forward-char 2))

             ((looking-at hif-string-literal-regexp)
              (setq token (match-string-no-properties 1))
              (goto-char (match-end 0))
              (when (looking-at white-regexp)
                (if (not (zerop (length (match-string-no-properties 1))))
                    (add-text-properties 0 1 '(hif-space t) token))
                (goto-char (match-end 0)))
              (push token token-list))

             ((looking-at hif-token-regexp)
              (goto-char (match-end 0))
              (setq token (hif-strtok (match-string-no-properties 0)))
              (push token token-list)
              (when (looking-at white-regexp)
                (if (not (zerop (length (match-string-no-properties 1))))
                    ;; We can't just append a space to the token string,
                    ;; otherwise `0xf0 ' ## `01' will become `0xf0 01' instead
                    ;; of the expected `0xf001', hence a standalone `hif-space'
                    ;; is placed instead.
                    (push 'hif-space token-list))
                (goto-char (match-end 0))))

             ((looking-at "\r") ; Sometimes MS-Windows user will leave CR in
              (forward-char 1)) ;  the source code. Let's not get stuck here.

             (t (error "Bad preprocessor expression: %s" (buffer-string)))))))
      (if (eq 'hif-space (car token-list))
          (setq token-list (cdr token-list))) ;; remove trailing white space
      (nreverse token-list))))

;;------------------------------------------------------------------------
;; Translate C preprocessor #if expressions using recursive descent.
;; This parser was limited to the operators &&, ||, !, and "defined".
;; Added ==, !=, +, and -.  Gary Oberbrunner, garyo@avs.com, 8/9/94
;;
;; Implement the C language operator precedence table. Add all those
;; missing operators that could be used in macros. Luke Lee 2013-09-04

;;  | Operator Type        | Operator                    | Associativity |
;;  +----------------------+-----------------------------+---------------+
;;  | Primary Expression   | () [] . -> expr++ expr--    | left-to-right |
;;  | Unary Operators      | * & + - ! ~ ++expr --expr   | right-to-left |
;;  |                      | (typecast) sizeof           |               |
;;  | Binary Operators     | * / %                       | left-to-right |
;;  |                      | + -                         |               |
;;  |                      | >> <<                       |               |
;;  |                      | < > <= >=                   |               |
;;  |                      | == !=                       |               |
;;  |                      | &                           |               |
;;  |                      | ^                           |               |
;;  |                      | |                           |               |
;;  |                      | &&                          |               |
;;  |                      | ||                          |               |
;;  | Ternary Operator     | ?:                          | right-to-left |
;; x| Assignment Operators | = += -= *= /= %= >>= <<= &= | right-to-left |
;;  |                      | ^= =                        |               |
;;  | Comma                | ,                           | left-to-right |

(defun hif-nexttoken (&optional keep-space)
  "Pop the next token from token-list into the let variable `hif-token'."
  (let ((prevtoken hif-token))
    (while (progn
             (setq hif-token (pop hif-token-list))
             (if keep-space ; keep only one space
                 (and (eq prevtoken 'hif-space)
                      (eq hif-token 'hif-space))
               (eq hif-token 'hif-space)))))
  hif-token)

(defun hif-split-signed-token ()
  "Split current numeric token into two (hif-plus/minus num)."
  (let* (val ch0 head)
    (when (and (stringp hif-token)
               (setq val (get-text-property 0 'hif-value hif-token))
               ;; explicitly signed?
               (memq (setq ch0 (aref hif-token 0)) '(?+ ?-)))
      (if (eq ch0 ?+)
          (setq head 'hif-plus)
        (setq head 'hif-minus
              val (- val)))
      (setq hif-token (substring hif-token 1))
      (add-text-properties 0 1 (list 'hif-value val) hif-token)
      (push hif-token hif-token-list)
      (setq hif-token head))))

(defsubst hif-if-valid-identifier-p (id)
  (not (or (numberp id)
           (stringp id)
           (and (atom id)
                (eq 'defined id)))))

(defun hif-define-operator (tokens)
  "\"Upgrade\" hif-define XXX to `(hif-define XXX)' so it won't be substituted."
  (if (memq 'hif-defined tokens)
      (let* ((hif-token-list tokens)
             hif-token
             target
             paren)
        (setq tokens nil) ;; now it becomes the result
        (while (hif-nexttoken t) ;; keep `hif-space'
          (when (eq hif-token 'hif-defined)
            ;; defined XXX, start ignoring `hif-space'
            (hif-nexttoken)
            (if (setq paren (eq hif-token 'hif-lparen))
                (hif-nexttoken))
            (if (not (hif-if-valid-identifier-p
                      (setq target hif-token)))
                (error "`defined' followed by non-identifier: %S" target))
            (if (and paren
                     (not (eq (hif-nexttoken) 'hif-rparen)))
                (error "Missing right parenthesis for `defined'"))
            (setq hif-token
                  (list 'hif-defined 'hif-lparen target 'hif-rparen)))
          (push hif-token tokens))
        (nreverse tokens))
    tokens))

(define-obsolete-function-alias 'hif-flatten #'flatten-tree "27.1")

(defun hif-keep-single (l e)
  "Prevent two or more consecutive E in list L."
  (if (memq e l)
      (let (prev curr result)
        (while (progn
                 (setq prev curr
                       curr (car l)
                       l (cdr l))
                 curr)
          (unless (and (eq prev e)
                       (eq curr e))
            (push curr result)))
        (nreverse result))
    l))

(defun hif-expand-token-list (tokens &optional macroname expand_list level)
  "Perform expansion on TOKENS till everything expanded.
Self-reference (directly or indirectly) tokens are not expanded.
EXPAND_LIST is the list of macro names currently being expanded, used for
detecting self-reference.
Function-like macros with calling depth LEVEL 0 does not expand arguments,
this is to emulate the stringification behavior of C++ preprocessor."
  (catch 'self-referencing
    (let ((expanded nil)
          (remains (hif-define-operator
                    (hif-token-concatenation
                     (hif-token-stringification tokens))))
          tok rep)
      (setq level (if level level 0))
      (if macroname
          (setq expand_list (cons macroname expand_list)))
      ;; Expanding all tokens till list exhausted
      (while (setq tok (pop remains))
        (if (memq tok expand_list)
            ;; For self-referencing tokens, don't expand it
            (throw 'self-referencing tokens))
        (push
         (cond
          ((or (memq tok hif-valid-token-list)
               (numberp tok)
               (stringp tok))
           tok)

          ((setq rep (hif-lookup tok))
           (if (and (listp rep)
                    (eq (car rep) 'hif-define-macro)) ; A defined macro
               ;; Recursively expand it
               ;; only in defined macro do we increase the nesting LEVEL
               (if (cadr rep) ; Argument list is not nil
                   (if (not (or (eq (car remains) 'hif-lparen)
                                ;; hif-space hif-lparen
                                (and (eq (car remains) 'hif-space)
                                     (eq (cadr remains) 'hif-lparen)
                                     (setq remains (cdr remains)))))
                       ;; No argument list, no invocation
                       tok
                     ;; Argumented macro, get arguments and invoke it.
                     ;; Dynamically bind `hif-token-list' and `hif-token'
                     ;; for `hif-macro-supply-arguments'
                     (let* ((hif-token-list (cdr remains))
                            (hif-token nil)
                            (parmlist
                             (if (zerop level)
                                 (hif-get-argument-list t)
                               (mapcar (lambda (a)
                                         (hif-expand-token-list
                                          a nil nil (1+ level)))
                                       (hif-get-argument-list t))))
                            (result
                             (hif-expand-token-list
                              (hif-macro-supply-arguments tok parmlist)
                              tok expand_list (1+ level))))
                       (setq remains (cons hif-token hif-token-list))
                       result))
                 ;; Argument list is nil, direct expansion
                 (setq rep (hif-expand-token-list
                            (nth 2 rep) ; Macro's token list
                            tok expand_list))
                 ;; Replace all remaining references immediately
                 (setq remains (cl-substitute tok rep remains))
                 rep)
             ;; Lookup tok returns an atom
             rep))

          ;;[2013-10-22 16:06:12 +0800] Must keep the token, removing
          ;; this token might results in an incomplete expression that
          ;; cannot be parsed further.
          ;;((= 1 (hif-defined tok)) ; defined (hif-defined tok)=1,
          ;;  ;;but empty (hif-lookup tok)=nil, thus remove this token
          ;; (setq remains (delete tok remains))
          ;; nil)

          (t ; Usual IDs
           tok))

         expanded))

      (flatten-tree (nreverse expanded)))))

(defun hif-parse-exp (token-list &optional macroname)
  "Parse the TOKEN-LIST.
Return translated list in prefix form.  MACRONAME is applied when invoking
macros to prevent self-reference."
  (let ((hif-token-list (hif-expand-token-list token-list macroname nil))
        (hif-token nil))
    (hif-nexttoken)
    (prog1
        (and hif-token
             (hif-exprlist))
      (if hif-token ; is there still a token?
          (error "Error: unexpected token at line %d: `%s'"
                 (line-number-at-pos)
                 (or (car (rassq hif-token hif-token-alist))
                     hif-token))))))

(defun hif-exprlist ()
  "Parse an exprlist: expr { `,' expr }."
  (let ((result (hif-expr)))
    (if (eq hif-token 'hif-comma)
        (let ((temp (list result)))
          (while
            (progn
              (hif-nexttoken)
              (push (hif-expr) temp)
              (eq hif-token 'hif-comma)))
          (cons 'hif-comma (nreverse temp)))
      result)))

(defun hif-expr ()
  "Parse an expression as found in #if.
expr : or-expr | or-expr `?' expr `:' expr."
  (let ((result (hif-or-expr))
        middle)
    (while (eq hif-token 'hif-conditional)
      (hif-nexttoken)
      (setq middle (hif-expr))
      (if (eq hif-token 'hif-colon)
          (progn
            (hif-nexttoken)
            (setq result (list 'hif-conditional result middle (hif-expr))))
        (error "Error: unexpected token: %s" hif-token)))
    result))

(defun hif-or-expr ()
  "Parse an or-expr : and-expr | or-expr `||' and-expr."
  (let ((result (hif-and-expr)))
    (while (eq hif-token 'hif-or)
      (hif-nexttoken)
      (setq result (list 'hif-or result (hif-and-expr))))
  result))

(defun hif-and-expr ()
  "Parse an and-expr : logior-expr | and-expr `&&' logior-expr."
  (let ((result (hif-logior-expr)))
    (while (eq hif-token 'hif-and)
      (hif-nexttoken)
      (setq result (list 'hif-and result (hif-logior-expr))))
    result))

(defun hif-logior-expr ()
  "Parse a logor-expr : logxor-expr | logor-expr `|' logxor-expr."
  (let ((result (hif-logxor-expr)))
    (while (eq hif-token 'hif-logior)
      (hif-nexttoken)
      (setq result (list 'hif-logior result (hif-logxor-expr))))
    result))

(defun hif-logxor-expr ()
  "Parse a logxor-expr : logand-expr | logxor-expr `^' logand-expr."
  (let ((result (hif-logand-expr)))
    (while (eq hif-token 'hif-logxor)
      (hif-nexttoken)
      (setq result (list 'hif-logxor result (hif-logand-expr))))
    result))

(defun hif-logand-expr ()
  "Parse a logand-expr : eq-expr | logand-expr `&' eq-expr."
  (let ((result (hif-eq-expr)))
    (while (eq hif-token 'hif-logand)
      (hif-nexttoken)
      (setq result (list 'hif-logand result (hif-eq-expr))))
    result))

(defun hif-eq-expr ()
  "Parse an eq-expr : comp | eq-expr `=='|`!=' comp."
  (let ((result (hif-comp-expr))
        (eq-token nil))
    (while (memq hif-token '(hif-equal hif-notequal))
      (setq eq-token hif-token)
      (hif-nexttoken)
      (setq result (list eq-token result (hif-comp-expr))))
    result))

(defun hif-comp-expr ()
  "Parse a comp-expr : logshift | comp-expr `<'|`>'|`>='|`<=' logshift."
  (let ((result (hif-logshift-expr))
        (comp-token nil))
    (while (memq hif-token '(hif-greater hif-less hif-greater-equal
                                         hif-less-equal))
      (setq comp-token hif-token)
      (hif-nexttoken)
      (setq result (list comp-token result (hif-logshift-expr))))
    result))

(defun hif-logshift-expr ()
  "Parse a logshift : math | logshift `<<'|`>>' math."
  (let ((result (hif-math))
        (shift-token nil))
    (while (memq hif-token '(hif-shiftleft hif-shiftright))
      (setq shift-token hif-token)
      (hif-nexttoken)
      (setq result (list shift-token result (hif-math))))
    result))

(defun hif-math ()
  "Parse an expression with + or -.
       math : muldiv | math `+'|`-' muldiv."
  (let ((result (hif-muldiv-expr))
        (math-op nil))
    (while (or (memq hif-token '(hif-plus hif-minus))
               ;; One token lookahead
               (hif-split-signed-token))
      (setq math-op hif-token)
      (hif-nexttoken)
      (setq result (list math-op result (hif-muldiv-expr))))
    result))

(defun hif-muldiv-expr ()
  "Parse an expression with *,/,%.
       muldiv : factor | muldiv `*'|`/'|`%' factor."
  (let ((result (hif-factor))
        (math-op nil))
    (while (memq hif-token '(hif-multiply hif-divide hif-modulo))
      (setq math-op hif-token)
      (hif-nexttoken)
      (setq result (list math-op result (hif-factor))))
  result))

(defun hif-factor ()
  "Parse a factor.
factor : `!' factor | `~' factor | `(' exprlist `)' | `defined(' id `)' |
         id `(' parmlist `)' | strings | id."
  (cond
   ((eq hif-token 'hif-not)
    (hif-nexttoken)
    (list 'hif-not (hif-factor)))

   ((eq hif-token 'hif-lognot)
    (hif-nexttoken)
    (list 'hif-lognot (hif-factor)))

   ((eq hif-token 'hif-lparen)
    (hif-nexttoken)
    (let ((result (hif-exprlist)))
      (if (not (eq hif-token 'hif-rparen))
          (error "Bad token in parenthesized expression: %s" hif-token)
        (hif-nexttoken)
        result)))

   ((eq hif-token 'hif-defined)
    (hif-nexttoken)
    (let ((paren (when (eq hif-token 'hif-lparen) (hif-nexttoken) t))
          (ident hif-token))
      (if (memq hif-token '(or and not hif-defined hif-lparen hif-rparen))
          (error "Error: unexpected token: %s" hif-token))
      (when paren
        (hif-nexttoken)
        (unless (eq hif-token 'hif-rparen)
          (error "Error: expected \")\" after identifier")))
      (hif-nexttoken)
      `(hif-defined (quote ,ident))))

   ((stringp hif-token)
    (if (get-text-property 0 'hif-value hif-token)
        ;; new hideif internal number format for string concatenation
        (prog1 hif-token (hif-nexttoken))
      (hif-string-concatenation)))

   ((numberp hif-token)
    (prog1 hif-token (hif-nexttoken)))

   ;; Unary plus/minus.
   ((memq hif-token '(hif-minus hif-plus))
    (list (prog1 hif-token (hif-nexttoken)) 0 (hif-factor)))

   (t                                   ; identifier
    (let ((ident hif-token))
      (hif-nexttoken)
      (if (eq hif-token 'hif-lparen)
          (hif-place-macro-invocation ident)
        `(hif-lookup (quote ,ident)))))))

(defun hif-get-argument-list (&optional keep-space)
  (let ((nest 0)
        (parmlist nil) ; A "token" list of parameters, will later be parsed
        (parm nil))

    (while (and (or (not (eq (hif-nexttoken keep-space) 'hif-rparen))
                    (/= nest 0))
                hif-token)
      (if (eq (car (last parm)) 'hif-comma)
          (setq parm nil))
      (cond
       ((eq hif-token 'hif-lparen)
        (setq nest (1+ nest)))
       ((eq hif-token 'hif-rparen)
        (setq nest (1- nest)))
       ((and (eq hif-token 'hif-comma)
             (= nest 0))
        (push (nreverse parm) parmlist)
        (setq parm nil)))
      (push hif-token parm))

    (if (equal parm '(hif-comma)) ;; missing the last argument
        (setq parm '(nil)))
    (push (nreverse parm) parmlist) ; Okay even if PARM is nil
    (hif-nexttoken keep-space) ; Drop the `hif-rparen', get next token
    (nreverse parmlist)))

(defun hif-place-macro-invocation (ident)
  (let ((parmlist (hif-get-argument-list)))
    `(hif-invoke (quote ,ident) (quote ,parmlist))))

(defun hif-string-concatenation ()
  "Parse concatenated strings: string | strings string."
  (let ((result (substring-no-properties hif-token)))
    (while (stringp (hif-nexttoken))
      (setq result (concat
                    (substring result 0 -1)    ; remove trailing '"'
                    (substring hif-token 1)))) ; remove leading  '"'
    result))

(defun hif-define-macro (_parmlist _token-body)
  "A marker for defined macro with arguments.
This macro cannot be evaluated alone without parameters input."
  ;;TODO: input arguments at run time, use minibuffer to query all arguments
  (error
   "Argumented macro cannot be evaluated without passing any parameter"))

(defun hif-stringify (a)
  "Stringify a number, string or symbol."
  (cond
   ((numberp a)
    (number-to-string a))
   ((stringp a)
    ;; Remove properties here otherwise a string like "0x12 + 0x34" will be
    ;; later evaluated as (0x12 + 0x34) and become 0x70.
    ;; See also `hif-eval' and `hif-mathify'.
    (concat (substring-no-properties a)
            (if (get-text-property 0 'hif-space a) " ")))
   ((atom a)
    (if (memq a hif-valid-token-list)
        (car (rassq a hif-token-alist))
      (if (eq a 'hif-space)
          " "
        (symbol-name a))))
   ((listp a)  ;; stringify each element then concat
    (cl-loop for e in a
             concat (hif-stringify e)))
   (t
    (error "Invalid token to stringify"))))

(defun hif--intern-safe (str)
  (if (stringp str)
      (intern str)))

(defun hif-token-concat (l)
  "Concatenate a list of tokens into a longer token.
Also support weird (but valid) token concatenation like `>' ## `>' becomes `>>'.
Here we take care only those that can be evaluated during preprocessing time and
ignore all those that can only be evaluated at C(++) runtime (like `++', `--'
and `+='...)."
  (let ((str nil))
    (dolist (i l)
      ;;(assert (not (eq i 'hif-space)) nil ;; debug
      ;;        "Internal error: should not be concatenating `hif-space'")
      (setq str
            (concat str
                    (if (memq i hif-valid-token-list)
                        (car (rassq i hif-token-alist))
                      (hif-stringify i)))))
    ;; Check if it's a number, if yes, return the number instead of a symbol.
    ;; 'hif-value and 'hif-space properties are trimmed off by `hif-stringify'
    (hif-strtok str t)))

(defun hif-mathify (val)
  "Treat VAL as a hideif number: if it's t or nil, use 1 or 0."
  (cond
   ((stringp val)
    (or (get-text-property 0 'hif-value val)
        val))
   ((eq val t) 1)
   ((null val) 0)
   (t val)))

(defun hif-conditional (a b c)
  (if (not (zerop (hif-mathify a))) (hif-mathify b) (hif-mathify c)))
(defun hif-and (a b)
  (and (not (zerop (hif-mathify a))) (not (zerop (hif-mathify b)))))
(defun hif-or (a b)
  (or (not (zerop (hif-mathify a))) (not (zerop (hif-mathify b)))))
(defun hif-not (a)
  (zerop (hif-mathify a)))
(defun hif-lognot (a)
  (lognot (hif-mathify a)))

(defmacro hif-mathify-binop (fun)
  `(lambda (a b)
     ,(format "Like `%s' but treat t and nil as 1 and 0." fun)
     (,fun (hif-mathify a) (hif-mathify b))))

(defun hif-shiftleft (a b)
  (setq a (hif-mathify a))
  (setq b (hif-mathify b))
  (ash a b))

(defun hif-shiftright (a b)
  (setq a (hif-mathify a))
  (setq b (hif-mathify b))
  (ash a (- b)))


(defalias 'hif-multiply      (hif-mathify-binop *))
(defalias 'hif-divide        (hif-mathify-binop /))
(defalias 'hif-modulo        (hif-mathify-binop %))
(defalias 'hif-plus          (hif-mathify-binop +))
(defalias 'hif-minus         (hif-mathify-binop -))
(defalias 'hif-equal         (hif-mathify-binop =))
(defalias 'hif-notequal      (hif-mathify-binop /=))
(defalias 'hif-greater       (hif-mathify-binop >))
(defalias 'hif-less          (hif-mathify-binop <))
(defalias 'hif-greater-equal (hif-mathify-binop >=))
(defalias 'hif-less-equal    (hif-mathify-binop <=))
(defalias 'hif-logior        (hif-mathify-binop logior))
(defalias 'hif-logxor        (hif-mathify-binop logxor))
(defalias 'hif-logand        (hif-mathify-binop logand))

(defun hif-__LINE__ ()
  (line-number-at-pos))

(defun hif-__FILE__ ()
  (file-name-nondirectory (buffer-file-name)))

(defvar hif-__COUNTER__ 0)
(defun hif-__COUNTER__ ()
  (prog1 hif-__COUNTER__ (cl-incf hif-__COUNTER__)))

(defun hif-__cplusplus ()
  (and (string-match
        "\\.c\\(c\\|xx\\|pp\\|\\+\\+\\)\\'"
        (buffer-file-name))
       (memq major-mode '(c++-mode cc-mode cpp-mode))
       201710))

(defun hif-__DATE__ ()
  (format-time-string "%Y/%m/%d"))

(defun hif-__TIME__ ()
  (format-time-string "%H:%M:%S"))

(defun hif-__STDC__ ()         1)
(defun hif-__STDC_VERSION__ () 201710)
(defun hif-__STDC_HOST__ ()    1)

(defun hif-comma (&rest expr)
  "Evaluate a list of EXPR, return the result of the last item."
  (let ((result nil))
    (dolist (e expr result)
      (ignore-errors
        (setq result (funcall hide-ifdef-evaluator e))))))

(defun hif-token-stringification (l)
  "Scan token list for `hif-stringify' (`#') token and stringify the next token."
  (if (memq 'hif-stringify l)
      (let (result)
        (while l
          (push (if (eq (car l) 'hif-stringify)
                    (prog1
                        (if (cadr l)
                            (hif-stringify (cadr l))
                          (error "No token to stringify"))
                      (setq l (cdr l)))
                  (car l))
                result)
          (setq l (cdr l)))
        (nreverse result))
    ;; no `#' presents
    l))

(defun hif-token-concatenation (l)
  "Scan token list for `hif-token-concat' ('##') token and concatenate tokens."
  (if (memq 'hif-token-concat l)
      ;; Notice that after some substitutions, there could be more than
      ;; one `hif-space' in a list.
      (let ((items nil)
            (tk nil)
            (count 0) ; count of `##'
            result)
        (setq l (hif-keep-single l 'hif-space))
        (while (setq tk (car l))
          (if (not (eq tk 'hif-token-concat))
              ;; In reverse order so that we don't have to use `last' or
              ;; `butlast'
              (progn
                (push tk result)
                (setq l (cdr l)))
            ;; First `##' met, start `##' sequence
            ;; We only drop `hif-space' when doing token concatenation
            (setq items nil
                  count 0)
            (setq tk (pop result))
            (if (or (null tk)
                    (and (eq tk 'hif-space)
                         (null (setq tk (pop result)))))
                (error "No token before `##' to concatenate")
              (push tk items) ; first item, in reverse order
              (setq tk 'hif-token-concat))
            (while (eq tk 'hif-token-concat)
              (cl-incf count)
              ;; 2+ item
              (setq l (cdr l)
                    tk (car l))
              ;; only one 'hif-space could appear here
              (if (eq tk 'hif-space) ; ignore it
                  (setq l (cdr l)
                        tk (car l)))
              (if (or (null tk)
                      (eq tk 'hif-token-concat))
                  (error
                   "No token after the %d-th `##' to concatenate at line %d"
                   count (line-number-at-pos))
                (push tk items)
                (setq l (cdr l)
                      tk (car l))))
            ;; `##' sequence ended, concat them, then push into result
            (push (hif-token-concat (nreverse items)) result)))
        (nreverse result))
    ;; no need to reassemble the list if no `##' presents
    l))

(defun hif-delimit (lis elem)
  (nconc (mapcan (lambda (l) (list l elem))
                 (butlast lis))
         (last lis)))

(defun hif-delete-nth (n lst)
  "Non-destructively delete the nth item from a list."
  (if (zerop n)
      (cdr lst)
    ;; non-destructive
    (let* ((duplst (copy-sequence lst))
           (node (nthcdr (1- n) duplst)))
      (setcdr node (cddr node))
      duplst)))

;; Perform token replacement:
(defun hif-macro-supply-arguments (macro-name actual-parms)
  "Expand a macro call, replace ACTUAL-PARMS in the macro body."
  (let* ((SA                   (assq macro-name hide-ifdef-env))
         (macro                (and SA
                                    (cdr SA)
                                    (eq (cadr SA) 'hif-define-macro)
                                    (cddr SA)))
         (formal-parms         (and macro (car macro)))
         (macro-body           (and macro (cadr macro)))
         actual-count
         formal-count
         formal
         etc)

    (when (and actual-parms formal-parms macro-body)
      ;; For each actual parameter, evaluate each one and associate it
      ;; with an actual parameter, put it into local table and finally
      ;; evaluate the macro body.
      (if (setq etc (or (eq (car formal-parms) 'hif-etc)
                        (and (eq (car formal-parms) 'hif-etc-c99) 'c99)))
          ;; Take care of `hif-etc' first. Prefix `hif-comma' back if needed.
          (setq formal-parms (cdr formal-parms)))
      (setq formal-count (length formal-parms)
            actual-count (length actual-parms))

      ;; Fix empty arguments applied
      (if (and (= formal-count 1)
               (null (car formal-parms)))
          (setq formal-parms nil
                formal-count (1- formal-count)))
      (if (and (= actual-count 1)
               (or (null (car actual-parms))
                   ;; white space as the only argument
                   (equal '(hif-space) (car actual-parms))))
          (setq actual-parms nil
                actual-count (1- actual-count)))

      ;; Basic error checking
      (if etc
          (if (eq etc 'c99)
              (if (and (> formal-count 1) ; f(a,b,...)
                       (< actual-count formal-count))
                  (error "C99 variadic argument macro %S need at least %d arguments"
                         macro-name formal-count))
            ;; GNU style variadic argument
            (if (and (> formal-count 1)
                     (< actual-count (1- formal-count)))
                (error "GNU variadic argument macro %S need at least %d arguments"
                       macro-name (1- formal-count))))
        (if (> formal-count actual-count)
            (error "Too few parameters for macro %S; %d instead of %d"
                   macro-name actual-count formal-count)
          (if (< formal-count actual-count)
              (error "Too many parameters for macro %S; %d instead of %d"
                     macro-name actual-count formal-count))))

      ;; Perform token replacement on the MACRO-BODY with the parameters

      ;; Every substituted argument in the macro-body must be in list form so
      ;; that it won't again be substituted incorrectly in later iterations.
      ;; Finally we will flatten the list to fix that.
      (cl-loop
       do
       ;; Note that C99 '...' and GNU 'x...' allow empty match
       (setq formal (pop formal-parms))
       ;;
       ;; Prevent repetitive substitution, thus cannot use `subst'
       ;; for example:
       ;;   #define mac(a,b) (a+b)
       ;;   #define testmac mac(b,y)
       ;;   testmac should expand to (b+y): replace of argument a and b
       ;;   occurs simultaneously, not sequentially. If sequentially,
       ;;   according to the argument order, it will become:
       ;;   1. formal parm #1 'a' replaced by actual parm 'b', thus (a+b)
       ;;      becomes (b+b)
       ;;   2. formal parm #2 'b' replaced by actual parm 'y', thus (b+b)
       ;;      becomes (y+y).
       ;; Unlike `subst', `cl-substitute' replace only the top level
       ;; instead of the whole tree; more importantly, it's not
       ;; destructive.
       ;;
       (if (not (and (null formal-parms) etc))
           ;; One formal with one actual
           (setq macro-body
                 (cl-substitute (car actual-parms) formal macro-body))
         ;; `formal-parms' used up, now take care of '...'
         (cond

          ((eq etc 'c99) ; C99 __VA_ARGS__ style '...'
           (when formal
             (setq macro-body
                   (cl-substitute (car actual-parms) formal macro-body))
             ;; Now the whole __VA_ARGS__ represents the whole
             ;; remaining actual params
             (pop actual-parms))
           ;; Replace if __VA_ARGS__ presents:
           ;;   if yes, see if it's prefixed with ", ##" or not,
           ;;    if yes, remove the "##", then if actual-params is
           ;;   exhausted, remove the prefixed ',' as well.
           ;; Prepare for destructive operation
           (let ((rem-body (copy-sequence macro-body))
                 new-body va left part)
             ;; Find each __VA_ARGS__ and remove its immediate prefixed '##'
             ;; and comma if presents and if `formal_param' is exhausted
             (while (setq va (cl-position '__VA_ARGS__ rem-body))
               ;; Split REM-BODY @ __VA_ARGS__ into LEFT and right
               (setq part nil)
               (if (zerop va)
                   (setq left nil ; __VA_ARGS__ trimmed
                         rem-body (cdr rem-body))
                 (setq left rem-body
                       rem-body (cdr (nthcdr va rem-body))) ; _V_ removed
                 (setcdr (nthcdr va left) nil) ; now _V_ be the last in LEFT
                 ;; now LEFT=(, w? ## w? _V_) rem=(W X Y) where w = white space
                 (setq left (cdr (nreverse left)))) ; left=(w? ## w? ,)

               ;; Try to recognize w?##w? and remove ", ##" if found
               ;;   (remember head = __VA_ARGS__ is temporarily removed)
               (while (and left (eq 'hif-space (car left))) ; skip whites
                 (setq part (cons 'hif-space part)
                       left (cdr left)))

               (if (eq (car left) 'hif-token-concat) ; match '##'
                   (if actual-parms
                       ;; Keep everything
                       (setq part (append part (cdr left)))
                     ;; `actual-params' exhausted, delete ',' if presents
                     (while (and left (eq 'hif-space (car left))) ; skip whites
                       (setq part (cons 'hif-space part)
                             left (cdr left)))
                     (setq part
                           (append part
                                   (if (eq (car left) 'hif-comma) ; match ','
                                       (cdr left)
                                     left))))
                 ;; No immediate '##' found
                 (setq part (append part left)))

               ;; Insert __VA_ARGS__ as a list
               (push (hif-delimit actual-parms 'hif-comma) part)
               ;; Reverse `left' back
               (setq left (nreverse part)
                     new-body (append new-body left)))

             ;; Replacement of __VA_ARGS__ done here, add rem-body back
             (setq macro-body (append new-body rem-body)
                   actual-parms nil)))

          (etc ; GNU style '...', substitute last argument
           (if (null actual-parms)
               ;; Must be non-destructive otherwise the original function
               ;; definition defined in `hide-ifdef-env' will be destroyed.
               (setq macro-body (remove formal macro-body))
             (setq macro-body
                   (cl-substitute (hif-delimit actual-parms 'hif-comma)
                                  formal macro-body)
                   actual-parms nil)))

          (t
           (error "Internal error: impossible case"))))

       (pop actual-parms)
       while actual-parms) ; end cl-loop

      ;; Replacement completed, stringifiy and concatenate the token list.
      ;; Stringification happens must take place before flattening, otherwise
      ;; only the first token will be stringified.
      (setq macro-body
            (flatten-tree (hif-token-stringification macro-body))))

    ;; Token concatenation happens here, keep single 'hif-space
    (hif-keep-single (hif-token-concatenation macro-body) 'hif-space)))

(defun hif-invoke (macro-name actual-parms)
  "Invoke a macro by expanding it, reparse macro-body and finally invoke it."
  ;; Reparse the macro body and evaluate it
  (funcall hide-ifdef-evaluator
           (hif-parse-exp
            (hif-macro-supply-arguments macro-name actual-parms)
            macro-name)))

;;;----------- end of parser -----------------------


(defun hif-canonicalize-tokens (regexp) ; For debugging
  "Return the expanded result of the scanned tokens."
  (save-excursion
    (re-search-forward regexp)
    (let* ((curr-regexp (match-string 0))
           (defined (string-match hif-ifxdef-regexp curr-regexp))
           (negate (and defined
                        (string= (match-string 2 curr-regexp) "n")))
           (hif-simple-token-only nil) ;; Dynamic binding var for `hif-tokenize'
           (tokens (hif-tokenize (point)
                                 (progn (hif-end-of-line) (point)))))
      (if defined
          (setq tokens (list 'hif-defined tokens)))
      (if negate
          (setq tokens (list 'hif-not tokens)))
      tokens)))

(defun hif-canonicalize (regexp)
  "Return a Lisp expression for its condition by scanning current buffer.
Do this when cursor is at the beginning of `regexp' (i.e. #ifX)."
  (let ((case-fold-search nil))
    (save-excursion
      (if (re-search-forward regexp)
          (if (= ?\( (char-before)) ;; "#if(" found
              (goto-char (1- (point)))))
      (let* ((curr-regexp (match-string 0))
             (defined (string-match hif-ifxdef-regexp curr-regexp))
             (negate (and defined
                          (string= (match-string 2 curr-regexp) "n")))
             (hif-simple-token-only nil) ; Dynamic binding for `hif-tokenize'
             (tokens (hif-tokenize (point)
                                   (progn (hif-end-of-line) (point)))))
        (if defined
            (setq tokens (list 'hif-defined tokens)))
        (if negate
            (setq tokens (list 'hif-not tokens)))
        (hif-parse-exp tokens)))))

(defun hif-is-in-comment ()
  "Check if we're currently within a C(++) comment."
  (or (nth 4 (syntax-ppss))
      (looking-at "/[/*]")))

(defun hif-search-ifX-regexp (hif-regexp &optional backward)
  "Search for a valid ifX regexp defined in hideif."
  (let ((start (point))
        (re-search-func (if backward
                            #'re-search-backward
                          #'re-search-forward))
        (limit (if backward (point-min) (point-max)))
        found)
    (while (and (setq found
                      (funcall re-search-func hif-regexp limit t))
                (hif-is-in-comment)))
    ;; Jump to the pattern if found
    (if found
        (unless backward
          (setq found
                (goto-char (- (point) (length (match-string 0))))))
      (goto-char start))
    found))

(defun hif-find-any-ifX ()
  "Move to next #if..., or #ifndef, at point or after."
  ;; (message "find ifX at %d" (point))
  (hif-search-ifX-regexp hif-ifx-regexp))

(defun hif-find-next-relevant ()
  "Move to next #if..., #elif..., #else, or #endif, after the current line."
  ;; (message "hif-find-next-relevant at %d" (point))
  (end-of-line)
  ;; Avoid infinite recursion by going to the pattern only if a match is found
  (hif-search-ifX-regexp hif-ifx-else-endif-regexp))

(defun hif-find-previous-relevant ()
  "Move to previous #if..., #else, or #endif, before the current line."
  ;; (message "hif-find-previous-relevant at %d" (point))
  (beginning-of-line)
  ;; Avoid infinite recursion by going to the pattern only if a match is found
  (hif-search-ifX-regexp hif-ifx-else-endif-regexp 't))


(defun hif-looking-at-ifX ()
  (looking-at hif-ifx-regexp))   ; Should eventually see #if
(defun hif-looking-at-endif ()
  (looking-at hif-endif-regexp))
(defun hif-looking-at-else ()
  (looking-at hif-else-regexp))

(defun hif-looking-at-elif ()
  (looking-at hif-elif-regexp))


(defun hif-ifdef-to-endif ()
  "If positioned at #ifX, #elif, or #else form, skip to corresponding #endif."
  ;; (message "hif-ifdef-to-endif at %d" (point)) (sit-for 1)
  (hif-find-next-relevant)
  (cond ((hif-looking-at-ifX)
         (hif-ifdef-to-endif) ; Find endif of nested if
         (hif-ifdef-to-endif)) ; Find outer endif or else
        ((hif-looking-at-elif)
         (hif-ifdef-to-endif))
        ((hif-looking-at-else)
         (hif-ifdef-to-endif)) ; Find endif following else
        ((hif-looking-at-endif)
         'done)
        (t
         (error "Mismatched #ifdef #endif pair"))))


(defun hif-endif-to-ifdef ()
  "If positioned at #endif form, skip backward to corresponding #ifX."
  ;; (message "hif-endif-to-ifdef at %d" (point))
  (let ((start (point)))
    (hif-find-previous-relevant)
    (if (= start (point))
        (error "Mismatched #ifdef #endif pair")))
  (cond ((hif-looking-at-endif)
         (hif-endif-to-ifdef) ; Find beginning of nested if
         (hif-endif-to-ifdef)) ; Find beginning of outer if or else
        ((hif-looking-at-elif)
         (hif-endif-to-ifdef))
        ((hif-looking-at-else)
         (hif-endif-to-ifdef))
        ((hif-looking-at-ifX)
         'done)
        (t
         (error "Mismatched #endif"))))                 ; never gets here


(defun forward-ifdef (&optional arg)
  "Move point to beginning of line of the next ifdef-endif.
With argument, do this that many times."
  (interactive "p")
  (or arg (setq arg 1))
  (if (< arg 0) (backward-ifdef (- arg))
    (while (< 0 arg)
      (setq arg (- arg))
      (let ((start (point)))
	(unless (hif-looking-at-ifX)
	  (hif-find-next-relevant))
	(if (hif-looking-at-ifX)
	    (hif-ifdef-to-endif)
	  (goto-char start)
	  (error "No following #ifdef"))))))


(defun backward-ifdef (&optional arg)
  "Move point to beginning of the previous ifdef-endif.
With argument, do this that many times."
  (interactive "p")
  (or arg (setq arg 1))
  (if (< arg 0) (forward-ifdef (- arg))
    (while (< 0 arg)
      (setq arg (1- arg))
      (beginning-of-line)
      (let ((start (point)))
	(unless (hif-looking-at-endif)
	  (hif-find-previous-relevant))
	(if (hif-looking-at-endif)
	    (hif-endif-to-ifdef)
	  (goto-char start)
	  (error "No previous #ifdef"))))))


(defun down-ifdef ()
  "Move point to beginning of nested ifdef or else-part."
    (interactive)
    (let ((start (point)))
      (hif-find-next-relevant)
      (if (or (hif-looking-at-ifX) (hif-looking-at-else))
	  ()
	(goto-char start)
	(error "No following #ifdef"))))


(defun up-ifdef ()
  "Move point to beginning of enclosing ifdef or else-part."
  (interactive)
  (beginning-of-line)
  (let ((start (point)))
    (unless (hif-looking-at-endif)
      (hif-find-previous-relevant))
    (if (hif-looking-at-endif)
	(hif-endif-to-ifdef))
      (if (= start (point))
	  (error "No previous #ifdef"))))

(defun next-ifdef (&optional arg)
  "Move to the beginning of the next #ifX, #else, or #endif.
With argument, do this that many times."
  (interactive "p")
  (or arg (setq arg 1))
  (if (< arg 0) (previous-ifdef (- arg))
    (while (< 0 arg)
      (setq arg (1- arg))
      (hif-find-next-relevant)
      (when (eolp)
	(beginning-of-line)
	(error "No following #ifdefs, #elses, or #endifs")))))

(defun previous-ifdef (&optional arg)
  "Move to the beginning of the previous #ifX, #else, or #endif.
With argument, do this that many times."
  (interactive "p")
  (or arg (setq arg 1))
  (if (< arg 0) (next-ifdef (- arg))
    (while (< 0 arg)
      (setq arg (1- arg))
      (let ((start (point)))
	(hif-find-previous-relevant)
	(if (= start (point))
	    (error "No previous #ifdefs, #elses, or #endifs"))))))


;;===%%SF%% parsing (End)  ===


;;===%%SF%% hide-ifdef-hiding (Start)  ===


;; A range is a structure with four components:
;; START       The start of the range. (beginning of line)
;; ELSE        The else marker (beginning of line)
;; END         The end of the range.  (beginning of line)
;; ELIF        A sequence of #elif markers (beginning of line)

(defsubst hif-make-range (start end &optional else elif)
  (list start else end elif))

(defsubst hif-range-start (range) (elt range 0))
(defsubst hif-range-else (range) (elt range 1))
(defsubst hif-range-end (range) (elt range 2))
(defsubst hif-range-elif (range) (elt range 3))


;; Find-Range
;; The workhorse, it delimits the #if region.  Reasonably simple:
;; Skip until an #else or #endif is found, remembering positions.  If
;; an #else was found, skip some more, looking for the true #endif.

(defun hif-find-range ()
  "Return a Range structure describing the current #if region.
Point is left unchanged."
  ;; (message "hif-find-range at %d" (point))
  (save-excursion
    (beginning-of-line)
    (let ((start (point))
          (elif nil)
          (else nil)
          (end nil))
      ;; Part one.  Look for either #elif, #else or #endif.
      ;; This loop-and-a-half dedicated to E. Dijkstra.
      (while (and (not else) (not end))
        (while (progn
                 (hif-find-next-relevant)
                 (hif-looking-at-ifX))            ; Skip nested ifdef
          (hif-ifdef-to-endif))
        ;; Found either a #else, #elif, or an #endif.
        (cond ((hif-looking-at-elif)
               (setq elif (nconc elif (list (point)))))
              ((hif-looking-at-else)
               (setq else (point)))
              (t
               (beginning-of-line)  ; otherwise #endif line will be hidden
               (setq end (point)))))
      ;; If found #else, look for #endif.
      (when else
        (while (progn
                 (hif-find-next-relevant)
                 (hif-looking-at-ifX))  ; Skip nested ifdef
          (hif-ifdef-to-endif))
        (if (hif-looking-at-else)
            (error "Found two elses in a row?  Broken!"))
        (beginning-of-line) ; otherwise #endif line will be hidden
        (setq end (point)))            ; (line-end-position)
      (hif-make-range start end else elif))))


;; A bit slimy.

(defun hif-hide-line (point)
  "Hide the line containing POINT.
Does nothing if `hide-ifdef-lines' is nil."
  (when hide-ifdef-lines
    (save-excursion
      (goto-char point)
      (hide-ifdef-region-internal
       (line-beginning-position) (progn (hif-end-of-line) (point))))))


;;  hif-Possibly-Hide
;;  There are four cases.  The #ifX expression is "taken" if it
;;  the hide-ifdef-evaluator returns T.  Presumably, this means the code
;;  inside the #ifdef would be included when the program was
;;  compiled.
;;
;;  Case 1:  #ifX taken, and there's an #else.
;;     The #else part must be hidden.  The #if (then) part must be
;;     processed for nested #ifX's.
;;  Case 2:  #ifX taken, and there's no #else.
;;     The #if part must be processed for nested #ifX's.
;;  Case 3:  #ifX not taken, and there's an #elif
;;     The #if part must be hidden, and then evaluate
;;     the #elif condition like a new #ifX.
;;  Case 4:  #ifX not taken, and there's just an #else.
;;     The #if part must be hidden.  The #else part must be processed
;;     for nested #ifs.
;;  Case 5:  #ifX not taken, and there's no #else.
;;     The #ifX part must be hidden.
;;
;;  Further processing is done by narrowing to the relevant region
;;  and just recursively calling hide-ifdef-guts.
;;
;;  When hif-possibly-hide returns, point is at the end of the
;;  possibly-hidden range.

(defvar hif-recurse-level 0)

(defun hif-recurse-on (start end &optional dont-go-eol)
  "Call `hide-ifdef-guts' after narrowing to end of START line and END line."
  (save-excursion
    (save-restriction
      (goto-char start)
      (unless dont-go-eol
        (end-of-line))
      (narrow-to-region (point) end)
      (let ((hif-recurse-level (1+ hif-recurse-level)))
        (hide-ifdef-guts)))))

(defun hif-possibly-hide (expand-reinclusion)
  "Called at #ifX expression, this hides those parts that should be hidden.
It uses the judgment of `hide-ifdef-evaluator'.  EXPAND-REINCLUSION is a flag
indicating that we should expand the #ifdef even if it should be hidden.
Refer to `hide-ifdef-expand-reinclusion-guard' for more details."
  ;; (message "hif-possibly-hide") (sit-for 1)
  (let* ((case-fold-search nil)
         (test (hif-canonicalize hif-ifx-regexp))
         (range (hif-find-range))
         (elifs (hif-range-elif range))
         (if-part t) ; Every time we start from if-part
         (complete nil))
    ;; (message "test = %s" test) (sit-for 1)

    (hif-hide-line (hif-range-end range))
    (while (not complete)
      (if (and (not (and expand-reinclusion if-part))
               (hif-not (funcall hide-ifdef-evaluator test)))
          ;; ifX/elif is FALSE
          (if elifs
              ;; Case 3 - Hide the #ifX and eval #elif
              (let ((newstart (car elifs)))
                (hif-hide-line (hif-range-start range))
                (hide-ifdef-region (hif-range-start range)
                                   (1- newstart))
                (setcar range newstart)
                (goto-char newstart)
                (setq elifs (cdr elifs))
                (setq test (hif-canonicalize hif-elif-regexp)))

            ;; Check for #else
            (cond ((hif-range-else range)
                   ;; Case 4 - #else block visible
                   (hif-hide-line (hif-range-else range))
                   (hide-ifdef-region (hif-range-start range)
                                      (1- (hif-range-else range)))
                   (hif-recurse-on (hif-range-else range)
                                   (hif-range-end range)))
                  (t
                   ;; Case 5 - No #else block, hide #ifX
                   (hide-ifdef-region (point)
                                      (1- (hif-range-end range)))))
            (setq complete t))

        ;; ifX/elif is TRUE
        (cond (elifs
               ;; Luke fix: distinguish from #elif..#elif to #elif..#else
               (let ((elif (car elifs)))
                 ;; hide all elifs
                 (hif-hide-line elif)
                 (hide-ifdef-region elif (1- (hif-range-end range)))
                 (hif-recurse-on (hif-range-start range)
                                 elif)))
              ((hif-range-else range)
               ;; Case 1 - Hide #elif and #else blocks, recurse #ifX
               (hif-hide-line (hif-range-else range))
               (hide-ifdef-region (hif-range-else range)
                                  (1- (hif-range-end range)))
               (hif-recurse-on (hif-range-start range)
                               (hif-range-else range)))
              (t
               ;; Case 2 - No #else, just recurse #ifX
               (hif-recurse-on (hif-range-start range)
                               (hif-range-end range))))
        (setq complete t))
      (setq if-part nil))

    ;; complete = t
    (hif-hide-line (hif-range-start range)) ; Always hide start.
    (goto-char (hif-range-end range))
    (end-of-line)))

(defun hif-evaluate-region (start end)
  (let* ((tokens (ignore-errors ; Prevent C statement things like
                                ; 'do { ... } while (0)'
                   (hif-tokenize start end)))
         (expr (and tokens
                    (condition-case nil
                        (hif-parse-exp tokens)
                      (error
                       tokens))))
         (result (funcall hide-ifdef-evaluator expr)))
    result))

(defun hif-display-macro (name def &optional result)
  (if (and def
           (listp def)
           (eq (car def) 'hif-define-macro))
      (let ((cdef (concat "#define " name))
            (parmlist (cadr def))
            p s etc)
        (setq def (caddr def))
        ;; parmlist
        (when parmlist
          (setq cdef (concat cdef "("))
          (if (setq etc (or (eq (setq p (car parmlist)) 'hif-etc)
                            (and (eq p 'hif-etc-c99) 'c99)))
              (pop parmlist))
          (while (setq p (car parmlist))
            (setq cdef (concat cdef (symbol-name p) (if (cdr parmlist) ","))
                  parmlist (cdr parmlist)))
          (setq cdef (concat cdef
                             (if etc (concat (if (eq etc 'c99) ",") "..."))
                             ")")))
        (setq cdef (concat cdef " "))
        ;; body
        (while def
          (if (listp def)
              (setq s (car def)
                    def (cdr def))
            (setq s def
                  def nil))
          (setq cdef
                (concat cdef
                        (cond
                         ;;((setq tok (car (rassoc s hif-token-alist)))
                         ;; (concat tok (if (eq s 'hif-comma) " ")))
                         ((symbolp s)
                          (concat (hif-stringify s)
                                  (if (eq s 'hif-comma) " ")))
                         ((stringp s)
                          (hif-stringify s))
                         (t ;; (numberp s)
                          (format "%S" s))))))
        (if (and result
                 ;; eg: "#define RECURSIVE_SYMBOL RECURSIVE_SYMBOL"
                 (not (and (listp result)
                           (eq (car result) 'hif-define-macro))))
            (setq cdef (concat cdef
                               (if (integerp result)
                                   (format "\n=> %S (%#x)" result result)
                                 (format "\n=> %S" result)))))
        (message "%s" cdef))
    (message "%S <= `%s'" def name)))

(defun hif-evaluate-macro (rstart rend)
  "Evaluate the macro expansion result for the active region.
If no region is currently active, find the current #ifdef/#define and evaluate
the result; otherwise it looks for current word at point.
Currently it supports only math calculations, strings or argumented macros can
not be expanded.
This function by default ignores parsing error and return `false' on evaluating
runtime C(++) statements or tokens that normal C(++) preprocessor can't perform;
however, when this command is prefixed, it will display the error instead."
  (interactive
   (if (not (use-region-p))
       '(nil nil)
     (list (region-beginning) (region-end))))
  (run-hooks 'hide-ifdef-evalulate-enter-hook)
  (let ((case-fold-search nil)
        (currpnt (point))
        bounds)
    (save-excursion
      (unless (use-region-p)
        (setq rstart nil rend nil)
        (beginning-of-line)
        (if (and (re-search-forward hif-macro-expr-prefix-regexp nil t)
                 (= (line-number-at-pos currpnt) (line-number-at-pos)))
            (if (string= "define" (match-string 2))
                (re-search-forward hif-macroref-regexp nil t))
          (goto-char currpnt)
          (setq bounds (bounds-of-thing-at-point 'word)
                ;; TODO: BOUNDS need a C++ syntax word boundary finder
                rstart (car bounds)
                rend   (cdr bounds))))
      (let* ((start (or rstart (point)))
             (end   (or rend (progn (hif-end-of-line) (point))))
             (defined nil)
             (simple 't)
             (tokens (ignore-errors ; Prevent C statement things like
                                        ; 'do { ... } while (0)'
                       (hif-tokenize start end)))
             ;; Note that on evaluating we can't simply define the symbol
             ;; even if we are currently at a #define line, as this #define
             ;; might actually be wrapped up in a #if 0 block.  We can only
             ;; define that explicitly with `hide-ifdef-define'.
             (expr (or (and (<= (length tokens) 1) ; Simple token
                            (setq defined
                                  (or (assq (car tokens) hide-ifdef-env)
                                      (assq (car tokens) hif-predefine-alist)))
                            (setq simple (atom (hif-lookup (car tokens))))
                            (hif-lookup (car tokens)))
                       (and tokens
                            (condition-case err
                                (hif-parse-exp tokens)
                              (error
                               ;; when prefixed, pass the error on for later
                               ;; `hide-ifdef-evaluator'
                               (if current-prefix-arg err))))))
             (exprstring (hif-stringify tokens))
             (result (condition-case err
                         (funcall hide-ifdef-evaluator expr)
                       ;; in case of arithmetic error or others
                       (error (error "Error: line %d %S when evaluating `%s'"
                                     (line-number-at-pos) err exprstring)))))
        (setq
         result
         (cond
          ((= (length tokens) 0)
           (message "`%s'" exprstring))
          ((= (length tokens) 1) ; Simple token
           (if simple
               (if defined
                   (hif-display-macro exprstring result)
                 (if (and (hif-is-number exprstring)
                          result (numberp result))
                     (message "%S (%#x)" result result)
                   (if (and (hif-is-float exprstring)
                            result (numberp result))
                       (message "%S (%s)" result exprstring)
                     (if (string-match hif-string-literal-regexp exprstring)
                         (message "%s" exprstring)
                       (message "`%s' is not defined" exprstring)))))
             (if defined
                 (hif-display-macro exprstring (cdr defined) result)
               (message "`%s' is not defined" exprstring))))
          ((integerp result)
           (if (or (= 0 result) (= 1 result))
               (message "%S <= `%s'" result exprstring)
             (message "%S (%#x) <= `%s'" result result exprstring)))
          ((null result)
           (message "%S <= `%s'" 'false exprstring))
          ((eq t result)
           (message "%S <= `%s'" 'true exprstring))
          (t
           (message "%S <= `%s'" result exprstring))))
        (run-hooks 'hide-ifdef-evalulate-leave-hook)
        result))))

(defun hif-parse-macro-arglist (str)
  "Parse argument list formatted as `( arg1 [ , argn] [,] [...] )'.
The `...' is also included.  Return a list of the arguments, if `...' exists the
first arg will be `hif-etc'."
  (let* ((hif-simple-token-only nil) ; Dynamic binding var for `hif-tokenize'
         (tokenlist
          (cdr (hif-tokenize
                (- (point) (length str)) (point)))) ; Remove `hif-lparen'
         etc result token prevtok prev2tok)
    (while (not (eq (setq prev2tok prevtok
                          prevtok token
                          token (pop tokenlist)) 'hif-rparen))
      (cond
       ((eq token 'hif-etc)
        ;; GNU type "..." or C99 type
        (setq etc (if (or (null prevtok)
                          (eq prevtok 'hif-comma)
                          (and (eq prevtok 'hif-space)
                               (eq prev2tok 'hif-comma)))
                      'c99 t)))
       ((eq token 'hif-comma)
        (if etc
            (error "Syntax error: no comma allowed after `...'")))
       (t
        (push token result))))
    (setq result (nreverse result))
    (cond
     ((eq etc 'c99)
      (cons 'hif-etc-c99 result))
     ((eq etc t)
      (cons 'hif-etc result))
     (t
      result))))

;; The original version of hideif evaluates the macro early and store the
;; final values for the defined macro into the symbol database (aka
;; `hide-ifdef-env').  The evaluation process is "strings -> tokens -> parsed
;; tree -> [value]".  (The square bracket refers to what's stored in our
;; `hide-ifdef-env'.)
;;
;; This forbids the evaluation of an argumented macro since the parameters
;; are applied at run time. In order to support argumented macro I then
;; postponed the evaluation process one stage and store the "parsed tree"
;; into symbol database. The evaluation process was then "strings -> tokens
;; -> [parsed tree] -> value". Hideif therefore run slower since it need to
;; evaluate the parsed tree every time when trying to expand the symbol. These
;; temporarily code changes are obsolete and not in Emacs source repository.
;;
;; Furthermore, CPP did allow partial expression to be defined in several
;; macros and later got concatenated into a complete expression and then
;; evaluate it. In order to match this behavior I had to postpone one stage
;; further, otherwise those partial expression will be fail on parsing and
;; we'll miss all macros that reference it. The evaluation process thus
;; became "strings -> [tokens] -> parsed tree -> value." This degraded the
;; performance since we need to parse tokens and evaluate them every time
;; when that symbol is referenced.
;;
;; In real cases I found a lot portion of macros are "simple macros" that
;; expand to literals like integers or other symbols. In order to enhance
;; the performance I use this `hif-simple-token-only' to notify my code and
;; save the final [value] into symbol database. [lukelee]

(defvar hif-verbose-define-count 0)

(defun hif-find-define (&optional min max)
  "Parse texts and retrieve all defines within the region MIN and MAX."
  (interactive)
  (and min (goto-char min))
  (and (re-search-forward hif-define-regexp max t)
       (or
        (let* ((defining (string= "define" (match-string 2)))
               (name (and (re-search-forward hif-macroref-regexp max t)
                          (match-string 1)))
               (parmlist (or (and (or (match-string 3) ; First arg id found
                                      (match-string 6)) ; '...' found
                                  (delq 'hif-space
                                        (hif-parse-macro-arglist
                                         (match-string 2))))
                             (and (match-string 2) ; empty arglist
                                  (list nil)))))
          (if defining
              ;; Ignore name (still need to return 't), or define the name
              (or (and hide-ifdef-exclude-define-regexp
                       (string-match hide-ifdef-exclude-define-regexp
                                     name))

                  (let* ((start (point))
                         (end   (progn (hif-end-of-line) (point)))
                         (hif-simple-token-only nil) ; Dynamic binding
                         (tokens
                          (and name
                               (prog1 t
                                 (cl-incf hif-verbose-define-count)
                                 ;; only show 1/50 to not slow down to much
                                 (if (and hide-ifdef-verbose
                                          (= (% hif-verbose-define-count 50) 1))
                                     (message "[Line %d] defining %S"
                                              (line-number-at-pos (point))
                                              (substring-no-properties name))))
                               ;; `hif-simple-token-only' is set/clear
                               ;; only in this block
                               (condition-case nil
                                   ;; Prevent C statements like
                                   ;; 'do { ... } while (0)'
                                   (hif-tokenize start end)
                                 (error
                                  ;; We can't just return nil here since
                                  ;; this will stop hideif from searching
                                  ;; for more #defines.
                                  (setq hif-simple-token-only t)
                                  (replace-regexp-in-string
                                   "^[ \t]*\\|[ \t]*$"  ""
                                   (buffer-substring-no-properties
                                    start end))))))
                         ;; For simple tokens we save only the parsed result;
                         ;; otherwise we save the tokens and parse it after
                         ;; parameter replacement
                         (expr (and tokens
                                    ;; `hif-simple-token-only' is checked only
                                    ;; here.
                                    (or (and (null parmlist)
                                             hif-simple-token-only
                                             (listp tokens)
                                             (= (length tokens) 1)
                                             (hif-parse-exp tokens))
                                        `(hif-define-macro ,parmlist
                                                           ,tokens))))
                         (SA (and name
                                  (assq (intern name) hide-ifdef-env))))
                    (and name
                         (if SA
                             (or (setcdr SA expr) t)
                           ;; Lazy evaluation, eval only if `hif-lookup' find it.
                           ;; Define it anyway, even if nil it's still in list
                           ;; and therefore considered defined.
                           (push (cons (intern name) expr) hide-ifdef-env)))))
            ;; #undef
            (and name
                 (intern-soft name)
                 (hif-undefine-symbol (intern name)))
            t)))
       t))


(defun hif-add-new-defines (&optional min max)
  "Scan and add all #define macros between MIN and MAX."
  (interactive)
  (save-excursion
    (save-restriction
      ;; (mark-region min max) ;; for debugging
      (and min (goto-char min))
      (setq hif-verbose-define-count 0)
      (forward-comment (point-max))
      (setq min (point))
      (let ((breakloop nil))
        (while (and (not breakloop)
                    (hif-find-define min max))
          (forward-comment (point-max))
          (if (and max
                   (> (point) max))
              (setq max (point)
                    breakloop t))
          (setq min (point))))
      (if max (goto-char max)
        (goto-char (point-max))
        nil))))

(defun hide-ifdef-guts ()
  "Does most of the work of `hide-ifdefs'.
It does not do the work that's pointless to redo on a recursive entry."
  (save-excursion
    (let* ((case-fold-search t) ; Ignore case for `hide-ifdef-header-regexp'
           (expand-header (and hide-ifdef-expand-reinclusion-guard
                               (buffer-file-name)
                               (string-match hide-ifdef-header-regexp
                                             (buffer-file-name))
                               (zerop hif-recurse-level)))
           (case-fold-search nil)
           min max)
      (setq hif-__COUNTER__ 0)
      (goto-char (point-min))
      (setq min (point))
      ;; Without this `condition-case' it would be easier to see which
      ;; operation went wrong thru the backtrace `iff' user realize
      ;; the underlying meaning of all hif-* operation; for example,
      ;; `hif-shiftleft' refers to C(++) '<<' operator and floating
      ;; operation arguments would be invalid.
      (condition-case err
          (cl-loop do
                   (setq max (hif-find-any-ifX))
                   (setq max (hif-add-new-defines min max))
                   (if max
                       (hif-possibly-hide expand-header))
                   (setq min (point))
                   while max)
        (error (error "Error: failed at line %d %S"
                      (line-number-at-pos) err))))))

;;===%%SF%% hide-ifdef-hiding (End)  ===


;;===%%SF%% exports (Start)  ===

(defun hide-ifdef-toggle-read-only ()
  "Toggle `hide-ifdef-read-only'."
  (interactive)
  (setq hide-ifdef-read-only (not hide-ifdef-read-only))
  (message "Hide-Read-Only %s"
	   (if hide-ifdef-read-only "ON" "OFF"))
  (if hide-ifdef-hiding
      (setq buffer-read-only (or hide-ifdef-read-only
                                 hif-outside-read-only)))
  (force-mode-line-update))

(defun hide-ifdef-toggle-outside-read-only ()
  "Replacement for `read-only-mode' within Hide-Ifdef mode."
  (interactive)
  (setq hif-outside-read-only (not hif-outside-read-only))
  (message "Read only %s"
	   (if hif-outside-read-only "ON" "OFF"))
  (setq buffer-read-only
	(or (and hide-ifdef-hiding hide-ifdef-read-only)
	    hif-outside-read-only))
  (force-mode-line-update))

(defun hide-ifdef-toggle-shadowing ()
  "Toggle shadowing."
  (interactive)
  (setq-local hide-ifdef-shadow (not hide-ifdef-shadow))
  (message "Shadowing %s" (if hide-ifdef-shadow "ON" "OFF"))
  (save-restriction
    (widen)
    (dolist (overlay (overlays-in (point-min) (point-max)))
      (when (overlay-get overlay 'hide-ifdef)
	(if hide-ifdef-shadow
	    (progn
	      (overlay-put overlay 'invisible nil)
	      (overlay-put overlay 'face 'hide-ifdef-shadow))
	  (overlay-put overlay 'face nil)
	  (overlay-put overlay 'invisible 'hide-ifdef))))))

(defun hide-ifdef-define (var &optional val)
  "Define a VAR to VAL (default 1) in `hide-ifdef-env'.
This allows #ifdef VAR to be hidden."
  (interactive
   (let* ((default (save-excursion
                     (beginning-of-line)
                     (cond ((looking-at hif-ifx-else-endif-regexp)
                            (forward-word-strictly 2)
                            (current-word 'strict))
                           (t
                            nil))))
          (var (read-minibuffer "Define what? " default))
          (val (read-from-minibuffer (format-prompt "Set %s to?" "1" var)
                                     nil nil t nil "1")))
     (list var val)))
  (hif-set-var var (or val 1))
  (if hide-ifdef-hiding (hide-ifdefs))
  (message "%s set to %s" var (or val 1)))

(defun hif-undefine-symbol (var)
  (when (assq var hide-ifdef-env)
    (setq hide-ifdef-env
          (delete (assq var hide-ifdef-env) hide-ifdef-env))
    ;; We can override things in `hif-predefine-alist' so keep them
    (unless (assq var hif-predefine-alist)
      (unintern (symbol-name var) nil))
    t))

(defun hide-ifdef-undef (start end)
  "Undefine a VAR so that #ifdef VAR would not be included."
  (interactive
   (if (use-region-p)
       (list (region-beginning) (region-end))
     '(nil nil)))
  (let* ((symstr
          (or (and (number-or-marker-p start)
                   (number-or-marker-p end)
                   (buffer-substring-no-properties start end))
              (read-string "Undefine what? " (current-word))))
         (sym (and symstr
                   (intern symstr))))
    (if (zerop (hif-defined sym))
        (message "`%s' not defined, no need to undefine it" symstr)
      (hif-undefine-symbol sym)
      (if hide-ifdef-hiding (hide-ifdefs))
      (message "`%S' undefined" sym))))

(defun hide-ifdefs (&optional start end nomsg)
  "Hide the contents of some #ifdefs.
Assume that defined symbols have been added to `hide-ifdef-env'.
The text hidden is the text that would not be included by the C
preprocessor if it were given the file with those symbols defined.
With prefix command presents it will also hide the #ifdefs themselves.

Hiding will only be performed within the marked region if there is one.

Turn off hiding by calling `show-ifdefs'."

  (interactive
   (if (use-region-p)
       (list (region-beginning) (region-end))
     (list (point-min) (point-max))))

  (setq current-prefix-arg (or hide-ifdef-lines current-prefix-arg))
  (save-restriction
    (let* ((hide-ifdef-lines current-prefix-arg)
           (outer-hide-ifdef-verbose hide-ifdef-verbose)
           (hide-ifdef-verbose (and outer-hide-ifdef-verbose
                                    (not (or nomsg (use-region-p)))))
           (hide-start-time (current-time)))
      (and hide-ifdef-verbose
           (message "Hiding..."))
      (setq hif-outside-read-only buffer-read-only)
      (unless hide-ifdef-mode (hide-ifdef-mode 1)) ; Turn on hide-ifdef-mode
      (if hide-ifdef-hiding
          (show-ifdefs))                    ; Otherwise, deep confusion.
      (setq hide-ifdef-hiding t)
      (narrow-to-region (or start (point-min)) (or end (point-max)))
      (hide-ifdef-guts)
      (setq buffer-read-only
            (or hide-ifdef-read-only hif-outside-read-only))
      (and hide-ifdef-verbose
           (message "Hiding done, %.1f seconds elapsed"
		    (float-time (time-subtract nil hide-start-time)))))))


(defun show-ifdefs (&optional start end)
  "Cancel the effects of `hide-ifdef': show the contents of all #ifdefs."
  (interactive
   (if (use-region-p)
       (list (region-beginning) (region-end))
     (list (point-min) (point-max))))
  (setq buffer-read-only hif-outside-read-only)
  (hif-show-all (or start (point-min)) (or end (point-max)))
  (setq hide-ifdef-hiding nil))


(defun hif-find-ifdef-block ()
  "Utility to hide and show ifdef block.
Return as (TOP . BOTTOM) the extent of ifdef block."
  (let (max-bottom)
    (cons (save-excursion
            (beginning-of-line)
            (unless (or (hif-looking-at-else) (hif-looking-at-ifX))
              (up-ifdef))
            (prog1 (point)
              (hif-ifdef-to-endif)
              (setq max-bottom (1- (point)))))
          (save-excursion
            (beginning-of-line)
            (unless (hif-looking-at-endif)
              (hif-find-next-relevant))
            (while (hif-looking-at-ifX)
              (hif-ifdef-to-endif)
              (hif-find-next-relevant))
              (min max-bottom (1- (point)))))))


(defun hide-ifdef-block (&optional arg start end)
  "Hide the ifdef block (true or false part) enclosing or before the cursor.
With optional prefix argument ARG, also hide the #ifdefs themselves."
  (interactive "P\nr")
  (let ((hide-ifdef-lines arg))
    (if (use-region-p)
        (let ((hif-recurse-level (1+ hif-recurse-level)))
          (hif-recurse-on start end t)
          (setq mark-active nil))
      (unless hide-ifdef-mode (hide-ifdef-mode 1))
      (let ((top-bottom (hif-find-ifdef-block)))
        (hide-ifdef-region (car top-bottom) (cdr top-bottom))
        (when hide-ifdef-lines
          (hif-hide-line (car top-bottom))
          (hif-hide-line (1+ (cdr top-bottom))))
        (setq hide-ifdef-hiding t))
      (setq buffer-read-only
            (or hide-ifdef-read-only hif-outside-read-only)))))

(defun show-ifdef-block (&optional start end)
  "Show the ifdef block (true or false part) enclosing or before the cursor."
  (interactive
   (if (use-region-p)
       (list (region-beginning) (region-end))
     '(nil nil)))
  (if (and (number-or-marker-p start)
           (number-or-marker-p end))
      (progn
        (dolist (o (overlays-in start end))
          (if (overlay-get o 'hide-ifdef)
              (delete-overlay o)))
        (setq mark-active nil))
    (let ((top-bottom (condition-case nil
                          (hif-find-ifdef-block)
                        (error
                         nil)))
          (ovrs (overlays-in (max (point-min) (1- (point)))
                             (min (point-max) (1+ (point)))))
          (del nil))
      (if top-bottom
    (if hide-ifdef-lines
        (hif-show-ifdef-region
         (save-excursion
           (goto-char (car top-bottom)) (line-beginning-position))
         (save-excursion
           (goto-char (1+ (cdr top-bottom)))
           (hif-end-of-line) (point)))
      (setf del (hif-show-ifdef-region
                 (1- (car top-bottom)) (cdr top-bottom)))))
      (if (not (and top-bottom
                    del))
          (dolist (o ovrs)
            ;;(dolist (o (overlays-in (1- (point)) (1+ (point))))
            ;;   (if (overlay-get o 'hide-ifdef) (message "%S" o)))
            (if (overlay-get o 'hide-ifdef)
                (delete-overlay o)))))))


;;;  definition alist support
;; The old implementation that match symbol only to 't is now considered
;; obsolete.

(defvar hide-ifdef-define-alist nil
  "A global assoc list of pre-defined symbol lists.")

(defun hide-ifdef-set-define-alist (name)
  "Set the association for NAME to `hide-ifdef-env'."
  (interactive "SSet define list: ")
  (push (cons name hide-ifdef-env)
        hide-ifdef-define-alist))

(defun hide-ifdef-use-define-alist (name)
  "Set `hide-ifdef-env' to the define list specified by NAME."
  (interactive
   (list (completing-read "Use define list: "
			  (mapcar (lambda (x) (symbol-name (car x)))
                                  hide-ifdef-define-alist)
                          nil t)))
  (if (stringp name) (setq name (intern name)))
  (let ((define-list (assoc name hide-ifdef-define-alist)))
    (if define-list
        (setq hide-ifdef-env
              (cdr define-list))
      (error "No define list for %s" name))
    (if hide-ifdef-hiding (hide-ifdefs))))

(provide 'hideif)

;;; hideif.el ends here