;;; fortran.el --- Fortran mode for GNU Emacs

;; Copyright (C) 1986, 1993-1995, 1997-2017 Free Software Foundation,
;; Inc.

;; Author: Michael D. Prange <prange@erl.mit.edu>
;; Maintainer: Glenn Morris <rgm@gnu.org>
;; Keywords: fortran, languages

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

;;; Commentary:

;; This mode is documented in the Emacs manual.
;;
;; Note that it is for editing Fortran77 or Fortran90 fixed source
;; form.  For editing Fortran 90 free format source, use `f90-mode'
;; (f90.el).  It is meant to support the GNU Fortran language
;; implemented by g77 (its extensions to Fortran77 and
;; interpretations, e.g. of backslash in strings).

;;; History:

;; Fortran mode was upgraded by Stephen A. Wood (saw@cebaf.gov).

;; We acknowledge many contributions and valuable suggestions by
;; Lawrence R. Dodd, Ralf Fassel, Ralph Finch, Stephen Gildea,
;; Dr. Anil Gokhale, Ulrich Mueller, Mark Neale, Eric Prestemon,
;; Gary Sabot and Richard Stallman.

;;; Code:

;; Todo:

;; * Tidy it all up (more)!
;; * Implement insertion and removal of statement continuations in
;;   mixed f77/f90 style, with the first `&' past column 72 and the
;;   second in column 6.
;; * Support any other extensions to f77 grokked by GNU Fortran I've missed.

;; silence compiler
(defvar dabbrev-case-fold-search)
(defvar gud-find-expr-function)
(defvar imenu-case-fold-search)
(defvar imenu-syntax-alist)
(defvar comment-region-function)
(defvar uncomment-region-function)

(defgroup fortran nil
  "Major mode for editing fixed format Fortran code."
  :link '(custom-group-link :tag "Font Lock Faces group" font-lock-faces)
  :link '(custom-manual "(emacs)Fortran")
  :group 'languages)

(defgroup fortran-indent nil
  "Indentation variables in Fortran mode."
  :prefix "fortran-"
  :group  'fortran)

(defgroup fortran-comment nil
  "Comment-handling variables in Fortran mode."
  :prefix "fortran-"
  :group  'fortran)


(defcustom fortran-tab-mode-default nil
  "Default tabbing/carriage control style for empty files in Fortran mode.
A non-nil value specifies tab-digit style of continuation control.
A value of nil specifies that continuation lines are marked
with a character in column 6."
  :type  'boolean
  :safe  'booleanp
  :group 'fortran-indent)

;; TODO add more detail of what tab mode is to doc string.
(defcustom fortran-tab-mode-string
  (propertize "/t" 'help-echo "This buffer is in Fortran TAB mode"
              'mouse-face 'mode-line-highlight
              'local-map
              (make-mode-line-mouse-map 'mouse-1
                                        (lambda ()
                                          (interactive)
                                          (describe-variable
                                           'fortran-tab-mode-string))))
  "String to appear in mode line in TAB format buffers.
See Info node `(emacs)ForIndent Cont'."
  :type  'string
  :risky t
  :group 'fortran-indent)

(defcustom fortran-do-indent 3
  "Extra indentation applied to DO blocks."
  :type  'integer
  :safe  'integerp
  :group 'fortran-indent)

(defcustom fortran-if-indent 3
  "Extra indentation applied to IF, SELECT CASE and WHERE blocks."
  :type  'integer
  :safe  'integerp
  :group 'fortran-indent)

(defcustom fortran-structure-indent 3
  "Extra indentation applied to STRUCTURE, UNION, MAP and INTERFACE blocks."
  :type  'integer
  :safe  'integerp
  :group 'fortran-indent)

(defcustom fortran-continuation-indent 5
  "Extra indentation applied to continuation lines."
  :type  'integer
  :safe  'integerp
  :group 'fortran-indent)

(defcustom fortran-comment-indent-style 'fixed
  "How to indent comments.
nil forces comment lines not to be touched;
`fixed' indents to `fortran-comment-line-extra-indent' columns beyond
  `fortran-minimum-statement-indent-fixed' (if `indent-tabs-mode' nil), or
  `fortran-minimum-statement-indent-tab' (if `indent-tabs-mode' non-nil);
`relative' indents to current Fortran indentation plus
  `fortran-comment-line-extra-indent'."
  :type  '(radio (const :tag "Untouched" nil) (const fixed) (const relative))
  :safe  (lambda (value) (memq value '(nil fixed relative)))
  :group 'fortran-indent)

(defcustom fortran-comment-line-extra-indent 0
  "Amount of extra indentation for text within full-line comments."
  :type  'integer
  :safe  'integerp
  :group 'fortran-indent
  :group 'fortran-comment)

(defcustom fortran-comment-line-start "C"
  "Delimiter inserted to start new full-line comment.
You might want to change this to \"*\", for instance; or \"!\" to
allow trailing comments on a line."
  :version "21.1"
  :type    'string
  :safe    'stringp
  :group   'fortran-comment)

;; This used to match preprocessor lines too, but that messes up
;; filling and doesn't seem to be necessary.
(defcustom fortran-comment-line-start-skip
  "^[CcDd*!]\\(\\([^ \t\n]\\)\\2+\\)?[ \t]*"
  "Regexp to match the start of a full-line comment."
  :version "21.1"
  :type    'regexp
  :safe    'stringp
  :group   'fortran-comment)

(defcustom fortran-directive-re
  "^[ \t]*#.*"
  "Regexp to match a directive line.
The matching text will be fontified with `font-lock-preprocessor-face'.
The matching line will be given zero indentation."
  :version "22.1"
  :type    'regexp
  :safe    'stringp
  :group   'fortran-indent)

(defcustom fortran-minimum-statement-indent-fixed 6
  "Minimum statement indentation for fixed format continuation style."
  :type  'integer
  :safe  'integerp
  :group 'fortran-indent)

(defcustom fortran-minimum-statement-indent-tab (max tab-width 6)
  "Minimum statement indentation for TAB format continuation style."
  :type  'integer
  :safe  'integerp
  :group 'fortran-indent)

;; Note that this is documented in the v18 manuals as being a string
;; of length one rather than a single character.
;; The code in this file accepts either format for compatibility.
(defcustom fortran-comment-indent-char " "
  "Single-character string inserted for Fortran comment indentation.
Normally a space."
  :type  'string
  :safe  (lambda (value) (or (characterp value)
                             (and (stringp value) (= (length value) 1))))
  :group 'fortran-comment)

(defcustom fortran-line-number-indent 1
  "Maximum indentation for Fortran line numbers.
5 means right-justify them within their five-column field."
  :type  'integer
  :safe  'integerp
  :group 'fortran-indent)

(defcustom fortran-check-all-num-for-matching-do nil
  "Non-nil causes all numbered lines to be treated as possible DO loop ends."
  :type  'boolean
  :safe  'booleanp
  :group 'fortran)

(defcustom fortran-blink-matching-if nil
  "Non-nil causes \\[fortran-indent-line] on ENDIF to blink on matching IF.
Also, from an ENDDO statement blink on matching DO [WHILE] statement."
  :type  'boolean
  :safe  'booleanp
  :group 'fortran)

(defcustom fortran-continuation-string "$"
  "Single-character string used for Fortran continuation lines.
In fixed format continuation style, this character is inserted in
column 6 by \\[fortran-split-line] to begin a continuation line.
Also, if \\[fortran-indent-line] finds this at the beginning of a
line, it will convert the line into a continuation line of the
appropriate style.  Normally \"$\"."
  :type  'string
  :safe  (lambda (value) (and (stringp value) (= (length value) 1)))
  :group 'fortran)

(defcustom fortran-comment-region "c$$$"
  "String inserted by \\[fortran-comment-region] at start of each \
line in region."
  :type  'string
  :safe  'stringp
  :group 'fortran-comment)

(defcustom fortran-electric-line-number t
  "Non-nil causes line numbers to be moved to the correct column as typed."
  :type  'boolean
  :safe  'booleanp
  :group 'fortran)

;; TODO use fortran-line-length, somehow.
(defcustom fortran-column-ruler-fixed
  "0   4 6  10        20        30        40        5\
0        60        70\n\
[   ]|{   |    |    |    |    |    |    |    |    \
|    |    |    |    |}\n"
  "String displayed above current line by \\[fortran-column-ruler].
This variable is used in fixed format mode.
See the variable `fortran-column-ruler-tab' for TAB format mode."
  :type  'string
  :safe  'stringp
  :group 'fortran)

;; TODO use fortran-line-length, somehow.
(defcustom fortran-column-ruler-tab
  "0       810        20        30        40        5\
0        60        70\n\
[   ]|  { |    |    |    |    |    |    |    |    \
|    |    |    |    |}\n"
  "String displayed above current line by \\[fortran-column-ruler].
This variable is used in TAB format mode.
See the variable `fortran-column-ruler-fixed' for fixed format mode."
  :type  'string
  :safe  'stringp
  :group 'fortran)

(defcustom fortran-analyze-depth 100
  "Number of lines to scan to identify fixed or TAB format style."
  :type  'integer
  :safe  'integerp
  :group 'fortran)

(defcustom fortran-break-before-delimiters t
  "Non-nil causes filling to break lines before delimiters.
Delimiters are characters matching the regexp `fortran-break-delimiters-re'."
  :type  'boolean
  :safe  'booleanp
  :group 'fortran)

;; TODO 0 as no-limit, as per g77.
(defcustom fortran-line-length 72
  "Maximum number of characters in a line of fixed-form Fortran code.
Characters beyond this point are treated as comments.  Setting
this variable directly (after fortran mode is loaded) does not
take effect.  Use either \\[customize] (which affects all Fortran
buffers and the default) or the function
`fortran-line-length' (which can also operate on just the current
buffer).  This corresponds to the g77 compiler option
`-ffixed-line-length-N'."
  :type 'integer
  :safe 'integerp
  :initialize 'custom-initialize-default
  :set (lambda (_symbol value)
         ;; Do all fortran buffers, and the default.
         (fortran-line-length value t))
  :version "23.1"
  :group 'fortran)

(make-variable-buffer-local 'fortran-line-length)

(defcustom fortran-mode-hook nil
  "Hook run when entering Fortran mode."
  :type  'hook
  :group 'fortran)


(defconst fortran-break-delimiters-re "[-+*/><=, \t]"
  "Regexp matching delimiter characters at which lines may be broken.
There are certain tokens comprised entirely of characters
matching this regexp that should not be split, and these are
specified by the constant `fortran-no-break-re'.")

;; The ">=", etc F77 extensions are supported by g77.
(defconst fortran-no-break-re
  (regexp-opt '("**" "//" "=>" ">=" "<=" "==" "/=") 'paren)
  "Regexp specifying where not to break lines when filling.
This regexp matches certain tokens comprised entirely of
characters matching the regexp `fortran-break-delimiters-re' that should
not be split by filling.  Each element is assumed to be two
characters long.")

(defconst fortran-if-start-re "\\(\\(\\sw\\|\\s_\\)+:[ \t]*\\)?if[ \t]*("
  "Regexp matching the start of an IF statement.")

;; Note fortran-current-defun uses the subgroups.
(defconst fortran-start-prog-re
  "^[ \t]*\\(program\\|subroutine\\|function\
\\|[ \ta-z0-9*()]*[ \t]+function\\|\
\\(block[ \t]*data\\)\\)"
  "Regexp matching the start of a subprogram, from the line start.")

(defconst fortran-end-prog-re1
  "end\
\\([ \t]*\\(program\\|subroutine\\|function\\|block[ \t]*data\\)\\>\
\\([ \t]*\\(\\sw\\|\\s_\\)+\\)?\\)?"
  "Regexp possibly matching the end of a subprogram.")

(defconst fortran-end-prog-re
  (concat "^[ \t0-9]*" fortran-end-prog-re1)
  "Regexp possibly matching the end of a subprogram, from the line start.
See also `fortran-end-prog-re1'.")

(defconst fortran-type-types
  (concat "\\<"
          (mapconcat 'identity          ; " " -> "[ \t]*"
                     (split-string
                      (regexp-opt
                       (let ((simple-types
                              '("character" "byte" "integer" "logical"
                                "none" "real" "complex"
                                "double precision" "double complex"))
                             (structured-types '("structure" "union" "map"))
                             (other-types '("record" "dimension"
                                            "parameter" "common" "save"
                                            "external" "intrinsic" "data"
                                            "equivalence")))
                         (append
                          (mapcar (lambda (x) (concat "implicit " x))
                                  simple-types)
                          simple-types
                          (mapcar (lambda (x) (concat "end " x))
                                  structured-types)
                          structured-types
                          other-types)) 'paren))
                     "[ \t]*") "\\>")
  "Regexp matching Fortran types.")

(defvar fortran-font-lock-keywords-1
  ;; Program, subroutine and function declarations, plus calls.
  '(("\\<\\(block[ \t]*data\\|call\\|entry\\|function\\|\
program\\|subroutine\\)\\>[ \t]*\\(\\sw+\\)?"
     (1 font-lock-keyword-face)
     (2 font-lock-function-name-face nil t)))
  "Subdued level highlighting for Fortran mode.")

(defvar fortran-font-lock-keywords-2
  (append fortran-font-lock-keywords-1
          (list
           ;; Fontify all type specifiers (must be first - see below).
           (cons fortran-type-types 'font-lock-type-face)
           ;; Builtin keywords (except logical, do and goto - see below).
           (concat "\\<" (regexp-opt
                          '("continue" "format" "end" "enddo"
                            "if" "then" "else" "endif" "elseif"
                            "while" "inquire" "stop" "return"
                            "include" "open" "close" "read"
                            "write" "format" "print" "select" "case"
                            "cycle" "exit" "rewind" "backspace"
                            "where" "elsewhere")
                          'paren) "\\>")
           ;; Builtin operators.
           (concat "\\." (regexp-opt
                          '("and" "eq" "eqv" "false" "ge" "gt" "le" "lt" "ne"
                            "neqv" "not" "or" "true")
                          'paren) "\\.")
           ;; do/goto keywords and targets, and goto tags.
           '("\\<\\(do\\|go *to\\)\\>[ \t]*\\([0-9]+\\)?"
             (1 font-lock-keyword-face)
             (2 font-lock-constant-face nil t))
           '("^ *\\([0-9]+\\)" . font-lock-constant-face)))
  "Medium level highlighting for Fortran mode.")

;; See bug#1385. Never really looked into _why_ this matters...
(defun fortran-match-and-skip-declaration (limit)
  "Like `font-lock-match-c-style-declaration-item-and-skip-to-next'.
The only difference is, it returns t in a case when the default returns nil."
  (when (looking-at "[ \n\t*]*\\(\\sw+\\)[ \t\n]*\\(((?\\)?")
    (when (and (match-end 2) (> (- (match-end 2) (match-beginning 2)) 1))
      (let ((pos (point)))
	(skip-chars-backward " \t\n")
	(skip-syntax-backward "w")
	(unless (looking-at "\\(\\sw+\\)[ \t\n]*\\sw+[ \t\n]*\\(((?\\)?")
	  (goto-char pos)
	  (looking-at "[ \n\t*]*\\(\\sw+\\)[ \t\n]*\\(((?\\)?"))))
    (save-match-data
      (condition-case nil
	  (save-restriction
	    (narrow-to-region (point-min) limit)
	    (goto-char (match-end 1))
	    (while (not (looking-at "[ \t\n]*\\(\\(,\\)\\|;\\|\\'\\)"))
	      (goto-char (or (scan-sexps (point) 1) (point-max))))
            (goto-char (match-end 2)))
	(error t)))))

(defvar fortran-font-lock-keywords-3
  (append
   fortran-font-lock-keywords-1
   ;; All type specifiers plus their declared items.
   (list
    (list (concat fortran-type-types "[ \t(/]*\\(*\\)?")
          ;; Type specifier.
          '(1 font-lock-type-face)
          ;; Declaration item (or just /.../ block name).
          `(fortran-match-and-skip-declaration
            ;; Start after any *(...) expression.
            (condition-case nil
                (and (match-beginning ,(1+ (regexp-opt-depth
                                            fortran-type-types)))
                     (forward-sexp)
                     (forward-sexp))
              (error nil))
            ;; No need to clean up.
            nil
            ;; Fontify as a variable name, functions fontified elsewhere.
            (1 font-lock-variable-name-face nil t))))
   ;; Things extra to `fortran-font-lock-keywords-3' (must be done first).
   (list
    ;; Goto-like `err=label'/`end=label' in read/write statements.
    '(", *\\(e\\(nd\\|rr\\)\\)\\> *\\(= *\\([0-9]+\\)\\)?"
      (1 font-lock-keyword-face) (4 font-lock-constant-face nil t))
    ;; Standard continuation character and in a TAB-formatted line.
    '("^ \\{5\\}\\([^ 0\n]\\)" 1 font-lock-string-face)
    '("^\t\\([1-9]\\)"         1 font-lock-string-face))
   `((,fortran-directive-re (0 font-lock-preprocessor-face t)))
   ;; `fortran-font-lock-keywords-2' without types (see above).
   (cdr (nthcdr (length fortran-font-lock-keywords-1)
                fortran-font-lock-keywords-2)))
  "Gaudy level highlighting for Fortran mode.")

(defvar fortran-font-lock-keywords-4
  (append fortran-font-lock-keywords-3
          (list (list
                 (concat "\\<"
                         (regexp-opt
                          '("int" "ifix" "idint" "real" "float" "sngl"
                            "dble" "cmplx" "ichar" "char" "aint" "dint"
                            "anint" "dnint" "nint" "idnint" "iabs" "abs"
                            "dabs" "cabs" "mod" "amod" "dmod" "isign"
                            "sign" "dsign" "idim" "dim" "ddim" "dprod"
                            "max" "max0" "amax1" "dmax1" "amax0" "max1"
                            "min" "min0" "amin1" "dmin1" "amin0" "min1"
                            "len" "index" "lge" "lgt" "lle" "llt" "aimag"
                            "conjg" "sqrt" "dsqrt" "csqrt" "exp" "dexp"
                            "cexp" "log" "alog" "dlog" "clog" "log10"
                            "alog10" "dlog10" "sin" "dsin" "csin" "cos"
                            "dcos" "ccos" "tan" "dtan" "asin" "dasin"
                            "acos" "dacos" "atan" "datan" "atan2" "datan2"
                            "sinh" "dsinh" "cosh" "dcosh" "tanh" "dtanh")
                          'paren) "[ \t]*(") '(1 font-lock-builtin-face))))
  "Maximum highlighting for Fortran mode.
Consists of level 3 plus all other intrinsics not already highlighted.")

;; Comments are real pain in Fortran because there is no way to
;; represent the standard comment syntax in an Emacs syntax table.
;; (We can do so for F90-style).  Therefore an unmatched quote in a
;; standard comment will throw fontification off on the wrong track.
;; So we do syntactic fontification with regexps.
(defun fortran-make-syntax-propertize-function (line-length)
  "Return a value for `syntax-propertize-function' in Fortran mode.
This varies according to the value of LINE-LENGTH.
This is used to fontify fixed-format Fortran comments."
  ;; This results in a non-byte-compiled function.  We could pass it through
  ;; `byte-compile', but simple benchmarks indicate that it's probably not
  ;; worth the trouble (about 0.5% of slow down).
  (eval                         ;I hate `eval', but it's hard to avoid it here.
   `(syntax-propertize-rules
     ("^[CcDd\\*]" (0 "<"))
     ;; We mark all chars after line-length as "comment-start", rather than
     ;; just the first one.  This is so that a closing ' that's past the
     ;; line-length will indeed be ignored (and will result in a string that
     ;; leaks into subsequent lines).
     ((format "^[^CcDd\\*\t\n].\\{%d\\}\\(.+\\)" (1- line-length))
      (1 "<")))))

(defvar fortran-font-lock-keywords fortran-font-lock-keywords-1
  "Default expressions to highlight in Fortran mode.")

(defvar fortran-imenu-generic-expression
  ;; These patterns could be confused by sequence nos. in cols 72+ and
  ;; don't allow continuations everywhere.
  (list
   (list
    nil
    ;; [This will be fooled by `end function' allowed by G77.  Also,
    ;; it assumes sensible whitespace is employed.]
    (concat
     ;; leading whitespace:
     "^\\s-+\\("
     ;; function declaration with optional type, e.g. `real',
     ;; `real*4', character(*), `double precision':
     "\\(\\sw\\|\\s-\\|[*()+]\\)*"
     "\\<function\\|subroutine\\|entry\\|block\\s-*data\\|program\\)"
     ;; Possible statement continuation:
     "[ \t" fortran-continuation-string "]+"
     ;; Variable to index:
     "\\(\\sw+\\)")
    3)
   ;; Un-named block data.
   '(nil "^\\s-+\\(block\\s-*data\\)\\s-*$" 1))
  "Value for `imenu-generic-expression' in Fortran mode.")


;; Hideshow support.
(defconst fortran-blocks-re
  (concat "block[ \t]*data\\|select[ \t]*case\\|"
          (regexp-opt '("do" "if" "interface" "function" "map" "program"
                        "structure" "subroutine" "union" "where")))
  "Regexp potentially indicating the start or end of a Fortran \"block\".
Omits naked END statements, and DO-loops closed by anything other
than ENDDO.")

(defconst fortran-end-block-re
  ;; Do-loops terminated by things other than ENDDO cannot be handled
  ;; with a regexp. This omission does not seem to matter to hideshow...
  (concat "^[ \t0-9]*\\<end[ \t]*\\("
          fortran-blocks-re
          ;; Naked END statement.
          "\\|!\\|$\\)")
  "Regexp matching the end of a Fortran \"block\", from the line start.
Note that only ENDDO is handled for the end of a DO-loop.  Used
in the Fortran entry in `hs-special-modes-alist'.")

(defconst fortran-start-block-re
  (concat
   "^[ \t0-9]*\\("                      ; statement number
   ;; Structure label for DO, IF, SELECT, WHERE.
   "\\(\\(\\sw+[ \t]*:[ \t]*\\)?"
   ;; IF blocks are a nuisance:
   ;; IF ( ... ) foo   is not a block, but a single statement.
   ;; IF ( ... ) THEN  can be split over multiple lines.
   ;; [So can, eg, a DO WHILE (... ), but that is less common, I hope.]
   ;; The regexp below allows for it to be split over at most 2 lines.
   ;; That leads to the problem of not matching two consecutive IF
   ;; statements as one, eg:
   ;; IF ( ... ) foo
   ;; IF ( ... ) THEN
   ;; It simply is not possible to do this in a 100% correct fashion
   ;; using a regexp - see the functions fortran-end-if,
   ;; fortran-beginning-if for the hoops we have to go through.
   ;; An alternative is to match on THEN at a line end, eg:
   ;;   ".*)[ \t]*then[ \t]*\\($\\|!\\)"
   ;; This would also match ELSE branches, though. This does not seem
   ;; right to me, because then one has neighboring blocks that are
   ;; not nested in each other.
   "\\(if[ \t]*(\\(.*\\|"
   ".*\n\\([^if]*\\([^i].\\|.[^f]\\|.\\>\\)\\)\\)\\<then\\|"
   "do\\|select[ \t]*case\\|where\\)\\)\\|"
   (regexp-opt '("interface" "function" "map" "program"
                 "structure" "subroutine" "union"))
   "\\|block[ \t]*data\\)[ \t]*")
  "Regexp matching the start of a Fortran \"block\", from the line start.
A simple regexp cannot do this in fully correct fashion, so this
tries to strike a compromise between complexity and flexibility.
Used in the Fortran entry in `hs-special-modes-alist'.")

(add-to-list 'hs-special-modes-alist
             `(fortran-mode ,fortran-start-block-re ,fortran-end-block-re
                            "^[cC*!]" fortran-end-of-block nil))


(defvar fortran-mode-syntax-table
  (let ((table (make-syntax-table)))
    ;; Was a word-constituent (for abbrevs), now punctuation (g77
    ;; multi-statement lines).
    (modify-syntax-entry ?\; "."  table)
    (modify-syntax-entry ?\r " "  table)
    (modify-syntax-entry ?+  "."  table)
    (modify-syntax-entry ?-  "."  table)
    (modify-syntax-entry ?=  "."  table)
    (modify-syntax-entry ?*  "."  table)
    (modify-syntax-entry ?/  "."  table)
    (modify-syntax-entry ?%  "."  table) ; bug#8820
    (modify-syntax-entry ?\' "\"" table)
    (modify-syntax-entry ?\" "\"" table)
    ;; Consistent with GNU Fortran's default -- see the manual.
    ;; The F77 standard imposes no rule on this issue.
    (modify-syntax-entry ?\\ "\\" table)
    ;; This might be better as punctuation, as for C, but this way you
    ;; can treat floating-point numbers as symbols.
    (modify-syntax-entry ?.  "_"  table) ; e.g. `a.ne.b'
    (modify-syntax-entry ?_  "_"  table)
    (modify-syntax-entry ?$  "_"  table) ; esp. VMSisms
    (modify-syntax-entry ?\! "<"  table)
    (modify-syntax-entry ?\n ">"  table)
    table)
  "Syntax table used in Fortran mode.")

(defvar fortran-gud-syntax-table
  (let ((st (make-syntax-table fortran-mode-syntax-table)))
    (modify-syntax-entry ?\n "." st)
    st)
  "Syntax table used to parse Fortran expressions for printing in GUD.")

(defvar fortran-mode-map
  (let ((map (make-sparse-keymap)))
    (define-key map ";"        'fortran-abbrev-start)
    (define-key map "\C-c;"    'fortran-comment-region)
    ;; The default comment-dwim does at least as much as this.
;;;    (define-key map "\M-;"     'fortran-indent-comment)
    (define-key map "\M-\n"    'fortran-split-line)
    (define-key map "\M-\C-n"  'fortran-end-of-block)
    (define-key map "\M-\C-p"  'fortran-beginning-of-block)
    (define-key map "\M-\C-q"  'fortran-indent-subprogram)
    (define-key map "\C-c\C-w" 'fortran-window-create-momentarily)
    (define-key map "\C-c\C-r" 'fortran-column-ruler)
    (define-key map "\C-c\C-p" 'fortran-previous-statement)
    (define-key map "\C-c\C-n" 'fortran-next-statement)
    (define-key map "\C-c\C-d" 'fortran-join-line) ; like f90
    (define-key map "\M-^"     'fortran-join-line) ; subvert delete-indentation
    (define-key map "0" 'fortran-electric-line-number)
    (define-key map "1" 'fortran-electric-line-number)
    (define-key map "2" 'fortran-electric-line-number)
    (define-key map "3" 'fortran-electric-line-number)
    (define-key map "4" 'fortran-electric-line-number)
    (define-key map "5" 'fortran-electric-line-number)
    (define-key map "6" 'fortran-electric-line-number)
    (define-key map "7" 'fortran-electric-line-number)
    (define-key map "8" 'fortran-electric-line-number)
    (define-key map "9" 'fortran-electric-line-number)

    (easy-menu-define fortran-menu map "Menu for Fortran mode."
      `("Fortran"
        ["Manual" (info "(emacs)Fortran") :active t
         :help "Read the Emacs manual chapter on Fortran mode"]
        ("Customization"
         ,(custom-menu-create 'fortran)
         ;; FIXME useless?
         ["Set"  Custom-set :active t
          :help "Set current value of all edited settings in the buffer"]
         ["Save" Custom-save :active t
          :help "Set and save all edited settings"]
         ["Reset to Current" Custom-reset-current :active t
          :help "Reset all edited settings to current"]
         ["Reset to Saved" Custom-reset-saved :active t
          :help "Reset all edited or set settings to saved"]
         ["Reset to Standard Settings" Custom-reset-standard :active t
          :help "Erase all customizations in buffer"]
         )
        "--"
        ["Comment Region" fortran-comment-region mark-active]
        ["Uncomment Region"
         (fortran-comment-region (region-beginning) (region-end) 1)
         mark-active]
        ["Indent Region"     indent-region mark-active]
        ["Indent Subprogram" fortran-indent-subprogram t]
        "--"
        ["Beginning of Subprogram" fortran-beginning-of-subprogram :active t
         :help "Move point to the start of the current subprogram"]
        ["End of Subprogram" fortran-end-of-subprogram :active t
         :help "Move point to the end of the current subprogram"]
        ("Mark"
         :help "Mark a region of code"
         ["Subprogram" mark-defun      t]
         ["IF Block"   fortran-mark-if t]
         ["DO Block"   fortran-mark-do t]
         )
        ["Narrow to Subprogram" narrow-to-defun t]
        ["Widen" widen t]
        "--"
        ["Temporary Column Ruler" fortran-column-ruler :active t
         :help "Briefly display Fortran column numbers"]
        ;; May not be '72', depending on fortran-line-length, but this
        ;; seems ok for a menu item.
        ["72-column Window" fortran-window-create :active t
         :help "Set window width to Fortran line length"]
        ["Full Width Window"
         (enlarge-window-horizontally (- (frame-width) (window-width)))
         :active (not (window-full-width-p))
         :help "Make window full width"]
        ["Momentary 72-Column Window" fortran-window-create-momentarily
         :active t :help "Briefly set window width to Fortran line length"]
        "--"
        ["Break Line at Point" fortran-split-line :active t
         :help "Break the current line at point"]
        ["Join Line" fortran-join-line :active t
         :help "Join the current line to the previous one"]
        ["Fill Statement/Comment" fill-paragraph t]
        "--"
        ["Toggle Auto Fill" auto-fill-mode :selected auto-fill-function
         :style toggle
         :help "Automatically fill text while typing in this buffer"]
        ["Toggle Abbrev Mode" abbrev-mode :selected abbrev-mode
         :style toggle :help "Expand abbreviations while typing in this buffer"]
        ["Add Imenu Menu" imenu-add-menubar-index
         :active   (not (lookup-key (current-local-map) [menu-bar index]))
         :included (fboundp 'imenu-add-to-menubar)
         :help "Add an index menu to the menu-bar"]))
    map)
  "Keymap used in Fortran mode.")


(define-abbrev-table 'fortran-mode-abbrev-table
  (mapcar (lambda (e) (list (car e) (cdr e) nil :system t))
          '((";au"   . "automatic"         )
            (";b"    . "byte"              )
            (";bd"   . "block data"        )
            (";ch"   . "character"         )
            (";cl"   . "close"             )
            (";c"    . "continue"          )
            (";cm"   . "common"            )
            (";cx"   . "complex"           )
            (";df"   . "define"            )
            (";di"   . "dimension"         )
            (";do"   . "double"            )
            (";dc"   . "double complex"    )
            (";dp"   . "double precision"  )
            (";dw"   . "do while"          )
            (";e"    . "else"              )
            (";ed"   . "enddo"             )
            (";el"   . "elseif"            )
            (";en"   . "endif"             )
            (";eq"   . "equivalence"       )
            (";ew"   . "endwhere"          )
            (";ex"   . "external"          )
            (";ey"   . "entry"             )
            (";f"    . "format"            )
            (";fa"   . ".false."           )
            (";fu"   . "function"          )
            (";g"    . "goto"              )
            (";im"   . "implicit"          )
            (";ib"   . "implicit byte"     )
            (";ic"   . "implicit complex"  )
            (";ich"  . "implicit character")
            (";ii"   . "implicit integer"  )
            (";il"   . "implicit logical"  )
            (";ir"   . "implicit real"     )
            (";inc"  . "include"           )
            (";in"   . "integer"           )
            (";intr" . "intrinsic"         )
            (";l"    . "logical"           )
            (";n"    . "namelist"          )
            (";o"    . "open"              ) ; was ;op
            (";pa"   . "parameter"         )
            (";pr"   . "program"           )
            (";ps"   . "pause"             )
            (";p"    . "print"             )
            (";rc"   . "record"            )
            (";re"   . "real"              )
            (";r"    . "read"              )
            (";rt"   . "return"            )
            (";rw"   . "rewind"            )
            (";s"    . "stop"              )
            (";sa"   . "save"              )
            (";st"   . "structure"         )
            (";sc"   . "static"            )
            (";su"   . "subroutine"        )
            (";tr"   . ".true."            )
            (";ty"   . "type"              )
            (";vo"   . "volatile"          )
            (";w"    . "write"             )
            (";wh"   . "where"             )))
  "Abbrev table for Fortran mode."
  ;; Accept ; as the first char of an abbrev.  Also allow _ in abbrevs.
  :regexp "\\(?:[^[:word:]_;]\\|^\\)\\(;?[[:word:]_]+\\)[^[:word:]_]*")


;;;###autoload
(define-derived-mode fortran-mode prog-mode "Fortran"
  "Major mode for editing Fortran code in fixed format.
For free format code, use `f90-mode'.

\\[fortran-indent-line] indents the current Fortran line correctly.
Note that DO statements must not share a common CONTINUE.

Type ;? or ;\\[help-command] to display a list of built-in abbrevs for\
 Fortran keywords.

Key definitions:
\\{fortran-mode-map}

Variables controlling indentation style and extra features:

`fortran-comment-line-start'
  To use comments starting with `!', set this to the string \"!\".
`fortran-do-indent'
  Extra indentation within DO blocks (default 3).
`fortran-if-indent'
  Extra indentation within IF blocks (default 3).
`fortran-structure-indent'
  Extra indentation within STRUCTURE, UNION, MAP and INTERFACE blocks.
  (default 3)
`fortran-continuation-indent'
  Extra indentation applied to continuation statements (default 5).
`fortran-comment-line-extra-indent'
  Amount of extra indentation for text in full-line comments (default 0).
`fortran-comment-indent-style'
  How to indent the text in full-line comments. Allowed values are:
  nil         don't change the indentation
  `fixed'     indent to `fortran-comment-line-extra-indent' beyond the
              value of either
                `fortran-minimum-statement-indent-fixed' (fixed format) or
                `fortran-minimum-statement-indent-tab' (TAB format),
              depending on the continuation format in use.
  `relative'  indent to `fortran-comment-line-extra-indent' beyond the
              indentation for a line of code.
  (default `fixed')
`fortran-comment-indent-char'
  Single-character string to be inserted instead of space for
  full-line comment indentation (default \" \").
`fortran-minimum-statement-indent-fixed'
  Minimum indentation for statements in fixed format mode (default 6).
`fortran-minimum-statement-indent-tab'
  Minimum indentation for statements in TAB format mode (default 9).
`fortran-line-number-indent'
  Maximum indentation for line numbers (default 1).  A line number will
  get less than this much indentation if necessary to avoid reaching
  column 5.
`fortran-check-all-num-for-matching-do'
  Non-nil causes all numbered lines to be treated as possible \"continue\"
  statements (default nil).
`fortran-blink-matching-if'
  Non-nil causes \\[fortran-indent-line] on an ENDIF (or ENDDO) statement
  to blink on the matching IF (or DO [WHILE]).  (default nil)
`fortran-continuation-string'
  Single-character string to be inserted in column 5 of a continuation
  line (default \"$\").
`fortran-comment-region'
  String inserted by \\[fortran-comment-region] at start of each line in
  the region (default \"c$$$\").
`fortran-electric-line-number'
  Non-nil causes line number digits to be moved to the correct column
  as typed (default t).
`fortran-break-before-delimiters'
  Non-nil causes lines to be broken before delimiters (default t).

Turning on Fortran mode calls the value of the variable `fortran-mode-hook'
with no args, if that value is non-nil."
  :group 'fortran
  :syntax-table fortran-mode-syntax-table
  :abbrev-table fortran-mode-abbrev-table
  (set (make-local-variable 'indent-line-function) 'fortran-indent-line)
  (set (make-local-variable 'indent-region-function)
       (lambda (start end)
         (let (fortran-blink-matching-if ; avoid blinking delay
               indent-region-function)
           (indent-region start end nil))))
  (set (make-local-variable 'require-final-newline) mode-require-final-newline)
  ;; The syntax tables don't understand the column-0 comment-markers.
  (set (make-local-variable 'comment-use-syntax) nil)
  (set (make-local-variable 'comment-padding) "$$$")
  (set (make-local-variable 'comment-start) fortran-comment-line-start)
  (set (make-local-variable 'comment-start-skip)
       ;; We can't reuse `fortran-comment-line-start-skip' directly because
       ;; it contains backrefs whereas we need submatch-1 to end at the
       ;; beginning of the comment delimiter.
       ;; (concat "\\(\\)\\(![ \t]*\\|" fortran-comment-line-start-skip "\\)")
       "\\(\\)\\(?:^[CcDd*]\\|!\\)\\(?:\\([^ \t\n]\\)\\2+\\)?[ \t]*")
  (set (make-local-variable 'comment-indent-function) 'fortran-comment-indent)
  (set (make-local-variable 'comment-region-function) 'fortran-comment-region)
  (set (make-local-variable 'uncomment-region-function)
       'fortran-uncomment-region)
  (set (make-local-variable 'comment-insert-comment-function)
       'fortran-indent-comment)
  (set (make-local-variable 'abbrev-all-caps) t)
  (set (make-local-variable 'normal-auto-fill-function) 'fortran-auto-fill)
  (set (make-local-variable 'indent-tabs-mode) (fortran-analyze-file-format))
  (setq mode-line-process '(indent-tabs-mode fortran-tab-mode-string))
  (set (make-local-variable 'fill-column) fortran-line-length)
  (set (make-local-variable 'fill-paragraph-function) 'fortran-fill-paragraph)
  (set (make-local-variable 'font-lock-defaults)
       '((fortran-font-lock-keywords
          fortran-font-lock-keywords-1
          fortran-font-lock-keywords-2
          fortran-font-lock-keywords-3
          fortran-font-lock-keywords-4)
         nil t ((?/ . "$/") ("_$" . "w"))
         fortran-beginning-of-subprogram))
  (set (make-local-variable 'syntax-propertize-function)
       (fortran-make-syntax-propertize-function fortran-line-length))
  (set (make-local-variable 'imenu-case-fold-search) t)
  (set (make-local-variable 'imenu-generic-expression)
       fortran-imenu-generic-expression)
  (set (make-local-variable 'imenu-syntax-alist) '(("_$" . "w")))
  (set (make-local-variable 'beginning-of-defun-function)
       #'fortran-beginning-of-subprogram)
  (set (make-local-variable 'end-of-defun-function)
       #'fortran-end-of-subprogram)
  (set (make-local-variable 'add-log-current-defun-function)
       #'fortran-current-defun)
  (set (make-local-variable 'dabbrev-case-fold-search) 'case-fold-search)
  (set (make-local-variable 'gud-find-expr-function) 'fortran-gud-find-expr)
  (add-hook 'hack-local-variables-hook 'fortran-hack-local-variables nil t))


(defun fortran-line-length (nchars &optional global)
  "Set the length of fixed-form Fortran lines to NCHARS.
By default this only affects the current buffer, which must be in
Fortran mode.  If the optional argument GLOBAL is non-nil, it affects
all Fortran buffers, and also the default.  The default value of NCHARS
is the current column.  A numeric prefix argument specifies a value to
use instead of the current column.  A non-numeric prefix argument prompts
for the value to use."
  (interactive
   (list (cond
          ((numberp current-prefix-arg) current-prefix-arg)
          (current-prefix-arg
           (read-number "Line length: " (default-value 'fortran-line-length)))
          (t (current-column)))))
  (dolist (buff (if global
                    (buffer-list)
                  (list (current-buffer))))
    (with-current-buffer buff
      (when (derived-mode-p 'fortran-mode)
        (unless (eq fortran-line-length nchars)
          (setq fortran-line-length nchars
                fill-column fortran-line-length
                syntax-propertize-function
                (fortran-make-syntax-propertize-function nchars))
          (syntax-ppss-flush-cache (point-min))
          (if font-lock-mode (font-lock-mode 1))))))
          (if global
      (setq-default fortran-line-length nchars)))

(defun fortran-hack-local-variables ()
  "Fortran mode adds this to `hack-local-variables-hook'."
  (fortran-line-length fortran-line-length))

(declare-function gud-find-c-expr "gud.el" nil)

(defun fortran-gud-find-expr ()
  ;; Consider \n as punctuation (end of expression).
  (with-syntax-table fortran-gud-syntax-table
    (gud-find-c-expr)))

(defsubst fortran-comment-indent ()
  "Return the indentation appropriate for the current comment line.
This is 0 for a line matching `fortran-comment-line-start-skip', else
the value of `comment-column' (leaving at least one space after code)."
  (if (looking-at fortran-comment-line-start-skip) 0
    (save-excursion
      (skip-chars-backward " \t")
      (max (1+ (current-column)) comment-column))))

(defun fortran-indent-comment ()
  "Align or create comment on current line.
Existing comments of all types are recognized and aligned.
If the line has no comment, a side-by-side comment is inserted and aligned,
if the value of `comment-start' is not nil and allows such comments.
Otherwise, a separate-line comment is inserted, on this line
or on a new line inserted before this line if this line is not blank."
  (interactive "*")
  (beginning-of-line)
  ;; Recognize existing comments of either kind.
  (cond ((fortran-find-comment-start-skip 'all)
         (goto-char (match-beginning 0))
         (if (bolp)
             (fortran-indent-line)
           (unless (= (current-column) (fortran-comment-indent))
             (delete-horizontal-space)
             (indent-to (fortran-comment-indent)))))
        ;; No existing comment.
        ;; If side-by-side comments are defined, insert one,
        ;; unless line is now blank.
        ((and comment-start (not (looking-at "[ \t]*$"))
              (string-match comment-start-skip (concat " " comment-start)))
         (end-of-line)
         (delete-horizontal-space)
         (indent-to (fortran-comment-indent))
         (insert comment-start))
        ;; Else insert separate-line comment, making a new line if nec.
        (t
         (if (looking-at "^[ \t]*$")
             (delete-horizontal-space)
           (beginning-of-line)
           (insert ?\n)
           (forward-char -1))
         (insert fortran-comment-line-start)
         (insert-char (if (stringp fortran-comment-indent-char)
                          (aref fortran-comment-indent-char 0)
                        fortran-comment-indent-char)
                      (- (fortran-calculate-indent) (current-column))))))

(defun fortran-comment-region (beg-region end-region arg)
  "Comment every line in the region.
Inserts the string variable `fortran-comment-region' at the beginning of
every line in the region.
BEG-REGION and END-REGION specify the region boundaries.
With non-nil ARG, uncomments the region."
  (interactive "*r\nP")
  (let ((end-region-mark (copy-marker end-region))
        (save-point (point-marker)))
    (goto-char beg-region)
    (beginning-of-line)
    (if arg
        (let ((com (regexp-quote fortran-comment-region))) ; uncomment
          (if (looking-at com)
              (delete-region (point) (match-end 0)))
          (while (and (zerop (forward-line 1))
                      (< (point) end-region-mark))
            (if (looking-at com)
                (delete-region (point) (match-end 0)))))
      (insert fortran-comment-region)   ; comment
      (while (and (zerop (forward-line 1))
                  (< (point) end-region-mark))
        (insert fortran-comment-region)))
    (goto-char save-point)
    (set-marker end-region-mark nil)
    (set-marker save-point nil)))

;; uncomment-region calls this with 3 args.
(defun fortran-uncomment-region (start end &optional ignored)
  "Uncomment every line in the region."
  (fortran-comment-region start end t))


(defun fortran-abbrev-start ()
  "Typing ;\\[help-command] or ;? lists all the Fortran abbrevs.
Any other key combination is executed normally."
  (interactive "*")
  (insert last-command-event)
  (let* ((event (if (fboundp 'next-command-event) ; XEmacs
                    (next-command-event)
                  (read-event)))
         (char (if (fboundp 'event-to-character)
                   (event-to-character event) event)))
    ;; Insert char if not equal to `?', or if abbrev-mode is off.
    (if (and abbrev-mode (or (eq char ??) (eq char help-char)
                             (memq event help-event-list)))
        (fortran-abbrev-help)
      (push event unread-command-events))))

(defun fortran-abbrev-help ()
  "List the currently defined abbrevs in Fortran mode."
  (interactive)
  (message "Listing abbrev table...")
  (display-buffer (fortran-prepare-abbrev-list-buffer))
  (message "Listing abbrev table...done"))

(defun fortran-prepare-abbrev-list-buffer ()
  "Create a buffer listing the Fortran mode abbreviations."
  (with-current-buffer (get-buffer-create "*Abbrevs*")
    (erase-buffer)
    (insert-abbrev-table-description 'fortran-mode-abbrev-table t)
    (goto-char (point-min))
    (set-buffer-modified-p nil)
    (edit-abbrevs-mode))
  (get-buffer-create "*Abbrevs*"))

(defun fortran-column-ruler ()
  "Insert a column ruler momentarily above current line, till next keystroke.
The ruler is defined by the value of `fortran-column-ruler-fixed' in fixed
format mode, and `fortran-column-ruler-tab' in TAB format mode.
The next key typed is executed unless it is SPC."
  (interactive)
  (momentary-string-display
   (if indent-tabs-mode
       fortran-column-ruler-tab
     fortran-column-ruler-fixed)
   (save-excursion
     (beginning-of-line)
     (if (eq (window-start) (window-point))
         (line-beginning-position 2)
       (point)))
   nil "Type SPC or any command to erase ruler."))

(defun fortran-window-create ()
  "Make the window `fortran-line-length' (default 72) columns wide.
See also `fortran-window-create-momentarily'."
  (interactive)
  (let ((window-min-width 2))
    (unless (window-full-width-p)
        (enlarge-window-horizontally (- (frame-width)
                                        (window-width) 1)))
    (let* ((window-edges (window-edges))
           (scroll-bar-width (- (nth 2 window-edges)
                                (car window-edges)
                                (window-width))))
      (split-window-right (+ fortran-line-length scroll-bar-width)))
    (other-window 1)
    (switch-to-buffer " fortran-window-extra" t)
    (select-window (previous-window))))

(defun fortran-window-create-momentarily (&optional arg)
  "Momentarily make the window `fortran-line-length' (default 72) columns wide.
Optional ARG non-nil and non-unity disables the momentary feature.
See also `fortran-window-create'."
  (interactive "p")
  (if (or (not arg)
          (= arg 1))
      (save-window-excursion
        (progn
          (condition-case nil
              (fortran-window-create)
            (error (error "No room for Fortran window")))
          (message "Type SPC to continue editing.")
          (let ((char (read-event)))
            (or (equal char ?\s)
                (push char unread-command-events)))))
    (fortran-window-create)))

(defun fortran-split-line ()
  "Break line at point and insert continuation marker and alignment."
  (interactive "*")
  (delete-horizontal-space)
  (if (save-excursion
        (let ((pos (point)))
          (beginning-of-line)
          (and (fortran-find-comment-start-skip 'all)
               (< (match-beginning 0) pos))))
      (insert ?\n (match-string 0))
    (if indent-tabs-mode
        (insert ?\n ?\t (fortran-numerical-continuation-char))
      (insert "\n " fortran-continuation-string))) ; space after \n important
  (fortran-indent-line))               ; when cont string is C, c or *

(defun fortran-remove-continuation ()
  "Delete any Fortran continuation characters at point.
Returns t if anything actually deleted."
  (when (looking-at "\\( \\{5\\}[^ 0\n]\\|\t[1-9]\\|&\\)")
    (replace-match "")
    (delete-indentation)
    t))

(defun fortran-join-line (arg)
  "Join current line to the previous one and re-indent.
With a prefix argument, repeat this operation that many times.
If the prefix argument ARG is negative, join the next -ARG lines.
Continuation lines are correctly handled."
  (interactive "*p")
  (save-excursion
    (when (> 0 arg)
      (setq arg (- arg))
      (forward-line arg))
    (while (not (zerop arg))
      (beginning-of-line)
      (or (fortran-remove-continuation)
          (delete-indentation))
      (setq arg (1- arg)))
    (fortran-indent-line)))

(defun fortran-numerical-continuation-char ()
  "Return a digit for tab-digit style of continuation lines.
If previous line is a tab-digit continuation line, return that digit
plus one, otherwise return 1.  Zero not allowed."
  (save-excursion
    (forward-line -1)
    (if (looking-at "\t[1-9]")
        (+ ?1 (% (- (char-after (1+ (point))) ?0) 9))
      ?1)))

(put 'fortran-electric-line-number 'delete-selection t)
(defun fortran-electric-line-number (arg)
  "Self insert, but if part of a Fortran line number indent it automatically.
Auto-indent does not happen if a numeric ARG is used."
  (interactive "*P")
  (if (or arg (not fortran-electric-line-number))
      (if arg
          (self-insert-command (prefix-numeric-value arg))
        (self-insert-command 1))
    (if (or (and (= 5 (current-column))
                 (save-excursion
                   (beginning-of-line)
                    ;; In col 5 with only spaces to the left.
                   (looking-at " \\{5\\}")))
            (and (= (if indent-tabs-mode
                        fortran-minimum-statement-indent-tab
                      fortran-minimum-statement-indent-fixed) (current-column))
                 ;; In col 8 with a single tab to the left.
                 (eq ?\t (char-after (line-beginning-position)))
                 (not (or (eq last-command 'fortran-indent-line)
                          (eq last-command
                              'fortran-indent-new-line))))
            (save-excursion
              (re-search-backward "[^ \t0-9]"
                                  (line-beginning-position)
                                  t))   ; not a line number
            (looking-at "[0-9]"))       ; within a line number
        (self-insert-command (prefix-numeric-value arg))
      (skip-chars-backward " \t")
      (insert last-command-event)
      (fortran-indent-line))))


(defun fortran-check-end-prog-re ()
  "Check a preliminary match against `fortran-end-prog-re'."
  ;; Having got a possible match for the subprogram end, we need a
  ;; match of whitespace, avoiding possible column 73+ stuff.
  (save-match-data
    (string-match "^\\s-*\\(\\'\\|\\s<\\)"
                  (buffer-substring (match-end 0)
                                    (min (line-end-position)
                                         (+ fortran-line-length
                                            (line-beginning-position)))))))

;; This is more complex than first expected because the beginning of a
;; main program may be implicit (ie not marked by a PROGRAM statement).
;; This would be fine (we could just go to bob in the absence of a match),
;; except it need not even be the first subprogram in the file (eg it
;; could follow a subroutine).  Hence we have to search for END
;; statements instead.
;; cf fortran-beginning-of-block, f90-beginning-of-subprogram
;; Note that unlike the latter, we don't have to worry about nested
;; subprograms (?).
;; FIXME push-mark?
(defun fortran-beginning-of-subprogram ()
  "Move point to the beginning of the current Fortran subprogram."
  (interactive)
  (let ((case-fold-search t))
    ;; If called already at the start of subprogram, go to the previous.
    (beginning-of-line (if (bolp) 0 1))
    (save-match-data
      (or (looking-at fortran-start-prog-re)
          ;; This leaves us at bob if before the first subprogram.
          (eq (fortran-previous-statement) 'first-statement)
          (if (or (catch 'ok
                    (while (re-search-backward fortran-end-prog-re nil 'move)
                      (if (fortran-check-end-prog-re) (throw 'ok t))))
                  ;; If the search failed, must be at bob.
                  ;; First code line is the start of the subprogram.
                  ;; FIXME use a more rigorous test, cf fortran-next-statement?
                  ;; Though that needs to handle continuations too.
                  (not (looking-at "^\\([ \t]*[0-9]\\|[ \t]+[^!#]\\)")))
              (fortran-next-statement))))))

;; This is simpler than f-beginning-of-s because the end of a
;; subprogram is never implicit.
(defun fortran-end-of-subprogram ()
  "Move point to the end of the current Fortran subprogram."
  (interactive)
  (let ((case-fold-search t))
    (beginning-of-line)
    (save-match-data
      (while (and (re-search-forward fortran-end-prog-re nil 'move)
                  (not (fortran-check-end-prog-re))))
      (forward-line))))

(defun fortran-previous-statement ()
  "Move point to beginning of the previous Fortran statement.
Returns `first-statement' if that statement is the first
non-comment Fortran statement in the file, and nil otherwise.
Directive lines are treated as comments."
  (interactive)
  (let (not-first-statement continue-test)
    (beginning-of-line)
    (setq continue-test
          (and
           (not (looking-at fortran-comment-line-start-skip))
           (not (looking-at fortran-directive-re))
           (or (looking-at
                (concat "[ \t]*"
                        (regexp-quote fortran-continuation-string)))
               (looking-at " \\{5\\}[^ 0\n]\\|\t[1-9]"))))
    (while (and (setq not-first-statement (zerop (forward-line -1)))
                (or (looking-at fortran-comment-line-start-skip)
                    (looking-at fortran-directive-re)
                    (looking-at
                     (concat "[ \t]*"
                             (regexp-quote fortran-continuation-string)))
                    (looking-at "[ \t]*$\\| \\{5\\}[^ 0\n]\\|\t[1-9]")
                    (looking-at (concat "[ \t]*" comment-start-skip)))))
    (cond ((and continue-test
                (not not-first-statement))
           (message "Incomplete continuation statement."))
          (continue-test
           (fortran-previous-statement))
          ((not not-first-statement)
           'first-statement))))

(defun fortran-next-statement ()
  "Move point to beginning of the next Fortran statement.
Returns `last-statement' if that statement is the last
non-comment Fortran statement in the file, and nil otherwise.
Directive lines are treated as comments."
  (interactive)
  (let (not-last-statement)
    (beginning-of-line)
    (while (and (setq not-last-statement
                      (and (zerop (forward-line 1))
                           (not (eobp))))
                (or (looking-at fortran-comment-line-start-skip)
                    (looking-at fortran-directive-re)
                    (looking-at "[ \t]*$\\|     [^ 0\n]\\|\t[1-9]")
                    (looking-at (concat "[ \t]*" comment-start-skip)))))
    (if (not not-last-statement)
        'last-statement)))

(defun fortran-looking-at-if-then ()
  "Return non-nil if at the start of a line with an IF ... THEN statement."
  ;; cf f90-looking-at-if-then.
  (let ((p (point))
        (i (fortran-beginning-if)))
    (if i
        (save-excursion
          (goto-char i)
          (= (line-beginning-position) p)))))

;; Used in hs-special-modes-alist.
(defun fortran-end-of-block (&optional num)
  "Move point forward to the end of the current code block.
With optional argument NUM, go forward that many balanced blocks.
If NUM is negative, go backward to the start of a block.  Does
not check for consistency of block types.  Interactively, pushes
mark before moving point."
  (interactive "p")
  (if (called-interactively-p 'any) (push-mark (point) t))
  (and num (< num 0) (fortran-beginning-of-block (- num)))
  (let ((case-fold-search t)
        (count (or num 1)))
    (end-of-line)
    (while (and (> count 0)
                (re-search-forward
                 (concat "\\(" fortran-blocks-re
                         (if fortran-check-all-num-for-matching-do
                             "\\|^[ \t]*[0-9]+" "")
                         "\\|continue\\|end\\)\\>")
                 nil 'move))
      (beginning-of-line)
      (if (if (looking-at (concat "^[0-9 \t]*" fortran-if-start-re))
              (fortran-looking-at-if-then)
            (looking-at fortran-start-block-re))
          (setq count (1+ count))
        (if (or (looking-at fortran-end-block-re)
                (and (or (looking-at "^[0-9 \t]*continue")
                         (and fortran-check-all-num-for-matching-do
                              (looking-at "[ \t]*[0-9]+")))
                     (fortran-check-for-matching-do)))
            (setq count (1- count))))
      (end-of-line))
    (if (> count 0) (error "Missing block end"))))

(defun fortran-beginning-of-block (&optional num)
  "Move point backwards to the start of the current code block.
With optional argument NUM, go backward that many balanced
blocks.  If NUM is negative, go forward to the end of a block.
Does not check for consistency of block types.  Interactively,
pushes mark before moving point."
  (interactive "p")
  (if (called-interactively-p 'any) (push-mark (point) t))
  (and num (< num 0) (fortran-end-of-block (- num)))
  (let ((case-fold-search t)
        (count (or num 1)))
    (beginning-of-line)
    (while (and (> count 0)
                (re-search-backward
                 (concat "\\(" fortran-blocks-re
                         (if fortran-check-all-num-for-matching-do
                             "\\|^[ \t]*[0-9]+" "")
                         "\\|continue\\|end\\)\\>")
                 nil 'move))
      (beginning-of-line)
      (if (if (looking-at (concat "^[0-9 \t]*" fortran-if-start-re))
              (fortran-looking-at-if-then)
            (looking-at fortran-start-block-re))
          (setq count (1- count))
        (if (or (looking-at fortran-end-block-re)
                (and (or (looking-at "^[0-9 \t]*continue")
                         (and fortran-check-all-num-for-matching-do
                              (looking-at "[ \t]*[0-9]+")))
                     (fortran-check-for-matching-do)))
            (setq count (1+ count)))))
    ;; Includes an un-named main program block.
    (if (> count 0) (error "Missing block start"))))


(defun fortran-blink-match (regex keyword find-begin)
  "From a line matching REGEX, blink matching KEYWORD statement line.
Use function FIND-BEGIN to match it."
  (let ((top-of-window (window-start))
        (end-point (point))
        (case-fold-search t)
        matching
        message)
    (when (save-excursion
            (beginning-of-line)
            (skip-chars-forward " \t0-9")
            (looking-at regex))
      (if (not (setq matching (funcall find-begin)))
          (setq message (concat "No matching " keyword "."))
        (if (< matching top-of-window)
            (save-excursion
              (goto-char matching)
              (beginning-of-line)
              (setq message
                    (concat "Matches "
                            (buffer-substring (point)
                                              (line-end-position)))))))
      (if message
          (message "%s" message)
        (goto-char matching)
        (sit-for blink-matching-delay)
        (goto-char end-point)))))

(defun fortran-blink-matching-if ()
  "From an ENDIF or ELSE statement, blink the matching IF statement."
  (fortran-blink-match "e\\(nd[ \t]*if\\|lse\\([ \t]*if\\)?\\)\\b"
                       "if" #'fortran-beginning-if))

(defun fortran-blink-matching-do ()
  "From an ENDDO statement, blink the matching DO or DO WHILE statement."
  (fortran-blink-match "end[ \t]*do\\b" "do" #'fortran-beginning-do))

(defun fortran-mark-do ()
  "Put mark at end of Fortran DO [WHILE]-ENDDO construct, point at beginning.
The marks are pushed."
  (interactive)
  (let (enddo-point do-point)
    (if (setq enddo-point (fortran-end-do))
        (if (not (setq do-point (fortran-beginning-do)))
            (message "No matching do.")
          (goto-char enddo-point)
          (push-mark)
          (goto-char do-point)))))

(defun fortran-end-do ()
  "Search forward for first unmatched ENDDO.
Return point or nil."
  (let ((case-fold-search t))
    (if (save-excursion (beginning-of-line)
                        (skip-chars-forward " \t0-9")
                        (looking-at "end[ \t]*do\\b"))
        ;; Sitting on one.
        (match-beginning 0)
      ;; Search for one.
      (save-excursion
        (let ((count 1))
          (while (and (not (zerop count))
                      (not (eq (fortran-next-statement) 'last-statement))
                      ;; Keep local to subprogram.
                      (not (and (looking-at fortran-end-prog-re)
                                (fortran-check-end-prog-re))))
            (skip-chars-forward " \t0-9")
            (cond ((looking-at "end[ \t]*do\\b")
                   (setq count (1- count)))
                  ((looking-at
                    "\\(\\(\\sw\\|\\s_\\)+:[ \t]*\\)?do[ \t]+[^0-9]")
                   (setq count (1+ count)))))
          (and (zerop count)
               ;; All pairs accounted for.
               (point)))))))

(defun fortran-beginning-do ()
  "Search backwards for first unmatched DO [WHILE].
Return point or nil.  Ignores labeled DO loops (ie DO 10 ... 10 CONTINUE)."
  (let ((case-fold-search t)
        (dostart-re "\\(\\(\\sw\\|\\s_\\)+:[ \t]*\\)?do[ \t]+[^0-9]"))
    (if (save-excursion
          (beginning-of-line)
          (skip-chars-forward " \t0-9")
          (looking-at dostart-re))
        ;; Sitting on one.
        (match-beginning 0)
      ;; Search for one.
      (save-excursion
        (let ((count 1))
          (while (and (not (zerop count))
                      (not (eq (fortran-previous-statement) 'first-statement))
                      ;; Keep local to subprogram.
                      (not (and (looking-at fortran-end-prog-re)
                                (fortran-check-end-prog-re))))
            (skip-chars-forward " \t0-9")
            (cond ((looking-at dostart-re)
                   (setq count (1- count)))
                  ;; Note labeled loop ends not considered.
                  ((looking-at "end[ \t]*do\\b")
                   (setq count (1+ count)))))
          (and (zerop count)
               ;; All pairs accounted for.
               (point)))))))

(defun fortran-mark-if ()
  "Put mark at end of Fortran IF-ENDIF construct, point at beginning.
The marks are pushed."
  (interactive)
  (let (endif-point if-point)
    (if (setq endif-point (fortran-end-if))
        (if (not (setq if-point (fortran-beginning-if)))
            (message "No matching if.")
          ;; Set mark, move point.
          (goto-char endif-point)
          (push-mark)
          (goto-char if-point)))))

(defun fortran-end-if ()
  "Search forwards for first unmatched ENDIF.
Return point or nil."
  (let ((case-fold-search t))
    (if (save-excursion (beginning-of-line)
                        (skip-chars-forward " \t0-9")
                        (looking-at "end[ \t]*if\\b"))
        ;; Sitting on one.
        (match-beginning 0)
      ;; Search for one.  The point has been already been moved to first
      ;; letter on line but this should not cause troubles.
      (save-excursion
        (let ((count 1))
          (while (and (not (zerop count))
                      (not (eq (fortran-next-statement) 'last-statement))
                      ;; Keep local to subprogram.
                      (not (and (looking-at fortran-end-prog-re)
                                (fortran-check-end-prog-re))))
            (skip-chars-forward " \t0-9")
            (cond ((looking-at "end[ \t]*if\\b")
                   (setq count (1- count)))
                  ((looking-at fortran-if-start-re)
                   (save-excursion
                     (if (or
                          (looking-at ".*)[ \t]*then\\b[ \t]*[^ \t(=a-z0-9]")
                          (let (then-test) ; multi-line if-then
                            (while
                                (and
                                 (zerop (forward-line 1))
                                 ;; Search forward for then.
                                 (looking-at " \\{5\\}[^ 0\n]\\|\t[1-9]")
                                 (not
                                  (setq then-test
                                        (looking-at
                                         ".*then\\b[ \t]*[^ \t(=a-z0-9]")))))
                            then-test))
                         (setq count (1+ count)))))))
          (and (zerop count)
               ;; All pairs accounted for.
               (point)))))))

(defun fortran-beginning-if ()
  "Search backwards for first unmatched IF-THEN.
Return point or nil."
  (let ((case-fold-search t))
    (if (save-excursion
          ;; May be sitting on multi-line if-then statement, first
          ;; move to beginning of current statement.  Note:
          ;; `fortran-previous-statement' moves to previous statement
          ;; *unless* current statement is first one.  Only move
          ;; forward if not first-statement.
          (if (not (eq (fortran-previous-statement) 'first-statement))
              (fortran-next-statement))
          (skip-chars-forward " \t0-9")
          (and
           (looking-at fortran-if-start-re)
           (save-match-data
             (or (looking-at ".*)[ \t]*then\\b[ \t]*[^ \t(=a-z0-9]")
                 ;; Multi-line if-then.
                 (let (then-test)
                   (while
                       (and (zerop (forward-line 1))
                            ;; Search forward for then.
                            (looking-at " \\{5\\}[^ 0\n]\\|\t[1-9]")
                            (not
                             (setq then-test
                                   (looking-at
                                    ".*then\\b[ \t]*[^ \t(=a-z0-9]")))))
                   then-test)))))
        ;; Sitting on one.
        (match-beginning 0)
      ;; Search for one.
      (save-excursion
        (let ((count 1))
          (while (and (not (zerop count))
                      (not (eq (fortran-previous-statement) 'first-statement))
                      ;; Keep local to subprogram.
                      (not (and (looking-at fortran-end-prog-re)
                                (fortran-check-end-prog-re))))
            (skip-chars-forward " \t0-9")
            (cond ((looking-at fortran-if-start-re)
                   (save-excursion
                     (if (or
                          (looking-at ".*)[ \t]*then\\b[ \t]*[^ \t(=a-z0-9]")
                          (let (then-test) ; multi-line if-then
                            (while
                                (and
                                 (zerop (forward-line 1))
                                 ;; Search forward for then.
                                 (looking-at " \\{5\\}[^ 0\n]\\|\t[1-9]")
                                 (not
                                  (setq then-test
                                        (looking-at
                                         (concat ".*then\\b[ \t]*"
                                                 "[^ \t(=a-z0-9]"))))))
                            then-test))
                         (setq count (1- count)))))
                  ((looking-at "end[ \t]*if\\b")
                   (setq count (1+ count)))))
          (and (zerop count)
               ;; All pairs accounted for.
               (point)))))))


(defun fortran-indent-line ()
  "Indent current Fortran line based on its contents and on previous lines."
  (interactive "*")
  (let ((cfi (fortran-calculate-indent)))
    (save-excursion
      (beginning-of-line)
      (if (or (not (= cfi (fortran-current-line-indentation)))
              (and (re-search-forward "^[ \t]*[0-9]+" (+ (point) 4) t)
                   (not (fortran-line-number-indented-correctly-p))))
          (fortran-indent-to-column cfi)
        (beginning-of-line)
        (if (fortran-find-comment-start-skip)
            (fortran-indent-comment))))
    ;; Never leave point in left margin.
    (if (< (current-column) cfi)
        (move-to-column cfi))
    (and auto-fill-function
         (> (save-excursion (end-of-line) (current-column))
            fill-column)
         (save-excursion
           (end-of-line)
           (fortran-fill)))
    (when fortran-blink-matching-if
      (fortran-blink-matching-if)
      (fortran-blink-matching-do))))

(defun fortran-auto-fill ()
  "Function to use for `normal-auto-fill-function' in Fortran mode."
  (if (> (current-column) (current-fill-column))
      (let ((cfi (fortran-calculate-indent)))
        (save-excursion
          (beginning-of-line)
          (if (or (not (= cfi (fortran-current-line-indentation)))
                  (and (re-search-forward "^[ \t]*[0-9]+"
                                          (+ (point) 4) t)
                       (not (fortran-line-number-indented-correctly-p))))
              (fortran-indent-to-column cfi)
            (beginning-of-line)
            (if (fortran-find-comment-start-skip)
                (fortran-indent-comment))))
        (fortran-fill)
        ;; Never leave point in left margin.
        (if (< (current-column) cfi)
            (move-to-column cfi)))))

;; Historically this was a separate function which advertised itself
;; as reindenting but only did so where `most likely to be necessary'.
(defalias 'fortran-indent-new-line 'reindent-then-newline-and-indent)

(defun fortran-indent-subprogram ()
  "Properly indent the Fortran subprogram containing point."
  (interactive "*")
  (save-excursion
    (mark-defun)
    (message "Indenting subprogram...")
    (indent-region (point) (mark) nil))
  (message "Indenting subprogram...done."))

(defun fortran-calculate-indent ()
  "Calculates the Fortran indent column based on previous lines."
  (let (icol first-statement (case-fold-search t)
             (fortran-minimum-statement-indent
              (if indent-tabs-mode
                  fortran-minimum-statement-indent-tab
                fortran-minimum-statement-indent-fixed)))
    (save-excursion
      (setq first-statement (fortran-previous-statement))
      (if first-statement
          (setq icol fortran-minimum-statement-indent)
        (if (= (point) (point-min))
            (setq icol fortran-minimum-statement-indent)
          (setq icol (fortran-current-line-indentation)))
        (skip-chars-forward " \t0-9")
        (cond ((looking-at "\\(\\(\\sw\\|\\s_\\)+:[ \t]*\\)?if[ \t]*(")
               (if (or (looking-at ".*)[ \t]*then\\b[ \t]*[^ \t_$(=a-z0-9]")
                       (let (then-test) ; multi-line if-then
                         (while (and (zerop (forward-line 1))
                                     ;; Search forward for then.
                                     (looking-at " \\{5\\}[^ 0\n]\\|\t[1-9]")
                                     (not (setq then-test
                                                (looking-at
                                                 ".*then\\b[ \t]\
*[^ \t_$(=a-z0-9]")))))
                         then-test))
                   (setq icol (+ icol fortran-if-indent))))
              ((looking-at "else\\(if\\)?\\b")
               (setq icol (+ icol fortran-if-indent)))
              ((looking-at "select[ \t]*case[ \t](.*)")
               (setq icol (+ icol fortran-if-indent)))
              ((looking-at "case[ \t]*(.*)")
               (setq icol (+ icol fortran-if-indent)))
              ((looking-at "case[ \t]*default\\b")
               (setq icol (+ icol fortran-if-indent)))
              ((looking-at "\\(otherwise\\|else[ \t]*where\\)\\b")
               (setq icol (+ icol fortran-if-indent)))
              ((looking-at "where[ \t]*(.*)[ \t]*\n")
               (setq icol (+ icol fortran-if-indent)))
              ((looking-at "do\\b")
               (setq icol (+ icol fortran-do-indent)))
              ((looking-at
                "\\(structure\\|union\\|map\\|interface\\)\
\\b[ \t]*[^ \t=(a-z]")
               (setq icol (+ icol fortran-structure-indent)))
              ((and (looking-at fortran-end-prog-re1)
                    (fortran-check-end-prog-re))
               ;; Previous END resets indent to minimum.
               (setq icol fortran-minimum-statement-indent))
              ;; Previous statement was a numbered DO loop without a
              ;; closing CONTINUE or END DO, so we indented the
              ;; terminator like the loop body.
              ((and fortran-check-all-num-for-matching-do
                    (not (looking-at "\\(continue\\|end[ \t]*do\\)\\>"))
                    (progn
                      (beginning-of-line)
                      (and (looking-at "[ \t]*[0-9]+")
                           (fortran-check-for-matching-do))))
               (setq icol (- icol fortran-do-indent))))))
    (save-excursion
      (beginning-of-line)
      (cond ((looking-at "[ \t]*$"))
            ;; Check for directive before comment, so as not to indent.
            ((looking-at fortran-directive-re)
             (setq fortran-minimum-statement-indent 0 icol 0))
            ((looking-at fortran-comment-line-start-skip)
             (cond ((eq fortran-comment-indent-style 'relative)
                    (setq icol (+ icol fortran-comment-line-extra-indent)))
                   ((eq fortran-comment-indent-style 'fixed)
                    (setq icol (+ fortran-minimum-statement-indent
                                  fortran-comment-line-extra-indent))))
             (setq fortran-minimum-statement-indent 0))
            ((or (looking-at (concat "[ \t]*"
                                     (regexp-quote
                                      fortran-continuation-string)))
                 (looking-at " \\{5\\}[^ 0\n]\\|\t[1-9]"))
             (skip-chars-forward " \t")
             ;; Do not introduce extra whitespace into a broken string.
             (setq icol
                   (if (fortran-is-in-string-p (point))
                       6
                     (+ icol fortran-continuation-indent))))
            (first-statement)
            ;; The terminating statement is actually part of the
            ;; loop body, so unless it is a CONTINUE or END DO, we
            ;; indent it like the loop body (see above).
            ((and fortran-check-all-num-for-matching-do
                  (looking-at "[ \t]*[0-9]+[ \t]*\
\\(continue\\|end[ \t]*do\\)\\>")
                  (fortran-check-for-matching-do))
             (setq icol (- icol fortran-do-indent)))
            (t
             (skip-chars-forward " \t0-9")
             (cond ((looking-at "end[ \t]*\\(if\\|select\\|where\\)\\b")
                    (setq icol (- icol fortran-if-indent)))
                   ((looking-at "else\\(if\\)?\\b")
                    (setq icol (- icol fortran-if-indent)))
                   ((looking-at "case[ \t]*\\((.*)\\|default\\>\\)")
                    (setq icol (- icol fortran-if-indent)))
                   ((looking-at "\\(otherwise\\|else[ \t]*where\\)\\b")
                    (setq icol (- icol fortran-if-indent)))
                   ((and (looking-at "continue\\b")
                         (fortran-check-for-matching-do))
                    (setq icol (- icol fortran-do-indent)))
                   ((looking-at "end[ \t]*do\\b")
                    (setq icol (- icol fortran-do-indent)))
                   ((looking-at "end[ \t]*\
\\(structure\\|union\\|map\\|interface\\)\\b[ \t]*[^ \t=(a-z]")
                    (setq icol (- icol fortran-structure-indent)))
                   ((and (looking-at fortran-end-prog-re1)
                         (fortran-check-end-prog-re)
                         (not (= icol fortran-minimum-statement-indent)))
                    (message "Warning: `end' not in column %d.  Probably\
 an unclosed block." fortran-minimum-statement-indent))))))
    (max fortran-minimum-statement-indent icol)))


(defun fortran-current-line-indentation ()
  "Indentation of current line, ignoring Fortran line number or continuation.
This is the column position of the first non-whitespace character
aside from the line number and/or column 5/8 line-continuation character.
For comment lines, returns indentation of the first
non-indentation text within the comment."
  (save-excursion
    (beginning-of-line)
    (cond ((looking-at fortran-comment-line-start-skip)
           (goto-char (match-end 0))
           (skip-chars-forward
            (if (stringp fortran-comment-indent-char)
                fortran-comment-indent-char
              (char-to-string fortran-comment-indent-char))))
          ((or (looking-at " \\{5\\}[^ 0\n]\\|\t[1-9]"))
           (goto-char (match-end 0)))
          (t
           ;; Move past line number.
           (skip-chars-forward "[ \t0-9]")))
    ;; Move past whitespace.
    (skip-chars-forward " \t")
    (current-column)))

(defun fortran-indent-to-column (col)
  "Indent current line to column COL.
notes: 1) A non-zero/non-blank character in column 5 indicates a continuation
          line, and this continuation character is retained on indentation;
       2) If `fortran-continuation-string' is the first non-whitespace
          character, this is a continuation line;
       3) A non-continuation line which has a number as the first
          non-whitespace character is a numbered line.
       4) A TAB followed by a digit indicates a continuation line."
  (save-excursion
    (beginning-of-line)
    (if (looking-at fortran-comment-line-start-skip)
        (if fortran-comment-indent-style
            (let* ((char (if (stringp fortran-comment-indent-char)
                             (aref fortran-comment-indent-char 0)
                           fortran-comment-indent-char))
                   (chars (string ?\s ?\t char)))
              (goto-char (match-end 0))
              (skip-chars-backward chars)
              (delete-region (point) (progn (skip-chars-forward chars)
                                            (point)))
              (insert-char char (- col (current-column)))))
      (if (looking-at "\t[1-9]")
          (if indent-tabs-mode
              (goto-char (match-end 0))
            (delete-char 2)
            (insert-char ?\s 5)
            (insert fortran-continuation-string))
        (if (looking-at " \\{5\\}[^ 0\n]")
            (if indent-tabs-mode
                (progn (delete-char 6)
                       (insert ?\t (fortran-numerical-continuation-char) 1))
              (forward-char 6))
          (delete-horizontal-space)
          ;; Put line number in columns 0-4, or
          ;; continuation character in column 5.
          (cond ((eobp))
                ((looking-at (regexp-quote fortran-continuation-string))
                 (if indent-tabs-mode
                     (progn
                       (indent-to
                        (if indent-tabs-mode
                            fortran-minimum-statement-indent-tab
                          fortran-minimum-statement-indent-fixed))
                       (delete-char 1)
                       (insert-char (fortran-numerical-continuation-char) 1))
                   (indent-to 5)
                   (forward-char 1)))
                ((looking-at "[0-9]+")
                 (let ((extra-space (- 5 (- (match-end 0) (point)))))
                   (if (< extra-space 0)
                       (message "Warning: line number exceeds 5-digit limit.")
                     (indent-to (min fortran-line-number-indent extra-space))))
                 (skip-chars-forward "0-9")))))
      ;; Point is now after any continuation character or line number.
      ;; Put body of statement where specified.
      (delete-horizontal-space)
      (indent-to col)
      ;; Indent any comment following code on the same line.
      (when (fortran-find-comment-start-skip)
        (goto-char (match-beginning 0))
        (unless (= (current-column) (fortran-comment-indent))
          (delete-horizontal-space)
          (indent-to (fortran-comment-indent)))))))

(defun fortran-line-number-indented-correctly-p ()
  "Return t if current line's line number is correctly indented.
Do not call if there is no line number."
  (save-excursion
    (beginning-of-line)
    (skip-chars-forward " \t")
    (and (<= (current-column) fortran-line-number-indent)
         (or (= (current-column) fortran-line-number-indent)
             (progn (skip-chars-forward "0-9")
                    (= (current-column) 5))))))

(defun fortran-check-for-matching-do ()
  "When called from a numbered statement, return t if matching DO is found.
Otherwise return nil."
  (let ((case-fold-search t)
        charnum)
    (save-excursion
      (beginning-of-line)
      (when (looking-at "[ \t]*[0-9]+")
        (skip-chars-forward " \t")
        (skip-chars-forward "0")        ; skip past leading zeros
        (setq charnum
              (buffer-substring (point) (progn
                                          (skip-chars-forward "0-9")
                                          (point))))
        (beginning-of-line)
        (save-restriction
          (save-excursion
            (narrow-to-defun)
            (and (re-search-backward
                  (concat
                   "\\(^[ \t0-9]*do[ \t]*0*"
                   charnum "\\b\\)\\|" "\\(^[ \t]*0*"
                   charnum "\\b\\)")
                  nil t)
                 (looking-at
                  (concat "^[ \t0-9]*do[ \t]*0*"
                          charnum)))))))))

(defun fortran-find-comment-start-skip (&optional all)
  "Move to past `comment-start-skip' found on current line.
Return non-nil if `comment-start-skip' found, nil if not.
If ALL is nil, only match comments that start in column > 0."
  ;; Hopefully at some point we can just use the line below!  -stef
  ;; (comment-search-forward (line-end-position) t))
  (when (or all comment-start-skip)
    (let ((pos (point))
          (css (if comment-start-skip
                   (concat fortran-comment-line-start-skip
                           "\\|" comment-start-skip)
                 fortran-comment-line-start-skip)))
      (when (re-search-forward css (line-end-position) t)
        (if (and (or all (> (match-beginning 0) (line-beginning-position)))
                 (or (save-match-data
                       (not (fortran-is-in-string-p (match-beginning 0))))
                     ;; Recurse for rest of line.
                     (fortran-find-comment-start-skip all)))
            (point)
          (goto-char pos)
          nil)))))

;; From: ralf@up3aud1.gwdg.de (Ralf Fassel)
;; Test if TAB format continuation lines work.
(defun fortran-is-in-string-p (where)
  "Return non-nil if WHERE (a buffer position) is inside a Fortran string."
  (save-excursion
    (goto-char where)
    (cond
     ((bolp) nil)                       ; bol is never inside a string
     ((save-excursion                   ; comment lines too
        (beginning-of-line)
        (looking-at fortran-comment-line-start-skip)) nil)
     (t (let ((parse-state '(0 nil nil nil nil nil 0))
              (quoted-comment-start (if comment-start
                                        (regexp-quote comment-start)))
              (not-done t)
              parse-limit end-of-line)
          ;; Move to start of current statement.
          (fortran-next-statement)
          (fortran-previous-statement)
          ;; Now parse up to WHERE.
          (while not-done
            (if (or ;; Skip to next line if:
                 ;; - comment line?
                 (looking-at fortran-comment-line-start-skip)
                 ;; - at end of line?
                 (eolp)
                 ;; - not in a string and after comment-start?
                 (and (not (nth 3 parse-state))
                      comment-start
                      (equal comment-start
                             (char-to-string (preceding-char)))))
                (if (> (forward-line) 0)
                    (setq not-done nil))
              ;; else:
              ;; If we are at beginning of code line, skip any
              ;; whitespace, labels and tab continuation markers.
              (if (bolp) (skip-chars-forward " \t0-9"))
              ;; If we are in column <= 5 now, check for continuation char.
              (cond ((= 5 (current-column)) (forward-char 1))
                    ((and (< (current-column) 5)
                          (equal fortran-continuation-string
                                 (char-to-string (following-char)))
                          (forward-char 1))))
              ;; Find out parse-limit from here.
              (setq end-of-line (line-end-position))
              (setq parse-limit (min where end-of-line))
              ;; Parse max up to comment-start, if non-nil and in current line.
              (if comment-start
                  (save-excursion
                    (if (re-search-forward quoted-comment-start end-of-line t)
                        (setq parse-limit (min (point) parse-limit)))))
              ;; Now parse if still in limits.
              (if (< (point) where)
                  (setq parse-state (parse-partial-sexp
                                     (point) parse-limit nil nil parse-state))
                (setq not-done nil))))
          ;; Result.
          (nth 3 parse-state))))))

;; From old version.
(defalias 'fortran-auto-fill-mode 'auto-fill-mode)

(defun fortran-fill ()
  "Fill the current line at an appropriate point(s)."
  (let* ((auto-fill-function #'fortran-auto-fill)
         (opoint (point))
         (bol (line-beginning-position))
         (eol (line-end-position))
         (bos (min eol (+ bol (fortran-current-line-indentation))))
         ;; If in a string at fill-column, break it either before the
         ;; initial quote, or at fill-col (if string is too long).
         (quote
          (save-excursion
            (goto-char bol)
            ;; OK to break quotes on comment lines.
            (unless (looking-at fortran-comment-line-start-skip)
              (let (fcpoint start)
                (move-to-column fill-column)
                (when (fortran-is-in-string-p (setq fcpoint (point)))
                  (save-excursion
                    (re-search-backward "\\S\"\\s\"\\S\"?" bol t)
                    (setq start
                          (if fortran-break-before-delimiters
                              (point)
                            (1+ (point)))))
                  (if (re-search-forward "\\S\"\\s\"\\S\"" eol t)
                      (backward-char 2))
                  ;; If the current string is longer than (fill-column
                  ;; - 6) chars, break it at the fill column (else
                  ;; infinite loop).
                  (if (> (- (point) start)
                         (- fill-column 6 fortran-continuation-indent))
                      fcpoint
                    start))))))
         ;; Decide where to split the line. If a position for a quoted
         ;; string was found above then use that, else break the line
         ;; before/after the last delimiter.
         (fill-point
          (or quote
              (save-excursion
                ;; If f-b-b-d is t, have an extra column to play with,
                ;; since delimiter gets shifted to new line.
                (move-to-column (if fortran-break-before-delimiters
                                    (1+ fill-column)
                                  fill-column))
                (let ((repeat t))
                  (while repeat
                    (setq repeat nil)
                    ;; Adapted from f90-find-breakpoint.
                    (re-search-backward fortran-break-delimiters-re bol)
                    (if (not fortran-break-before-delimiters)
                        (if (looking-at fortran-no-break-re)
                            ;; Deal with cases such as "**" split over
                            ;; fill-col. Simpler alternative would be
                            ;; to start from (1- fill-column) above.
                            (if (> (+ 2 (current-column)) fill-column)
                                (setq repeat t)
                              (forward-char 2))
                          (forward-char 1))
                      (backward-char)
                      (or (looking-at fortran-no-break-re)
                          (forward-char)))))
                ;; Line indented beyond fill-column?
                (when (<= (point) bos)
                  (move-to-column (1+ fill-column))
                  ;; What is this doing???
                  (or (re-search-forward "[\t\n,'+-/*)=]" eol t)
                      (goto-char bol)))
                (if (bolp)
                    (re-search-forward "[ \t]" opoint t))
                (point)))))
    ;; If we are in an in-line comment, don't break unless the
    ;; line of code is longer than it should be. Otherwise
    ;; break the line at the column computed above.
    ;;
    ;; Need to use fortran-find-comment-start-skip to make sure that
    ;; quoted !'s don't prevent a break.
    (when (and (save-excursion
                 (beginning-of-line)
                 (if (not (fortran-find-comment-start-skip))
                     t
                   (goto-char (match-beginning 0))
                   (>= (point) fill-point)))
               (save-excursion
                 (goto-char fill-point)
                 (not (bolp)))
               (> (save-excursion
                    (goto-char opoint)
                    (current-column))
                  (min (1+ fill-column)
                       (+ (fortran-calculate-indent)
                          fortran-continuation-indent))))
      (goto-char fill-point)
      (fortran-break-line)
      (end-of-line))))

(defun fortran-break-line ()
  "Call `fortran-split-line'.  Joins continuation lines first, then refills."
  (let ((bol (line-beginning-position))
        (comment-string
         (save-excursion
           (if (fortran-find-comment-start-skip)
               (delete-and-extract-region
                (match-beginning 0) (line-end-position))))))
    ;; Forward line 1 really needs to go to next non white line.
    (if (save-excursion (forward-line)
                        (looking-at " \\{5\\}[^ 0\n]\\|\t[1-9]"))
        (progn
          (end-of-line)
          (delete-region (point) (match-end 0))
          (delete-horizontal-space)
          (fortran-fill))
      (fortran-split-line))
    (if comment-string
        (save-excursion
          (goto-char bol)
          (end-of-line)
          (delete-horizontal-space)
          (indent-to (fortran-comment-indent))
          (insert comment-string)))))

(defun fortran-analyze-file-format ()
  "Return nil if fixed format is used, t if TAB formatting is used.
Use `fortran-tab-mode-default' if no non-comment statements are found
before the end or in the first `fortran-analyze-depth' lines."
  (let ((i 0))
    (save-excursion
      (goto-char (point-min))
      (while (not (or
                   (eobp)
                   (eq (char-after) ?\t)
                   (looking-at " \\{6\\}")
                   (> i fortran-analyze-depth)))
        (forward-line)
        (setq i (1+ i)))
      (cond
       ((eq (char-after) ?\t) t)
       ((looking-at " \\{6\\}") nil)
       (t fortran-tab-mode-default)))))

(defun fortran-fill-paragraph (&optional justify)
  "Fill surrounding comment block as paragraphs, else fill statement.
Intended as the value of `fill-paragraph-function'.
A comment block is filled by calling `fill-comment-paragraph' with
argument JUSTIFY, otherwise `fortran-fill-statement' is called.
Always returns non-nil (to prevent `fill-paragraph' being called)."
  (interactive "*P")
  (or (fill-comment-paragraph justify)
      (fortran-fill-statement)
      t))

(defun fortran-fill-statement ()
  "Fill a Fortran statement up to `fill-column'."
  (interactive "*")
  (let ((auto-fill-function #'fortran-auto-fill))
    (unless (save-excursion
              (beginning-of-line)
              (or (looking-at "[ \t]*$")
                  (looking-at fortran-comment-line-start-skip)
                  (and comment-start-skip
                       (looking-at (concat "[ \t]*" comment-start-skip)))))
      (save-excursion
        ;; Find beginning of statement.
        (fortran-next-statement)
        (fortran-previous-statement)
        ;; Re-indent initially.
        (fortran-indent-line)
        ;; Replace newline plus continuation field plus indentation with
        ;; single space.
        (while (progn
                 (forward-line)
                 (fortran-remove-continuation)))
        (fortran-previous-statement)))
    (fortran-indent-line)))

(defun fortran-strip-sequence-nos (&optional do-space)
  "Delete all text in column `fortran-line-length' (default 72) and up.
This is assumed to be sequence numbers.  Normally also deletes
trailing whitespace after stripping such text.  Supplying prefix
arg DO-SPACE prevents stripping the whitespace."
  (interactive "*p")
  (save-excursion
    (goto-char (point-min))
    (while (re-search-forward (format "^.\\{%d\\}\\(.*\\)" fortran-line-length)
                              nil t)
      (replace-match "" nil nil nil 1)
      (unless do-space (delete-horizontal-space)))))

;; This code used to live in add-log.el, but this is a better place for it.
(defun fortran-current-defun ()
  "Function to use for `add-log-current-defun-function' in Fortran mode."
  (save-excursion
    ;; We must be inside function body for this to work.
    (fortran-beginning-of-subprogram)
    (let ((case-fold-search t))
      ;; Search for fortran subprogram start.
      (if (re-search-forward
           fortran-start-prog-re
           (save-excursion (fortran-end-of-subprogram)
                           (point))
           t)
          (or (match-string-no-properties 2)
              (progn
                ;; Move to EOL or before first left paren.
                (if (re-search-forward "[(\n]" nil t)
                    (progn (backward-char)
                           (skip-chars-backward " \t"))
                  (end-of-line))
                ;; Use the name preceding that.
                (buffer-substring-no-properties (point) (progn (backward-sexp)
                                                               (point)))))
        "main"))))

(provide 'fortran)

;;; fortran.el ends here
