docstrings.lisp

;;; -*- lisp -*-

;;;; A docstring extractor for the SBCL. Creates @include-ready documentation
;;;; from the docstrings of exported symbols of specified packages.

;;;; This software is part of the SBCL software system. SBCL is in the public
;;;; domain and is provided with absolutely no warranty. See the COPYING file
;;;; for more information.
;;;;
;;;; Written by Rudi Schlatte <rudi@constantly.at>, mangled
;;;; by Nikodemus Siivola <nikodemus@random-state.net>.

;;;; TODO
;;;; * Verbatim text
;;;; * Quotations
;;;; * Method documentation untested
;;;; * Method sorting, somehow
;;;; * Index for macros & constants?
;;;; * This is getting complicated enough that tests would be good
;;;; * Nesting (currently only nested itemizations work)
;;;; * doc -> internal form -> texinfo (so that non-texinfo format are also
;;;;   easily generated)

;;;; FIXME: The description below is no longer complete. This
;;;; should possibly be turned into a contrib with proper documentation.

;;;; Formatting heuristics (tweaked to format SAVE-LISP-AND-DIE sanely):
;;;;
;;;; Formats SYMBOL as @code{symbol}, or @var{symbol} if symbol is in
;;;; the argument list of the defun / defmacro.
;;;;
;;;; Lines starting with * or - that are followed by intented lines
;;;; are marked up with @itemize.
;;;;
;;;; Lines containing only a SYMBOL that are followed by indented
;;;; lines are marked up as @table @code, with the SYMBOL as the item.

(defpackage :sb-texinfo
  (:use :cl :sb-mop :split-sequence :uiop)
  (:shadow #:documentation)
  (:export #:generate-includes #:generate-comment-includes
           #:document-package #:document-package-pathname
           #:document-system)
  (:documentation
   "Tools to generate TexInfo documentation from docstrings."))

(in-package :sb-texinfo)

;;;; various specials and parameters

(defvar *texinfo-output*)
(defvar *texinfo-variables*)
(defvar *documentation-package*)
(defvar *base-package*)
(defvar *tex-bold-hack* nil
  "Inhibit @&key macros designed to work around boldness in TeX output.")
(defvar *inhibit-sections* t
  "Inhibit the output of the description of sections in the index list.")
(defvar *inhibit-sb-texinfo-macros* t
  "Inhibit the output of the repeated inclusion of sb texinfo macros.")

(defparameter *undocumented-packages* '(sb-pcl sb-int sb-kernel sb-sys sb-c))

(defparameter *documentation-types*
  '(compiler-macro
    function
    method-combination
    setf
    ;;structure  ; also handled by `type'
    type
    variable)
  "A list of symbols accepted as second argument of `documentation'")

(defparameter *character-replacements*
  '((#\* . "star")
    (#\/ . "slash")
    (#\+ . "plus")
    (#\< . "lt")
    (#\> . "gt")
    (#\= . "equals")
    (#\? . "question-mark")
    (#\{ . "curly-brace-left")
    (#\} . "curly-brace-right")
    (#\) . "paren-left")
    (#\( . "paren-right")
    (#\@ . "atsign")
    (#\! . "exclamationpoint")
    (#\" . "doublequote")
    (#\$ . "dollarsign")
    (#\& . "ampersand")
    (#\[ . "square-brace-left")
    (#\] . "square-brace-right")
    (#\| . "pipe")
    (#\\ . "forward-slash")
    (#\` . "backquote")
    (#\' . "singlequote")
    (#\? . "questionmark")
    (#\Tab . "tab")
    (#\Newline . "newline")
    (#\Backspace . "backspace")
    (#\Linefeed . "linefeed")
    (#\Page . "page")
    (#\Return . "return")
    (#\Rubout . "rubout")
    (#\z_notation_right_image_bracket . "z_notation_right_image_bracket")
    (#\z_notation_left_image_bracket . "z_notation_left_image_bracket")
    (#\right_white_curly_bracket . "right_white_curly_bracket")
    (#\left_white_curly_bracket . "left_white_curly_bracket")
    (#\not_sign . "not_sign")
    (#\element_of . "element_of")
    (#\square_root . "square_root")
    (#\cube_root . "cube_root")
    (#\fourth_root . "fourth_root"))
  "Characters and their replacement names that `alphanumize' uses. If
the replacements contain any of the chars they're supposed to replace,
you deserve to lose.")

(defparameter *characters-to-drop* nil
  "Characters that should be removed by `alphanumize'.")

(defparameter *texinfo-escaped-chars* "@{}"
  "Characters that must be escaped with #\@ for Texinfo.")

(defparameter *itemize-start-characters* '(#\* #\-)
  "Characters that might start an itemization in docstrings when
  at the start of a line.")

(defparameter *symbol-characters* "ABCDEFGHIJKLMNOPQRSTUVWXYZ*=<>:-+&#'!?/"
  "List of characters that make up symbols in a docstring.")

(defparameter *symbol-delimiters* " ,.!?;[]")

(defparameter *ordered-documentation-kinds*
  '(package type structure condition class variable macro function))

;;;; utilities

(defun flatten (list)
  (cond ((null list)
         nil)
        ((consp (car list))
         (nconc (flatten (car list)) (flatten (cdr list))))
        ((null (cdr list))
         (cons (car list) nil))
        (t
         (cons (car list) (flatten (cdr list))))))

(defun whitespacep (char)
  (find char #(#\tab #\space #\page)))

(defun setf-name-p (name)
  (or (symbolp name)
      (and (listp name) (= 2 (length name)) (eq (car name) 'setf))))

(defgeneric specializer-name (specializer))

(defmethod specializer-name ((specializer eql-specializer))
  (list 'eql (eql-specializer-object specializer)))

(defmethod specializer-name ((specializer class))
  (class-name specializer))

(defun ensure-class-precedence-list (class)
  (unless (class-finalized-p class)
    (finalize-inheritance class))
  (class-precedence-list class))

(defun specialized-lambda-list (method)
  ;; courtecy of AMOP p. 61
  (let* ((specializers (method-specializers method))
         (lambda-list (method-lambda-list method))
         (n-required (length specializers)))
    (append (mapcar (lambda (arg specializer)
                      (if  (eq specializer (find-class 't))
                           arg
                           `(,arg ,(specializer-name specializer))))
                    (subseq lambda-list 0 n-required)
                    specializers)
           (subseq lambda-list n-required))))

(defun string-lines (string)
  "Lines in STRING as a vector."
  (coerce (with-input-from-string (s string)
            (loop for line = (read-line s nil nil)
               while line collect line))
          'vector))

(defun indentation (line)
  "Position of first non-SPACE character in LINE."
  (position-if-not (lambda (c) (char= c #\Space)) line))

(defun docstring (x doc-type)
  (cl:documentation x doc-type))

(defun flatten-to-string (list)
  (format nil "~{~A~^-~}" (flatten list)))

(defgeneric alphanumize (original)
  (:documentation "Construct a string without characters like *`' that will f-star-ck
up filename handling. See `*character-replacements*' and
`*characters-to-drop*' for customization.")
  (:method ((symbol symbol))
    (intern (alphanumize (symbol-name symbol))))
  (:method (original)
    (let ((name (remove-if (lambda (x) (member x *characters-to-drop*))
                           (if (listp original)
                               (flatten-to-string original)
                               (string original))))
          (chars-to-replace (mapcar #'car *character-replacements*)))
      ;; Replace space if it is the last character in the name
      (when (eql #\Space (elt name (1- (length name))))
        (setf name (subseq name 0 (1- (length name)))))
      (flet ((replacement-delimiter (index)
               (cond ((or (< index 0) (>= index (length name))) "")
                     ((alphanumericp (char name index)) "-")
                     (t ""))))
        (loop for index = (position-if #'(lambda (x) (member x chars-to-replace))
                                       name)
           while index
           do (setf name (concatenate 'string (subseq name 0 index)
                                      (replacement-delimiter (1- index))
                                      (cdr (assoc (aref name index)
                                                  *character-replacements*))
                                      (replacement-delimiter (1+ index))
                                      (subseq name (1+ index))))))
      ;; Replace multiple -- in order with something else as makeinfo combines them.
      (loop :while (search "--" name) :do (setf name (cl-ppcre::regex-replace "--" name "-_-")))
      name)))

;;;; generating various names

(defgeneric name (thing)
  (:documentation "Name for a documented thing. Names are either
symbols or lists of symbols."))

(defmethod name ((symbol symbol))
  symbol)

(defmethod name ((cons cons))
  cons)

(defmethod name ((package package))
  (package-shortest-name package))

(defmethod name ((method method))
  (list
   (generic-function-name (method-generic-function method))
   (method-qualifiers method)
   (specialized-lambda-list method)))

;;; Node names for DOCUMENTATION instances

(defgeneric name-using-kind/name (kind name doc))

(defmethod name-using-kind/name (kind (name string) doc)
  (declare (ignore kind))
  (assert (get-package doc))
  (format nil "~@[~A:~]~A" (package-shortest-name (get-package doc)) name))

(defmethod name-using-kind/name (kind (name symbol) doc)
  (declare (ignore kind))
  (assert (get-package doc))
  (format nil "~@[~A:~]~A" (package-shortest-name (get-package doc)) name))

(defmethod name-using-kind/name (kind (name list) doc)
  (declare (ignore kind))
  (assert (setf-name-p name))
  (assert (get-package doc))
  (format nil "(setf ~@[~A:~]~A)" (package-shortest-name (get-package doc)) (second name)))

(defmethod name-using-kind/name ((kind (eql 'method)) name doc)
  (assert (get-package doc))
  (format nil "~A~{ ~A~} ~A"
          (name-using-kind/name nil (first name) doc)
          (second name)
          (third name)))

(defun get-safe-name (doc)
  (let ((*character-replacements*
         (remove-if (lambda (it) (member it (coerce *symbol-characters* 'list)))
                    *character-replacements* :key #'car)))
    (etypecase (get-name doc)
      (symbol (intern (alphanumize (symbol-name (get-name doc)))
                      (get-package doc)))
      (string (alphanumize (get-name doc)))
      (list (get-name doc)))))

(defun node-name (doc)
  "Returns TexInfo node name as a string for a DOCUMENTATION instance."
  (let ((kind (get-kind doc)))
    (format nil "~:(~A~) ~(~A~)" kind (name-using-kind/name kind (get-safe-name doc) doc))))

(defun package-shortest-name (package)
  (let* ((names (cons (package-name package) (package-nicknames package)))
         (sorted (sort (copy-list names) #'< :key #'length)))
    (car sorted)))

(defun package-macro-name (package)
  (let ((short-name (package-shortest-name package)))
    (when short-name
      (remove-if-not #'alpha-char-p (string-downcase short-name)))))

;;; Definition titles for DOCUMENTATION instances

(defgeneric title-using-kind/name (kind name doc))

(defmethod title-using-kind/name (kind (name string) doc)
  (declare (ignore kind doc))
  name)

(defmethod title-using-kind/name (kind (name symbol) doc)
  (declare (ignore kind))
  (let* ((symbol-name (symbol-name name))
         (earmuffsp (and (char= (char symbol-name 0) #\*)
                         (char= (char symbol-name (1- (length symbol-name))) #\*)
                         (some #'alpha-char-p symbol-name)))
         (pmacro-name (package-macro-name (get-package doc))))
    (if pmacro-name
        (if earmuffsp
            (format nil "@~A{@earmuffs{~A}}"
                    pmacro-name (subseq symbol-name 1 (1- (length symbol-name))))
         (format nil "@~A{~A}" pmacro-name name))
        (if earmuffsp
            (format nil "@earmuffs{~A}" (subseq symbol-name 1 (1- (length symbol-name))))
            (format nil "~A" name)))))

(defmethod title-using-kind/name (kind (name list) doc)
  (declare (ignore kind))
  (assert (setf-name-p name))
  (let ((pmacro-name (package-macro-name (get-package doc))))
    (if pmacro-name
        (format nil "@setf{@~A{~A}}" pmacro-name (second name))
        (format nil "@setf{~A}" (second name)))))

(defmethod title-using-kind/name ((kind (eql 'method)) name doc)
  (format nil "~{~A ~}~A"
          (second name)
          (title-using-kind/name nil (first name) doc)))

(defun title-name (doc)
  "Returns a string to be used as name of the definition."
  (string-downcase (title-using-kind/name (get-kind doc) (get-safe-name doc) doc)))

(defun include-pathname (doc)
  (let* ((kind (get-kind doc))
         (name (nstring-downcase
                (if (eq 'package kind)
                    (format nil "package-~A" (alphanumize (get-name doc)))
                    (format nil "~A-~A-~A"
                            (case (get-kind doc)
                              ((function generic-function) "fun")
                              (structure "struct")
                              (variable "var")
                              (otherwise (symbol-name (get-kind doc))))
                            (alphanumize (let ((*base-package* nil))
                                           (package-shortest-name (get-package doc))))
                            (alphanumize (get-name doc)))))))
    (make-pathname :name name  :type "texinfo")))

;;;; documentation class and related methods

(defclass documentation ()
  ((name :initarg :name :reader get-name)
   (kind :initarg :kind :reader get-kind)
   (string :initarg :string :reader get-string)
   (children :initarg :children :initform nil :accessor get-children)
   (package :initform *documentation-package* :reader get-package)))

(defclass comment ()
  ((filename :initarg :filename :reader get-filename)
   (string :initarg :string :reader get-string)
   (package :initform *documentation-package* :reader get-package)))

(defun function-documentation-p (doc)
  (member (get-kind doc) '(special-operator macro generic-function function method
                           compiler-macro method-combination setf)))

(defun variable-documentation-p (doc)
  (member (get-kind doc) '(variable constant)))

(defun type-documentation-p (doc)
  (member (get-kind doc) '(structure class condition type)))

(defmethod print-object ((documentation documentation) stream)
  (print-unreadable-object (documentation stream :type t)
    (princ (list (get-kind documentation) (get-name documentation)) stream)))

(defgeneric make-documentation (x doc-type string))

(defmethod make-documentation ((x package) doc-type string)
  (declare (ignore doc-type))
  (make-instance 'documentation
                 :name (let ((*base-package* nil))
                         (name x))
                 :kind 'package
                 :string string))

(defmethod make-documentation (x (doc-type (eql 'function)) string)
  (declare (ignore doc-type))
  (let* ((fdef (and (fboundp x) (fdefinition x)))
         (name x)
         (kind (cond ((and (symbolp x) (special-operator-p x))
                      'special-operator)
                     ((and (symbolp x) (macro-function x))
                      'macro)
                     ((typep fdef 'generic-function)
                      (assert (or (symbolp name) (setf-name-p name)))
                      'generic-function)
                     (fdef
                      (assert (or (symbolp name) (setf-name-p name)))
                      'function)))
         (children (when (eq kind 'generic-function)
                     (collect-gf-documentation fdef))))
    (make-instance 'documentation
                   :name (name x)
                   :string string
                   :kind kind
                   :children children)))

(defmethod make-documentation ((x method) doc-type string)
  (declare (ignore doc-type))
  (make-instance 'documentation
                 :name (name x)
                 :kind 'method
                 :string string))

(defmethod make-documentation (x (doc-type (eql 'type)) string)
  (make-instance 'documentation
                 :name (name x)
                 :string string
                 :kind (etypecase (find-class x nil)
                         (structure-class 'structure)
                         (standard-class 'class)
                         (sb-pcl::condition-class 'condition)
                         ((or built-in-class null) 'type))))

(defmethod make-documentation (x (doc-type (eql 'variable)) string)
  (make-instance 'documentation
                 :name (name x)
                 :string string
                 :kind (if (constantp x)
                           'constant
                           'variable)))

(defmethod make-documentation (x (doc-type (eql 'setf)) string)
  (declare (ignore doc-type))
  (make-instance 'documentation
                 :name (name x)
                 :kind 'setf-expander
                 :string string))

(defmethod make-documentation (x doc-type string)
  (make-instance 'documentation
                 :name (name x)
                 :kind doc-type
                 :string string))

(defun maybe-documentation (x doc-type)
  "Returns a DOCUMENTATION instance for X and DOC-TYPE, or NIL if
there is no corresponding docstring."
  (let ((docstring (docstring x doc-type)))
    (when docstring
      (make-documentation x doc-type docstring))))

(defun lambda-list (doc)
  (case (get-kind doc)
    ((package constant variable type structure class condition nil)
     nil)
    (method
     (third (get-name doc)))
    (t
     ;; KLUDGE: Eugh.
     ;;
     ;; believe it or not, the above comment was written before CSR
     ;; came along and obfuscated this.  (2005-07-04)
     (let ((name (get-name doc)))
       (when (or (symbolp name)
                 (and (consp name) (eq 'setf (car name))))
         (labels ((clean (x &key optional key)
                    (typecase x
                      (atom x)
                      ((cons (member &optional))
                       (cons (car x) (clean (cdr x) :optional t)))
                      ((cons (member &key))
                       (cons (car x) (clean (cdr x) :key t)))
                      ((cons (member &whole &environment))
                       ;; Skip these
                       (clean (cddr x) :optional optional :key key))
                      ((cons (member &aux))
                       ;; Drop everything after &AUX.
                       nil)
                      ((cons cons)
                       (cons
                        (cond (key (if (consp (caar x))
                                       (caaar x)
                                       (caar x)))
                              (optional (caar x))
                              (t (clean (car x))))
                        (clean (cdr x) :key key :optional optional)))
                      (cons
                       (cons
                        (cond ((or key optional) (car x))
                              (t (clean (car x))))
                        (clean (cdr x) :key key :optional optional))))))
           (clean (sb-introspect:function-lambda-list name))))))))

(defun get-string-name (x)
  (let ((name (get-name x)))
    (cond ((symbolp name)
           (symbol-name name))
          ((and (consp name) (eq 'setf (car name)))
           (symbol-name (second name)))
          ((and (consp name) (symbolp (first name)))
           (symbol-name (first name)))
          ((stringp name)
           name)
          (t
           (error "Don't know which symbol to use for name ~S" name)))))

(defun documentation< (x y)
  (let ((p1 (position (get-kind x) *ordered-documentation-kinds*))
        (p2 (position (get-kind y) *ordered-documentation-kinds*)))
    (if (or (not (and p1 p2)) (= p1 p2))
        (string< (get-string-name x) (get-string-name y))
        (< p1 p2))))

;;;; turning text into texinfo

(defgeneric escape-for-texinfo (string &optional downcasep)
  (:documentation "Return STRING with characters in *TEXINFO-ESCAPED-CHARS* escaped
with #\@. Optionally downcase the result.")
  (:method ((symbol symbol) &optional downcasep)
    (intern (escape-for-texinfo (symbol-name symbol))))
  (:method ((string string) &optional downcasep)
    (let ((result (with-output-to-string (s)
                    (loop for char across string
                       when (find char *texinfo-escaped-chars*)
                       do (write-char #\@ s)
                       do (write-char char s)))))
      (if downcasep (nstring-downcase result) result))))

;;; TODO: Maybe everything in here should at some point get
;;;       first-class support as specialized syntax.
(defun unescape-for-texinfo (string &aux last-char)
  "Unescape obvious texinfo commands in STRING.
STRING is assumed to be the result of `escape-for-texinfo'."
  (let ((w/o-braces '("section" "subsection" "subsubsection" "cindex" "node"
                      "include" "end" "menu" "subsubheading"))
        (w/braces '("uref" "ref" "pxref" "url" "code" "anchor" "file"
                    "code" "env"))
        (braces 0))
    (flet ((subword-at (i word)
             (string= (subseq string i (min (length string)
                                            (+ i (length word))))
                      word))
           (next-char (i) (aref string i)))
      (with-output-to-string (s)
        (loop
           for char across string
           as i upfrom 1
           ;; This conditional is admittedly convoluted, it manages
           ;; two things.  First, it checks for words which we don't
           ;; want to escape, in `w/o-braces' or `w/braces'.  Second,
           ;; when something is is `w/braces' it handles not escaping
           ;; the next two braces using the `braces' counter.
           unless (or (and (> braces 0) ; Handle brace un-escaping.
                           (when (or (and (equal (next-char i) #\{)
                                          (= braces 2))
                                     (and (equal (next-char i) #\})
                                          (= braces 1)))
                             (decf braces)
                             t))
                      (and (equal last-char #\@) ; Handle word un-escaping.
                           (equal char #\@)
                           (or (some (lambda (word) (subword-at i word))
                                     w/o-braces)
                               (when (some (lambda (word) (subword-at i word))
                                           w/braces)
                                 (setf braces 2)
                                 t))))
           do (write-char char s)
           do (setf last-char char))))))

(defun empty-p (line-number lines)
  (or (< line-number 0)
   (and (< -1 line-number)
        (< line-number (length lines))
        (not (indentation (svref lines line-number))))))

;;; line markups

(defvar *not-symbols*
  '("ANSI" "CLHS" "UNIX" "SBCL" "POSIX" "ISO" "ASM" "C" "C++" "AST" "*" "I/O"
    "PAPI" "API" "REST" "HTTP" "JSON"))

(defun frob-ellipsis (line)
  ;; READ-FROM-STRING chokes on ... so replace it.
  (let ((p (search "..." line)))
    (if p
        (frob-ellipsis (replace (copy-seq line) "+++" :start1 p))
        line)))

(defun locate-symbols (line)
  "Return a list of index pairs of symbol-like parts of LINE."
  ;; This would be a good application for a regex ...
  (let (result)
    (flet ((grab (start end)
             (unless (member (subseq line start end) *not-symbols*
                             :test #'string=)
               (push (list start end) result)))
           (got-symbol-p (start)
             (let ((end (when (< start (length line))
                          (position-if (lambda (char) (find char " )"))
                                       line :start start))))
               (when end
                 (every (lambda (char) (find char *symbol-characters*))
                        (subseq line start end))))))
      (do ((begin nil)
           (maybe-begin t)
           (i 0 (1+ i)))
          ((>= i (length line))
           ;; symbol at end of line
           (when (and begin (or (> i (1+ begin))
                                (not (member (char line begin) '(#\A #\I)))))
             (grab begin i))
           (nreverse result))
        (cond
          ((and begin (find (char line i) *symbol-delimiters*))
           ;; symbol end; remember it if it's not "A" or "I"
           (when (or (> i (1+ begin)) (not (member (char line begin) '(#\A #\I))))
             (grab begin i))
           (setf begin nil
                 maybe-begin t))
          ((and begin (not (find (char line i) *symbol-characters*)))
           ;; Not a symbol: abort
           (setf begin nil))
          ((and maybe-begin (not begin) (find (char line i) *symbol-characters*))
           ;; potential symbol begin at this position
           (setf begin i
                 maybe-begin nil))
          ((find (char line i) *symbol-delimiters*)
           ;; potential symbol begin after this position
           (setf maybe-begin t))
          ((and (eql #\( (char line i)) (got-symbol-p (1+ i)))
           ;; a type designator, or a function call as part of the text?
           (multiple-value-bind (exp end)
               (let ((*package* (find-package :cl-user)))
                 (ignore-errors (read-from-string (frob-ellipsis line) nil nil :start i)))
             (when exp
               (grab i end)
               (setf begin nil
                     maybe-begin nil
                     i end))))
          (t
           ;; Not reading a symbol, not at potential start of symbol
           (setf maybe-begin nil)))))))

(defun texinfo-line (line)
  "Format symbols in LINE texinfo-style: either as code or as
variables if the symbol in question is contained in symbols
*TEXINFO-VARIABLES*."
  (with-output-to-string (result)
    (let ((last 0))
      (dolist (symbol/index (locate-symbols line))
        (write-string (subseq line last (first symbol/index)) result)
        (let ((symbol-name (apply #'subseq line symbol/index)))
          (format result (if (member symbol-name *texinfo-variables*
                                     :test #'string=)
                             "@var{~A}"
                             "@code{~A}")
                  (string-downcase symbol-name)))
        (setf last (second symbol/index)))
      (write-string (subseq line last) result))))

;;; example sections

(defun example-section-p (line line-number lines)
  "Returns T if the given LINE looks like start of example code --
ie. if it starts with 4 whitespace and the previous line is empty"
  (let ((offset (indentation line)))
    (and offset
         (= 4 offset)
         (empty-p (1- line-number) lines))))

(defun collect-example-section (lines line-number)
  (flet ((maybe-line (index)
           (and (< index (length lines)) (svref lines index))))
    (let ((example (loop for index = line-number then (1+ index)
                      for line = (maybe-line index)
                      while (or (indentation line)
                                ;; Allow empty lines in middle of example sections.
                                (let ((next (1+ index)))
                                  (example-section-p (maybe-line next) next lines)))
                      collect line)))
     (values (length example)
             `("@cartouche" "@example" ,@example "@end example" "@end cartouche")))))

;;; lisp sections

(defun lisp-section-p (line line-number lines)
  "Returns T if the given LINE looks like start of lisp code --
ie. if it starts with whitespace followed by a paren or
semicolon, and the previous line is empty"
  (let ((offset (indentation line)))
    (and offset
         (plusp offset)
         (find (find-if-not #'whitespacep line) "(;<") ; < is a KLUDGE
         (empty-p (1- line-number) lines))))

(defun collect-lisp-section (lines line-number)
  (flet ((maybe-line (index)
           (and (< index (length lines)) (svref lines index))))
    (let ((lisp (loop for index = line-number then (1+ index)
                      for line = (maybe-line index)
                      while (or (indentation line)
                                ;; Allow empty lines in middle of lisp sections.
                                (let ((next (1+ index)))
                                  (lisp-section-p (maybe-line next) next lines)))
                      collect line)))
     (values (length lisp) `("@lisp" ,@lisp "@end lisp")))))

;;; itemized sections

(defun maybe-itemize-offset (line)
  "Return NIL or the indentation offset if LINE looks like it starts
an item in an itemization."
  (let* ((offset (indentation line))
         (char (when offset (char line offset))))
    (and offset
         (member char *itemize-start-characters* :test #'char=)
         (char= #\Space (find-if-not (lambda (c) (char= c char))
                                     line :start offset))
         offset)))

(defun collect-maybe-itemized-section (lines starting-line)
  ;; Return index of next line to be processed outside
  (let ((this-offset (maybe-itemize-offset (svref lines starting-line)))
        (result nil)
        (lines-consumed 0))
    (loop for line-number from starting-line below (length lines)
       for line = (svref lines line-number)
       for indentation = (indentation line)
       for offset = (maybe-itemize-offset line)
       when (search "@end menu" line) do (setf result nil)
       do (cond
            ((not indentation)
             ;; empty line -- inserts paragraph.
             (push "" result)
             (incf lines-consumed))
            ((and offset (> indentation this-offset))
             ;; nested itemization -- handle recursively
             ;; FIXME: tables in itemizations go wrong
             (multiple-value-bind (sub-lines-consumed sub-itemization)
                 (collect-maybe-itemized-section lines line-number)
               (when sub-lines-consumed
                 (incf line-number (1- sub-lines-consumed)) ; +1 on next loop
                 (incf lines-consumed sub-lines-consumed)
                 (setf result (nconc (nreverse sub-itemization) result)))))
            ((and offset (= indentation this-offset))
             ;; start of new item
             (push (format nil "@item ~A"
                           (texinfo-line (subseq line (1+ offset))))
                   result)
             (incf lines-consumed))
            ((and (not offset) (> indentation this-offset))
             ;; continued item from previous line
             (push (texinfo-line line) result)
             (incf lines-consumed))
            (t
             ;; end of itemization
             (loop-finish))))
    ;; a single-line itemization isn't.
    (if (> (count-if (lambda (line) (> (length line) 0)) result) 1)
        (values lines-consumed `("@itemize" ,@(reverse result) "@end itemize"))
        nil)))

;;; table sections

(defun tabulation-body-p (offset line-number lines)
  (when (< line-number (length lines))
    (let ((offset2 (indentation (svref lines line-number))))
      (and offset2 (< offset offset2)))))

(defun tabulation-p (offset line-number lines direction)
  (let ((step  (ecase direction
                 (:backwards (1- line-number))
                 (:forwards (1+ line-number)))))
    (when (and (plusp line-number) (< line-number (length lines)))
      (and (eql offset (indentation (svref lines line-number)))
           (or (when (eq direction :backwards)
                 (empty-p step lines))
               (tabulation-p offset step lines direction)
               (tabulation-body-p offset step lines))))))

(defun maybe-table-offset (line-number lines)
  "Return NIL or the indentation offset if LINE looks like it starts
an item in a tabulation. Ie, if it is (1) indented, (2) preceded by an
empty line, another tabulation label, or a tabulation body, (3) and
followed another tabulation label or a tabulation body."
  (let* ((line (svref lines line-number))
         (offset (indentation line))
         (prev (1- line-number))
         (next (1+ line-number)))
    (when (and offset (plusp offset))
      (and (or (empty-p prev lines)
               (tabulation-body-p offset prev lines)
               (tabulation-p offset prev lines :backwards))
           (or (tabulation-body-p offset next lines)
               (tabulation-p offset next lines :forwards))
           offset))))

;;; FIXME: This and itemization are very similar: could they share
;;; some code, mayhap?

(defun collect-maybe-table-section (lines starting-line)
  ;; Return index of next line to be processed outside
  (let ((this-offset (maybe-table-offset starting-line lines))
        (result nil)
        (lines-consumed 0))
    (loop for line-number from starting-line below (length lines)
          for line = (svref lines line-number)
          for indentation = (indentation line)
          for offset = (maybe-table-offset line-number lines)
          do (cond
               ((not indentation)
                ;; empty line -- inserts paragraph.
                (push "" result)
                (incf lines-consumed))
               ((and offset (= indentation this-offset))
                ;; start of new item, or continuation of previous item
                (if (and result (search "@item" (car result) :test #'char=))
                    (push (format nil "@itemx ~A" (texinfo-line line))
                          result)
                    (progn
                      (push "" result)
                      (push (format nil "@item ~A" (texinfo-line line))
                            result)))
                (incf lines-consumed))
               ((> indentation this-offset)
                ;; continued item from previous line
                (push (texinfo-line line) result)
                (incf lines-consumed))
               (t
                ;; end of itemization
                (loop-finish))))
     ;; a single-line table isn't.
    (if (> (count-if (lambda (line) (> (length line) 0)) result) 1)
        (values lines-consumed
                `("" "@table @emph" ,@(reverse result) "@end table" ""))
        nil)))

;;; section markup

(defmacro with-maybe-section (index &rest forms)
  `(multiple-value-bind (count collected) (progn ,@forms)
    (when count
      (dolist (line collected)
        (write-line line *texinfo-output*))
      (incf ,index (1- count)))))

(defun write-texinfo-string (string &optional lambda-list)
  "Try to guess as much formatting for a raw docstring as possible."
  (let ((*texinfo-variables* (flatten lambda-list))
        (lines (string-lines (unescape-for-texinfo
                              (escape-for-texinfo string nil)))))
      (loop for line-number from 0 below (length lines)
            for line = (svref lines line-number)
            do (cond
                 ((with-maybe-section line-number
                    (and (example-section-p line line-number lines)
                         (collect-example-section lines line-number))))
                 ((with-maybe-section line-number
                    (and (lisp-section-p line line-number lines)
                         (collect-lisp-section lines line-number))))
                 ((with-maybe-section line-number
                    (and (maybe-itemize-offset line)
                         (collect-maybe-itemized-section lines line-number))))
                 ((with-maybe-section line-number
                    (and (maybe-table-offset line-number lines)
                         (collect-maybe-table-section lines line-number))))
                 (t
                  (write-line (texinfo-line line) *texinfo-output*))))))

;;;; texinfo formatting tools

(defun hide-superclass-p (class-name super-name)
  (let ((super-package (symbol-package super-name)))
    (or
     ;; KLUDGE: We assume that we don't want to advertise internal
     ;; classes in CP-lists, unless the symbol we're documenting is
     ;; internal as well.
     (and (member super-package #.'(mapcar #'find-package *undocumented-packages*))
          (not (eq super-package (symbol-package class-name))))
     ;; KLUDGE: We don't generally want to advertise SIMPLE-ERROR or
     ;; SIMPLE-CONDITION in the CPLs of conditions that inherit them
     ;; simply as a matter of convenience. The assumption here is that
     ;; the inheritance is incidental unless the name of the condition
     ;; begins with SIMPLE-.
     (and (member super-name '(simple-error simple-condition))
          (let ((prefix "SIMPLE-"))
            (mismatch prefix (string class-name) :end2 (length prefix)))
          t ; don't return number from MISMATCH
          ))))

(defun hide-slot-p (symbol slot)
  ;; FIXME: There is no pricipal reason to avoid the slot docs fo
  ;; structures and conditions, but their DOCUMENTATION T doesn't
  ;; currently work with them the way we'd like.
  (not (and (typep (find-class symbol nil) 'standard-class)
            (docstring slot t))))

(defun texinfo-anchor (doc)
  (format *texinfo-output* "@anchor{~A}~%" (node-name doc)))

;;; KLUDGE: &AUX *PRINT-PRETTY* here means "no linebreaks please"
(defun texinfo-begin (doc &aux *print-pretty*)
  (let ((kind (get-kind doc)))
    (format *texinfo-output* "@~A {~:(~A~)} ~({~A}~@[ ~{~A~^ ~}~]~)~%"
            (case kind
              ((package constant variable)
               "defvr")
              ((structure class condition type)
               "deftp")
              (t
               "deffn"))
            (map 'string (lambda (char) (if (eql char #\-) #\Space char)) (string kind))
            (title-name doc)
            ;; &foo would be amusingly bold in the pdf thanks to TeX/Texinfo
            ;; interactions,so we escape the ampersand -- amusingly for TeX.
            ;; sbcl.texinfo defines macros that expand @&key and friends to &key.
            (mapcar (lambda (name)
                      (if (and *tex-bold-hack* (member name lambda-list-keywords))
                          (format nil "texmacro~A" name)
                          name))
                    (lambda-list doc)))))

(defun texinfo-index (doc)
  (let ((title (title-name doc)))
    (case (get-kind doc)
      ((structure type class condition)
       (format *texinfo-output* "@tindex ~A~%" title))
      ((variable constant)
       (format *texinfo-output* "@vindex ~A~%" title))
      ((compiler-macro function method-combination macro generic-function)
       (format *texinfo-output* "@findex ~A~%" title)))))

(defun texinfo-inferred-body (doc)
  (when (member (get-kind doc) '(class structure condition))
    (let ((name (get-name doc)))
      ;; class precedence list
      (format *texinfo-output* "Class precedence list: @code{~(~{@lw{~A}~^, ~}~)}~%~%"
              (remove-if (lambda (class) (hide-superclass-p name class))
                         (mapcar #'alphanumize
                          (mapcar #'class-name
                                  (ensure-class-precedence-list (find-class name))))))
      ;; slots
      (let ((slots (remove-if (lambda (slot) (hide-slot-p name slot))
                              (class-direct-slots (find-class name)))))
        (when slots
          (format *texinfo-output* "Slots:~%@itemize~%")
          (dolist (slot slots)
            (format *texinfo-output*
                    "@item ~(@code{~A}~#[~:; --- ~]~
                      ~:{~2*~@[~2:*~A~P: ~{@code{@w{~S}}~^, ~}~]~:^; ~}~)~%~%"
                    (slot-definition-name slot)
                    (remove
                     nil
                     (mapcar
                      (lambda (name things)
                        (if things
                            (list name (length things) things)))
                      '("initarg" "reader"  "writer")
                      (list
                       (slot-definition-initargs slot)
                       (slot-definition-readers slot)
                       (slot-definition-writers slot)))))
            ;; FIXME: Would be neater to handler as children
            (write-texinfo-string (docstring slot t)))
          (format *texinfo-output* "@end itemize~%~%"))))))

(defun texinfo-body (doc)
  (write-texinfo-string (get-string doc)))

(defun texinfo-end (doc)
  (write-line (case (get-kind doc)
                ((package variable constant) "@end defvr")
                ((structure type class condition) "@end deftp")
                (t "@end deffn"))
              *texinfo-output*))

(defun write-texinfo (doc)
  "Writes TexInfo for a DOCUMENTATION instance to *TEXINFO-OUTPUT*."
  ;;  (texinfo-index doc)
  (texinfo-anchor doc)
  (texinfo-begin doc)
  (texinfo-inferred-body doc)
  (texinfo-body doc)
  (texinfo-end doc)
  ;; FIXME: Children should be sorted one way or another
  (mapc #'write-texinfo (get-children doc)))

;;;; main logic
(defun flatten-documentation-list (docs)
  "Take a list of documentation objects and return a flattened list.
The flattening means that for each documentation object the children
are removed and added as toplevel entries to the list.  This happens recursively."
  (loop for doc in docs
     for children = (get-children doc)
     when children append (flatten-documentation-list children)
     when t collect doc
     do (setf (get-children doc) nil)))


(defun collect-gf-documentation (gf)
  "Collects method documentation for the generic function GF"
  (loop for method in (generic-function-methods gf)
        for doc = (maybe-documentation method t)
        when doc
        collect doc))

(defun collect-name-documentation (name)
  (loop for type in *documentation-types*
        for doc = (maybe-documentation name type)
        when doc
        collect doc))

(defun collect-symbol-documentation (symbol)
  "Collects all docs for a SYMBOL and (SETF SYMBOL), returns a list of
the form DOC instances. See `*documentation-types*' for the possible
values of doc-type."
  (nconc (collect-name-documentation symbol)
         (collect-name-documentation (list 'setf symbol))))

(defun collect-documentation (package &key no-package flatten extra-symbols)
  "Collects all documentation for all external symbols of the given
npackage, as well as for the package itself.  Optionally, you may
supply EXTRA-SYMBOLS that are not external, to be collected as well.
For example, the names of structures or classes may not be exported,
although their accessors are."
  (let* ((*documentation-package* (find-package package))
         (docs nil))
    (check-type package package)
    (do-external-symbols (symbol package)
      (setf docs (nconc (collect-symbol-documentation symbol) docs)))
    (dolist (symbol extra-symbols)
      (when (eq (symbol-package symbol) package)
        (setf docs (nconc (collect-symbol-documentation symbol) docs))))
    (let ((doc (unless no-package
                 (maybe-documentation *documentation-package* t))))
      (when doc
        (push doc docs))
      (when flatten
        (setf docs (flatten-documentation-list docs)))
      (sort docs #'documentation<))))

(defmacro with-texinfo-file (pathname &body forms)
  `(with-open-file (*texinfo-output* ,pathname
                                    :direction :output
                                    :if-does-not-exist :create
                                    :if-exists :supersede)
    ,@forms))

(defun write-package-macro (package)
  (let* ((package-name (package-shortest-name package))
         (macro-name (package-macro-name package)))
    (write-packageish-macro package-name macro-name)))

(defun write-texinfo-macros ()
  (write-line "
@c MACHINE GENERATED FILE! Do not edit by hand!
@c See SB-TEXINFO for details."
              *texinfo-output*)
  (when *tex-bold-hack*
    ;; We use @&key, etc to escape & from TeX in lambda lists -- so we
    ;; need to define them for info as well.
    (write-line "
@ifnottex
@macro &allow-other-keys
&allow-other-keys
@end macro
@macro &optional
&optional
@end macro
@macro &rest
&rest
@end macro
@macro &key
&key
@end macro
@macro &body
&body
@end macro
@end ifnottex"
                *texinfo-output*))
  ;; Some index prettification helper macros, for tricking the texindex
  ;; collation engine
  (write-line "
@macro earmuffs{name}
*\\name\\*
@end macro
@macro setf{name}
\(setf \\name\\)
@end macro"
              *texinfo-output*)
  ;; Some plain TeX macrology to wrap text in \hbox{} only if the text
  ;; contains no hyphens.
  (write-line "
@iftex
@tex
\\newif\\ifdash
\\long\\def\\dashp#1{\\expandafter\\setnext#1-\\dashphelper}
\\long\\def\\setnext#1-{\\futurelet\\next\\dashphelper}
\\long\\def\\dashphelper#1\\dashphelper{
  \\ifx\\dashphelper\\next\\dashfalse\\else\\dashtrue\\fi
}
\\def\\lw#1{\\leavevmode\\dashp{#1}\\ifdash#1\\else\\hbox{#1}\\fi}
@end tex
@end iftex"
              *texinfo-output*)
  ;; A Texinfo binding for the plain TeX above.  Analogous to Texinfo's
  ;; @w, but for Lisp symbols.  AFAICT, the comment characters are
  ;; necessary to prevent treating the newline as a space.
  (write-line "
@macro lw{word}
\\word\\
@end macro"
              *texinfo-output*)
  ;; Easy XREFs to variables, macros, and functions.
  (write-line "
@macro refvar{name}
@ref{Variable \\name\\, @code{\\name\\}}
@end macro

@macro refmacro{name}
@ref{Macro \\name\\, @code{\\name\\}}
@end macro

@macro reffun{name}
@ref{Function \\name\\, @code{\\name\\}}
@end macro"
              *texinfo-output*))

(defun write-packageish-macro (package-name macro-name)
  ;; a word of explanation about the iftex branch here is probably
  ;; warranted.  The package information should be present for
  ;; clarity, because these produce body text as well as index
  ;; entries (though in info output it's more important to use a
  ;; very restricted character set because the info reader parses
  ;; the link, and colon is a special character).  In TeX output we
  ;; make the package name unconditionally small, and arrange such
  ;; that the start of the symbol name is at a constant horizontal
  ;; offset, that offset being such that the longest package names
  ;; have the "sb-" extending into the left margin.  (At the moment,
  ;; the length of the longest package name, sb-concurrency, is
  ;; hard-coded).
  (format *texinfo-output* "~
@iftex
@macro ~A{name}
{@smallertt@phantom{concurrency:}~@[@llap{~(~A~):}~]}\\name\\
@end macro
@end iftex
@ifinfo
@macro ~2:*~A{name}
\\name\\
@end macro
@end ifinfo
@ifnottex
@ifnotinfo
@macro ~:*~A{name}
\\name\\ ~@[[~(~A~)]~]
@end macro
@end ifnotinfo
@end ifnottex~%"
          macro-name package-name))

(defun write-backmatter (&key (concept-index t)
                              (function-index t)
                              (variable-index t)
                              (type-index t)
                              (colophon t))
  (when concept-index
    (write-line "
@node Concept Index
@comment  node-name,  next,  previous,  up
@appendix Concept Index

@printindex cp
"
                *texinfo-output*))
  (when function-index
    (write-line "
@node Function Index
@comment  node-name,  next,  previous,  up
@appendix Function Index

@printindex fn
"
                *texinfo-output*))
  (when variable-index
    (write-line "
@node Variable Index
@comment  node-name,  next,  previous,  up
@appendix Variable Index

@printindex vr
"
                *texinfo-output*))
  (when type-index
    (write-line "
@node Type Index
@comment  node-name,  next,  previous,  up
@appendix Type Index

@printindex tp
"
                *texinfo-output*))
  (when colophon
    (write-line "
@node Colophon
@comment  node-name,  next,  previous,  up
@unnumbered Colophon

This manual is maintained in Texinfo, and automatically translated
into other forms (e.g. HTML or pdf). If you're @emph{reading} this
manual in one of these non-Texinfo translated forms, that's fine, but
if you want to @emph{modify} this manual, you are strongly advised to
seek out a Texinfo version and modify that instead of modifying a
translated version."
                *texinfo-output*)))

(defun write-texinfo-header (title filename description long-description)
  (format *texinfo-output* "
\\input texinfo   @c -*-texinfo-*-
@c %**start of header
@setfilename ~A.info
@settitle ~A
@c %**end of header

@c for install-info
@dircategory Software development
@direntry
* ~A:~@[           ~A~]
@end direntry

@finalout
@setcontentsaftertitlepage

@titlepage
@title ~A
~@[@subtitle ~A~]

@end titlepage

@node Top
@top Introduction

This is an @sc{sb-texinfo} autogenerated manual for ~A.

@c DO NOT EDIT BY HAND
@c
@c ...unless you're just using this as a template for a manually maintained
@c versiom, which is obviously OK.

~@[~A~]

@contents
"
          filename
          title
          filename
          description
          title
          description
          title
          long-description))

(defun write-menu (maybe-package-name docs)
  (write-line "@menu" *texinfo-output*)
  (when maybe-package-name
    (format *texinfo-output* "* Package ~A::~%" maybe-package-name))
  (write-line "* Dictionary::" *texinfo-output*)
  (when (find-if #'function-documentation-p docs)
    (write-line "* Function Index::" *texinfo-output*))
  (when (find-if #'variable-documentation-p docs)
    (write-line "* Variable Index::" *texinfo-output*))
  (when (find-if #'type-documentation-p docs)
    (write-line "* Type Index::" *texinfo-output*))
  (write-line "@end menu" *texinfo-output*))

(defun write-chapter/package (package doc)
  (declare (ignorable package))
  (when doc
    ;;    (format *texinfo-output* "
    ;; @node Package ~A~:*
    ;; @comment  node-name,  next,  previous,  up
    ;; @chapter Package ~A~%"
    ;;            (package-shortest-name package))
    (texinfo-body doc)))

(defun write-chapter/dictionary (docs)
  (unless *inhibit-sections*
    (write-line "
@node Dictionary
@comment  node-name,  next,  previous,  up
@chapter Dictionary
"
                *texinfo-output*))
  ;; FIXME: find out what's causing duplicates instead of just removing them.
  (mapc (lambda (doc)
          (format *texinfo-output* "@include include/~A~%" doc))
        (remove-duplicates (mapcar #'include-pathname docs) :test #'equalp)))

(defun files-for-package (package &aux paths)
  (flet ((%add (def)
           (when def
	     (let ((source (sb-introspect::find-definition-source def)))
	       (when source
		 (let ((path (sb-introspect::definition-source-pathname source)))
		   (when (and path (probe-file path))
		     (pushnew path paths :test #'equalp))))))))
    (do-external-symbols (sym package)
      (when (fboundp sym) (%add (symbol-function sym)))
      (%add (find-class sym nil)))
    paths))

(defun collect-comments (file &aux in-comment-p (first-line t) comments)
  "Collect all top-level comment blocks preceded by a page-break.
The page feed \"^L\" character or the beginning of a page both count.
A heuristic is used to try to drop common top-line comments at the
very beginning of a source file."
  (labels ((interleave (list sep &optional rest)
             (cond
               ((cdr list)
                (interleave (cdr list) sep (cons sep (cons (car list) rest))))
               (list (reverse (cons (car list) rest)))
               (t nil)))
           (mapconcat (func list sep)
             (apply #'concatenate 'string
                    (interleave (mapcar func list) sep)))
           (clean-line (line)
             (let ((trimmed (string-trim ";" line)))
               (if (and (> (length trimmed) 0)
                        (equal #\Space (aref trimmed 0)))
                   (subseq trimmed 1)
                   trimmed))))
    (let* ((sb-impl::*default-external-format* (detect-encoding file))
           (string (with-open-file (in file)
                     (let ((seq (make-string (file-length in))))
                       (read-sequence seq in)
                       seq)))
           (lines (split-sequence #\Newline string )))
      ;; Collect all top-level comments.
      (dolist (line lines)
        (when (> (length line) 0)
          (if first-line
              ;; Special handling of very top of the file.
              (progn
                (setf first-line nil)
                ;; Unless it looks special collect it.  "Special"
                ;; means like a top-of-line comment or an Emacs hint.
                (when (equal #\; (aref line 0))
                  (setf in-comment-p t)
                  (if (or (search "-*-" line)
                          (search ".lisp ---" line)
                          (search "Copyright (C)" line))
                      (push '() comments)
                      (push (list (clean-line line)) comments))))
              (if in-comment-p
                  (if (equal #\; (aref line 0))
                      ;; Ignore first lines with four ;;;;'s because
                      ;; these are likely labels.
                      (unless (and (zerop (length (car comments)))
                                   (> (length line) 4)
                                   (string= ";;;;" (subseq line 0 4)))
                        (push (clean-line line) (car comments)))
                      (setf in-comment-p nil))
                  (when (equal #\Page (aref line 0))
                    (setf in-comment-p t)
                    (push '() comments))))))
      (remove nil
        (mapcar
         (lambda (comment)
           (let* ((magic "@texi{")
                  (start (search magic comment)))
             (when start
               (let* ((start-ind (+ start (length magic)))
                      (end-ind (search "}" comment :start2 start-ind)))
                 (make-instance 'comment
                   :filename (subseq comment start-ind end-ind)
                   :string (concatenate 'string
                             (subseq comment 0 start)
                             (subseq comment (1+ end-ind))))))))
         (reverse
          (mapcar (lambda (lines)
                    (mapconcat #'identity (reverse lines) (list #\Newline)))
                  comments)))))))

(defun generate-comment-includes (directory packages &key base-package)
  "Create files in DIRECTORY containing Texinfo markup of all comments
of files defining functions or classes in PACKAGES. The DIRECTORY is
created if it does not exist yet. Trailing slash is required.

Top-level block comments preceded by page feeds and including
\"@texi{filename}\" strings will be exported to the specified filename
and can be included in Texinfo source via @include statements.
Texinfo syntax-significant characters are escaped in symbol names, but
if a comment contains invalid Texinfo markup, you lose."
  (handler-bind ((warning #'muffle-warning))
    (let ((directory (merge-pathnames (pathname directory)))
          (*base-package* (when base-package (find-package base-package))))
      (when (or (pathname-type directory) (pathname-name directory))
        (error "Not a directory pathname: ~S" directory))
      (ensure-directories-exist directory)
      (dolist (package packages)
        (dolist (file (files-for-package (find-package package)))
          (dolist (comment
                    (let ((*documentation-package* (find-package package)))
                      (collect-comments file)))
            (with-texinfo-file (make-pathname
                                :name (get-filename comment)
                                :type "texi"
                                :directory (pathname-directory directory))
              (write-texinfo-string (get-string comment))))))
      directory)))

(defun generate-includes (directory packages &key base-package flatten extra-symbols)
  "Create files in DIRECTORY containing Texinfo markup of all docstrings of
each exported symbol in PACKAGES. The DIRECTORY is created if it does not
exist yet. Trailing slash is required.

The names of the generated files are of the form

    <doc-type>-<packagename>-<symbol-name>.texinfo

and can be included in Texinfo source via @include statements. Texinfo
syntax-significant characters are escaped in symbol names, but if a docstring
contains invalid Texinfo markup, you lose.

If flatten is nil, the default, a generic method with all its defmethods is written
to a single file containing the documentation of them all.

With flatten t, each and individual method documentation is written to its own file.
The names of the method definition files is of the form

    method-<packagename>-<function-name>-NIL-<arg1>-<arg1-spec>-<arg2>-...

If no specializer is specified the corresponding -<argn-spec> is ommitted.
contains invalid Texinfo markup, you lose.

EXTRA-SYMBOLS are for optionally supplying symbols that are not exported
for which we wish to create include files, as well."
  (handler-bind ((warning #'muffle-warning))
    (let ((directory (merge-pathnames (pathname directory)))
          (*base-package* (when base-package (find-package base-package)))
          (funsp nil)
          (varsp nil)
          (typesp nil))
      (when (or (pathname-type directory) (pathname-name directory))
        (error "Not a directory pathname: ~S" directory))
      (ensure-directories-exist directory)
      (dolist (package packages)
        (dolist (doc (collect-documentation (find-package package) :flatten flatten :extra-symbols extra-symbols))
          (cond ((function-documentation-p doc)
                 (setf funsp t))
                ((variable-documentation-p doc)
                 (setf varsp t))
                ((type-documentation-p doc)
                 (setf typesp t)))
          (with-texinfo-file (merge-pathnames (include-pathname doc) directory)
            (write-texinfo doc))))
      (with-texinfo-file (merge-pathnames "sb-texinfo.texinfo" directory)
        (write-texinfo-macros)
        (dolist (package packages)
          (write-package-macro package))
        (write-packageish-macro nil "nopkg"))
      (with-texinfo-file (merge-pathnames "short-backmatter.texinfo" directory)
        (write-backmatter :concept-index t
                          :function-index funsp
                          :variable-index varsp
                          :type-index typesp
                          :colophon nil))
      (with-texinfo-file (merge-pathnames "backmatter.texinfo" directory)
        (write-backmatter))
      directory)))

(defun document-package-pathname (package &key output-file &allow-other-keys)
  "Returns the pathname used for OUTPUT-FILE by DOCUMENT-PACKAGE when called
with the same arguments."
  (let ((*base-package* nil))
    (merge-pathnames
     (or (when output-file
           (merge-pathnames output-file (make-pathname :type "texinfo")))
         (make-pathname
          :name (string-downcase (package-shortest-name package))
          :type "texinfo")))))

(defun document-package (package &key output-file (standalone t) title (includes t))
  "Creates Texinfo documentation for PACKAGE in OUTPUT-FILE, which defaults to
the <shortest-package-name>.texinfo. Returns the pathname of the created file
as the primary value. An \"include/\" directory is created in the same
location as the Texinfo file, which contains parts included in the Texinfo
file.

If STANDALONE is true (the default), a standalone Texinfo file is created.
Otherwise a file suitable for including in other Texinfo files is created.

The TITLE is used for the documentation, defaulting to capitalized shortest
package name.

The generated Texinfo uses include files generated by GENERATE-INCLUDES,
making this function a convenient way to generate an initial template
for a manually maintained Texinfo manual."
  (when includes
    (generate-includes "include/" (list package) :base-package package))
  (generate-comment-includes "include/" (list package) :base-package package)
  (handler-bind ((warning #'muffle-warning))
    (let* ((filename (document-package-pathname package :output-file output-file))
           (*base-package* (find-package package))
           (system (asdf:find-system package nil))
           (desc (when system
                   (ignore-errors (asdf:system-description system))))
           (long-desc (when system
                        (ignore-errors (asdf:system-description system))))
           (package-doc (let ((*documentation-package* *base-package*))
                          (maybe-documentation *base-package* t)))
           (docs (collect-documentation *base-package* :no-package t)))
      (with-texinfo-file filename
        (when standalone
          (write-texinfo-header (or title
                                    (string-capitalize
                                     (package-shortest-name package)))
                                (pathname-name filename)
                                desc
                                long-desc))
        (unless *inhibit-sb-texinfo-macros*
          (write-line "@include include/sb-texinfo.texinfo" *texinfo-output*))
        (unless *inhibit-sections*
          (write-menu (when package-doc (package-shortest-name package)) docs))
        (write-chapter/package package package-doc)
        (write-chapter/dictionary docs)
        (when standalone
          (write-line "@include include/short-backmatter.texinfo" *texinfo-output*)
          (write-line "@bye" *texinfo-output*)))
      filename)))

(defun name-to-path (name)
  (cl-ppcre:regex-replace-all " " (string-downcase (alphanumize name)) "-"))

(defun document-system
    (chapter-name packages
     &key (dir *default-pathname-defaults*)
       (index-file (concatenate 'string
                                (name-to-path chapter-name)  "-sb-texinfo.texi"))
       (menu-offset 36)
       next previous top)
  "Calls `document-package' on PACKAGES creating a single index for CHAPTER-NAME.
Suitable for documenting a multi-package system as defined with
package-inferred-system."
  (labels ((doc-shortname (package)
             (let ((package (find-package package)))
               (or (car (package-nicknames package))
                   (package-name package))))
           (doc-name (package)
             (package-name (find-package package)))
           (doc-path-basename (package)
             (name-to-path (doc-shortname package))))
    (uiop/filesystem:with-current-directory (dir)
      (generate-includes "include/" packages)
      (let ((pkgs (mapcar
                   (lambda (package) ; Generate package docs.
                     (let ((title (doc-name package))
                           (base (doc-path-basename package)))
                       (document-package package
                                         :output-file (concatenate
                                                       'string
                                                       base
                                                       "-sb-texinfo.texi")
                                         :standalone nil
                                         :includes nil
                                         :title title)
                       (list package title base)))
                   packages)))
        (with-texinfo-file index-file
          (unless *inhibit-sb-texinfo-macros*
            (write-line "@include include/sb-texinfo.texinfo" *texinfo-output*)
            (terpri *texinfo-output*))
          (format *texinfo-output*
                  "@node ~@[~A~], ~@[~A~], ~@[~A~], ~A~%@appendix ~A~%~%"
                  chapter-name next previous top
                  chapter-name)
          (write-line "@menu" *texinfo-output*)
          (dolist (pkg pkgs)
            (destructuring-bind (package title base) pkg
              (declare (ignorable package))
              (format *texinfo-output* "* ~a:: ~a~a.~%"
                      title
                      (make-string (max 0 (- (- menu-offset 4) (length base)))
                                   :initial-element #\Space)
                      title)))
          (write-line "@end menu" *texinfo-output*)
          ;; Write Sections
          (loop :with last
             :for current := (pop pkgs)
             :for next := (car pkgs)
             :do (destructuring-bind (l l-title l-base)
                     (or last (list nil chapter-name nil))
                   (declare (ignorable l l-base))
                   (destructuring-bind (c c-title c-base) current
                     (declare (ignorable c))
                     (destructuring-bind (n n-title n-base)
                         (or next (list nil nil nil))
                       (declare (ignorable n n-base))
                       (format *texinfo-output*
                               "~%@node ~@[~A~], ~@[~A~], ~@[~A~], ~A
@section ~A
@include ~A-sb-texinfo.texi~%"
                               c-title n-title l-title chapter-name
                               c-title
                               c-base))))
               (setq last current)
             :until (null pkgs))))))
  (merge-pathnames index-file dir))