(defpackage :swank-backend
  (:use :common-lisp)
  (:export #:*debug-swank-backend*
           #:sldb-condition
           #:compiler-condition
           #:original-condition
           #:message
           #:source-context
           #:condition
           #:severity
           #:with-compilation-hooks
           #:location
           #:location-p
           #:location-buffer
           #:location-position
           #:position-p
           #:position-pos
           #:print-output-to-string
           #:quit-lisp
           #:references
           #:unbound-slot-filler
           #:declaration-arglist
           #:type-specifier-arglist
           #:with-struct
           #:when-let
           ;; interrupt macro for the backend
           #:*pending-slime-interrupts*
           #:check-slime-interrupts
           #:*interrupt-queued-handler*
           ;; inspector related symbols
           #:emacs-inspect
           #:label-value-line
           #:label-value-line*
           #:with-symbol))

(defpackage :swank-mop
  (:use)
  (:export
   ;; classes
   #:standard-generic-function
   #:standard-slot-definition
   #:standard-method
   #:standard-class
   #:eql-specializer
   #:eql-specializer-object
   ;; standard-class readers
   #:class-default-initargs
   #:class-direct-default-initargs
   #:class-direct-slots
   #:class-direct-subclasses
   #:class-direct-superclasses
   #:class-finalized-p
   #:class-name
   #:class-precedence-list
   #:class-prototype
   #:class-slots
   #:specializer-direct-methods
   ;; generic function readers
   #:generic-function-argument-precedence-order
   #:generic-function-declarations
   #:generic-function-lambda-list
   #:generic-function-methods
   #:generic-function-method-class
   #:generic-function-method-combination
   #:generic-function-name
   ;; method readers
   #:method-generic-function
   #:method-function
   #:method-lambda-list
   #:method-specializers
   #:method-qualifiers
   ;; slot readers
   #:slot-definition-allocation
   #:slot-definition-documentation
   #:slot-definition-initargs
   #:slot-definition-initform
   #:slot-definition-initfunction
   #:slot-definition-name
   #:slot-definition-type
   #:slot-definition-readers
   #:slot-definition-writers
   #:slot-boundp-using-class
   #:slot-value-using-class
   #:slot-makunbound-using-class
   ;; generic function protocol
   #:compute-applicable-methods-using-classes
   #:finalize-inheritance))

(in-package :swank-backend)


;;;; Metacode

(defparameter *debug-swank-backend* nil
  "If this is true, backends should not catch errors but enter the
debugger where appropriate. Also, they should not perform backtrace
magic but really show every frame including SWANK related ones.")

(defparameter *interface-functions* '()
  "The names of all interface functions.")

(defparameter *unimplemented-interfaces* '()
  "List of interface functions that are not implemented.
DEFINTERFACE adds to this list and DEFIMPLEMENTATION removes.")

(defmacro definterface (name args documentation &rest default-body)
  "Define an interface function for the backend to implement.
A function is defined with NAME, ARGS, and DOCUMENTATION.  This
function first looks for a function to call in NAME's property list
that is indicated by 'IMPLEMENTATION; failing that, it looks for a
function indicated by 'DEFAULT. If neither is present, an error is
signaled.

If a DEFAULT-BODY is supplied, then a function with the same body and
ARGS will be added to NAME's property list as the property indicated
by 'DEFAULT.

Backends implement these functions using DEFIMPLEMENTATION."
  (check-type documentation string "a documentation string")
  (assert (every #'symbolp args) ()
          "Complex lambda-list not supported: ~S ~S" name args)
  (labels ((gen-default-impl ()
             `(setf (get ',name 'default) (lambda ,args ,@default-body)))
           (args-as-list (args)
             (destructuring-bind (req opt key rest) (parse-lambda-list args)
               `(,@req ,@opt 
                       ,@(loop for k in key append `(,(kw k) ,k)) 
                       ,@(or rest '(())))))
           (parse-lambda-list (args)
             (parse args '(&optional &key &rest) 
                    (make-array 4 :initial-element nil)))
           (parse (args keywords vars)
             (cond ((null args) 
                    (reverse (map 'list #'reverse vars)))
                   ((member (car args) keywords)
                    (parse (cdr args) (cdr (member (car args) keywords)) vars))
                   (t (push (car args) (aref vars (length keywords)))
                      (parse (cdr args) keywords vars))))
           (kw (s) (intern (string s) :keyword)))
    `(progn 
       (defun ,name ,args
         ,documentation
         (let ((f (or (get ',name 'implementation)
                      (get ',name 'default))))
           (cond (f (apply f ,@(args-as-list args)))
                 (t (error "~S not implemented" ',name)))))
       (pushnew ',name *interface-functions*)
       ,(if (null default-body)
            `(pushnew ',name *unimplemented-interfaces*)
            (gen-default-impl))
       (eval-when (:compile-toplevel :load-toplevel :execute)
         (export ',name :swank-backend))
       ',name)))

(defmacro defimplementation (name args &body body)
  (assert (every #'symbolp args) ()
          "Complex lambda-list not supported: ~S ~S" name args)
  `(progn
     (setf (get ',name 'implementation)
           ;; For implicit BLOCK. FLET because of interplay w/ decls.
           (flet ((,name ,args ,@body)) #',name))
     (if (member ',name *interface-functions*)
         (setq *unimplemented-interfaces*
               (remove ',name *unimplemented-interfaces*))
         (warn "DEFIMPLEMENTATION of undefined interface (~S)" ',name))
     ',name))

(defun warn-unimplemented-interfaces ()
  "Warn the user about unimplemented backend features.
The portable code calls this function at startup."
  (let ((*print-pretty* t))
    (warn "These Swank interfaces are unimplemented:~% ~:<~{~A~^ ~:_~}~:>"
          (list (sort (copy-list *unimplemented-interfaces*) #'string<)))))

(defun import-to-swank-mop (symbol-list)
  (dolist (sym symbol-list)
    (let* ((swank-mop-sym (find-symbol (symbol-name sym) :swank-mop)))
      (when swank-mop-sym
        (unintern swank-mop-sym :swank-mop))
      (import sym :swank-mop)
      (export sym :swank-mop))))

(defun import-swank-mop-symbols (package except)
  "Import the mop symbols from PACKAGE to SWANK-MOP.
EXCEPT is a list of symbol names which should be ignored."
  (do-symbols (s :swank-mop)
    (unless (member s except :test #'string=)
      (let ((real-symbol (find-symbol (string s) package)))
        (assert real-symbol () "Symbol ~A not found in package ~A" s package)
        (unintern s :swank-mop)
        (import real-symbol :swank-mop)
        (export real-symbol :swank-mop)))))

(defvar *gray-stream-symbols*
  '(:fundamental-character-output-stream
    :stream-write-char
    :stream-write-string
    :stream-fresh-line
    :stream-force-output
    :stream-finish-output
    :fundamental-character-input-stream
    :stream-read-char
    :stream-peek-char
    :stream-read-line
    ;; STREAM-FILE-POSITION is not available on all implementations, or
    ;; partially under a different name.
    ; :stream-file-posiion
    :stream-listen
    :stream-unread-char
    :stream-clear-input
    :stream-line-column
    :stream-read-char-no-hang
    ;; STREAM-LINE-LENGTH is an extension to gray streams that's apparently
    ;; supported by CMUCL, OpenMCL, SBCL and SCL.
    #+(or cmu openmcl sbcl scl)
    :stream-line-length))

(defun import-from (package symbol-names &optional (to-package *package*))
  "Import the list of SYMBOL-NAMES found in the package PACKAGE."
  (dolist (name symbol-names)
    (multiple-value-bind (symbol found) (find-symbol (string name) package)
      (assert found () "Symbol ~A not found in package ~A" name package)
      (import symbol to-package))))


;;;; Utilities

(defmacro with-struct ((conc-name &rest names) obj &body body)
  "Like with-slots but works only for structs."
  (check-type conc-name symbol)
  (flet ((reader (slot)
           (intern (concatenate 'string
                                (symbol-name conc-name)
                                (symbol-name slot))
                   (symbol-package conc-name))))
    (let ((tmp (gensym "OO-")))
      ` (let ((,tmp ,obj))
          (symbol-macrolet
              ,(loop for name in names collect 
                     (typecase name
                       (symbol `(,name (,(reader name) ,tmp)))
                       (cons `(,(first name) (,(reader (second name)) ,tmp)))
                       (t (error "Malformed syntax in WITH-STRUCT: ~A" name))))
            ,@body)))))

(defmacro when-let ((var value) &body body)
  `(let ((,var ,value))
     (when ,var ,@body)))

(defun with-symbol (name package)
  "Generate a form suitable for testing with #+."
  (if (and (find-package package)
           (find-symbol (string name) package))
      '(:and)
      '(:or)))


;;;; UFT8

(deftype octet () '(unsigned-byte 8))
(deftype octets () '(simple-array octet (*)))

;; Helper function.  Decode the next N bytes starting from INDEX.
;; Return the decoded char and the new index.
(defun utf8-decode-aux (buffer index limit byte0 n)
  (declare (type octets buffer) (fixnum index limit byte0 n))
  (if (< (- limit index) n)
      (values nil index)
      (do ((i 0 (1+ i))
           (code byte0 (let ((byte (aref buffer (+ index i))))
                         (cond ((= (ldb (byte 2 6) byte) #b10)
                                (+ (ash code 6) (ldb (byte 6 0) byte)))
                               (t
                                (error "Invalid encoding"))))))
          ((= i n)
           (values (cond ((<= code #xff) (code-char code))
                         ((<= #xd800 code #xdfff)
                          (error "Invalid Unicode code point: #x~x" code))
                         ((and (< code char-code-limit) 
                               (code-char code)))
                         (t
                          (error
                           "Can't represent code point: #x~x ~
                            (char-code-limit is #x~x)" 
                           code char-code-limit)))
                   (+ index n))))))

;; Decode one character in BUFFER starting at INDEX.
;; Return 2 values: the character and the new index.
;; If there aren't enough bytes between INDEX and LIMIT return nil. 
(defun utf8-decode (buffer index limit)
  (declare (type octets buffer) (fixnum index limit))
  (if (= index limit)
      (values nil index)
      (let ((b (aref buffer index)))
        (if (<= b #x7f)
            (values (code-char b) (1+ index))
            (macrolet ((try (marker else)
                         (let* ((l (integer-length marker))
                                (n (- l 2)))
                           `(if (= (ldb (byte ,l ,(- 8 l)) b) ,marker)
                                (utf8-decode-aux buffer (1+ index) limit
                                                 (ldb (byte ,(- 8 l) 0) b)
                                                 ,n)
                                ,else))))
              (try #b110
                   (try #b1110
                        (try #b11110
                             (try #b111110
                                  (try #b1111110
                                       (error "Invalid encoding")))))))))))

;; Decode characters from BUFFER and write them to STRING.
;; Return 2 values: LASTINDEX and LASTSTART where
;; LASTINDEX is the last index in BUFFER that was not decoded
;; and LASTSTART is the last index in STRING not written.
(defun utf8-decode-into (buffer index limit string start end)
  (declare (string string) (fixnum index limit start end) (type octets buffer))
  (loop
   (cond ((= start end)
          (return (values index start)))
         (t
          (multiple-value-bind (c i) (utf8-decode buffer index limit)
            (cond (c
                   (setf (aref string start) c)
                   (setq index i)
                   (setq start (1+ start)))
                  (t
                   (return (values index start)))))))))

(defun default-utf8-to-string (octets)
  (let* ((limit (length octets))
         (str (make-string limit)))
    (multiple-value-bind (i s) (utf8-decode-into octets 0 limit str 0 limit)
      (if (= i limit)
          (if (= limit s)
              str
              (adjust-array str s))
          (loop
           (let ((end (+ (length str) (- limit i))))
             (setq str (adjust-array str end))
             (multiple-value-bind (i2 s2)
                 (utf8-decode-into octets i limit str s end)
               (cond ((= i2 limit)
                      (return (adjust-array str s2)))
                     (t
                      (setq i i2)
                      (setq s s2))))))))))

(defmacro utf8-encode-aux (code buffer start end n)
  `(cond ((< (- ,end ,start) ,n)
          ,start)
         (t
          (setf (aref ,buffer ,start)
                (dpb (ldb (byte ,(- 7 n) ,(* 6 (1- n))) ,code)
                     (byte ,(- 7 n) 0)
                     ,(dpb 0 (byte 1 (- 7 n)) #xff)))
          ,@(loop for i from 0 upto (- n 2) collect
                  `(setf (aref ,buffer (+ ,start ,(- n 1 i)))
                         (dpb (ldb (byte 6 ,(* 6 i)) ,code)
                              (byte 6 0)
                              #b10111111)))
          (+ ,start ,n))))

(defun utf8-encode (char buffer start end)
  (declare (character char) (type octets buffer) (fixnum start end))
  (let ((code (char-code char)))
    (cond ((<= code #x7f)
           (cond ((< start end)
                  (setf (aref buffer start) code)
                  (1+ start))
                 (t start)))
          ((<= code #x7ff) (utf8-encode-aux code buffer start end 2))
          ((<= #xd800 code #xdfff)
           (error "Invalid Unicode code point (surrogate): #x~x" code))
          ((<= code #xffff) (utf8-encode-aux code buffer start end 3))
          ((<= code #x1fffff) (utf8-encode-aux code buffer start end 4))
          ((<= code #x3ffffff) (utf8-encode-aux code buffer start end 5))
          ((<= code #x7fffffff) (utf8-encode-aux code buffer start end 6))
          (t (error "Can't encode ~s (~x)" char code)))))

(defun utf8-encode-into (string start end buffer index limit)
  (declare (string string) (type octets buffer) (fixnum start end index limit))
  (loop
   (cond ((= start end)
          (return (values start index)))
         ((= index limit)
          (return (values start index)))
         (t
          (let ((i2 (utf8-encode (char string start) buffer index limit)))
            (cond ((= i2 index)
                   (return (values start index)))
                  (t
                   (setq index i2)
                   (incf start))))))))

(defun default-string-to-utf8 (string)
  (let* ((len (length string))
         (b (make-array len :element-type 'octet)))
    (multiple-value-bind (s i) (utf8-encode-into string 0 len b 0 len)
      (if (= s len)
          b
          (loop
           (let ((limit (+ (length b) (- len s))))
             (setq b (coerce (adjust-array b limit) 'octets))
             (multiple-value-bind (s2 i2)
                 (utf8-encode-into string s len b i limit)
               (cond ((= s2 len)
                      (return (coerce (adjust-array b i2) 'octets)))
                     (t
                      (setq i i2)
                      (setq s s2))))))))))

(definterface string-to-utf8 (string)
  "Convert the string STRING to a (simple-array (unsigned-byte 8))"
  (default-string-to-utf8 string))

(definterface utf8-to-string (octets)
  "Convert the (simple-array (unsigned-byte 8)) OCTETS to a string."
  (default-utf8-to-string octets))

;;; Codepoint length

;; we don't need this anymore.
(definterface codepoint-length (string)
  "Return the number of codepoints in STRING.
With some Lisps, like cmucl, LENGTH returns the number of UTF-16 code
units, but other Lisps return the number of codepoints. The slime
protocol wants string lengths in terms of codepoints."
  (length string))


;;;; TCP server

(definterface create-socket (host port &key backlog)
  "Create a listening TCP socket on interface HOST and port PORT.
BACKLOG queue length for incoming connections.")

(definterface local-port (socket)
  "Return the local port number of SOCKET.")

(definterface close-socket (socket)
  "Close the socket SOCKET.")

(definterface accept-connection (socket &key external-format
                                        buffering timeout)
   "Accept a client connection on the listening socket SOCKET.  
Return a stream for the new connection.
If EXTERNAL-FORMAT is nil return a binary stream
otherwise create a character stream.
BUFFERING can be one of:
  nil   ... no buffering
  t     ... enable buffering
  :line ... enable buffering with automatic flushing on eol.")

(definterface add-sigio-handler (socket fn)
  "Call FN whenever SOCKET is readable.")

(definterface remove-sigio-handlers (socket)
  "Remove all sigio handlers for SOCKET.")

(definterface add-fd-handler (socket fn)
  "Call FN when Lisp is waiting for input and SOCKET is readable.")

(definterface remove-fd-handlers (socket)
  "Remove all fd-handlers for SOCKET.")

(definterface preferred-communication-style ()
  "Return one of the symbols :spawn, :sigio, :fd-handler, or NIL."
  nil)

(definterface set-stream-timeout (stream timeout)
  "Set the 'stream 'timeout.  The timeout is either the real number
  specifying the timeout in seconds or 'nil for no timeout."
  (declare (ignore stream timeout))
  nil)

;;; Base condition for networking errors.
(define-condition network-error (simple-error) ())

(definterface emacs-connected ()
   "Hook called when the first connection from Emacs is established.
Called from the INIT-FN of the socket server that accepts the
connection.

This is intended for setting up extra context, e.g. to discover
that the calling thread is the one that interacts with Emacs."
   nil)


;;;; Unix signals

(defconstant +sigint+ 2)

(definterface getpid ()
  "Return the (Unix) process ID of this superior Lisp.")

(definterface install-sigint-handler (function)
  "Call FUNCTION on SIGINT (instead of invoking the debugger).
Return old signal handler."
  (declare (ignore function))
  nil)

(definterface call-with-user-break-handler (handler function)
  "Install the break handler HANDLER while executing FUNCTION."
  (let ((old-handler (install-sigint-handler handler)))
    (unwind-protect (funcall function)
      (install-sigint-handler old-handler))))

(definterface quit-lisp ()
  "Exit the current lisp image.")

(definterface lisp-implementation-type-name ()
  "Return a short name for the Lisp implementation."
  (lisp-implementation-type))

(definterface lisp-implementation-program ()
  "Return the argv[0] of the running Lisp process, or NIL."
  (let ((file (car (command-line-args))))
    (when (and file (probe-file file))
      (namestring (truename file)))))

(definterface socket-fd (socket-stream)
  "Return the file descriptor for SOCKET-STREAM.")

(definterface make-fd-stream (fd external-format)
  "Create a character stream for the file descriptor FD.")

(definterface dup (fd)
  "Duplicate a file descriptor.
If the syscall fails, signal a condition.
See dup(2).")

(definterface exec-image (image-file args)
  "Replace the current process with a new process image.
The new image is created by loading the previously dumped
core file IMAGE-FILE.
ARGS is a list of strings passed as arguments to
the new image.
This is thin wrapper around exec(3).")

(definterface command-line-args ()
  "Return a list of strings as passed by the OS."
  nil)


;; pathnames are sooo useless

(definterface filename-to-pathname (filename)
  "Return a pathname for FILENAME.
A filename in Emacs may for example contain asterisks which should not
be translated to wildcards."
  (parse-namestring filename))

(definterface pathname-to-filename (pathname)
  "Return the filename for PATHNAME."
  (namestring pathname))

(definterface default-directory ()
  "Return the default directory."
  (directory-namestring (truename *default-pathname-defaults*)))

(definterface set-default-directory (directory)
  "Set the default directory.
This is used to resolve filenames without directory component."
  (setf *default-pathname-defaults* (truename (merge-pathnames directory)))
  (default-directory))


(definterface call-with-syntax-hooks (fn)
  "Call FN with hooks to handle special syntax."
  (funcall fn))

(definterface default-readtable-alist ()
  "Return a suitable initial value for SWANK:*READTABLE-ALIST*."
  '())


;;;; Compilation

(definterface call-with-compilation-hooks (func)
  "Call FUNC with hooks to record compiler conditions.")

(defmacro with-compilation-hooks ((&rest ignore) &body body)
  "Execute BODY as in CALL-WITH-COMPILATION-HOOKS."
  (declare (ignore ignore))
  `(call-with-compilation-hooks (lambda () (progn ,@body))))

(definterface swank-compile-string (string &key buffer position filename
                                           policy)
  "Compile source from STRING.
During compilation, compiler conditions must be trapped and
resignalled as COMPILER-CONDITIONs.

If supplied, BUFFER and POSITION specify the source location in Emacs.

Additionally, if POSITION is supplied, it must be added to source
positions reported in compiler conditions.

If FILENAME is specified it may be used by certain implementations to
rebind *DEFAULT-PATHNAME-DEFAULTS* which may improve the recording of
source information.

If POLICY is supplied, and non-NIL, it may be used by certain
implementations to compile with optimization qualities of its
value.

Should return T on successful compilation, NIL otherwise.
")

(definterface swank-compile-file (input-file output-file load-p 
                                             external-format
                                             &key policy)
   "Compile INPUT-FILE signalling COMPILE-CONDITIONs.
If LOAD-P is true, load the file after compilation.
EXTERNAL-FORMAT is a value returned by find-external-format or
:default.

If POLICY is supplied, and non-NIL, it may be used by certain
implementations to compile with optimization qualities of its
value.

Should return OUTPUT-TRUENAME, WARNINGS-P and FAILURE-p
like `compile-file'")

(deftype severity () 
  '(member :error :read-error :warning :style-warning :note :redefinition))

;; Base condition type for compiler errors, warnings and notes.
(define-condition compiler-condition (condition)
  ((original-condition
    ;; The original condition thrown by the compiler if appropriate.
    ;; May be NIL if a compiler does not report using conditions.
    :type (or null condition)
    :initarg :original-condition
    :accessor original-condition)

   (severity :type severity
             :initarg :severity
             :accessor severity)

   (message :initarg :message
            :accessor message)

   ;; Macro expansion history etc. which may be helpful in some cases
   ;; but is often very verbose.
   (source-context :initarg :source-context
                   :type (or null string)
                   :initform nil
                   :accessor source-context)

   (references :initarg :references
               :initform nil
               :accessor references)

   (location :initarg :location
             :accessor location)))

(definterface find-external-format (coding-system)
  "Return a \"external file format designator\" for CODING-SYSTEM.
CODING-SYSTEM is Emacs-style coding system name (a string),
e.g. \"latin-1-unix\"."
  (if (equal coding-system "iso-latin-1-unix")
      :default
      nil))

(definterface guess-external-format (pathname)
  "Detect the external format for the file with name pathname.
Return nil if the file contains no special markers."
  ;; Look for a Emacs-style -*- coding: ... -*- or Local Variable: section.
  (with-open-file (s pathname :if-does-not-exist nil
                     :external-format (or (find-external-format "latin-1-unix")
                                          :default))
    (if s 
        (or (let* ((line (read-line s nil))
                   (p (search "-*-" line)))
              (when p
                (let* ((start (+ p (length "-*-")))
                       (end (search "-*-" line :start2 start)))
                  (when end
                    (%search-coding line start end)))))
            (let* ((len (file-length s))
                   (buf (make-string (min len 3000))))
              (file-position s (- len (length buf)))
              (read-sequence buf s)
              (let ((start (search "Local Variables:" buf :from-end t))
                    (end (search "End:" buf :from-end t)))
                (and start end (< start end)
                     (%search-coding buf start end))))))))

(defun %search-coding (str start end)
  (let ((p (search "coding:" str :start2 start :end2 end)))
    (when p
      (incf p (length "coding:"))
      (loop while (and (< p end)
                       (member (aref str p) '(#\space #\tab)))
            do (incf p))
      (let ((end (position-if (lambda (c) (find c '(#\space #\tab #\newline)))
                              str :start p)))
        (find-external-format (subseq str p end))))))


;;;; Streams

(definterface make-output-stream (write-string)
  "Return a new character output stream.
The stream calls WRITE-STRING when output is ready.")

(definterface make-input-stream (read-string)
  "Return a new character input stream.
The stream calls READ-STRING when input is needed.")


;;;; Documentation

(definterface arglist (name)
   "Return the lambda list for the symbol NAME. NAME can also be
a lisp function object, on lisps which support this.

The result can be a list or the :not-available keyword if the
arglist cannot be determined."
   (declare (ignore name))
   :not-available)

(defgeneric declaration-arglist (decl-identifier)
  (:documentation
   "Return the argument list of the declaration specifier belonging to the
declaration identifier DECL-IDENTIFIER. If the arglist cannot be determined,
the keyword :NOT-AVAILABLE is returned.

The different SWANK backends can specialize this generic function to
include implementation-dependend declaration specifiers, or to provide
additional information on the specifiers defined in ANSI Common Lisp.")
  (:method (decl-identifier)
    (case decl-identifier
      (dynamic-extent '(&rest variables))
      (ignore         '(&rest variables))
      (ignorable      '(&rest variables))
      (special        '(&rest variables))
      (inline         '(&rest function-names))
      (notinline      '(&rest function-names))
      (declaration    '(&rest names))
      (optimize       '(&any compilation-speed debug safety space speed))  
      (type           '(type-specifier &rest args))
      (ftype          '(type-specifier &rest function-names))
      (otherwise
       (flet ((typespec-p (symbol) 
                (member :type (describe-symbol-for-emacs symbol))))
         (cond ((and (symbolp decl-identifier) (typespec-p decl-identifier))
                '(&rest variables))
               ((and (listp decl-identifier) 
                     (typespec-p (first decl-identifier)))
                '(&rest variables))
               (t :not-available)))))))

(defgeneric type-specifier-arglist (typespec-operator)
  (:documentation
   "Return the argument list of the type specifier belonging to
TYPESPEC-OPERATOR.. If the arglist cannot be determined, the keyword
:NOT-AVAILABLE is returned.

The different SWANK backends can specialize this generic function to
include implementation-dependend declaration specifiers, or to provide
additional information on the specifiers defined in ANSI Common Lisp.")
  (:method (typespec-operator)
    (declare (special *type-specifier-arglists*)) ; defined at end of file.
    (typecase typespec-operator
      (symbol (or (cdr (assoc typespec-operator *type-specifier-arglists*))
                  :not-available))
      (t :not-available))))

(definterface function-name (function)
  "Return the name of the function object FUNCTION.

The result is either a symbol, a list, or NIL if no function name is
available."
  (declare (ignore function))
  nil)

(definterface valid-function-name-p (form)
  "Is FORM syntactically valid to name a function?
   If true, FBOUNDP should not signal a type-error for FORM."
  (flet ((length=2 (list)
           (and (not (null (cdr list))) (null (cddr list)))))
    (or (symbolp form)
        (and (consp form) (length=2 form)
             (eq (first form) 'setf) (symbolp (second form))))))

(definterface macroexpand-all (form)
   "Recursively expand all macros in FORM.
Return the resulting form.")

(definterface compiler-macroexpand-1 (form &optional env)
  "Call the compiler-macro for form.
If FORM is a function call for which a compiler-macro has been
defined, invoke the expander function using *macroexpand-hook* and
return the results and T.  Otherwise, return the original form and
NIL."
  (let ((fun (and (consp form) 
                  (valid-function-name-p (car form))
                  (compiler-macro-function (car form)))))
    (if fun
	(let ((result (funcall *macroexpand-hook* fun form env)))
          (values result (not (eq result form))))
	(values form nil))))

(definterface compiler-macroexpand (form &optional env)
  "Repetitively call `compiler-macroexpand-1'."
  (labels ((frob (form expanded)
	     (multiple-value-bind (new-form newly-expanded)
		 (compiler-macroexpand-1 form env)
	       (if newly-expanded
		   (frob new-form t)
		   (values new-form expanded)))))
    (frob form env)))

(definterface format-string-expand (control-string)
  "Expand the format string CONTROL-STRING."
  (macroexpand `(formatter ,control-string)))

(definterface describe-symbol-for-emacs (symbol)
   "Return a property list describing SYMBOL.

The property list has an entry for each interesting aspect of the
symbol. The recognised keys are:

  :VARIABLE :FUNCTION :SETF :SPECIAL-OPERATOR :MACRO :COMPILER-MACRO
  :TYPE :CLASS :ALIEN-TYPE :ALIEN-STRUCT :ALIEN-UNION :ALIEN-ENUM

The value of each property is the corresponding documentation string,
or :NOT-DOCUMENTED. It is legal to include keys not listed here (but
slime-print-apropos in Emacs must know about them).

Properties should be included if and only if they are applicable to
the symbol. For example, only (and all) fbound symbols should include
the :FUNCTION property.

Example:
\(describe-symbol-for-emacs 'vector)
  => (:CLASS :NOT-DOCUMENTED
      :TYPE :NOT-DOCUMENTED
      :FUNCTION \"Constructs a simple-vector from the given objects.\")")

(definterface describe-definition (name type)
  "Describe the definition NAME of TYPE.
TYPE can be any value returned by DESCRIBE-SYMBOL-FOR-EMACS.

Return a documentation string, or NIL if none is available.")


;;;; Debugging

(definterface install-debugger-globally (function)
  "Install FUNCTION as the debugger for all threads/processes. This
usually involves setting *DEBUGGER-HOOK* and, if the implementation
permits, hooking into BREAK as well."
  (setq *debugger-hook* function))

(definterface call-with-debugging-environment (debugger-loop-fn)
   "Call DEBUGGER-LOOP-FN in a suitable debugging environment.

This function is called recursively at each debug level to invoke the
debugger loop. The purpose is to setup any necessary environment for
other debugger callbacks that will be called within the debugger loop.

For example, this is a reasonable place to compute a backtrace, switch
to safe reader/printer settings, and so on.")

(definterface call-with-debugger-hook (hook fun)
  "Call FUN and use HOOK as debugger hook. HOOK can be NIL.

HOOK should be called for both BREAK and INVOKE-DEBUGGER."
  (let ((*debugger-hook* hook))
    (funcall fun)))

(define-condition sldb-condition (condition)
  ((original-condition
    :initarg :original-condition
    :accessor original-condition))
  (:report (lambda (condition stream)
             (format stream "Condition in debugger code~@[: ~A~]" 
                     (original-condition condition))))
  (:documentation
   "Wrapper for conditions that should not be debugged.

When a condition arises from the internals of the debugger, it is not
desirable to debug it -- we'd risk entering an endless loop trying to
debug the debugger! Instead, such conditions can be reported to the
user without (re)entering the debugger by wrapping them as
`sldb-condition's."))

;;; The following functions in this section are supposed to be called
;;; within the dynamic contour of CALL-WITH-DEBUGGING-ENVIRONMENT only.

(definterface compute-backtrace (start end)
   "Returns a backtrace of the condition currently being debugged,
that is an ordered list consisting of frames. ``Ordered list''
means that an integer I can be mapped back to the i-th frame of this
backtrace.

START and END are zero-based indices constraining the number of frames
returned. Frame zero is defined as the frame which invoked the
debugger. If END is nil, return the frames from START to the end of
the stack.")

(definterface print-frame (frame stream)
  "Print frame to stream.")

(definterface frame-restartable-p (frame)
  "Is the frame FRAME restartable?.
Return T if `restart-frame' can safely be called on the frame."
  (declare (ignore frame))
  nil)

(definterface frame-source-location (frame-number)
  "Return the source location for the frame associated to FRAME-NUMBER.")

(definterface frame-catch-tags (frame-number)
  "Return a list of catch tags for being printed in a debugger stack
frame."
  (declare (ignore frame-number))
  '())

(definterface frame-locals (frame-number)
  "Return a list of ((&key NAME ID VALUE) ...) where each element of
the list represents a local variable in the stack frame associated to
FRAME-NUMBER.

NAME, a symbol; the name of the local variable.

ID, an integer; used as primary key for the local variable, unique
relatively to the frame under operation.

value, an object; the value of the local variable.")

(definterface frame-var-value (frame-number var-id)
  "Return the value of the local variable associated to VAR-ID
relatively to the frame associated to FRAME-NUMBER.")

(definterface disassemble-frame (frame-number)
  "Disassemble the code for the FRAME-NUMBER.
The output should be written to standard output.
FRAME-NUMBER is a non-negative integer.")

(definterface eval-in-frame (form frame-number)
   "Evaluate a Lisp form in the lexical context of a stack frame
in the debugger.

FRAME-NUMBER must be a positive integer with 0 indicating the
frame which invoked the debugger.

The return value is the result of evaulating FORM in the
appropriate context.")

(definterface frame-package (frame-number)
  "Return the package corresponding to the frame at FRAME-NUMBER.
Return nil if the backend can't figure it out."
  (declare (ignore frame-number))
  nil)

(definterface frame-call (frame-number)
  "Return a string representing a call to the entry point of a frame.")

(definterface return-from-frame (frame-number form)
  "Unwind the stack to the frame FRAME-NUMBER and return the value(s)
produced by evaluating FORM in the frame context to its caller.

Execute any clean-up code from unwind-protect forms above the frame
during unwinding.

Return a string describing the error if it's not possible to return
from the frame.")

(definterface restart-frame (frame-number)
  "Restart execution of the frame FRAME-NUMBER with the same arguments
as it was called originally.")

(definterface format-sldb-condition (condition)
  "Format a condition for display in SLDB."
  (princ-to-string condition))

(definterface condition-extras (condition)
  "Return a list of extra for the debugger.
The allowed elements are of the form:
  (:SHOW-FRAME-SOURCE frame-number)
  (:REFERENCES &rest refs)