LET

[jscl.git] / src / compiler.lisp

;;; compiler.lisp ---

;; copyright (C) 2012, 2013 David Vazquez
;; Copyright (C) 2012 Raimon Grau

;; JSCL is free software: you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation, either version 3 of the
;; License, or (at your option) any later version.
;;
;; JSCL is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;; General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with JSCL.  If not, see <http://www.gnu.org/licenses/>.

;;;; Compiler

(/debug "loading compiler.lisp!")

;;; Translate the Lisp code to Javascript. It will compile the special
;;; forms. Some primitive functions are compiled as special forms
;;; too. The respective real functions are defined in the target (see
;;; the beginning of this file) as well as some primitive functions.

(defun interleave (list element &optional after-last-p)
  (unless (null list)
    (with-collect
      (collect (car list))
      (dolist (x (cdr list))
        (collect element)
        (collect x))
      (when after-last-p
        (collect element)))))

(defun code (&rest args)
  (mapconcat (lambda (arg)
               (cond
                 ((null arg) "")
                 ((integerp arg) (integer-to-string arg))
                 ((floatp arg) (float-to-string arg))
                 ((stringp arg) arg)
                 (t
                  (with-output-to-string (*standard-output*)
                    (js-expr arg)))))
             args))

;;; Wrap X with a Javascript code to convert the result from
;;; Javascript generalized booleans to T or NIL.
(defun js!bool (x)
  `(if ,x ,(ls-compile t) ,(ls-compile nil)))

;;; Concatenate the arguments and wrap them with a self-calling
;;; Javascript anonymous function. It is used to make some Javascript
;;; statements valid expressions and provide a private scope as well.
;;; It could be defined as function, but we could do some
;;; preprocessing in the future.
(defmacro js!selfcall (&body body)
  ``(call (function nil (code ,,@body))))

(defmacro js!selfcall* (&body body)
  ``(call (function nil ,,@body)))


;;; Like CODE, but prefix each line with four spaces. Two versions
;;; of this function are available, because the Ecmalisp version is
;;; very slow and bootstraping was annoying.

;;; A Form can return a multiple values object calling VALUES, like
;;; values(arg1, arg2, ...). It will work in any context, as well as
;;; returning an individual object. However, if the special variable
;;; `*multiple-value-p*' is NIL, is granted that only the primary
;;; value will be used, so we can optimize to avoid the VALUES
;;; function call.
(defvar *multiple-value-p* nil)

;;; Environment

(def!struct binding
  name
  type
  value
  declarations)

(def!struct lexenv
  variable
  function
  block
  gotag)

(defun lookup-in-lexenv (name lexenv namespace)
  (find name (ecase namespace
                (variable (lexenv-variable lexenv))
                (function (lexenv-function lexenv))
                (block    (lexenv-block    lexenv))
                (gotag    (lexenv-gotag    lexenv)))
        :key #'binding-name))

(defun push-to-lexenv (binding lexenv namespace)
  (ecase namespace
    (variable (push binding (lexenv-variable lexenv)))
    (function (push binding (lexenv-function lexenv)))
    (block    (push binding (lexenv-block    lexenv)))
    (gotag    (push binding (lexenv-gotag    lexenv)))))

(defun extend-lexenv (bindings lexenv namespace)
  (let ((env (copy-lexenv lexenv)))
    (dolist (binding (reverse bindings) env)
      (push-to-lexenv binding env namespace))))


(defvar *environment* (make-lexenv))

(defvar *variable-counter* 0)

(defun gvarname (symbol)
  (declare (ignore symbol))
  (incf *variable-counter*)
  (concat "v" (integer-to-string *variable-counter*)))

(defun translate-variable (symbol)
  (awhen (lookup-in-lexenv symbol *environment* 'variable)
    (binding-value it)))

(defun extend-local-env (args)
  (let ((new (copy-lexenv *environment*)))
    (dolist (symbol args new)
      (let ((b (make-binding :name symbol :type 'variable :value (gvarname symbol))))
        (push-to-lexenv b new 'variable)))))

;;; Toplevel compilations
(defvar *toplevel-compilations* nil)

(defun toplevel-compilation (string)
  (push string *toplevel-compilations*))

(defun get-toplevel-compilations ()
  (reverse *toplevel-compilations*))

(defun %compile-defmacro (name lambda)
  (toplevel-compilation (ls-compile `',name))
  (let ((binding (make-binding :name name :type 'macro :value lambda)))
    (push-to-lexenv binding  *environment* 'function))
  name)

(defun global-binding (name type namespace)
  (or (lookup-in-lexenv name *environment* namespace)
      (let ((b (make-binding :name name :type type :value nil)))
        (push-to-lexenv b *environment* namespace)
        b)))

(defun claimp (symbol namespace claim)
  (let ((b (lookup-in-lexenv symbol *environment* namespace)))
    (and b (member claim (binding-declarations b)))))

(defun !proclaim (decl)
  (case (car decl)
    (special
     (dolist (name (cdr decl))
       (let ((b (global-binding name 'variable 'variable)))
         (push 'special (binding-declarations b)))))
    (notinline
     (dolist (name (cdr decl))
       (let ((b (global-binding name 'function 'function)))
         (push 'notinline (binding-declarations b)))))
    (constant
     (dolist (name (cdr decl))
       (let ((b (global-binding name 'variable 'variable)))
         (push 'constant (binding-declarations b)))))))

#+jscl
(fset 'proclaim #'!proclaim)

(defun %define-symbol-macro (name expansion)
  (let ((b (make-binding :name name :type 'macro :value expansion)))
    (push-to-lexenv b *environment* 'variable)
    name))

#+jscl
(defmacro define-symbol-macro (name expansion)
  `(%define-symbol-macro ',name ',expansion))


;;; Special forms

(defvar *compilations* nil)

(defmacro define-compilation (name args &body body)
  ;; Creates a new primitive `name' with parameters args and
  ;; @body. The body can access to the local environment through the
  ;; variable *ENVIRONMENT*.
  `(push (list ',name (lambda ,args (block ,name ,@body)))
         *compilations*))

(define-compilation if (condition true &optional false)
  `(if (!== ,(ls-compile condition) ,(ls-compile nil))
       ,(ls-compile true *multiple-value-p*)
       ,(ls-compile false *multiple-value-p*)))

(defvar *ll-keywords* '(&optional &rest &key))

(defun list-until-keyword (list)
  (if (or (null list) (member (car list) *ll-keywords*))
      nil
      (cons (car list) (list-until-keyword (cdr list)))))

(defun ll-section (keyword ll)
  (list-until-keyword (cdr (member keyword ll))))

(defun ll-required-arguments (ll)
  (list-until-keyword ll))

(defun ll-optional-arguments-canonical (ll)
  (mapcar #'ensure-list (ll-section '&optional ll)))

(defun ll-optional-arguments (ll)
  (mapcar #'car (ll-optional-arguments-canonical ll)))

(defun ll-rest-argument (ll)
  (let ((rest (ll-section '&rest ll)))
    (when (cdr rest)
      (error "Bad lambda-list `~S'." ll))
    (car rest)))

(defun ll-keyword-arguments-canonical (ll)
  (flet ((canonicalize (keyarg)
           ;; Build a canonical keyword argument descriptor, filling
           ;; the optional fields. The result is a list of the form
           ;; ((keyword-name var) init-form).
           (let ((arg (ensure-list keyarg)))
             (cons (if (listp (car arg))
                       (car arg)
                       (list (intern (symbol-name (car arg)) "KEYWORD") (car arg)))
                   (cdr arg)))))
    (mapcar #'canonicalize (ll-section '&key ll))))

(defun ll-keyword-arguments (ll)
  (mapcar (lambda (keyarg) (second (first keyarg)))
          (ll-keyword-arguments-canonical ll)))

(defun ll-svars (lambda-list)
  (let ((args
         (append
          (ll-keyword-arguments-canonical lambda-list)
          (ll-optional-arguments-canonical lambda-list))))
    (remove nil (mapcar #'third args))))

(defun lambda-name/docstring-wrapper (name docstring code)
  (if (or name docstring)
      (js!selfcall*
        `(var (func ,code))
        (when name      `(= (get func "fname") ,name))
        (when docstring `(= (get func "docstring") ,docstring))
        `(return func))
      code))

(defun lambda-check-argument-count
    (n-required-arguments n-optional-arguments rest-p)
  ;; Note: Remember that we assume that the number of arguments of a
  ;; call is at least 1 (the values argument).
  (let ((min n-required-arguments)
        (max (if rest-p 'n/a (+ n-required-arguments n-optional-arguments))))
    (block nil
      ;; Special case: a positive exact number of arguments.
      (when (and (< 0 min) (eql min max))
        (return `(code "checkArgs(nargs, " ,min ");")))
      ;; General case:
      `(code
        ,(when (< 0 min)
           `(code "checkArgsAtLeast(nargs, " ,min ");"))
        ,(when (numberp max)
           `(code "checkArgsAtMost(nargs, " ,max ");"))))))

(defun compile-lambda-optional (ll)
  (let* ((optional-arguments (ll-optional-arguments-canonical ll))
         (n-required-arguments (length (ll-required-arguments ll)))
         (n-optional-arguments (length optional-arguments)))
    (when optional-arguments
      `(code "switch(nargs){"
             ,(let ((cases nil)
                    (idx 0))
                   (progn
                     (while (< idx n-optional-arguments)
                       (let ((arg (nth idx optional-arguments)))
                         (push `(code "case " ,(+ idx n-required-arguments) ":"
                                      (code ,(translate-variable (car arg))
                                            "="
                                            ,(ls-compile (cadr arg)) ";")
                                      ,(when (third arg)
                                         `(code ,(translate-variable (third arg))
                                                "="
                                                ,(ls-compile nil)
                                                ";")))
                               cases)
                         (incf idx)))
                     (push `(code "default: break;") cases)
                     `(code ,@(reverse cases))))
             "}"))))

(defun compile-lambda-rest (ll)
  (let ((n-required-arguments (length (ll-required-arguments ll)))
        (n-optional-arguments (length (ll-optional-arguments ll)))
        (rest-argument (ll-rest-argument ll)))
    (when rest-argument
      (let ((js!rest (translate-variable rest-argument)))
        `(code "var " ,js!rest "= " ,(ls-compile nil) ";"
               "for (var i = nargs-1; i>=" ,(+ n-required-arguments n-optional-arguments)
               "; i--)"
               (code ,js!rest " = {car: arguments[i+2], cdr: " ,js!rest "};"))))))

(defun compile-lambda-parse-keywords (ll)
  (let ((n-required-arguments
         (length (ll-required-arguments ll)))
        (n-optional-arguments
         (length (ll-optional-arguments ll)))
        (keyword-arguments
         (ll-keyword-arguments-canonical ll)))
    `(code
      ;; Declare variables
      ,@(mapcar (lambda (arg)
                  (let ((var (second (car arg))))
                    `(code "var " ,(translate-variable var) "; "
                           ,(when (third arg)
                              `(code "var " ,(translate-variable (third arg))
                                     " = " ,(ls-compile nil)
                                     ";" )))))
                keyword-arguments)
      ;; Parse keywords
      ,(flet ((parse-keyword (keyarg)
               ;; ((keyword-name var) init-form)
               `(code "for (i=" ,(+ n-required-arguments n-optional-arguments)
                      "; i<nargs; i+=2){"
                      "if (arguments[i+2] === " ,(ls-compile (caar keyarg)) "){"
                      ,(translate-variable (cadr (car keyarg)))
                      " = arguments[i+3];"
                      ,(let ((svar (third keyarg)))
                            (when svar
                              `(code ,(translate-variable svar) " = " ,(ls-compile t) ";" )))
                      "break;"
                      "}"
                      "}"
                      ;; Default value
                      "if (i == nargs){"
                      ,(translate-variable (cadr (car keyarg)))
                      " = "
                      ,(ls-compile (cadr keyarg))
                      ";"
                      "}")))
        (when keyword-arguments
          `(code "var i;"
                 ,@(mapcar #'parse-keyword keyword-arguments))))
      ;; Check for unknown keywords
      ,(when keyword-arguments
        `(code "var start = " ,(+ n-required-arguments n-optional-arguments) ";"
               "if ((nargs - start) % 2 == 1){"
               "throw 'Odd number of keyword arguments';" 
               "}"
               "for (i = start; i<nargs; i+=2){"
               "if ("
               ,@(interleave (mapcar (lambda (x)
                                       `(code "arguments[i+2] !== " ,(ls-compile (caar x))))
                                     keyword-arguments)
                            " && ")
               ")"
               "throw 'Unknown keyword argument ' + xstring(arguments[i+2].name);" 
               "}" )))))

(defun parse-lambda-list (ll)
  (values (ll-required-arguments ll)
          (ll-optional-arguments ll)
          (ll-keyword-arguments  ll)
          (ll-rest-argument      ll)))

;;; Process BODY for declarations and/or docstrings. Return as
;;; multiple values the BODY without docstrings or declarations, the
;;; list of declaration forms and the docstring.
(defun parse-body (body &key declarations docstring)
  (let ((value-declarations)
        (value-docstring))
    ;; Parse declarations
    (when declarations
      (do* ((rest body (cdr rest))
            (form (car rest) (car rest)))
           ((or (atom form) (not (eq (car form) 'declare)))
            (setf body rest))
        (push form value-declarations)))
    ;; Parse docstring
    (when (and docstring
               (stringp (car body))
               (not (null (cdr body))))
      (setq value-docstring (car body))
      (setq body (cdr body)))
    (values body value-declarations value-docstring)))

;;; Compile a lambda function with lambda list LL and body BODY. If
;;; NAME is given, it should be a constant string and it will become
;;; the name of the function. If BLOCK is non-NIL, a named block is
;;; created around the body. NOTE: No block (even anonymous) is
;;; created if BLOCk is NIL.
(defun compile-lambda (ll body &key name block)
  (multiple-value-bind (required-arguments
                        optional-arguments
                        keyword-arguments
                        rest-argument)
      (parse-lambda-list ll)
    (multiple-value-bind (body decls documentation)
        (parse-body body :declarations t :docstring t)
      (declare (ignore decls))
      (let ((n-required-arguments (length required-arguments))
            (n-optional-arguments (length optional-arguments))
            (*environment* (extend-local-env
                            (append (ensure-list rest-argument)
                                    required-arguments
                                    optional-arguments
                                    keyword-arguments
                                    (ll-svars ll)))))
        (lambda-name/docstring-wrapper name documentation
         `(code
           "(function ("
           ,(join (list* "values"
                         "nargs"
                         (mapcar #'translate-variable
                                 (append required-arguments optional-arguments)))
                  ",")
           "){"
           ;; Check number of arguments
           ,(lambda-check-argument-count n-required-arguments
                                         n-optional-arguments
                                         (or rest-argument keyword-arguments))
           ,(compile-lambda-optional ll)
           ,(compile-lambda-rest ll)
           ,(compile-lambda-parse-keywords ll)
           ,(let ((*multiple-value-p* t))
                 (if block
                     (ls-compile-block `((block ,block ,@body)) t)
                     (ls-compile-block body t)))
           "})"))))))


(defun setq-pair (var val)
  (let ((b (lookup-in-lexenv var *environment* 'variable)))
    (cond
      ((and b
            (eq (binding-type b) 'variable)
            (not (member 'special (binding-declarations b)))
            (not (member 'constant (binding-declarations b))))
       ;; TODO: Unnecesary make-symbol when codegen migration is
       ;; finished.
       `(= ,(make-symbol (binding-value b)) ,(ls-compile val)))
      ((and b (eq (binding-type b) 'macro))
       (ls-compile `(setf ,var ,val)))
      (t
       (ls-compile `(set ',var ,val))))))


(define-compilation setq (&rest pairs)
  (let ((result nil))
    (when (null pairs)
      (return-from setq (ls-compile nil)))
    (while t
      (cond
        ((null pairs)
         (return))
        ((null (cdr pairs))
         (error "Odd pairs in SETQ"))
        (t
         (push `,(setq-pair (car pairs) (cadr pairs)) result)
         (setq pairs (cddr pairs)))))
    `(progn ,@(reverse result))))


;;; Compilation of literals an object dumping

;;; BOOTSTRAP MAGIC: We record the macro definitions as lists during
;;; the bootstrap. Once everything is compiled, we want to dump the
;;; whole global environment to the output file to reproduce it in the
;;; run-time. However, the environment must contain expander functions
;;; rather than lists. We do not know how to dump function objects
;;; itself, so we mark the list definitions with this object and the
;;; compiler will be called when this object has to be dumped.
;;; Backquote/unquote does a similar magic, but this use is exclusive.
;;;
;;; Indeed, perhaps to compile the object other macros need to be
;;; evaluated. For this reason we define a valid macro-function for
;;; this symbol.
(defvar *magic-unquote-marker* (gensym "MAGIC-UNQUOTE"))
#-jscl
(setf (macro-function *magic-unquote-marker*)
      (lambda (form &optional environment)
        (declare (ignore environment))
        (second form)))

(defvar *literal-table* nil)
(defvar *literal-counter* 0)

(defun genlit ()
  (incf *literal-counter*)
  (concat "l" (integer-to-string *literal-counter*)))

(defun dump-symbol (symbol)
  #-jscl
  (let ((package (symbol-package symbol)))
    (if (eq package (find-package "KEYWORD"))
        `(new (call |Symbol| ,(dump-string (symbol-name symbol)) ,(dump-string (package-name package))))
        `(new (call |Symbol| ,(dump-string (symbol-name symbol))))))
  #+jscl
  (let ((package (symbol-package symbol)))
    (if (null package)
        `(new (call |Symbol| ,(dump-string (symbol-name symbol))))
        (ls-compile `(intern ,(symbol-name symbol) ,(package-name package))))))

(defun dump-cons (cons)
  (let ((head (butlast cons))
        (tail (last cons)))
    `(call |QIList|
           ,@(mapcar (lambda (x) `(code ,(literal x t))) head)
           (code ,(literal (car tail) t))
           (code ,(literal (cdr tail) t)))))

(defun dump-array (array)
  (let ((elements (vector-to-list array)))
    (list-to-vector (mapcar (lambda (x) `(code ,(literal x)))
                            elements))))

(defun dump-string (string)
  `(call |make_lisp_string| ,string))

(defun literal (sexp &optional recursive)
  (cond
    ((integerp sexp) (integer-to-string sexp))
    ((floatp sexp) (float-to-string sexp))
    ((characterp sexp) (js-escape-string (string sexp)))
    (t
     (or (cdr (assoc sexp *literal-table* :test #'eql))
         (let ((dumped (typecase sexp
                         (symbol (dump-symbol sexp))
                         (string (dump-string sexp))
                         (cons
                          ;; BOOTSTRAP MAGIC: See the root file
                          ;; jscl.lisp and the function
                          ;; `dump-global-environment' for futher
                          ;; information.
                          (if (eq (car sexp) *magic-unquote-marker*)
                              (ls-compile (second sexp))
                              (dump-cons sexp)))
                         (array (dump-array sexp)))))
           (if (and recursive (not (symbolp sexp)))
               dumped
               (let ((jsvar (genlit)))
                 (push (cons sexp jsvar) *literal-table*)
                 (toplevel-compilation `(code "var " ,jsvar " = " ,dumped))
                 (when (keywordp sexp)
                   (toplevel-compilation `(code ,jsvar ".value = " ,jsvar)))
                 jsvar)))))))


(define-compilation quote (sexp)
  (literal sexp))

(define-compilation %while (pred &rest body)
  (js!selfcall*
    `(while (!== ,(ls-compile pred) ,(ls-compile nil))
       0                                ; TODO: Force
                                        ; braces. Unnecesary when code
                                        ; is gone
       ,(ls-compile-block body))
   `(return ,(ls-compile nil))))

(define-compilation function (x)
  (cond
    ((and (listp x) (eq (car x) 'lambda))
     (compile-lambda (cadr x) (cddr x)))
    ((and (listp x) (eq (car x) 'named-lambda))
     (destructuring-bind (name ll &rest body) (cdr x)
       (compile-lambda ll body
                       :name (symbol-name name)
                       :block name)))
    ((symbolp x)
     (let ((b (lookup-in-lexenv x *environment* 'function)))
       (if b
           (binding-value b)
           (ls-compile `(symbol-function ',x)))))))


(defun make-function-binding (fname)
  (make-binding :name fname :type 'function :value (gvarname fname)))

(defun compile-function-definition (list)
  (compile-lambda (car list) (cdr list)))

(defun translate-function (name)
  (let ((b (lookup-in-lexenv name *environment* 'function)))
    (and b (binding-value b))))

(define-compilation flet (definitions &rest body)
  (let* ((fnames (mapcar #'car definitions))
         (cfuncs (mapcar (lambda (def)
                           (compile-lambda (cadr def)
                                           `((block ,(car def)
                                               ,@(cddr def)))))
                         definitions))
         (*environment*
          (extend-lexenv (mapcar #'make-function-binding fnames)
                         *environment*
                         'function)))
    `(call (function ,(mapcar #'make-symbol (mapcar #'translate-function fnames))
                ,(ls-compile-block body t))
           ,@cfuncs)))

(define-compilation labels (definitions &rest body)
  (let* ((fnames (mapcar #'car definitions))
         (*environment*
          (extend-lexenv (mapcar #'make-function-binding fnames)
                         *environment*
                         'function)))
    (js!selfcall*
      `(progn
         ,@(mapcar (lambda (func)
                     `(var (,(make-symbol (translate-function (car func)))
                             ,(compile-lambda (cadr func)
                                              `((block ,(car func) ,@(cddr func)))))))
                   definitions))
      (ls-compile-block body t))))


(defvar *compiling-file* nil)
(define-compilation eval-when-compile (&rest body)
  (if *compiling-file*
      (progn
        (eval (cons 'progn body))
        (ls-compile 0))
      (ls-compile `(progn ,@body))))

(defmacro define-transformation (name args form)
  `(define-compilation ,name ,args
     (ls-compile ,form)))

(define-compilation progn (&rest body)
  (if (null (cdr body))
      (ls-compile (car body) *multiple-value-p*)
      `(progn
         ,@(append (mapcar #'ls-compile (butlast body))
                   (list (ls-compile (car (last body)) t))))))

(define-compilation macrolet (definitions &rest body)
  (let ((*environment* (copy-lexenv *environment*)))
    (dolist (def definitions)
      (destructuring-bind (name lambda-list &body body) def
        (let ((binding (make-binding :name name :type 'macro :value
                                     (let ((g!form (gensym)))
                                       `(lambda (,g!form)
                                          (destructuring-bind ,lambda-list ,g!form
                                            ,@body))))))
          (push-to-lexenv binding  *environment* 'function))))
    (ls-compile `(progn ,@body) *multiple-value-p*)))


(defun special-variable-p (x)
  (and (claimp x 'variable 'special) t))

;;; Wrap CODE to restore the symbol values of the dynamic
;;; bindings. BINDINGS is a list of pairs of the form
;;; (SYMBOL . PLACE),  where PLACE is a Javascript variable
;;; name to initialize the symbol value and where to stored
;;; the old value.
(defun let-binding-wrapper (bindings body)
  (when (null bindings)
    (return-from let-binding-wrapper body))
  `(code
    "try {"
    (code "var tmp;"
          ,@(mapcar
             (lambda (b)
               (let ((s (ls-compile `(quote ,(car b)))))
                 `(code "tmp = " ,s ".value;"
                        ,s ".value = " ,(cdr b) ";"
                        ,(cdr b) " = tmp;" )))
             bindings)
          ,body
          )
    "}"
    "finally {"
    (code
     ,@(mapcar (lambda (b)
                 (let ((s (ls-compile `(quote ,(car b)))))
                   `(code ,s ".value" " = " ,(cdr b) ";" )))
               bindings))
    "}" ))

(define-compilation let (bindings &rest body)
  (let* ((bindings (mapcar #'ensure-list bindings))
         (variables (mapcar #'first bindings))
         (cvalues (mapcar #'ls-compile (mapcar #'second bindings)))
         (*environment* (extend-local-env (remove-if #'special-variable-p variables)))
         (dynamic-bindings))
    `(call (function ,(mapcar (lambda (x)
                                (if (special-variable-p x)
                                    (let ((v (gvarname x)))
                                      (push (cons x v) dynamic-bindings)
                                      (make-symbol v))
                                    (make-symbol (translate-variable x))))
                              variables)
                     ,(let ((body (ls-compile-block body t t)))
                           `(code ,(let-binding-wrapper dynamic-bindings body))))
           ,@cvalues)))


;;; Return the code to initialize BINDING, and push it extending the
;;; current lexical environment if the variable is not special.
(defun let*-initialize-value (binding)
  (let ((var (first binding))
        (value (second binding)))
    (if (special-variable-p var)
        `(code ,(ls-compile `(setq ,var ,value)) ";" )
        (let* ((v (gvarname var))
               (b (make-binding :name var :type 'variable :value v)))
          (prog1 `(code "var " ,v " = " ,(ls-compile value) ";" )
            (push-to-lexenv b *environment* 'variable))))))

;;; Wrap BODY to restore the symbol values of SYMBOLS after body. It
;;; DOES NOT generate code to initialize the value of the symbols,
;;; unlike let-binding-wrapper.
(defun let*-binding-wrapper (symbols body)
  (when (null symbols)
    (return-from let*-binding-wrapper body))
  (let ((store (mapcar (lambda (s) (cons s (gvarname s)))
                       (remove-if-not #'special-variable-p symbols))))
    `(code
      "try {"
      (code
       ,@(mapcar (lambda (b)
                   (let ((s (ls-compile `(quote ,(car b)))))
                     `(code "var " ,(cdr b) " = " ,s ".value;" )))
                 store)
       ,body)
      "}"
      "finally {"
      (code
       ,@(mapcar (lambda (b)
                   (let ((s (ls-compile `(quote ,(car b)))))
                     `(code ,s ".value" " = " ,(cdr b) ";" )))
                 store))
      "}" )))

(define-compilation let* (bindings &rest body)
  (let ((bindings (mapcar #'ensure-list bindings))
        (*environment* (copy-lexenv *environment*)))
    (js!selfcall
      (let ((specials (remove-if-not #'special-variable-p (mapcar #'first bindings)))
            (body `(code ,@(mapcar #'let*-initialize-value bindings)
                         ,(ls-compile-block body t t))))
        (let*-binding-wrapper specials body)))))


(define-compilation block (name &rest body)
  ;; We use Javascript exceptions to implement non local control
  ;; transfer. Exceptions has dynamic scoping, so we use a uniquely
  ;; generated object to identify the block. The instance of a empty
  ;; array is used to distinguish between nested dynamic Javascript
  ;; exceptions. See https://github.com/davazp/jscl/issues/64 for
  ;; futher details.
  (let* ((idvar (gvarname name))
         (b (make-binding :name name :type 'block :value idvar)))
    (when *multiple-value-p*
      (push 'multiple-value (binding-declarations b)))
    (let* ((*environment* (extend-lexenv (list b) *environment* 'block))
           (cbody (ls-compile-block body t)))
      (if (member 'used (binding-declarations b))
          (js!selfcall
            "try {"
            "var " idvar " = [];"
            `(code ,cbody)
            "}"
            "catch (cf){"
            "    if (cf.type == 'block' && cf.id == " idvar ")"
            (if *multiple-value-p*
                "        return values.apply(this, forcemv(cf.values));"
                "        return cf.values;")

            "    else"
            "        throw cf;"
            "}" )
          (js!selfcall cbody)))))

(define-compilation return-from (name &optional value)
  (let* ((b (lookup-in-lexenv name *environment* 'block))
         (multiple-value-p (member 'multiple-value (binding-declarations b))))
    (when (null b)
      (error "Return from unknown block `~S'." (symbol-name name)))
    (push 'used (binding-declarations b))
    ;; The binding value is the name of a variable, whose value is the
    ;; unique identifier of the block as exception. We can't use the
    ;; variable name itself, because it could not to be unique, so we
    ;; capture it in a closure.
    (js!selfcall
      (when multiple-value-p `(code "var values = mv;" ))
      "throw ({"
      "type: 'block', "
      "id: " (binding-value b) ", "
      "values: " (ls-compile value multiple-value-p) ", "
      "message: 'Return from unknown block " (symbol-name name) ".'"
      "})")))

(define-compilation catch (id &rest body)
  (js!selfcall*
    `(var (|id| ,(ls-compile id)))
    `(try
      ,(ls-compile-block body t))
    `(catch (|cf|)
       (if (and (== (get |cf| "type") "catch")
                (== (get |cf| "id") |id|))
           ,(if *multiple-value-p*
                `(return (call (get |values| "apply")
                               this
                               (call |forcemv| (get |cf| "values"))))
                `(return (call (get |pv| "apply")
                               this
                               (call |forcemv| (get |cf| "values")))))
           (throw |cf|)))))

(define-compilation throw (id value)
  (js!selfcall*
    `(var (|values| |mv|))
    `(throw (object
             |type| "catch"
             |id| ,(ls-compile id)
             |values| ,(ls-compile value t)
             |message| "Throw uncatched."))))

(defun go-tag-p (x)
  (or (integerp x) (symbolp x)))

(defun declare-tagbody-tags (tbidx body)
  (let* ((go-tag-counter 0)
         (bindings
          (mapcar (lambda (label)
                    (let ((tagidx (integer-to-string (incf go-tag-counter))))
                      (make-binding :name label :type 'gotag :value (list tbidx tagidx))))
                  (remove-if-not #'go-tag-p body))))
    (extend-lexenv bindings *environment* 'gotag)))

(define-compilation tagbody (&rest body)
  ;; Ignore the tagbody if it does not contain any go-tag. We do this
  ;; because 1) it is easy and 2) many built-in forms expand to a
  ;; implicit tagbody, so we save some space.
  (unless (some #'go-tag-p body)
    (return-from tagbody (ls-compile `(progn ,@body nil))))
  ;; The translation assumes the first form in BODY is a label
  (unless (go-tag-p (car body))
    (push (gensym "START") body))
  ;; Tagbody compilation
  (let ((branch (gvarname 'branch))
        (tbidx (gvarname 'tbidx)))
    (let ((*environment* (declare-tagbody-tags tbidx body))
          initag)
      (let ((b (lookup-in-lexenv (first body) *environment* 'gotag)))
        (setq initag (second (binding-value b))))
      (js!selfcall
        ;; TAGBODY branch to take
        "var " branch " = " initag ";"
        "var " tbidx " = [];"
        "tbloop:"
        "while (true) {"
        `(code "try {"
               ,(let ((content nil))
                  `(code "switch(" ,branch "){"
                        "case " ,initag ":"
                        ,@(dolist (form (cdr body) (reverse content))
                          (push (if (not (go-tag-p form))
                                    `(code ,(ls-compile form) ";" )
                                    (let ((b (lookup-in-lexenv form *environment* 'gotag)))
                                      `(code "case " ,(second (binding-value b)) ":" )))
                                content))
                           "default:"
                           "    break tbloop;"
                           "}" ))
               "}"
               "catch (jump) {"
               "    if (jump.type == 'tagbody' && jump.id == " ,tbidx ")"
               "        " ,branch " = jump.label;"
               "    else"
               "        throw(jump);"
               "}" )
        "}"
        "return " (ls-compile nil) ";" ))))

(define-compilation go (label)
  (let ((b (lookup-in-lexenv label *environment* 'gotag))
        (n (cond
             ((symbolp label) (symbol-name label))
             ((integerp label) (integer-to-string label)))))
    (when (null b)
      (error "Unknown tag `~S'" label))
    (js!selfcall
      "throw ({"
      "type: 'tagbody', "
      "id: " (first (binding-value b)) ", "
      "label: " (second (binding-value b)) ", "
      "message: 'Attempt to GO to non-existing tag " n "'"
      "})" )))

(define-compilation unwind-protect (form &rest clean-up)
  (js!selfcall*
    `(var (|ret| ,(ls-compile nil)))
    `(try
       (= |ret| ,(ls-compile form)))
    `(finally
      ,(ls-compile-block clean-up))
    `(return |ret|)))

(define-compilation multiple-value-call (func-form &rest forms)
  (js!selfcall
    "var func = " (ls-compile func-form) ";"
    "var args = [" (if *multiple-value-p* "values" "pv") ", 0];"
    "return "
    (js!selfcall
      "var values = mv;"
      "var vs;"
      `(code
        ,@(mapcar (lambda (form)
                    `(code "vs = " ,(ls-compile form t) ";"
                           "if (typeof vs === 'object' && 'multiple-value' in vs)"
                           (code " args = args.concat(vs);" )
                           " else "
                           (code "args.push(vs);" )))
                  forms))
      "args[1] = args.length-2;"
      "return func.apply(window, args);" ) ";" ))

(define-compilation multiple-value-prog1 (first-form &rest forms)
  (js!selfcall
    "var args = " (ls-compile first-form *multiple-value-p*) ";"
    (ls-compile-block forms)
    "return args;" ))

(define-transformation backquote (form)
  (bq-completely-process form))


;;; Primitives

(defvar *builtins* nil)

(defmacro define-raw-builtin (name args &body body)
  ;; Creates a new primitive function `name' with parameters args and
  ;; @body. The body can access to the local environment through the
  ;; variable *ENVIRONMENT*.
  `(push (list ',name (lambda ,args (block ,name ,@body)))
         *builtins*))

(defmacro define-builtin (name args &body body)
  `(define-raw-builtin ,name ,args
     (let ,(mapcar (lambda (arg) `(,arg (ls-compile ,arg))) args)
       ,@body)))

;;; DECLS is a list of (JSVARNAME TYPE LISPFORM) declarations.
(defmacro type-check (decls &body body)
  `(js!selfcall
     ,@(mapcar (lambda (decl)
                 `(let ((name ,(first decl))
                        (value ,(third decl)))
                    `(code "var " ,name " = " ,value ";" )))
               decls)
     ,@(mapcar (lambda (decl)
                 `(let ((name ,(first decl))
                        (type ,(second decl)))
                    `(code "if (typeof " ,name " != '" ,type "')"
                           (code "throw 'The value ' + "
                                 ,name
                                 " + ' is not a type "
                                 ,type
                                 ".';"
                                 ))))
               decls)
     `(code "return " ,,@body ";" )))

;;; VARIABLE-ARITY compiles variable arity operations. ARGS stands for
;;; a variable which holds a list of forms. It will compile them and
;;; store the result in some Javascript variables. BODY is evaluated
;;; with ARGS bound to the list of these variables to generate the
;;; code which performs the transformation on these variables.

(defun variable-arity-call (args function)
  (unless (consp args)
    (error "ARGS must be a non-empty list"))
  (let ((counter 0)
        (fargs '())
        (prelude '()))
    (dolist (x args)
      (cond
        ((or (floatp x) (numberp x)) (push x fargs))
        (t (let ((v (make-symbol (code "x" (incf counter)))))
             (push v fargs)
             (push `(code "var " ,v " = " ,(ls-compile x) ";"
                          "if (typeof " ,v " !== 'number') throw 'Not a number!';")
                   prelude)))))
    (js!selfcall
      `(code ,@(reverse prelude))
      (funcall function (reverse fargs)))))


(defmacro variable-arity (args &body body)
  (unless (symbolp args)
    (error "`~S' is not a symbol." args))
  `(variable-arity-call ,args
                        (lambda (,args)
                          `(code "return " ,,@body ";" ))))

(defun num-op-num (x op y)
  (type-check (("x" "number" x) ("y" "number" y))
    `(code "x" ,op "y")))

(define-raw-builtin + (&rest numbers)
  (if (null numbers)
      0
      (variable-arity numbers
        `(+ ,@numbers))))

(define-raw-builtin - (x &rest others)
  (let ((args (cons x others)))
    (variable-arity args `(- ,@args))))

(define-raw-builtin * (&rest numbers)
  (if (null numbers)
      1
      (variable-arity numbers `(* ,@numbers))))

(define-raw-builtin / (x &rest others)
  (let ((args (cons x others)))
    (variable-arity args
      (if (null others)
          `(/ 1 ,(car args))
          (reduce (lambda (x y) `(/ ,x ,y))
                  args)))))

(define-builtin mod (x y) (num-op-num x "%" y))


(defun comparison-conjuntion (vars op)
  (cond
    ((null (cdr vars))
     'true)
    ((null (cddr vars))
     `(,op ,(car vars) ,(cadr vars)))
    (t
     `(and (,op ,(car vars) ,(cadr vars))
           ,(comparison-conjuntion (cdr vars) op)))))

(defmacro define-builtin-comparison (op sym)
  `(define-raw-builtin ,op (x &rest args)
     (let ((args (cons x args)))
       (variable-arity args
         (js!bool (comparison-conjuntion args ',sym))))))

(define-builtin-comparison > >)
(define-builtin-comparison < <)
(define-builtin-comparison >= >=)
(define-builtin-comparison <= <=)
(define-builtin-comparison = ==)
(define-builtin-comparison /= !=)

(define-builtin numberp (x)
  (js!bool `(== (typeof ,x) "number")))

(define-builtin floor (x)
  (type-check (("x" "number" x))
    "Math.floor(x)"))

(define-builtin expt (x y)
  (type-check (("x" "number" x)
               ("y" "number" y))
    "Math.pow(x, y)"))

(define-builtin float-to-string (x)
  (type-check (("x" "number" x))
    "make_lisp_string(x.toString())"))

(define-builtin cons (x y)
  `(object "car" ,x "cdr" ,y))

(define-builtin consp (x)
  (js!bool
   (js!selfcall
     "var tmp = " x ";"
     "return (typeof tmp == 'object' && 'car' in tmp);" )))

(define-builtin car (x)
  (js!selfcall*
    `(var (tmp ,x))
    `(return (if (=== tmp ,(ls-compile nil))
                 ,(ls-compile nil)
                 (get tmp "car")))))

(define-builtin cdr (x)
  (js!selfcall*
    `(var (tmp ,x))
    `(return (if (=== tmp ,(ls-compile nil))
                 ,(ls-compile nil)
                 (get tmp "cdr")))))

(define-builtin rplaca (x new)
  (type-check (("x" "object" x))
    `(code "(x.car = " ,new ", x)")))

(define-builtin rplacd (x new)
  (type-check (("x" "object" x))
    `(code "(x.cdr = " ,new ", x)")))

(define-builtin symbolp (x)
  (js!bool `(instanceof ,x |Symbol|)))

(define-builtin make-symbol (name)
  `(new (call |Symbol| ,name)))

(define-builtin symbol-name (x)
  `(get ,x "name"))

(define-builtin set (symbol value)
  `(= (get ,symbol "value") ,value))

(define-builtin fset (symbol value)
  `(= (get ,symbol "fvalue") ,value))

(define-builtin boundp (x)
  (js!bool `(!== (get ,x "value") undefined)))

(define-builtin fboundp (x)
  (js!bool `(!== (get ,x "fvalue") undefined)))

(define-builtin symbol-value (x)
  (js!selfcall*
    `(var (symbol ,x)
          (value (get symbol "value")))
    `(if (=== value undefined)
         (throw (+ "Variable `" (call |xstring| (get symbol "name")) "' is unbound.")))
    `(return value)))

(define-builtin symbol-function (x)
  (js!selfcall*
    `(var (symbol ,x)
          (func (get symbol "fvalue")))
    `(if (=== func undefined)
         (throw (+ "Function `" (call |xstring| (get symbol "name")) "' is undefined.")))
    `(return func)))

(define-builtin symbol-plist (x)
  `(or (get ,x "plist") ,(ls-compile nil)))

(define-builtin lambda-code (x)
  `(call |make_lisp_string| (call (get ,x "toString"))))

(define-builtin eq (x y)
  (js!bool `(=== ,x ,y)))

(define-builtin char-code (x)
  (type-check (("x" "string" x))
    "char_to_codepoint(x)"))

(define-builtin code-char (x)
  (type-check (("x" "number" x))
    "char_from_codepoint(x)"))

(define-builtin characterp (x)
  (js!bool
   (js!selfcall*
     `(var (x ,x))
     `(return (and (== (typeof x) "string")
                   (or (== (get x "length") 1)
                       (== (get x "length") 2)))))))

(define-builtin char-upcase (x)
  `(call |safe_char_upcase| ,x))

(define-builtin char-downcase (x)
  `(call |safe_char_downcase| ,x))

(define-builtin stringp (x)
  (js!bool
   (js!selfcall*
     `(var (x ,x))
     `(return (and (and (===(typeof x) "object")
                        (in "length" x))
                   (== (get x "stringp") 1))))))

(define-raw-builtin funcall (func &rest args)
  (js!selfcall*
    `(var (f ,(ls-compile func)))
    `(return (call (if (=== (typeof f) "function")
                       f
                       (get f "fvalue"))
                   ,@(list* (if *multiple-value-p* '|values| '|pv|)
                            (length args)
                            (mapcar #'ls-compile args))))))

(define-raw-builtin apply (func &rest args)
  (if (null args)
      `(code "(" ,(ls-compile func) ")()")
      (let ((args (butlast args))
            (last (car (last args))))
        (js!selfcall
          "var f = " (ls-compile func) ";"
          "var args = [" `(code
                           ,@(interleave (list* (if *multiple-value-p* "values" "pv")
                                                (integer-to-string (length args))
                                                (mapcar #'ls-compile args))
                                         ", "))
          "];"
          "var tail = (" (ls-compile last) ");"
          "while (tail != " (ls-compile nil) "){"
          "    args.push(tail.car);"
          "    args[1] += 1;"
          "    tail = tail.cdr;"
          "}"
          "return (typeof f === 'function'? f : f.fvalue).apply(this, args);" ))))

(define-builtin js-eval (string)
  (if *multiple-value-p*
      (js!selfcall*
        `(var (v (call |globalEval| (call |xstring| ,string))))
        `(return (call (get |values| "apply") this (call |forcemv| v))))
      `(call |globalEval| (call |xstring| ,string))))

(define-builtin %throw (string)
  (js!selfcall* `(throw ,string)))

(define-builtin functionp (x)
  (js!bool `(=== (typeof ,x) "function")))

(define-builtin %write-string (x)
  `(call (get |lisp| "write") ,x))

(define-builtin /debug (x)
  `(call (get |console| "log") (call |xstring| ,x)))


;;; Storage vectors. They are used to implement arrays and (in the
;;; future) structures.

(define-builtin storage-vector-p (x)
  (js!bool
   (js!selfcall*
     `(var (x ,x))
     `(return (and (=== (typeof x) "object") (in "length" x))))))

(define-builtin make-storage-vector (n)
  (js!selfcall*
    `(var (r #()))
    `(= (get r "length") ,n)
    `(return r)))

(define-builtin storage-vector-size (x)
  `(get ,x "length"))

(define-builtin resize-storage-vector (vector new-size)
  `(= (get ,vector "length") ,new-size))

(define-builtin storage-vector-ref (vector n)
  (js!selfcall*
    `(var (x (property ,vector ,n)))
    `(if (=== x undefined) (throw "Out of range."))
    `(return x)))

(define-builtin storage-vector-set (vector n value)
  (js!selfcall*
    `(var (x ,vector))
    `(var (i ,n))
    `(if (or (< i 0) (>= i (get x "length")))
         (throw "Out of range."))
    `(return (= (property x i) ,value))))

(define-builtin concatenate-storage-vector (sv1 sv2)
  (js!selfcall*
    `(var (sv1 ,sv1))
    `(var (r (call (get sv1 "concat") ,sv2)))
    `(= (get r "type") (get sv1 "type"))
    `(= (get r "stringp") (get sv1 "stringp"))
    `(return r)))

(define-builtin get-internal-real-time ()
  `(call (get (new (call |Date|)) "getTime")))

(define-builtin values-array (array)
  (if *multiple-value-p*
      `(call (get |values| "apply") this ,array)
      `(call (get |pv| "apply") this ,array)))

(define-raw-builtin values (&rest args)
  (if *multiple-value-p*
      `(call |values| ,@(mapcar #'ls-compile args))
      `(call |pv| ,@(mapcar #'ls-compile args))))

;;; Javascript FFI

(define-builtin new ()
  '(object))

(define-raw-builtin oget* (object key &rest keys)
  (js!selfcall*
    `(progn
       (var (tmp (property ,(ls-compile object) (call |xstring| ,(ls-compile key)))))
       ,@(mapcar (lambda (key)
                   `(progn
                      (if (=== tmp undefined) (return ,(ls-compile nil)))
                      (= tmp (property tmp (call |xstring| ,(ls-compile key))))))
                 keys))
    `(return (if (=== tmp undefined) ,(ls-compile nil) tmp))))

(define-raw-builtin oset* (value object key &rest keys)
  (let ((keys (cons key keys)))
    (js!selfcall*
      `(progn
         (var (obj ,(ls-compile object)))
         ,@(mapcar (lambda (key)
                     `(progn
                        (= obj (property obj (call |xstring| ,(ls-compile key))))
                        (if (=== object undefined)
                            (throw "Impossible to set object property."))))
                   (butlast keys))
         (var (tmp
               (= (property obj (call |xstring| ,(ls-compile (car (last keys)))))
                  ,(ls-compile value))))
         (return (if (=== tmp undefined)
                     ,(ls-compile nil)
                     tmp))))))

(define-raw-builtin oget (object key &rest keys)
  `(call |js_to_lisp| ,(ls-compile `(oget* ,object ,key ,@keys))))

(define-raw-builtin oset (value object key &rest keys)
  (ls-compile `(oset* (lisp-to-js ,value) ,object ,key ,@keys)))

(define-builtin objectp (x)
  (js!bool `(=== (typeof ,x) "object")))

(define-builtin lisp-to-js (x) `(call |lisp_to_js| ,x))
(define-builtin js-to-lisp (x) `(call |js_to_lisp| ,x))


(define-builtin in (key object)
  (js!bool `(in (call |xstring| ,key) ,object)))

(define-builtin map-for-in (function object)
  (js!selfcall*
    `(var (f ,function)
          (g (if (=== (typeof f) "function") f (get f "fvalue")))
          (o ,object))
    `(for-in (key o)
       (call g ,(if *multiple-value-p* '|values| '|pv|) 1 (get o "key")))
    `(return ,(ls-compile nil))))

(define-compilation %js-vref (var)
  `(call |js_to_lisp| ,(make-symbol var)))

(define-compilation %js-vset (var val)
  `(= ,(make-symbol var) (call |lisp_to_js| ,(ls-compile val))))

(define-setf-expander %js-vref (var)
  (let ((new-value (gensym)))
    (unless (stringp var)
      (error "`~S' is not a string." var))
    (values nil
            (list var)
            (list new-value)
            `(%js-vset ,var ,new-value)
            `(%js-vref ,var))))


#-jscl
(defvar *macroexpander-cache*
  (make-hash-table :test #'eq))

(defun !macro-function (symbol)
  (unless (symbolp symbol)
    (error "`~S' is not a symbol." symbol))
  (let ((b (lookup-in-lexenv symbol *environment* 'function)))
    (if (and b (eq (binding-type b) 'macro))
        (let ((expander (binding-value b)))
          (cond
            #-jscl
            ((gethash b *macroexpander-cache*)
             (setq expander (gethash b *macroexpander-cache*)))
            ((listp expander)
             (let ((compiled (eval expander)))
               ;; The list representation are useful while
               ;; bootstrapping, as we can dump the definition of the
               ;; macros easily, but they are slow because we have to
               ;; evaluate them and compile them now and again. So, let
               ;; us replace the list representation version of the
               ;; function with the compiled one.
               ;;
               #+jscl (setf (binding-value b) compiled)
               #-jscl (setf (gethash b *macroexpander-cache*) compiled)
               (setq expander compiled))))
          expander)
        nil)))

(defun !macroexpand-1 (form)
  (cond
    ((symbolp form)
     (let ((b (lookup-in-lexenv form *environment* 'variable)))
       (if (and b (eq (binding-type b) 'macro))
           (values (binding-value b) t)
           (values form nil))))
    ((and (consp form) (symbolp (car form)))
     (let ((macrofun (!macro-function (car form))))
       (if macrofun
           (values (funcall macrofun (cdr form)) t)
           (values form nil))))
    (t
     (values form nil))))

(defun compile-funcall (function args)
  (let* ((values-funcs (if *multiple-value-p* "values" "pv"))
         (arglist `(code "(" ,@(interleave (list* values-funcs
                                                  (integer-to-string (length args))
                                                  (mapcar #'ls-compile args))
                                           ", ")
                         ")")))
    (unless (or (symbolp function)
                (and (consp function)
                     (member (car function) '(lambda oget))))
      (error "Bad function designator `~S'" function))
    (cond
      ((translate-function function)
       `(code ,(translate-function function) ,arglist))
      ((and (symbolp function)
            #+jscl (eq (symbol-package function) (find-package "COMMON-LISP"))
            #-jscl t)
       `(code ,(ls-compile `',function) ".fvalue" ,arglist))
      #+jscl((symbolp function)
       `(code ,(ls-compile `#',function) ,arglist))
      ((and (consp function) (eq (car function) 'lambda))
       `(code ,(ls-compile `#',function) ,arglist))
      ((and (consp function) (eq (car function) 'oget))
       `(code ,(ls-compile function) ,arglist))
      (t
       (error "Bad function descriptor")))))

(defun ls-compile-block (sexps &optional return-last-p decls-allowed-p)
  (multiple-value-bind (sexps decls)
      (parse-body sexps :declarations decls-allowed-p)
    (declare (ignore decls))
    (if return-last-p
        `(code ,(ls-compile-block (butlast sexps) nil decls-allowed-p)
               "return " ,(ls-compile (car (last sexps)) *multiple-value-p*) ";")
        `(code
          ,@(interleave (mapcar #'ls-compile sexps) ";
" *newline*)
          ";" ,*newline*))))

(defun ls-compile* (sexp &optional multiple-value-p)
  (multiple-value-bind (sexp expandedp) (!macroexpand-1 sexp)
    (when expandedp
      (return-from ls-compile* (ls-compile sexp multiple-value-p)))
    ;; The expression has been macroexpanded. Now compile it!
    (let ((*multiple-value-p* multiple-value-p))
      (cond
        ((symbolp sexp)
         (let ((b (lookup-in-lexenv sexp *environment* 'variable)))
           (cond
             ((and b (not (member 'special (binding-declarations b))))
              (binding-value b))
             ((or (keywordp sexp)
                  (and b (member 'constant (binding-declarations b))))
              `(code ,(ls-compile `',sexp) ".value"))
             (t
              (ls-compile `(symbol-value ',sexp))))))
        ((or (integerp sexp) (floatp sexp) (characterp sexp) (stringp sexp) (arrayp sexp))
         (literal sexp))
        ((listp sexp)
         (let ((name (car sexp))
               (args (cdr sexp)))
           (cond
             ;; Special forms
             ((assoc name *compilations*)
              (let ((comp (second (assoc name *compilations*))))
                (apply comp args)))
             ;; Built-in functions
             ((and (assoc name *builtins*)
                   (not (claimp name 'function 'notinline)))
              (let ((comp (second (assoc name *builtins*))))
                (apply comp args)))
             (t
              (compile-funcall name args)))))
        (t
         (error "How should I compile `~S'?" sexp))))))

(defun ls-compile (sexp &optional multiple-value-p)
  `(code "(" ,(ls-compile* sexp multiple-value-p) ")"))


(defvar *compile-print-toplevels* nil)

(defun truncate-string (string &optional (width 60))
  (let ((n (or (position #\newline string)
               (min width (length string)))))
    (subseq string 0 n)))

(defun convert-toplevel (sexp &optional multiple-value-p)
  (let ((*toplevel-compilations* nil))
    (cond
      ;; Non-empty toplevel progn
      ((and (consp sexp)
            (eq (car sexp) 'progn)
            (cdr sexp))
       `(progn
          ,@(mapcar (lambda (s) (convert-toplevel s t))
                    (cdr sexp))))
      (t
       (when *compile-print-toplevels*
         (let ((form-string (prin1-to-string sexp)))
           (format t "Compiling ~a..." (truncate-string form-string))))
       (let ((code (ls-compile sexp multiple-value-p)))
         `(code
           ,@(interleave (get-toplevel-compilations) ";
" t)
           ,(when code
                  `(code ,code ";"))))))))

(defun ls-compile-toplevel (sexp &optional multiple-value-p)
  (with-output-to-string (*standard-output*)
    (js (convert-toplevel sexp multiple-value-p))))