--- /dev/null
+;;; compiler-codege.lisp --- Naive Javascript unparser
+
+;; copyright (C) 2013 David Vazquez
+
+;; 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/>.
+
+;;; This code generator takes as input a S-expression representation
+;;; of the Javascript AST and generates Javascript code without
+;;; redundant syntax constructions like extra parenthesis.
+;;;
+;;; It is intended to be used with the new compiler. However, it is
+;;; quite independent so it has been integrated early in JSCL.
+
+(/debug "loading compiler-codegen.lisp!")
+
+(defvar *js-macros* nil)
+(defmacro define-js-macro (name lambda-list &body body)
+ (let ((form (gensym)))
+ `(push (cons ',name
+ (lambda (,form)
+ (block ,name
+ (destructuring-bind ,lambda-list ,form
+ ,@body))))
+ *js-macros*)))
+
+(defun js-macroexpand (js)
+ (if (and (consp js) (assoc (car js) *js-macros*))
+ (let ((expander (cdr (assoc (car js) *js-macros*))))
+ (multiple-value-bind (expansion stop-expand-p)
+ (funcall expander (cdr js))
+ (if stop-expand-p
+ expansion
+ (js-macroexpand expansion))))
+ js))
+
+
+(defconstant no-comma 12)
+
+(defvar *js-output* t)
+
+;;; Two seperate functions are needed for escaping strings:
+;;; One for producing JavaScript string literals (which are singly or
+;;; doubly quoted)
+;;; And one for producing Lisp strings (which are only doubly quoted)
+;;;
+;;; The same function would suffice for both, but for javascript string
+;;; literals it is neater to use either depending on the context, e.g:
+;;; foo's => "foo's"
+;;; "foo" => '"foo"'
+;;; which avoids having to escape quotes where possible
+(defun js-escape-string (string)
+ (let ((index 0)
+ (size (length string))
+ (seen-single-quote nil)
+ (seen-double-quote nil))
+ (flet ((%js-escape-string (string escape-single-quote-p)
+ (let ((output "")
+ (index 0))
+ (while (< index size)
+ (let ((ch (char string index)))
+ (when (char= ch #\\)
+ (setq output (concat output "\\")))
+ (when (and escape-single-quote-p (char= ch #\'))
+ (setq output (concat output "\\")))
+ (when (char= ch #\newline)
+ (setq output (concat output "\\"))
+ (setq ch #\n))
+ (setq output (concat output (string ch))))
+ (incf index))
+ output)))
+ ;; First, scan the string for single/double quotes
+ (while (< index size)
+ (let ((ch (char string index)))
+ (when (char= ch #\')
+ (setq seen-single-quote t))
+ (when (char= ch #\")
+ (setq seen-double-quote t)))
+ (incf index))
+ ;; Then pick the appropriate way to escape the quotes
+ (cond
+ ((not seen-single-quote)
+ (concat "'" (%js-escape-string string nil) "'"))
+ ((not seen-double-quote)
+ (concat "\"" (%js-escape-string string nil) "\""))
+ (t (concat "'" (%js-escape-string string t) "'"))))))
+
+
+(defun js-format (fmt &rest args)
+ (apply #'format *js-output* fmt args))
+
+(defun valid-js-identifier (string-designator)
+ (let ((string (typecase string-designator
+ (symbol (symbol-name string-designator))
+ (string string-designator)
+ (t
+ (return-from valid-js-identifier (values nil nil))))))
+ (flet ((constitutentp (ch)
+ (or (alphanumericp ch) (member ch '(#\$ #\_)))))
+ (if (and (every #'constitutentp string)
+ (if (plusp (length string))
+ (not (digit-char-p (char string 0)))
+ t))
+ (values (format nil "~a" string) t)
+ (values nil nil)))))
+
+(defun js-identifier (string-designator)
+ (multiple-value-bind (string valid)
+ (valid-js-identifier string-designator)
+ (unless valid
+ (error "~S is not a valid Javascript identifier." string))
+ (js-format "~a" string)))
+
+(defun js-primary-expr (form)
+ (cond
+ ((numberp form)
+ (if (<= 0 form)
+ (js-format "~a" form)
+ (js-expr `(- ,(abs form)))))
+ ((stringp form)
+ (js-format "~a" (js-escape-string form)))
+ ((symbolp form)
+ (case form
+ (true (js-format "true"))
+ (false (js-format "false"))
+ (null (js-format "null"))
+ (this (js-format "this"))
+ (undefined (js-format "undefined"))
+ (otherwise
+ (js-identifier form))))
+ (t
+ (error "Unknown Javascript syntax ~S." form))))
+
+(defun js-vector-initializer (vector)
+ (let ((size (length vector)))
+ (js-format "[")
+ (dotimes (i (1- size))
+ (let ((elt (aref vector i)))
+ (unless (eq elt 'null)
+ (js-expr elt no-comma))
+ (js-format ",")))
+ (when (plusp size)
+ (js-expr (aref vector (1- size)) no-comma))
+ (js-format "]")))
+
+(defun js-object-initializer (plist)
+ (js-format "{")
+ (do* ((tail plist (cddr tail)))
+ ((null tail))
+ (let ((key (car tail))
+ (value (cadr tail)))
+ (multiple-value-bind (identifier identifier-p) (valid-js-identifier key)
+ (declare (ignore identifier))
+ (if identifier-p
+ (js-identifier key)
+ (js-expr (string key) no-comma)))
+ (js-format ": ")
+ (js-expr value no-comma)
+ (unless (null (cddr tail))
+ (js-format ","))))
+ (js-format "}"))
+
+(defun js-function (arguments &rest body)
+ (js-format "function(")
+ (when arguments
+ (js-identifier (car arguments))
+ (dolist (arg (cdr arguments))
+ (js-format ",")
+ (js-identifier arg)))
+ (js-format ")")
+ (js-stmt `(group ,@body) t))
+
+(defun check-lvalue (x)
+ (unless (or (symbolp x)
+ (nth-value 1 (valid-js-identifier x))
+ (and (consp x)
+ (member (car x) '(get = property))))
+ (error "Bad Javascript lvalue ~S" x)))
+
+;;; Process the Javascript AST to reduce some syntax sugar.
+(defun js-expand-expr (form)
+ (if (consp form)
+ (case (car form)
+ (+
+ (case (length (cdr form))
+ (1 `(unary+ ,(cadr form)))
+ (t (reduce (lambda (x y) `(+ ,x ,y)) (cdr form)))))
+ (-
+ (case (length (cdr form))
+ (1 `(unary- ,(cadr form)))
+ (t (reduce (lambda (x y) `(- ,x ,y)) (cdr form)))))
+ ((and or)
+ (reduce (lambda (x y) `(,(car form) ,x ,y)) (cdr form)))
+ ((progn comma)
+ (reduce (lambda (x y) `(comma ,x ,y)) (cdr form) :from-end t))
+ (t
+ (js-macroexpand form)))
+ form))
+
+(defun js-operator-expression (op args precedence associativity operand-order)
+ (let ((op1 (car args))
+ (op2 (cadr args)))
+ (case op
+ ;; Accessors
+ (property
+ (js-expr (car args) 0)
+ (js-format "[")
+ (js-expr (cadr args) no-comma)
+ (js-format "]"))
+ (get
+ (multiple-value-bind (accessor accessorp)
+ (valid-js-identifier (cadr args))
+ (unless accessorp
+ (error "Invalid accessor ~S" (cadr args)))
+ (js-expr (car args) 0)
+ (js-format ".")
+ (js-identifier accessor)))
+ ;; Function call
+ (call
+ (js-expr (car args) 1)
+ (js-format "(")
+ (when (cdr args)
+ (js-expr (cadr args) no-comma)
+ (dolist (operand (cddr args))
+ (js-format ",")
+ (js-expr operand no-comma)))
+ (js-format ")"))
+ ;; Object syntax
+ (object
+ (js-object-initializer args))
+ ;; Function expressions
+ (function
+ (js-format "(")
+ (apply #'js-function args)
+ (js-format ")"))
+ (t
+ (labels ((low-precedence-p (op-precedence)
+ (cond
+ ((> op-precedence precedence))
+ ((< op-precedence precedence) nil)
+ (t (not (eq operand-order associativity)))))
+
+ (%unary-op (operator string operator-precedence operator-associativity post lvalue)
+ (when (eq op operator)
+ (when lvalue (check-lvalue op1))
+ (when (low-precedence-p operator-precedence) (js-format "("))
+ (cond
+ (post
+ (js-expr op1 operator-precedence operator-associativity 'left)
+ (js-format "~a" string))
+ (t
+ (js-format "~a" string)
+ (js-expr op1 operator-precedence operator-associativity 'right)))
+ (when (low-precedence-p operator-precedence) (js-format ")"))
+ (return-from js-operator-expression)))
+
+ (%binary-op (operator string operator-precedence operator-associativity lvalue)
+ (when (eq op operator)
+ (when lvalue (check-lvalue op1))
+ (when (low-precedence-p operator-precedence) (js-format "("))
+ (js-expr op1 operator-precedence operator-associativity 'left)
+ (js-format "~a" string)
+ (js-expr op2 operator-precedence operator-associativity 'right)
+ (when (low-precedence-p operator-precedence) (js-format ")"))
+ (return-from js-operator-expression))))
+
+ (macrolet ((unary-op (operator string precedence associativity &key post lvalue)
+ `(%unary-op ',operator ',string ',precedence ',associativity ',post ',lvalue))
+ (binary-op (operator string precedence associativity &key lvalue)
+ `(%binary-op ',operator ',string ',precedence ',associativity ',lvalue)))
+
+ (unary-op pre++ "++" 2 right :lvalue t)
+ (unary-op pre-- "--" 2 right :lvalue t)
+ (unary-op post++ "++" 2 right :lvalue t :post t)
+ (unary-op post-- "--" 2 right :lvalue t :post t)
+ (unary-op not "!" 2 right)
+ (unary-op bit-not "~" 2 right)
+ ;; Note that the leading space is necessary because it
+ ;; could break with post++, for example. TODO: Avoid
+ ;; leading space when it's possible.
+ (unary-op unary+ " +" 2 right)
+ (unary-op unary- " -" 2 right)
+ (unary-op delete "delete " 2 right)
+ (unary-op void "void " 2 right)
+ (unary-op typeof "typeof " 2 right)
+ (unary-op new "new " 2 right)
+
+ (binary-op * "*" 3 left)
+ (binary-op / "/" 3 left)
+ (binary-op mod "%" 3 left)
+ (binary-op % "%" 3 left)
+ (binary-op + "+" 4 left)
+ (binary-op - "-" 5 left)
+ (binary-op << "<<" 5 left)
+ (binary-op >> "<<" 5 left)
+ (binary-op >>> ">>>" 5 left)
+ (binary-op <= "<=" 6 left)
+ (binary-op < "<" 6 left)
+ (binary-op > ">" 6 left)
+ (binary-op >= ">=" 6 left)
+ (binary-op instanceof " instanceof " 6 left)
+ (binary-op in " in " 6 left)
+ (binary-op == "==" 7 left)
+ (binary-op != "!=" 7 left)
+ (binary-op === "===" 7 left)
+ (binary-op !== "!==" 7 left)
+ (binary-op bit-and "&" 8 left)
+ (binary-op bit-xor "^" 9 left)
+ (binary-op bit-or "|" 10 left)
+ (binary-op and "&&" 11 left)
+ (binary-op or "||" 12 left)
+ (binary-op = "=" 13 right :lvalue t)
+ (binary-op += "+=" 13 right :lvalue t)
+ (binary-op incf "+=" 13 right :lvalue t)
+ (binary-op -= "-=" 13 right :lvalue t)
+ (binary-op decf "-=" 13 right :lvalue t)
+ (binary-op *= "*=" 13 right :lvalue t)
+ (binary-op /= "*=" 13 right :lvalue t)
+ (binary-op bit-xor= "^=" 13 right :lvalue t)
+ (binary-op bit-and= "&=" 13 right :lvalue t)
+ (binary-op bit-or= "|=" 13 right :lvalue t)
+ (binary-op <<= "<<=" 13 right :lvalue t)
+ (binary-op >>= ">>=" 13 right :lvalue t)
+ (binary-op >>>= ">>>=" 13 right :lvalue t)
+
+ (binary-op comma "," 13 right)
+ (binary-op progn "," 13 right)
+
+ (when (member op '(? if))
+ (when (low-precedence-p 12) (js-format "("))
+ (js-expr (first args) 12 'right 'left)
+ (js-format "?")
+ (js-expr (second args) 12 'right 'right)
+ (js-format ":")
+ (js-expr (third args) 12 'right 'right)
+ (when (low-precedence-p 12) (js-format ")"))
+ (return-from js-operator-expression))
+
+ (error "Unknown operator `~S'" op)))))))
+
+(defun js-expr (form &optional (precedence 1000) associativity operand-order)
+ (let ((form (js-expand-expr form)))
+ (cond
+ ((or (symbolp form) (numberp form) (stringp form))
+ (js-primary-expr form))
+ ((vectorp form)
+ (js-vector-initializer form))
+ (t
+ (js-operator-expression (car form) (cdr form) precedence associativity operand-order)))))
+
+(defun js-expand-stmt (form)
+ (cond
+ ((and (consp form) (eq (car form) 'progn))
+ (destructuring-bind (&body body) (cdr form)
+ (cond
+ ((null body)
+ nil)
+ ((null (cdr body))
+ (js-expand-stmt (car body)))
+ (t
+ `(group ,@(cdr form))))))
+ (t
+ (js-macroexpand form))))
+
+(defun js-stmt (form &optional parent)
+ (let ((form (js-expand-stmt form)))
+ (flet ((js-stmt (x) (js-stmt x form)))
+ (cond
+ ((null form)
+ (unless (or (and (consp parent) (eq (car parent) 'group))
+ (null parent))
+ (js-format ";")))
+ ((atom form)
+ (progn
+ (js-expr form)
+ (js-format ";")))
+ (t
+ (case (car form)
+ (label
+ (destructuring-bind (label &body body) (cdr form)
+ (js-identifier label)
+ (js-format ":")
+ (js-stmt `(progn ,@body))))
+ (break
+ (destructuring-bind (&optional label) (cdr form)
+ (js-format "break")
+ (when label
+ (js-format " ")
+ (js-identifier label))
+ (js-format ";")))
+ (return
+ (destructuring-bind (value) (cdr form)
+ (js-format "return ")
+ (js-expr value)
+ (js-format ";")))
+ (var
+ (flet ((js-var (spec)
+ (destructuring-bind (variable &optional initial)
+ (ensure-list spec)
+ (js-identifier variable)
+ (when initial
+ (js-format "=")
+ (js-expr initial no-comma)))))
+ (destructuring-bind (var &rest vars) (cdr form)
+ (js-format "var ")
+ (js-var var)
+ (dolist (var vars)
+ (js-format ",")
+ (js-var var))
+ (js-format ";"))))
+ (if
+ (destructuring-bind (condition true &optional false) (cdr form)
+ (js-format "if (")
+ (js-expr condition)
+ (js-format ") ")
+ (js-stmt true)
+ (when false
+ (js-format " else ")
+ (js-stmt false))))
+ (group
+ (let ((in-group-p
+ (or (null parent)
+ (and (consp parent) (eq (car parent) 'group)))))
+ (unless in-group-p (js-format "{"))
+ (mapc #'js-stmt (cdr form))
+ (unless in-group-p (js-format "}"))))
+ (while
+ (destructuring-bind (condition &body body) (cdr form)
+ (js-format "while (")
+ (js-expr condition)
+ (js-format ")")
+ (js-stmt `(progn ,@body))))
+ (switch
+ (destructuring-bind (value &rest cases) (cdr form)
+ (js-format "switch(")
+ (js-expr value)
+ (js-format "){")
+ (dolist (case cases)
+ (cond
+ ((and (consp case) (eq (car case) 'case))
+ (js-format "case ")
+ (let ((value (cadr case)))
+ (unless (or (stringp value) (integerp value))
+ (error "Non-constant switch case `~S'." value))
+ (js-expr value))
+ (js-format ":"))
+ ((eq case 'default)
+ (js-format "default:"))
+ (t
+ (js-stmt case))))
+ (js-format "}")))
+ (for
+ (destructuring-bind ((start condition step) &body body) (cdr form)
+ (js-format "for (")
+ (js-expr start)
+ (js-format ";")
+ (js-expr condition)
+ (js-format ";")
+ (js-expr step)
+ (js-format ")")
+ (js-stmt `(progn ,@body))))
+ (for-in
+ (destructuring-bind ((x object) &body body) (cdr form)
+ (js-format "for (")
+ (js-identifier x)
+ (js-format " in ")
+ (js-expr object)
+ (js-format ")")
+ (js-stmt `(progn ,@body))))
+ (try
+ (destructuring-bind (&rest body) (cdr form)
+ (js-format "try")
+ (js-stmt `(group ,@body))))
+ (catch
+ (destructuring-bind ((var) &rest body) (cdr form)
+ (js-format "catch (")
+ (js-identifier var)
+ (js-format ")")
+ (js-stmt `(group ,@body))))
+ (finally
+ (destructuring-bind (&rest body) (cdr form)
+ (js-format "finally")
+ (js-stmt `(group ,@body))))
+ (throw
+ (destructuring-bind (object) (cdr form)
+ (js-format "throw ")
+ (js-expr object)
+ (js-format ";")))
+ (t
+ (js-expr form)
+ (js-format ";"))))))))
+
+(defun js (&rest stmts)
+ (mapc #'js-stmt stmts)
+ nil)
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