X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=lispstrack.lisp;h=f026618455e6a08fef3d00f3cb5d02a3d226f596;hb=73a1740242f47803a64ac77092be0263de150a4e;hp=abc1b2b70479e5f34fc92d0feecfc99a6fed44bf;hpb=b27fcd30accc24a70887798f9d61e08c38d083dd;p=jscl.git

diff --git a/lispstrack.lisp b/lispstrack.lisp
index abc1b2b..f026618 100644
--- a/lispstrack.lisp
+++ b/lispstrack.lisp
@@ -11,16 +11,6 @@
           strs
           :initial-value ""))
 
-
-(let ((counter 0))
-  (defun make-var-binding (symbol)
-    (cons symbol (format nil "v~d" (incf counter)))))
-
-(let ((counter 0))
-  (defun make-func-binding (symbol)
-    (cons symbol (format nil "f~d" (incf counter)))))
-
-
 ;;; Concatenate a list of strings, with a separator
 (defun join (list separator)
   (cond
@@ -33,7 +23,121 @@
              separator
              (join (cdr list) separator)))))
 
-;;; Compiler
+;;;; Reader
+
+;;; It is a basic Lisp reader. It does not use advanced stuff
+;;; intentionally, because we want to use it to bootstrap a simple
+;;; Lisp. The main entry point is the function `ls-read', which
+;;; accepts a strings as argument and return the Lisp expression.
+(defun make-string-stream (string)
+  (cons string 0))
+
+(defun %peek-char (stream)
+  (if (streamp stream)
+      (peek-char nil stream nil)
+      (and (< (cdr stream) (length (car stream)))
+           (char (car stream) (cdr stream)))))
+
+(defun %read-char (stream)
+  (if (streamp stream)
+      (read-char stream nil)
+      (and (< (cdr stream) (length (car stream)))
+           (prog1 (char (car stream) (cdr stream))
+             (incf (cdr stream))))))
+
+(defun whitespacep (ch)
+  (or (char= ch #\space) (char= ch #\newline) (char= ch #\tab)))
+
+(defun skip-whitespaces (stream)
+  (loop for ch = (%peek-char stream)
+     while (and ch (whitespacep ch))
+     do (%read-char stream)))
+
+(defun terminalp (ch)
+  (or (null ch) (whitespacep ch) (char= #\) ch)))
+
+(defun read-until (stream func)
+  (let ((string ""))
+    (loop for ch = (%peek-char stream)
+       until (funcall func ch)
+       do (setq string (concat string (string ch)))
+       do (%read-char stream))
+    string))
+
+(defun skip-whitespaces-and-comments (stream)
+  (let (ch)
+    (skip-whitespaces stream)
+    (setq ch (%peek-char stream))
+    (while (and ch (eql ch #\;))
+      (read-until stream (lambda (x) (eql x #\newline)))
+      (skip-whitespaces stream)
+      (setq ch (%peek-char stream)))))
+
+(defun %read-list (stream)
+  (skip-whitespaces-and-comments stream)
+  (let ((ch (%peek-char stream)))
+    (cond
+      ((char= ch #\))
+       (%read-char stream)
+       nil)
+      ((char= ch #\.)
+       (%read-char stream)
+       (skip-whitespaces-and-comments stream)
+       (prog1 (ls-read stream)
+         (unless (char= (%read-char stream) #\))
+           (error "')' was expected."))))
+      (t
+       (cons (ls-read stream) (%read-list stream))))))
+
+(defvar *eof* (make-symbol "EOF"))
+(defun ls-read (stream)
+  (skip-whitespaces-and-comments stream)
+  (let ((ch (%peek-char stream)))
+    (cond
+      ((null ch)
+       *eof*)
+      ((char= ch #\()
+       (%read-char stream)
+       (%read-list stream))
+      ((char= ch #\')
+       (%read-char stream)
+       (list 'quote (ls-read stream)))
+      ((char= ch #\`)
+       (%read-char stream)
+       (list 'backquote (ls-read stream)))
+      ((char= ch #\")
+       (%read-char stream)
+       (prog1 (read-until stream (lambda (ch) (char= ch #\")))
+         (%read-char stream)))
+      ((char= ch #\,)
+       (%read-char stream)
+       (if (eql (%peek-char stream) #\@)
+           (progn (%read-char stream) (list 'unquote-splicing (ls-read stream)))
+           (list 'unquote (ls-read stream))))
+      ((char= ch #\#)
+       (%read-char stream)
+       (ecase (%read-char stream)
+         (#\'
+          (list 'function (ls-read stream)))))
+      (t
+       (let ((string (read-until stream #'terminalp)))
+         (if (every #'digit-char-p string)
+             (parse-integer string)
+             (intern (string-upcase string))))))))
+
+(defun ls-read-from-string (string)
+  (ls-read (make-string-stream string)))
+
+
+;;;; Compiler
+
+(let ((counter 0))
+  (defun make-var-binding (symbol)
+    (cons symbol (format nil "v~d" (incf counter)))))
+
+(let ((counter 0))
+  (defun make-func-binding (symbol)
+    (cons symbol (format nil "f~d" (incf counter)))))
 
 (defvar *compilations* nil)
 
@@ -147,6 +251,13 @@
 	  (ls-compile pred env fenv)
 	  (ls-compile-block body env fenv)))
 
+(define-compilation function (x)
+  (cond
+    ((and (listp x) (eq (car x) 'lambda))
+     (ls-compile x env fenv))
+    ((symbolp x)
+     (lookup-function x fenv))))
+
 (defmacro eval-when-compile (&body body)
   `(eval-when (:compile-toplevel :execute)
      ,@body))
@@ -159,7 +270,6 @@
       nil
       *eval-when-compilations*))
 
-
 (defmacro define-transformation (name args form)
   `(define-compilation ,name ,args
      (ls-compile ,form env fenv)))
@@ -167,7 +277,66 @@
 (define-transformation progn (&rest body)
   `((lambda () ,@body)))
 
-;;; aritmetic primitives
+(define-transformation let (bindings &rest body)
+  `((lambda ,(mapcar 'car bindings) ,@body)
+    ,@(mapcar 'cadr bindings)))
+
+;;; A little backquote implementation without optimizations of any
+;;; kind for lispstrack.
+(defun backquote-expand-1 (form)
+  (cond
+    ((symbolp form)
+     (list 'quote form))
+    ((atom form)
+     form)
+    ((eq (car form) 'unquote)
+     (car form))
+    ((eq (car form) 'backquote)
+     (backquote-expand-1 (backquote-expand-1 (cadr form))))
+    (t
+     (cons 'append
+           (mapcar (lambda (s)
+                     (cond
+                       ((and (listp s) (eq (car s) 'unquote))
+                        (list 'list (cadr s)))
+                       ((and (listp s) (eq (car s) 'unquote-splicing))
+                        (cadr s))
+                       (t
+                        (list 'list (backquote-expand-1 s)))))
+                   form)))))
+
+(defun backquote-expand (form)
+  (if (and (listp form) (eq (car form) 'backquote))
+      (backquote-expand-1 (cadr form))
+      form))
+
+;;; Some Tests comparing backquote agains the backquote of the host
+;;; Lisp. It is not very exhaustive, but we just want a working
+;;; backquotation to be able bootstrap this program.
+(macrolet ((test (form1 form2)
+             `(assert (equal ,form1 ,form2))))
+  (test (backquote (1 2 3 4))
+        `(1 2 3 4))
+  (test (backquote (1 2 (+ 3 4)))
+        `(1 2 (+ 3 4)))
+  (test (backquote (1 2 (unquote (+ 3 4))))
+        `(1 2 ,(+ 3 4)))
+  (test (backquote (1 2 (unquote-splicing '(3 4))))
+        `(1 2 ,@'(3 4)))
+  (test (backquote (backquote x))
+        ``x)
+  (let ((x 10))
+    (test `',x
+          (backquote (quote (unquote x)))))
+  (let ((x 10))
+    (test (eval ``(,,x))
+          (eval (backquote (backquote ((unquote (unquote x)))))))))
+
+(define-transformation backquote (form)
+  (backquote-expand-1 form))
+
+;;; Primitives
+
 (define-compilation + (x y)
   (concat "((" (ls-compile x env fenv) ") + (" (ls-compile y env fenv) "))"))
 
@@ -260,17 +429,16 @@
                 code)
       (setq *literals* nil))))
 
-
 (defun ls-compile-file (filename output)
   (with-open-file (in filename)
     (with-open-file (out output :direction :output :if-exists :supersede)
       (loop
-         for x = (read in nil) while x
+         for x = (ls-read in)
+         until (eq x *eof*)
          for compilation = (ls-compile-toplevel x)
          when compilation do (write-line (concat compilation "; ") out)))))
 
 
 ;;; Testing
-
 (defun compile-test ()
   (ls-compile-file "test.lisp" "test.js"))