Parser.

diff --git a/implementations/scheme-chicken/s.scm b/implementations/scheme-chicken/s.scm
index d15a9a6..e910c96 100644 (file)
--- a/implementations/scheme-chicken/s.scm
+++ b/implementations/scheme-chicken/s.scm
@@ -1,14 +1,48 @@
+(import (chicken string))
+
 (define (string-replace str from to)
-  (string-intersperse (string-split str from) to)
-  )
+  (string-intersperse (string-split str from #t) to))
 
 (define (tokenize str)
   (string-split
-    (string-replace 
-      (string-replace str "]" " ] ")
-      "[" " [ "
-      )
-    )
-  )
+    (string-replace (string-replace str "]" " ] ") "[" " [ ")))
+
+(define (tokenator token)
+  (cond ((string->number token) (string->number token))
+        ((string=? token "true") #t)
+        ((string=? token "false") #f)
+        (else token)))
+
+(define (expect-right-bracket tokens acc) 
+  (if (null? tokens)
+    (/ 2 0)
+    (expect-right-bracket-lookahead (car tokens) (cdr tokens) acc)))
+
+(define (expect-right-bracket-lookahead token tokens acc)
+  (cond ((string=? token "]") (values acc tokens))
+        ((string=? token "[")
+          (receive (sub_list rest) (expect-right-bracket tokens '())
+            (receive (el rrest) (expect-right-bracket rest acc)
+              (values (cons sub_list el) rrest))))
+        (else 
+          (receive (el rest) (expect-right-bracket tokens acc)
+            (values (cons (tokenator token) el) rest)))))
+
+(define (one-token-lookahead token tokens)
+  (cond ((string=? token "]") (/ 1 0))
+        ((string=? token "[") (expect-right-bracket tokens '()))
+        (else (values (tokenator token) tokens))))
+
+(define (parse0 tokens acc)
+  (if (null? tokens)
+    acc
+    (receive (term rest_of_tokens)
+      (one-token-lookahead (car tokens) (cdr tokens))
+      (cons term (parse0 rest_of_tokens acc)))))
+
+(define (parse tokens) (parse0 tokens '()))
+
 
+(display (parse (tokenize "ab  cd [[]] 234 [true] false")))
+(newline)