Start implementing symbol ldict.

src/util-bst-ldict.scm

@@ -0,0 +1,48 @@
+
+(declare (unit util-bst-ldict))
+
+(import duck)
+
+(module*
+ util-bst-ldict
+ #:doc ("xxx")
+ (
+  )
+
+ (import scheme
+	 util-bst)
+
+ (define (symbol<? a b)
+   (string<? (symbol->string a)
+	     (symbol->string b)))
+
+ (define (make-ldict)
+   (make-bst 'symbol eq? symbol<?))
+
+ (define ldict? (bst? 'symbol))
+
+ (define ldict-empty? bst-empty?)
+ (define ldict-contains? bst-contains?)
+ (define ldict-ref bst-ref)
+ (define ldict-remove bst-remove)
+ (define ldict-set bst-set)
+ (define ldict-keys bst-keys)
+
+ (define (ldict-map proc ld)
+   (let ((i 0)
+	 (both? ((procedure-arity>=? 2) proc))
+	 (index? ((procedure-arity=>? 3) proc)))
+     (bst-map-bst ld
+		  (lambda (k v)
+		    (let ((r (if both?
+				 (if index?
+				     (proc k v i)
+				     (proc k v))
+				 (proc v))))
+		      (set! i (add1 i))
+		      r)))))
+
+ (define (ldict-filter pred? ld)
+   (bst-filter ld pred?))
+
+ )