Merge branch 'master' into dom

js-assembler/runtime-src/baselib-lists.js

@@ -48,19 +48,20 @@
         this.rest = rest;
     };
 
+    var makePair = function (first, rest) {
+        return new Cons(first, rest);
+    };
+
     Cons.prototype.reverse = function () {
         var lst = this;
         var ret = EMPTY;
         while (lst !== EMPTY) {
-            ret = Cons.makeInstance(lst.first, ret);
+            ret = makePair(lst.first, ret);
             lst = lst.rest;
         }
         return ret;
     };
     
-    Cons.makeInstance = function (first, rest) {
-        return new Cons(first, rest);
-    };
 
     // FIXME: can we reduce the recursion on this?
     Cons.prototype.equals = function (other, aUnionFind) {
@@ -82,7 +83,7 @@
         var ret = b;
         var lst = this.reverse();
         while (lst !== EMPTY) {
-            ret = Cons.makeInstance(lst.first, ret);
+            ret = makePair(lst.first, ret);
             lst = lst.rest;
         }
         
@@ -160,19 +161,18 @@
     var isEmpty = function (x) { return x === EMPTY; };
 
 
-    var makePair = Cons.makeInstance;
 
     var makeList = function () {
         var result = EMPTY, i;
         for (i = arguments.length - 1; i >= 0; i--) {
-            result = Cons.makeInstance(arguments[i], result);
+            result = makePair(arguments[i], result);
         }
         return result;
     };
 
 
     // Coerse a list back into a JavaScript array.
-    var listToArray = function(lst) {
+    var listToArray = function (lst) {
         var result = [];
         while (lst !== EMPTY) {
             result.push(lst.first);
@@ -185,14 +185,17 @@
     // isList: Any -> Boolean
     // Returns true if x is a list (a chain of pairs terminated by EMPTY).
     var isList = function (x) { 
-        while (x !== EMPTY) {
+        var tortoise, hare;
-            if (x instanceof Cons) {
+        tortoise = hare = x;
-                x = x.rest;
+        if (hare === EMPTY) { return true; }
-            } else {
+        while (true) {
-                return false;
+            if (!(hare instanceof Cons)) { return false; }
-            }
+            if (tortoise instanceof Cons) { tortoise = tortoise.rest; }
+            hare = hare.rest;
+            if (hare instanceof Cons) { hare = hare.rest; }
+            if (hare === EMPTY) { return true; }
+            if (tortoise === hare) { return false; }
         }
-        return true;
     };
 
 

js-assembler/runtime-src/baselib-vectors.js

@@ -59,7 +59,7 @@
     Vector.prototype.toList = function () {
         var ret = baselib.lists.EMPTY, i;
         for (i = this.length() - 1; i >= 0; i--) {
-            ret = baselib.lists.Cons.makeInstance(this.elts[i], ret);           
+            ret = baselib.lists.makePair(this.elts[i], ret);           
         }       
         return ret;
     };

tests/more-tests/lists.expected

@@ -2,6 +2,10 @@
 ("hello" "world")
 true
 true
+true
+false
+true
+true
 false
 true
 hello
@@ -19,3 +23,4 @@ true
 false
 false
 true
+(3 1 4)

tests/more-tests/lists.rkt

@@ -3,6 +3,11 @@
 '(1 2 3)
 (list "hello" "world")
 
+(list? empty)
+(list? '(1))
+(list? '(1 2))
+(list? 1)
+
 (empty? empty)
 (empty? '())
 (cons? '())
@@ -24,3 +29,6 @@
 (ormap even? '(5))
 (ormap even? '(1 3 5 7))
 (ormap even? '(1 3 8 7))
+
+
+(vector->list #(3 1 4))

tests/more-tests/sharing.expected

@@ -22,3 +22,5 @@ jill
 jane
 
 
+true
+false

tests/more-tests/sharing.rkt

@@ -71,3 +71,11 @@
   (newline)
   (for-each displayln (map person-name (person-friends c)))
   (newline))
+
+
+
+;; Make sure cyclic lists are treated correctly by list?
+(shared ([a (cons 1 a)])
+  (begin
+    (displayln (pair? a))
+    (displayln (list? a))))