opal · May 11, 2015 · May 12, 2015 · May 14, 2015 · May 14, 2015
Showing with 55 additions and 11 deletions.

+55 −1 opal/corelib/array.rb

+0 −10 spec/filters/bugs/array.rb
diff --git a/opal/corelib/array.rb b/opal/corelib/array.rb
@@ -573,7 +573,61 @@ def collect!(&block)
 
     self
   end
-
+
+  def combination(n)
+    num = Opal.coerce_to! n, Integer, :to_int
+    return enum_for :combination, num unless block_given?
+
+    %x{
+      var i;
+      var length;
+      var stack;
+      var chosen;
+      var lev;
+      var done;
+      var next;
+
+      if (num === 0) {
+        #{yield []}
+      } else if (num === 1) {
+        for (i = 0, length = self.length; i < length; i++) {
+          #{yield `[self[i]]`}
+        }
+      }
+      else if (num === self.length) {
+        #{yield `self.slice()`}
+      }
+      else if (num >= 0 && num < self.length) {
+        stack = [];
+        for (i = 0; i <= num + 1; i++) {
+          stack.push(0);
+        }
+        
+        chosen = [];
+        lev = 0;
+        done = false;        
+        stack[0] = -1;
+        
+        while (!done) {
+          chosen[lev] = self[stack[lev+1]];
+          while (lev < num - 1) {
+            lev++;
+            next = stack[lev+1] = stack[lev] + 1;
+            chosen[lev] = self[next];
+          }
+          #{ yield `chosen.slice()` }
+          lev++;
+          do {
+            done = (lev === 0);
+            stack[lev]++;
+            lev--;
+          } while ( stack[lev+1] + num === self.length + lev + 1 );
+        }
+      }
+    }
+    self
+  end
+
   def compact
     %x{
       var result = [];

diff --git a/spec/filters/bugs/array.rb b/spec/filters/bugs/array.rb
@@ -1,16 +1,6 @@
 opal_filter "Array" do
   fails "Array#clone copies singleton methods"
 
-  fails "Array#combination generates from a defensive copy, ignoring mutations"
-  fails "Array#combination yields a partition consisting of only singletons"
-  fails "Array#combination yields [] when length is 0"
-  fails "Array#combination yields a copy of self if the argument is the size of the receiver"
-  fails "Array#combination yields nothing if the argument is out of bounds"
-  fails "Array#combination yields the expected combinations"
-  fails "Array#combination yields nothing for out of bounds length and return self"
-  fails "Array#combination returns self when a block is given"
-  fails "Array#combination returns an enumerator when no block is provided"
-
   fails "Array#<=> calls <=> left to right and return first non-0 result"
   fails "Array#<=> returns -1 if the arrays have same length and a pair of corresponding elements returns -1 for <=>"
   fails "Array#<=> returns +1 if the arrays have same length and a pair of corresponding elements returns +1 for <=>"