Ticket #193: shell-sorts2.patch

HowTo/290-TranslatePseudoCodeToCobra1.cobra

@@ -25 +25 @@
             assert sortMethod([4,3,2,1]) == [1,2,3,4]
             assert sortMethod(['c','d','b','a']) == ['a','b','c','d']
             assert sortMethod([1,1,1,1]) == [1,1,1,1]
+            assert sortMethod([1,2]) == [1,2]
+            assert sortMethod([2,1]) == [1,2]
+            assert sortMethod([3,2,1]) == [1,2,3]
+            assert sortMethod([5,1,2,3,4]) == [1,2,3,4,5]
+            assert sortMethod([9,1,2,3,4]) == [1,2,3,4,9]
+            assert sortMethod([7,5,1,2,3,4,0]) == [0,1,2,3,4,5,7]
 
         def bubbleSort(list) as dynamic?
             """
@@ -195 +201 @@
                     result.addRange(.quickSort(more))
                     return result
 
-        def main
-            .quickSort([1,2,3,4])
+    def shellSort(list) as dynamic is shared
+        """
+        From http://en.wikipedia.org/wiki/Shell_sort#Shell_sort_algorithm_in_pseudocode
+            input: an array a of length n with array elements numbered 0 to n - 1
+            inc = round(n/2)
+            while inc > 0 do:
+                for i in inc : n - 1 do:
+                    temp = a[i]
+                    j = i
+                    while j >= inc and a[j - inc] > temp
+                        a[j] = a[j - inc]
+                        j = j - inc
+                    a[j] = temp
+                inc = round(inc / 2.2)
+        """
+        test 
+            .testSort(ref .shellSort) 
+        body 
+            n = list.count 
+            inc = n // 2
+            while inc > 0
+                for i in inc : n # vs n-1, Cobra range is exclusive of endval 
+                    temp = list[i]
+                    j = i
+                    while j >= inc and list[j - inc] > temp
+                        list[j] = list[j - inc]
+                        j = j - inc
+                    list[j] = temp
+                inc = (inc+1) // 2.2 # round upwards
+                #inc = Math.round(Convert.toDecimal(inc) / 2.2, MidpointRounding.AwayFromZero) to int
+            return list 
+        
+    def shellSortAlt(list) as dynamic is shared
+        """
+        Alternate shell sort implementation: uses bottom portion of range, end-of-loop conditions
+        and breaks early where no exchanges.
+        """
+        test 
+            .testSort(ref .shellSortAlt) 
+        body 
+            top = list.count 
+            nExchg = 0 
+            gap = top // 2
+            post while gap > 0 
+                post while nExchg # exchanges happened 
+                    nExchg = 0 
+                    for i in 0 : top - gap 
+                        value = list[i]
+                        if value > list[i+gap] 
+                            list[i] = list[i+gap] 
+                            list[i+gap] = value 
+                            nExchg += 1 
+                gap = gap // 2
+            return list 
+        
+            
+    def main
+        .quickSort([1,2,3,4])

HowTo/292-TranslatePseudoCodeToCobra2.cobra

@@ -22 +22 @@
             assert sortMethod([4,3,2,1]) == [1,2,3,4]
             assert sortMethod(['c','d','b','a']) == ['a','b','c','d']
             assert sortMethod([1,1,1,1]) == [1,1,1,1]
+            assert sortMethod([1,2]) == [1,2]
+            assert sortMethod([2,1]) == [1,2]
+            assert sortMethod([3,2,1]) == [1,2,3]
+            assert sortMethod([5,1,2,3,4]) == [1,2,3,4,5]
+            assert sortMethod([9,1,2,3,4]) == [1,2,3,4,9]
+            assert sortMethod([7,5,1,2,3,4,0]) == [0,1,2,3,4,5,7]
 
         def bubbleSort(list as IList) as dynamic
             """
@@ -188 +194 @@
                     result.addRange(.quickSort(more))
                     return result
 
-        def main
-            .quickSort([1,2,3,4])
+        def shellSort(list) as dynamic
+            """
+            From http://en.wikipedia.org/wiki/Shell_sort#Shell_sort_algorithm_in_pseudocode
+            input: an array a of length n with array elements numbered 0 to n - 1
+                inc = round(n/2)
+                while inc > 0 do:
+                    for i in inc : n - 1 do:
+                        temp = a[i]
+                        j = i
+                        while j >= inc and a[j - inc] > temp
+                            a[j] = a[j - inc]
+                            j = j - inc
+                        a[j] = temp
+                    inc = round(inc / 2.2)
+            """
+            test 
+                .testSort(ref .shellSort) 
+            body 
+                n = list.count 
+                inc = n // 2
+                while inc > 0
+                    for i in inc : n    # vs n-1, Cobra range is exclusive of endval 
+                        temp = list[i]
+                        j = i
+                        while j >= inc and list[j - inc] > temp
+                            list[j] = list[j - inc]
+                            j = j - inc
+                        list[j] = temp
+                    inc = ((inc+1) // 2.2)      # round upwards
+                    #inc = Math.round(Convert.toDecimal(inc) / 2.2, MidpointRounding.AwayFromZero) to int
+                return list 
+
+        def shellSortAlt(list) as dynamic
+            """
+            Alternate shell sort implementation: uses bottom portion of range, end-of-loop conditions
+            and breaks early where no exchanges.
+            """
+            test 
+                .testSort(ref .shellSortAlt) 
+            body 
+                top = list.count 
+                nExchg = false 
+                gap = top // 2
+                post while gap > 0 
+                    post while nExchg # exchanges happened 
+                        nExchg = false 
+                        for i in 0 : top - gap 
+                            value = list[i]
+                            if value > list[i+gap] 
+                                list[i] = list[i+gap] 
+                                list[i+gap] = value 
+                                nExchg = true 
+                    gap = gap // 2
+                return list 
+            
+    def main
+        .quickSort([1,2,3,4])