From 91321dab830328d4e5854aa9da7dd54c5e8cc520 Mon Sep 17 00:00:00 2001
From: Abhijith <abchatra@microsoft.com>
Date: Sun, 8 Jan 2017 18:43:14 -0800
Subject: [PATCH] Support for default values in array.

---
 libs/core/pxt.cpp | 66 ++++++++++++++---------------------------------
 libs/core/pxt.h   |  7 +----
 2 files changed, 21 insertions(+), 52 deletions(-)

diff --git a/libs/core/pxt.cpp b/libs/core/pxt.cpp
index 2f8c67cb..639b8da0 100644
--- a/libs/core/pxt.cpp
+++ b/libs/core/pxt.cpp
@@ -150,15 +150,10 @@ namespace pxt {
       
       if (i < length)
       {
-        if (data[i] != Segment::MissingValue)
-        {
           return data[i];          
-        }
-        error(ERR_MISSING_VALUE);
-        return 0;
       }
       error(ERR_OUT_OF_BOUNDS);
-      return 0;
+      return Segment::DefaultValue;
     }
 
     void Segment::set(uint32_t i, uint32_t value) 
@@ -223,12 +218,8 @@ namespace pxt {
          {
            memcpy(tmp, data, size * sizeof(uint32_t));
          }
-
-         //fill the rest with missing values;
-         for(uint16_t i = size; i < newSize; i++)
-         {
-           tmp[i] = Segment::MissingValue;
-         }
+        //fill the rest with default value
+         memset(tmp + size, Segment::DefaultValue, (newSize - size) * sizeof(uint32_t));
 
          //free older segment;
          ::operator delete(data); 
@@ -280,12 +271,12 @@ namespace pxt {
       if (length > 0)
       {
         uint32_t value = data[length];
-        data[length] = Segment::MissingValue;
+        data[length] = Segment::DefaultValue;
         --length;
         return value;
       }
       error(ERR_OUT_OF_BOUNDS);      
-      return 0;
+      return Segment::DefaultValue;
     }
 
     //this function removes an element at index i and shifts the rest of the elements to
@@ -306,7 +297,7 @@ namespace pxt {
           memmove(data + i, data + i + 1, (length - i - 1) * sizeof(uint32_t));
         }
         length--;        
-        data[length] = Segment::MissingValue;        
+        data[length] = Segment::DefaultValue;        
 #ifdef DEBUG_BUILD
         printf("After Segment::remove index:%u\n", i);
         this->print();
@@ -314,7 +305,7 @@ namespace pxt {
         return ret;
       }
       error(ERR_OUT_OF_BOUNDS);
-      return 0;
+      return Segment::DefaultValue;
     }
 
     //this function inserts element value at index i by shifting the rest of the elements right.     
@@ -360,32 +351,13 @@ namespace pxt {
 
     bool Segment::isValidIndex(uint32_t i)
     {
-      if (i > length || data[i] == Segment::MissingValue)
+      if (i > length)
       {
         return false;
       }
       return true;
     }
 
-    bool Segment::getNextValidIndex(uint32_t i, uint32_t *result)
-    {
-      while (i < length)
-      {
-        if (data[i] != Segment::MissingValue)
-        {
-           *result = i;
-
-#ifdef DEBUG_BUILD
-           printf("In Segment::getNextValidIndex result=%u\n",i);
-           this->print();
-#endif                  
-           return true;
-        }
-        i++;
-      }
-      return false;
-    }
-
     void Segment::destroy()
     {
 #ifdef DEBUG_BUILD
@@ -447,7 +419,7 @@ namespace pxt {
 
     void RefCollection::insertAt(int i, uint32_t value) 
     {
-      if (i < length())
+      if (((uint32_t)i) < length())
       {
         head.insert(i, value);
         if (isRef())
@@ -480,26 +452,31 @@ namespace pxt {
       {
         StringData *xx = (StringData*)x;
         uint32_t i = start;
-        while(head.getNextValidIndex(start, &i))
+        while(head.isValidIndex(i))
         {
           StringData *ee = (StringData*)head.get(i);
-          if (xx->len == ee->len && memcmp(xx->data, ee->data, xx->len) == 0)
+          if (ee == xx)
+          {
+            //handles ee being null
+            return (int) i;
+          }
+          if (ee && xx->len == ee->len && memcmp(xx->data, ee->data, xx->len) == 0)
           {
             return (int)i;
           }
-          start = i;
+          i++;
         }
       } 
       else 
       {
         uint32_t i = start;
-        while(head.getNextValidIndex(start, &i))
+        while(head.isValidIndex(i))
         {
           if (head.get(i) == x)
           {
             return (int)i;
           }
-          start = i;
+          i++;
         }
       }
 
@@ -550,12 +527,9 @@ namespace pxt {
     {
       if (this->isRef())
       {
-        uint32_t start = 0;
-        uint32_t i = 0;
-        while(head.getNextValidIndex(start, &i))
+        for(uint32_t i = 0; i < this->head.getLength(); i++)
         {
           decr(this->head.get(i));
-          start = i;
         }
       }
       this->head.destroy();
diff --git a/libs/core/pxt.h b/libs/core/pxt.h
index 6da5ec7c..95224382 100644
--- a/libs/core/pxt.h
+++ b/libs/core/pxt.h
@@ -38,7 +38,6 @@ namespace pxt {
     ERR_OUT_OF_BOUNDS = 8,
     ERR_REF_DELETED = 7,
     ERR_SIZE = 9,
-    ERR_MISSING_VALUE = 10,
   } ERROR;
 
   extern const uint32_t functionsAndBytecode[];
@@ -175,7 +174,7 @@ namespace pxt {
       uint16_t size;
 
       static const uint16_t MaxSize = 0xFFFF;
-      static const uint32_t MissingValue = 0x80000000;
+      static const uint32_t DefaultValue = 0x0;
 
       static uint16_t growthFactor(uint16_t size);      
       void growByMin(uint16_t minSize);
@@ -197,10 +196,6 @@ namespace pxt {
       uint32_t remove(uint32_t i);
       void insert(uint32_t i, uint32_t value);
 
-      //Returns true if there is a valid index greater than or equal to 'i', returns false otherwise
-      //If 'i' is valid returns it in 'result', if not tries to find the next valid
-      //index < length which is valid.
-      bool getNextValidIndex(uint32_t i, uint32_t *result);
       bool isValidIndex(uint32_t i);
 
       void destroy();