add exception to stack, and set const to other exceptions

Author: xtaci

include/binary_search_tree.h

@@ -53,7 +53,7 @@ namespace alg
 
 private:
 treeNode * m_root;
-BSTException error;
+const BSTException error;
 
 public:
 BST():m_root(NULL){};

include/perfect_hash.h

@@ -22,18 +22,19 @@
 
 namespace alg
 {
-class PerfHTException: public std::exception
+template<typename T=uintptr_t>
+class PerfHT 
 {
-public:
-virtual const char * what() const throw()
+private:
+class PerfHTException: public std::exception
 {
-return "key does not exist";
-}
-};
+public:
+virtual const char * what() const throw()
+{
+return "key does not exist";
+}
+};
 
-template<typename T=uintptr_t>
-class PerfHT {
-private:
 // Level-2 Slot definition
 class SlotL2 {
 public:
@@ -60,7 +61,7 @@ namespace alg
 struct SlotL1 * slots;// level 1 slots
 struct UHash params; // 1st level 
 uint32_t num_slots;
-PerfHTException error;
+const PerfHTException error;
 
 public:
 PerfHT(uint32_t keys[], uint32_t len) 

include/stack.h

@@ -19,6 +19,7 @@
 
 #include <stdint.h>
 #include <stdbool.h>
+#include <exception>
 
 /** 
  * Stack has three properties. capacity stands for the maximum number of
@@ -29,9 +30,29 @@ template<typename T=uintptr_t>
 class Stack
 {
 private:
+class StackEmptyException: public std::exception
+{
+public:
+virtual const char * what() const throw()
+{
+return "stack is empty";
+}
+};
+
+class StackIndexOutOfBoundException: public std::exception
+{
+public:
+virtual const char * what() const throw()
+{
+return "Index out of bound.";
+}
+};
+
 uint32_t m_capacity;// the total capacity
 uint32_t m_size;// current stack size
 T * m_elements;// the elements
+const StackEmptyException	exp_empty;
+const StackIndexOutOfBoundException exp_ioob;
 
 public:
 /**
@@ -47,10 +68,12 @@ class Stack
 delete [] m_elements;
 }
 
+
 private:
 Stack(const Stack&);
 Stack& operator=(const Stack&);
 
+
 public:
 /**
  * test whether the stack is empty
@@ -66,9 +89,12 @@ class Stack
 }
 
 /**
- * get the top element, test is_empty() before top()
+ * get the top element
 */
-inline const T& top() const { return m_elements[m_size-1]; };
+inline const T& top() const { 
+if (m_size==0) throw exp_empty;
+return m_elements[m_size-1]; 
+};
 
 /**
  * push an element into the stack
@@ -88,7 +114,13 @@ class Stack
  */
 inline uint32_t count() const { return m_size; }
 
-inline const T& operator[] (int idx) const { return m_elements[m_size-1-idx]; }
+/**
+ * return value by index
+ */
+inline const T& operator[] (int idx) const { 
+if (idx<0 || idx >= m_capacity) throw exp_ioob;
+return m_elements[m_size-1-idx]; 
+}
 };
 
 #endif //