Convert BaseQueue/Queue/PQueue into templates, including iterator support

src/CMakeLists.txt

@@ -272,7 +272,6 @@ set(MAIN_SRCS
     PolicyFile.cc
     PrefixTable.cc
     PriorityQueue.cc
-    Queue.cc
     RandTest.cc
     RE.cc
     Reassem.cc

src/Queue.cc

@@ -1,137 +0,0 @@
-// See the file "COPYING" in the main distribution directory for copyright.
-
-#include "zeek-config.h"
-
-#include <string.h>
-
-#include "Queue.h"
-
-BaseQueue::BaseQueue(int size)
-	{
-	const int DEFAULT_CHUNK_SIZE = 10;
-
-	chunk_size = DEFAULT_CHUNK_SIZE;
-
-	head = tail = num_entries = 0;
-
-	if ( size < 0 )
-		{
-		entry = new ent[1];
-		max_entries = 0;
-		}
-	else
-		{
-		if ( (entry = new ent[chunk_size+1]) )
-			max_entries = chunk_size;
-		else
-			{
-			entry = new ent[1];
-			max_entries = 0;
-			}
-		}
-	}
-
-void BaseQueue::push_front(ent a)
-	{
-	if ( num_entries == max_entries )
-		{
-		resize(max_entries+chunk_size);	// make more room
-		chunk_size *= 2;
-		}
-
-	++num_entries;
-	if ( head )
-		entry[--head] = a;
-	else
-		{
-		head = max_entries;
-		entry[head] = a;
-		}
-	}
-
-void BaseQueue::push_back(ent a)
-	{
-	if ( num_entries == max_entries )
-		{
-		resize(max_entries+chunk_size);	// make more room
-		chunk_size *= 2;
-		}
-
-	++num_entries;
-	if ( tail < max_entries )
-		entry[tail++] = a;
-	else
-		{
-		entry[tail] = a;
-		tail = 0;
-		}
-	}
-
-ent BaseQueue::pop_front()
-	{
-	if ( ! num_entries )
-		return 0;
-
-	--num_entries;
-	if ( head < max_entries )
-		return entry[head++];
-	else
-		{
-		head = 0;
-		return entry[max_entries];
-		}
-	}
-
-ent BaseQueue::pop_back()
-	{
-	if ( ! num_entries )
-		return 0;
-
-	--num_entries;
-	if ( tail )
-		return entry[--tail];
-	else
-		{
-		tail = max_entries;
-		return entry[tail];
-		}
-	}
-
-int BaseQueue::resize(int new_size)
-	{
-	if ( new_size < num_entries )
-		new_size = num_entries; // do not lose any entries
-
-	if ( new_size != max_entries )
-		{
-		// Note, allocate extra space, so that we can always
-		// use the [max_entries] element.
-		// ### Yin, why not use realloc()?
-		ent* new_entry = new ent[new_size+1];
-
-		if ( new_entry )
-			{
-			if ( head <= tail )
-				memcpy( new_entry, entry + head,
-					sizeof(ent) * num_entries );
-			else
-				{
-				int len = num_entries - tail;
-				memcpy( new_entry, entry + head,
-					sizeof(ent) * len );
-				memcpy( new_entry + len, entry,
-					sizeof(ent) * tail );
-				}
-			delete [] entry;
-			entry = new_entry;
-			max_entries = new_size;
-			head = 0;
-			tail = num_entries;
-			}
-		else
-			{ // out of memory
-			}
-		}
-
-	return max_entries;
-	}

src/Queue.h

@@ -3,8 +3,8 @@
 #ifndef queue_h
 #define queue_h
 
-// BaseQueue.h --
+// Queue.h --
-//	Interface for class BaseQueue, current implementation is as an
+//	Interface for class Queue, current implementation is as an
 //	array of ent's.  This implementation was chosen to optimize
 //	getting to the ent's rather than inserting and deleting.
 //	Also push's and pop's from the front or the end of the queue
@@ -21,35 +21,214 @@
 //	Entries must be either a pointer to the data or nonzero data with
 //	sizeof(data) <= sizeof(void*).
 
-#include "List.h"
+template<typename T>
-
+class QueueIterator
-class BaseQueue {
+	{
+	T* const entries;
+	int offset;
+	int num_entries;
 public:
-	~BaseQueue()		{ delete[] entry; }
+	QueueIterator(T* entries, int offset, int num_entries) :
+		entries(entries), offset(offset), num_entries(num_entries) {}
+	bool operator==(const QueueIterator& rhs) { return entries == rhs.entries && offset == rhs.offset; }
+	bool operator!=(const QueueIterator& rhs) { return entries != rhs.entries || offset != rhs.offset; }
+	QueueIterator & operator++() { offset++; return *this; }
+	QueueIterator operator++(int) { auto t = *this; offset++; return t; }
+	QueueIterator & operator--() { offset--; return *this; }
+	QueueIterator operator--(int) { auto t = *this; offset--; return t; }
+	std::ptrdiff_t operator-(QueueIterator const& sibling) const { return offset - sibling.offset; }
+	QueueIterator & operator+=(int amount) { offset += amount; return *this; }
+	QueueIterator & operator-=(int amount) { offset -= amount; return *this; }
+	bool operator<(QueueIterator const&sibling) const { return offset < sibling.offset;}
+	bool operator<=(QueueIterator const&sibling) const { return offset <= sibling.offset; }
+	bool operator>(QueueIterator const&sibling) const { return offset > sibling.offset; }
+	bool operator>=(QueueIterator const&sibling) const { return offset >= sibling.offset; }
+	T& operator[](int index)
+		{
+		return entries[index];
+		}
+	T& operator*()
+		{
+		return entries[offset];
+		}
+	};
+
+namespace std {
+	template<typename T>
+	class iterator_traits<QueueIterator<T> >
+	{
+	public:
+		using difference_type = std::ptrdiff_t;
+		using size_type = std::size_t;
+		using value_type = T;
+		using pointer = T*;
+		using reference = T&;
+		using iterator_category = std::random_access_iterator_tag;
+	};
+}
+
+
+template<typename T>
+class Queue {
+public:
+	explicit Queue(int size = 0)
+		{
+		const int DEFAULT_CHUNK_SIZE = 10;
+		chunk_size = DEFAULT_CHUNK_SIZE;
+
+		head = tail = num_entries = 0;
+
+		if ( size < 0 )
+			{
+			entries = new T[1];
+			max_entries = 0;
+			}
+		else
+			{
+			if ( (entries = new T[chunk_size+1]) )
+				max_entries = chunk_size;
+			else
+				{
+				entries = new T[1];
+				max_entries = 0;
+				}
+			}
+		}
+
+	~Queue()		{ delete[] entries; }
 
 	int length() const	{ return num_entries; }
-	int resize(int = 0);	// 0 => size to fit current number of entries
+	int resize(int new_size = 0)	// 0 => size to fit current number of entries
+		{
+		if ( new_size < num_entries )
+			new_size = num_entries; // do not lose any entries
+
+		if ( new_size != max_entries )
+			{
+			// Note, allocate extra space, so that we can always
+			// use the [max_entries] element.
+			// ### Yin, why not use realloc()?
+			T* new_entries = new T[new_size+1];
+
+			if ( new_entries )
+				{
+				if ( head <= tail )
+					memcpy( new_entries, entries + head,
+						sizeof(T) * num_entries );
+				else
+					{
+					int len = num_entries - tail;
+					memcpy( new_entries, entries + head,
+						sizeof(T) * len );
+					memcpy( new_entries + len, entries,
+						sizeof(T) * tail );
+					}
+				delete [] entries;
+				entries = new_entries;
+				max_entries = new_size;
+				head = 0;
+				tail = num_entries;
+				}
+			else
+				{ // out of memory
+				}
+			}
+
+		return max_entries;
+		}
 
 	// remove all entries without delete[] entry
 	void clear()		{ head = tail = num_entries = 0; }
 
 	// helper functions for iterating over queue
-	int front() const	{ return head; }
+	T& front()	{ return entries[head]; }
-	int back() const	{ return tail; }
+	T& back()	{ return entries[tail]; }
-	void incr(int& index)	{ index < max_entries ? ++index : index = 0; }
+	const T& front() const	{ return entries[head]; }
+	const T& back() const	{ return entries[tail]; }
 
-protected:
+	void push_front(const T& a)	// add in front of queue
-	explicit BaseQueue(int = 0);
+		{
+		if ( num_entries == max_entries )
+			{
+			resize(max_entries+chunk_size);	// make more room
+			chunk_size *= 2;
+			}
 
-	void push_front(ent);	// add in front of queue
+		++num_entries;
-	void push_back(ent);	// add at end of queue
+		if ( head )
-	ent pop_front();	// return and remove the front of queue
+			entries[--head] = a;
-	ent pop_back();		// return and remove the end of queue
+		else
+			{
+			head = max_entries;
+			entries[head] = a;
+			}
+		}
+
+	void push_back(const T& a)	// add at end of queue
+		{
+		if ( num_entries == max_entries )
+			{
+			resize(max_entries+chunk_size);	// make more room
+			chunk_size *= 2;
+			}
+
+		++num_entries;
+		if ( tail < max_entries )
+			entries[tail++] = a;
+		else
+			{
+			entries[tail] = a;
+			tail = 0;
+			}
+		}
+
+	void pop_front()
+		{
+		--num_entries;
+		if ( head < max_entries )
+			head++;
+		else
+			head = 0;
+		}
+
+	void pop_back()
+		{
+		--num_entries;
+		if ( tail )
+			--tail;
+		else
+			tail = max_entries;
+		}
 
 	// return nth *PHYSICAL* entry of queue (do not remove)
-	ent operator[](int i) const	{ return entry[i]; }
+	T& operator[](int i) const	{ return entries[i]; }
 
-	ent* entry;
+	// Type traits needed for some of the std algorithms to work
+	using value_type = T;
+
+	// Iterator support
+	using iterator = QueueIterator<T>;
+	using const_iterator = QueueIterator<const T>;
+	using reverse_iterator = std::reverse_iterator<iterator>;
+	using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+
+	iterator begin() { return { entries, 0, num_entries }; }
+	iterator end() { return { entries, num_entries, num_entries }; }
+	const_iterator begin() const { return { entries, 0, num_entries }; }
+	const_iterator end() const { return { entries, num_entries, num_entries }; }
+	const_iterator cbegin() const { return { entries, 0, num_entries }; }
+	const_iterator cend() const { return { entries, num_entries, num_entries }; }
+
+	reverse_iterator rbegin() { return reverse_iterator{end()}; }
+	reverse_iterator rend() { return reverse_iterator{begin()}; }
+	const_reverse_iterator rbegin() const { return const_reverse_iterator{end()}; }
+	const_reverse_iterator rend() const { return const_reverse_iterator{begin()}; }
+	const_reverse_iterator crbegin() const { return rbegin(); }
+	const_reverse_iterator crend() const { return rend(); }
+
+protected:
+
+	T* entries;
 	int chunk_size;		// increase size by this amount when necessary
 	int max_entries;	// entry's index range: 0 .. max_entries
 	int num_entries;
@@ -57,54 +236,14 @@ protected:
 	int tail;	// just beyond the end of the queue in the ring
 	};
 
-// Queue.h -- interface for class Queue
-//	Use:	to get a list of pointers to class foo you should:
-//		1) declare(PQueue,foo); (declare interest in lists of foo*'s)
-//		2) variables are declared like:
-//			PQueue(foo) bar; (bar is of type list of foo*'s)
 
-// For queues of "type"
+template<typename T>
-#define Queue(type) type ## Queue
+using PQueue = Queue<T*>;
-
-// For queues of pointers to "type"
-#define PQueue(type) type ## PQueue
-
-#define Queuedeclare(type)						\
-struct Queue(type) : BaseQueue						\
-	{								\
-	Queue(type)() : BaseQueue(0) {}					\
-	explicit Queue(type)(int sz) : BaseQueue(sz) {}				\
-									\
-	void push_front(type a)	{ BaseQueue::push_front(ent(a)); }	\
-	void push_back(type a)	{ BaseQueue::push_back(ent(a)); }	\
-	type pop_front()	{ return type(BaseQueue::pop_front()); }\
-	type pop_back()		{ return type(BaseQueue::pop_back()); }	\
-									\
-	type operator[](int i) const					\
-		{ return type(BaseQueue::operator[](i)); }		\
-	};								\
-
-#define PQueuedeclare(type)						\
-struct PQueue(type) : BaseQueue						\
-	{								\
-	PQueue(type)() : BaseQueue(0) {}				\
-	explicit PQueue(type)(int sz) : BaseQueue(sz) {}				\
-									\
-	void push_front(type* a){ BaseQueue::push_front(ent(a)); }	\
-	void push_back(type* a)	{ BaseQueue::push_back(ent(a)); }	\
-	type* pop_front()						\
-		{ return (type*)BaseQueue::pop_front(); }		\
-	type* pop_back()							\
-		{ return (type*)BaseQueue::pop_back(); }			\
-									\
-	type* operator[](int i) const					\
-		{ return (type*)BaseQueue::operator[](i); }		\
-	};								\
 
 // Macro to visit each queue element in turn.
 #define loop_over_queue(queue, iterator) \
 	int iterator; \
 	for ( iterator = (queue).front(); iterator != (queue).back(); \
-		(queue).incr(iterator) )				\
+		(queue).incr(iterator) )
 
 #endif /* queue_h */