//
// The LLVM Compiler Infrastructure
//
-// This file was developed by Chris Lattner and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
#ifndef LLVM_ADT_SMALLSET_H
#define LLVM_ADT_SMALLSET_H
+#include "llvm/ADT/None.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
+#include <set>
namespace llvm {
/// SmallSet - This maintains a set of unique values, optimizing for the case
/// when the set is small (less than N). In this case, the set can be
-/// maintained with no mallocs.
+/// maintained with no mallocs. If the set gets large, we expand to using an
+/// std::set to maintain reasonable lookup times.
///
-/// Note that this set does not guarantee that the elements in the set will be
-/// ordered.
-template <typename T, unsigned N>
+/// Note that this set does not provide a way to iterate over members in the
+/// set.
+template <typename T, unsigned N, typename C = std::less<T> >
class SmallSet {
+ /// Use a SmallVector to hold the elements here (even though it will never
+ /// reach its 'large' stage) to avoid calling the default ctors of elements
+ /// we will never use.
SmallVector<T, N> Vector;
+ std::set<T, C> Set;
+ typedef typename SmallVector<T, N>::const_iterator VIterator;
typedef typename SmallVector<T, N>::iterator mutable_iterator;
+
public:
+ typedef size_t size_type;
SmallSet() {}
- // Support iteration.
- typedef typename SmallVector<T, N>::const_iterator iterator;
- typedef typename SmallVector<T, N>::const_iterator const_iterator;
-
- iterator begin() const { return Vector.begin(); }
- iterator end() const { return Vector.end(); }
-
- bool empty() const { return Vector.empty(); }
- unsigned size() const { return Vector.size(); }
-
- iterator find(const T &V) const {
- for (iterator I = begin(), E = end(); I != E; ++I)
- if (*I == V)
- return I;
- return end();
+ bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const {
+ return Vector.empty() && Set.empty();
}
-
- /// count - Return true if the element is in the set.
- unsigned count(const T &V) const {
- // Since the collection is small, just do a linear search.
- return find(V) != end();
+
+ size_type size() const {
+ return isSmall() ? Vector.size() : Set.size();
}
-
+
+ /// count - Return 1 if the element is in the set, 0 otherwise.
+ size_type count(const T &V) const {
+ if (isSmall()) {
+ // Since the collection is small, just do a linear search.
+ return vfind(V) == Vector.end() ? 0 : 1;
+ } else {
+ return Set.count(V);
+ }
+ }
+
/// insert - Insert an element into the set if it isn't already there.
- std::pair<iterator,bool> insert(const T &V) {
- iterator I = find(V);
- if (I != end()) // Don't reinsert if it already exists.
- return std::make_pair(I, false);
- Vector.push_back(V);
- return std::make_pair(end()-1, true);
+ /// Returns true if the element is inserted (it was not in the set before).
+ /// The first value of the returned pair is unused and provided for
+ /// partial compatibility with the standard library self-associative container
+ /// concept.
+ // FIXME: Add iterators that abstract over the small and large form, and then
+ // return those here.
+ std::pair<NoneType, bool> insert(const T &V) {
+ if (!isSmall())
+ return std::make_pair(None, Set.insert(V).second);
+
+ VIterator I = vfind(V);
+ if (I != Vector.end()) // Don't reinsert if it already exists.
+ return std::make_pair(None, false);
+ if (Vector.size() < N) {
+ Vector.push_back(V);
+ return std::make_pair(None, true);
+ }
+
+ // Otherwise, grow from vector to set.
+ while (!Vector.empty()) {
+ Set.insert(Vector.back());
+ Vector.pop_back();
+ }
+ Set.insert(V);
+ return std::make_pair(None, true);
}
-
- void erase(const T &V) {
+
+ template <typename IterT>
+ void insert(IterT I, IterT E) {
+ for (; I != E; ++I)
+ insert(*I);
+ }
+
+ bool erase(const T &V) {
+ if (!isSmall())
+ return Set.erase(V);
for (mutable_iterator I = Vector.begin(), E = Vector.end(); I != E; ++I)
if (*I == V) {
Vector.erase(I);
- return;
+ return true;
}
+ return false;
}
-
+
void clear() {
Vector.clear();
+ Set.clear();
+ }
+
+private:
+ bool isSmall() const { return Set.empty(); }
+
+ VIterator vfind(const T &V) const {
+ for (VIterator I = Vector.begin(), E = Vector.end(); I != E; ++I)
+ if (*I == V)
+ return I;
+ return Vector.end();
}
-
};
+/// If this set is of pointer values, transparently switch over to using
+/// SmallPtrSet for performance.
+template <typename PointeeType, unsigned N>
+class SmallSet<PointeeType*, N> : public SmallPtrSet<PointeeType*, N> {};
} // end namespace llvm