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-rw-r--r--include/llvm/ADT/SmallBitVector.h38
1 files changed, 35 insertions, 3 deletions
diff --git a/include/llvm/ADT/SmallBitVector.h b/include/llvm/ADT/SmallBitVector.h
index 7563e81..884e631 100644
--- a/include/llvm/ADT/SmallBitVector.h
+++ b/include/llvm/ADT/SmallBitVector.h
@@ -52,6 +52,34 @@ class SmallBitVector {
SmallNumDataBits = SmallNumRawBits - SmallNumSizeBits
};
+public:
+ // Encapsulation of a single bit.
+ class reference {
+ SmallBitVector &TheVector;
+ unsigned BitPos;
+
+ public:
+ reference(SmallBitVector &b, unsigned Idx) : TheVector(b), BitPos(Idx) {}
+
+ reference& operator=(reference t) {
+ *this = bool(t);
+ return *this;
+ }
+
+ reference& operator=(bool t) {
+ if (t)
+ TheVector.set(BitPos);
+ else
+ TheVector.reset(BitPos);
+ return *this;
+ }
+
+ operator bool() const {
+ return const_cast<const SmallBitVector &>(TheVector).operator[](BitPos);
+ }
+ };
+
+private:
bool isSmall() const {
return X & uintptr_t(1);
}
@@ -81,7 +109,7 @@ class SmallBitVector {
void setSmallRawBits(uintptr_t NewRawBits) {
assert(isSmall());
- X = NewRawBits << 1 | uintptr_t(1);
+ X = (NewRawBits << 1) | uintptr_t(1);
}
// Return the size.
@@ -99,7 +127,7 @@ class SmallBitVector {
}
void setSmallBits(uintptr_t NewBits) {
- setSmallRawBits(NewBits & ~(~uintptr_t(0) << getSmallSize()) |
+ setSmallRawBits((NewBits & ~(~uintptr_t(0) << getSmallSize())) |
(getSmallSize() << SmallNumDataBits));
}
@@ -298,7 +326,11 @@ public:
}
// Indexing.
- // TODO: Add an index operator which returns a "reference" (proxy class).
+ reference operator[](unsigned Idx) {
+ assert(Idx < size() && "Out-of-bounds Bit access.");
+ return reference(*this, Idx);
+ }
+
bool operator[](unsigned Idx) const {
assert(Idx < size() && "Out-of-bounds Bit access.");
if (isSmall())