[llvm-commits] [llvm] r79382 - in /llvm/trunk: include/llvm/Support/raw_ostream.h lib/Support/raw_ostream.cpp
Daniel Dunbar
daniel at zuster.org
Tue Aug 18 16:42:36 PDT 2009
Author: ddunbar
Date: Tue Aug 18 18:42:36 2009
New Revision: 79382
URL: http://llvm.org/viewvc/llvm-project?rev=79382&view=rev
Log:
raw_ostream: Add the capability for subclasses to manually install an external
buffer.
Modified:
llvm/trunk/include/llvm/Support/raw_ostream.h
llvm/trunk/lib/Support/raw_ostream.cpp
Modified: llvm/trunk/include/llvm/Support/raw_ostream.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/raw_ostream.h?rev=79382&r1=79381&r2=79382&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Support/raw_ostream.h (original)
+++ llvm/trunk/include/llvm/Support/raw_ostream.h Tue Aug 18 18:42:36 2009
@@ -42,12 +42,25 @@
/// need to take the slow path to write a single character.
///
/// The buffer is in one of three states:
- /// 1. Unbuffered (Unbuffered == true)
- /// 1. Uninitialized (Unbuffered == false && OutBufStart == 0).
- /// 2. Buffered (Unbuffered == false && OutBufStart != 0 &&
+ /// 1. Unbuffered (BufferMode == Unbuffered)
+ /// 1. Uninitialized (BufferMode != Unbuffered && OutBufStart == 0).
+ /// 2. Buffered (BufferMode != Unbuffered && OutBufStart != 0 &&
/// OutBufEnd - OutBufStart >= 64).
+ ///
+ /// If buffered, then the raw_ostream owns the buffer if (BufferMode ==
+ /// InternalBuffer); otherwise the buffer has been set via SetBuffer and is
+ /// managed by the subclass.
+ ///
+ /// If a subclass installs an external buffer using SetBuffer then it can wait
+ /// for a \see write_impl() call to handle the data which has been put into
+ /// this buffer.
char *OutBufStart, *OutBufEnd, *OutBufCur;
- bool Unbuffered;
+
+ enum BufferKind {
+ Unbuffered = 0,
+ InternalBuffer,
+ ExternalBuffer
+ } BufferMode;
/// Error This flag is true if an error of any kind has been detected.
///
@@ -68,7 +81,7 @@
};
explicit raw_ostream(bool unbuffered=false)
- : Unbuffered(unbuffered), Error(false) {
+ : BufferMode(unbuffered ? Unbuffered : InternalBuffer), Error(false) {
// Start out ready to flush.
OutBufStart = OutBufEnd = OutBufCur = 0;
}
@@ -100,9 +113,12 @@
/// determined buffer size.
void SetBuffered();
- /// SetBufferrSize - Set the stream to be buffered, using the
+ /// SetBufferSize - Set the stream to be buffered, using the
/// specified buffer size.
- void SetBufferSize(size_t Size);
+ void SetBufferSize(size_t Size) {
+ flush();
+ SetBufferAndMode(new char[Size], Size, InternalBuffer);
+ }
size_t GetBufferSize() {
// If we're supposed to be buffered but haven't actually gotten around
@@ -118,7 +134,10 @@
/// unbuffered, the stream will flush after every write. This routine
/// will also flush the buffer immediately when the stream is being
/// set to unbuffered.
- void SetUnbuffered();
+ void SetUnbuffered() {
+ flush();
+ SetBufferAndMode(0, 0, Unbuffered);
+ }
size_t GetNumBytesInBuffer() const {
return OutBufCur - OutBufStart;
@@ -175,7 +194,9 @@
return *this;
}
- raw_ostream &operator<<(const std::string& Str) {
+ raw_ostream &operator<<(const std::string &Str) {
+ // Avoid the fast path, it would only increase code size for a marginal win.
+
write(Str.data(), Str.length());
return *this;
}
@@ -232,6 +253,13 @@
/// by subclasses. This writes the \args Size bytes starting at
/// \arg Ptr to the underlying stream.
///
+ /// This function is guaranteed to only be called at a point at which it is
+ /// safe for the subclass to install a new buffer via SetBuffer.
+ ///
+ /// \arg Ptr - The start of the data to be written. For buffered streams this
+ /// is guaranteed to be the start of the buffer.
+ /// \arg Size - The number of bytes to be written.
+ ///
/// \invariant { Size > 0 }
virtual void write_impl(const char *Ptr, size_t Size) = 0;
@@ -243,6 +271,14 @@
virtual uint64_t current_pos() = 0;
protected:
+ /// SetBuffer - Use the provided buffer as the raw_ostream buffer. This is
+ /// intended for use only by subclasses which can arrange for the output to go
+ /// directly into the desired output buffer, instead of being copied on each
+ /// flush.
+ void SetBuffer(char *BufferStart, size_t Size) {
+ SetBufferAndMode(BufferStart, Size, ExternalBuffer);
+ }
+
/// preferred_buffer_size - Return an efficient buffer size for the
/// underlying output mechanism.
virtual size_t preferred_buffer_size();
@@ -259,6 +295,9 @@
// Private Interface
//===--------------------------------------------------------------------===//
private:
+ /// SetBufferAndMode - Install the given buffer and mode.
+ void SetBufferAndMode(char *BufferStart, size_t Size, BufferKind Mode);
+
/// flush_nonempty - Flush the current buffer, which is known to be
/// non-empty. This outputs the currently buffered data and resets
/// the buffer to empty.
@@ -422,7 +461,7 @@
/// counting the bytes currently in the buffer.
virtual uint64_t current_pos();
public:
- explicit raw_svector_ostream(SmallVectorImpl<char> &O) : OS(O) {}
+ explicit raw_svector_ostream(SmallVectorImpl<char> &O);
~raw_svector_ostream();
/// tell - Return the current offset with the stream.
Modified: llvm/trunk/lib/Support/raw_ostream.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/raw_ostream.cpp?rev=79382&r1=79381&r2=79382&view=diff
==============================================================================
--- llvm/trunk/lib/Support/raw_ostream.cpp (original)
+++ llvm/trunk/lib/Support/raw_ostream.cpp Tue Aug 18 18:42:36 2009
@@ -52,7 +52,8 @@
assert(OutBufCur == OutBufStart &&
"raw_ostream destructor called with non-empty buffer!");
- delete [] OutBufStart;
+ if (BufferMode == InternalBuffer)
+ delete [] OutBufStart;
// If there are any pending errors, report them now. Clients wishing
// to avoid llvm_report_error calls should check for errors with
@@ -79,24 +80,21 @@
SetUnbuffered();
}
-void raw_ostream::SetBufferSize(size_t Size) {
- assert(Size >= 64 &&
- "Buffer size must be somewhat large for invariants to hold");
- flush();
-
- delete [] OutBufStart;
- OutBufStart = new char[Size];
+void raw_ostream::SetBufferAndMode(char *BufferStart, size_t Size,
+ BufferKind Mode) {
+ assert(((Mode == Unbuffered && BufferStart == 0 && Size == 0) ||
+ (Mode != Unbuffered && BufferStart && Size >= 64)) &&
+ "stream must be unbuffered, or have >= 64 bytes of buffer");
+ // Make sure the current buffer is free of content (we can't flush here; the
+ // child buffer management logic will be in write_impl).
+ assert(GetNumBytesInBuffer() == 0 && "Current buffer is non-empty!");
+
+ if (BufferMode == InternalBuffer)
+ delete [] OutBufStart;
+ OutBufStart = BufferStart;
OutBufEnd = OutBufStart+Size;
OutBufCur = OutBufStart;
- Unbuffered = false;
-}
-
-void raw_ostream::SetUnbuffered() {
- flush();
-
- delete [] OutBufStart;
- OutBufStart = OutBufEnd = OutBufCur = 0;
- Unbuffered = true;
+ BufferMode = Mode;
}
raw_ostream &raw_ostream::operator<<(unsigned long N) {
@@ -180,14 +178,15 @@
void raw_ostream::flush_nonempty() {
assert(OutBufCur > OutBufStart && "Invalid call to flush_nonempty.");
- write_impl(OutBufStart, OutBufCur - OutBufStart);
- OutBufCur = OutBufStart;
+ size_t Length = OutBufCur - OutBufStart;
+ OutBufCur = OutBufStart;
+ write_impl(OutBufStart, Length);
}
raw_ostream &raw_ostream::write(unsigned char C) {
// Group exceptional cases into a single branch.
if (OutBufCur >= OutBufEnd) {
- if (Unbuffered) {
+ if (BufferMode == Unbuffered) {
write_impl(reinterpret_cast<char*>(&C), 1);
return *this;
}
@@ -198,7 +197,7 @@
SetBuffered();
// It's possible for the underlying stream to decline
// buffering, so check this condition again.
- if (Unbuffered) {
+ if (BufferMode == Unbuffered) {
write_impl(reinterpret_cast<char*>(&C), 1);
return *this;
}
@@ -213,7 +212,7 @@
// Group exceptional cases into a single branch.
if (BUILTIN_EXPECT(OutBufCur+Size > OutBufEnd, false)) {
if (BUILTIN_EXPECT(!OutBufStart, false)) {
- if (Unbuffered) {
+ if (BufferMode == Unbuffered) {
write_impl(Ptr, Size);
return *this;
}
@@ -498,6 +497,9 @@
// raw_svector_ostream
//===----------------------------------------------------------------------===//
+raw_svector_ostream::raw_svector_ostream(SmallVectorImpl<char> &O) : OS(O) {
+}
+
raw_svector_ostream::~raw_svector_ostream() {
flush();
}
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