Write transform results to disk only once

    
Instead of writing the result of each transform to disk for every
transform, write the results to buffers in memory and pass those buffers
to the next transform as input. Only write the buffers to disk if the
final syntax check passes.

Reviewers: klimek
llvm-svn: 172657

1 files changed, 35 insertions, 0 deletions

diff --git a/clang-tools-extra/cpp11-migrate/Transform.cpp b/clang-tools-extra/cpp11-migrate/Transform.cpp
new file mode 100644
index 00000000000..c3203793fe8
--- /dev/null
+++ b/clang-tools-extra/cpp11-migrate/Transform.cpp
@@ -0,0 +1,35 @@
+#include "Transform.h"
+#include "clang/Rewrite/Core/Rewriter.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/SourceManager.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang;
+
+void collectResults(clang::Rewriter &Rewrite,
+                    FileContentsByPath &Results) {
+  for (Rewriter::buffer_iterator I = Rewrite.buffer_begin(),
+                                 E = Rewrite.buffer_end();
+       I != E; ++I) {
+    const FileEntry *Entry = Rewrite.getSourceMgr().getFileEntryForID(I->first);
+    assert(Entry != 0 && "Expected a FileEntry");
+    assert(Entry->getName() != 0 &&
+           "Unexpected NULL return from FileEntry::getName()");
+
+    FileContentsByPath::value_type ResultEntry;
+
+    ResultEntry.first = Entry->getName();
+
+    // Get a copy of the rewritten buffer from the Rewriter.
+    llvm::raw_string_ostream StringStream(ResultEntry.second);
+    I->second.write(StringStream);
+
+    // Cause results to be written to ResultEntry.second.
+    StringStream.str();
+
+    // FIXME: Use move semantics to avoid copies of the buffer contents if
+    // benchmarking shows the copies are expensive, especially for large source
+    // files.
+    Results.push_back(ResultEntry);
+  }
+}