Frontend: Factor out header include dumping (-H) into its own preprocessor

callbacks class.
 - Aside from being generally cleaner, this also allows -H to work correctly in
   modes other than standard preprocessing (e.g., -c, -MM, etc.)

llvm-svn: 124723

1 files changed, 87 insertions, 0 deletions

diff --git a/clang/lib/Frontend/HeaderIncludeGen.cpp b/clang/lib/Frontend/HeaderIncludeGen.cpp
new file mode 100644
index 00000000000..f29e8f159d7
--- /dev/null
+++ b/clang/lib/Frontend/HeaderIncludeGen.cpp
@@ -0,0 +1,87 @@
+//===--- HeaderIncludes.cpp - Generate Header Includes --------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Frontend/Utils.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Lex/Preprocessor.h"
+/*
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Frontend/PreprocessorOutputOptions.h"
+#include "clang/Lex/MacroInfo.h"
+#include "clang/Lex/PPCallbacks.h"
+#include "clang/Lex/Pragma.h"
+#include "clang/Lex/TokenConcatenation.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Config/config.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cstdio>
+*/
+using namespace clang;
+
+namespace {
+class HeaderIncludesCallback : public PPCallbacks {
+  SourceManager &SM;
+  unsigned CurrentIncludeDepth;
+  bool HasProcessedPredefines;
+
+public:
+  HeaderIncludesCallback(const Preprocessor *PP)
+    : SM(PP->getSourceManager()), CurrentIncludeDepth(0),
+      HasProcessedPredefines(false) {}
+
+  virtual void FileChanged(SourceLocation Loc, FileChangeReason Reason,
+                           SrcMgr::CharacteristicKind FileType);
+};
+}
+
+void clang::AttachHeaderIncludeGen(Preprocessor &PP) {
+  PP.addPPCallbacks(new HeaderIncludesCallback(&PP));
+}
+
+void HeaderIncludesCallback::FileChanged(SourceLocation Loc,
+                                         FileChangeReason Reason,
+                                       SrcMgr::CharacteristicKind NewFileType) {
+  // Unless we are exiting a #include, make sure to skip ahead to the line the
+  // #include directive was at.
+  PresumedLoc UserLoc = SM.getPresumedLoc(Loc);
+  if (UserLoc.isInvalid())
+    return;
+  
+  // Adjust the current include depth.
+  if (Reason == PPCallbacks::EnterFile) {
+    ++CurrentIncludeDepth;
+  } else {
+    if (CurrentIncludeDepth)
+      --CurrentIncludeDepth;
+
+    // We track when we are done with the predefines by watching for the first
+    // place where we drop back to a nesting depth of 0.
+    if (CurrentIncludeDepth == 0 && !HasProcessedPredefines)
+      HasProcessedPredefines = true;
+  }
+  
+  // Dump the header include information we are past the predefines buffer.
+  if (HasProcessedPredefines && Reason == PPCallbacks::EnterFile) {
+    // Write to a temporary string to avoid unnecessary flushing on errs().
+    llvm::SmallString<512> Filename(UserLoc.getFilename());
+    Lexer::Stringify(Filename);
+
+    llvm::SmallString<256> Msg;
+    for (unsigned i = 0; i != CurrentIncludeDepth; ++i)
+      Msg += '.';
+    Msg += ' ';
+    Msg += Filename;
+    Msg += '\n';
+
+    llvm::errs() << Msg;
+  }
+}
+