2 files changed, 68 insertions, 23 deletions

diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index 52a7a04567a..451e1cebfff 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -70,7 +70,6 @@ void Lexer::InitLexer(const char *BufStart, const char *BufPtr,
          " to simplify lexing!");
 
   Is_PragmaLexer = false;
-  IsEofCodeCompletion = false;
   
   // Start of the file is a start of line.
   IsAtStartOfLine = true;
@@ -105,10 +104,6 @@ Lexer::Lexer(FileID FID, const llvm::MemoryBuffer *InputFile, Preprocessor &PP)
 
   // Default to keeping comments if the preprocessor wants them.
   SetCommentRetentionState(PP.getCommentRetentionState());
-      
-  // If the input file is truncated, the EOF is a code-completion token.
-  if (PP.getSourceManager().isTruncatedFile(FID))
-    IsEofCodeCompletion = true;
 }
 
 /// Lexer constructor - Create a new raw lexer object.  This object is only
@@ -1326,24 +1321,16 @@ bool Lexer::LexEndOfFile(Token &Result, const char *CurPtr) {
   // Otherwise, check if we are code-completing, then issue diagnostics for 
   // unterminated #if and missing newline.
 
-  if (IsEofCodeCompletion) {
-    bool isIntendedFile = true;
-    if (PP && FileLoc.isFileID()) {
-      SourceManager &SM = PP->getSourceManager();
-      isIntendedFile = SM.isTruncatedFile(SM.getFileID(FileLoc));
-    }
+  if (PP && PP->isCodeCompletionFile(FileLoc)) {
+    // We're at the end of the file, but we've been asked to consider the
+    // end of the file to be a code-completion token. Return the
+    // code-completion token.
+    Result.startToken();
+    FormTokenWithChars(Result, CurPtr, tok::code_completion);
     
-    if (isIntendedFile) {
-      // We're at the end of the file, but we've been asked to consider the
-      // end of the file to be a code-completion token. Return the
-      // code-completion token.
-      Result.startToken();
-      FormTokenWithChars(Result, CurPtr, tok::code_completion);
-      
-      // Only do the eof -> code_completion translation once.
-      IsEofCodeCompletion = false;
-      return true;
-    }
+    // Only do the eof -> code_completion translation once.
+    PP->SetCodeCompletionPoint(0, 0, 0);
+    return true;
   }
   
   // If we are in a #if directive, emit an error.
diff --git a/clang/lib/Lex/Preprocessor.cpp b/clang/lib/Lex/Preprocessor.cpp
index 066909475fe..c7578204944 100644
--- a/clang/lib/Lex/Preprocessor.cpp
+++ b/clang/lib/Lex/Preprocessor.cpp
@@ -50,7 +50,8 @@ Preprocessor::Preprocessor(Diagnostic &diags, const LangOptions &opts,
                            bool OwnsHeaders)
   : Diags(&diags), Features(opts), Target(target),FileMgr(Headers.getFileMgr()),
     SourceMgr(SM), HeaderInfo(Headers), Identifiers(opts, IILookup),
-    BuiltinInfo(Target), CurPPLexer(0), CurDirLookup(0), Callbacks(0) {
+    BuiltinInfo(Target), CodeCompletionFile(0), CurPPLexer(0), CurDirLookup(0),
+    Callbacks(0) {
   ScratchBuf = new ScratchBuffer(SourceMgr);
   CounterValue = 0; // __COUNTER__ starts at 0.
   OwnsHeaderSearch = OwnsHeaders;
@@ -188,6 +189,63 @@ void Preprocessor::PrintStats() {
              << NumFastTokenPaste << " on the fast path.\n";
 }
 
+bool Preprocessor::SetCodeCompletionPoint(const FileEntry *File, 
+                                          unsigned TruncateAtLine, 
+                                          unsigned TruncateAtColumn) {
+  using llvm::MemoryBuffer;
+
+  CodeCompletionFile = File;
+
+  // Okay to clear out the code-completion point by passing NULL.
+  if (!CodeCompletionFile)
+    return false;
+
+  // Load the actual file's contents.
+  const MemoryBuffer *Buffer = SourceMgr.getMemoryBufferForFile(File);
+  if (!Buffer)
+    return true;
+
+  // Find the byte position of the truncation point.
+  const char *Position = Buffer->getBufferStart();
+  for (unsigned Line = 1; Line < TruncateAtLine; ++Line) {
+    for (; *Position; ++Position) {
+      if (*Position != '\r' && *Position != '\n')
+        continue;
+      
+      // Eat \r\n or \n\r as a single line.
+      if ((Position[1] == '\r' || Position[1] == '\n') &&
+          Position[0] != Position[1])
+        ++Position;
+      ++Position;
+      break;
+    }
+  }
+  
+  for (unsigned Column = 1; Column < TruncateAtColumn; ++Column, ++Position) {
+    if (!*Position)
+      break;
+    
+    if (*Position == '\t')
+      Column += 7;
+  }
+  
+  // Truncate the buffer.
+  if (Position != Buffer->getBufferEnd()) {
+    MemoryBuffer *TruncatedBuffer 
+      = MemoryBuffer::getMemBufferCopy(Buffer->getBufferStart(), Position, 
+                                       Buffer->getBufferIdentifier());
+    SourceMgr.overrideFileContents(File, TruncatedBuffer);
+  }
+
+  return false;
+}
+
+bool Preprocessor::isCodeCompletionFile(SourceLocation FileLoc) {
+  return CodeCompletionFile && FileLoc.isFileID() &&
+    SourceMgr.getFileEntryForID(SourceMgr.getFileID(FileLoc))
+      == CodeCompletionFile;
+}
+
 //===----------------------------------------------------------------------===//
 // Token Spelling
 //===----------------------------------------------------------------------===//