Make clang's rewrite engine a core feature

The rewrite facility's footprint is small so it's not worth going to these
lengths to support disabling at configure time, particularly since key compiler
features now depend on it.

Meanwhile the Objective-C rewriters have been moved under the
ENABLE_CLANG_ARCMT umbrella for now as they're comparatively heavy and still
potentially worth excluding from lightweight builds.

Tests are now passing with any combination of feature flags. The flags
historically haven't been tested by LLVM's build servers so caveat emptor.

llvm-svn: 213171

1 files changed, 495 insertions, 0 deletions

diff --git a/clang/lib/Rewrite/Rewriter.cpp b/clang/lib/Rewrite/Rewriter.cpp
new file mode 100644
index 00000000000..eab4ccfeadc
--- /dev/null
+++ b/clang/lib/Rewrite/Rewriter.cpp
@@ -0,0 +1,495 @@
+//===--- Rewriter.cpp - Code rewriting interface --------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the Rewriter class, which is used for code
+//  transformations.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Rewrite/Core/Rewriter.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/PrettyPrinter.h"
+#include "clang/AST/Stmt.h"
+#include "clang/Basic/DiagnosticIDs.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Lex/Lexer.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Config/llvm-config.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace clang;
+
+raw_ostream &RewriteBuffer::write(raw_ostream &os) const {
+  // Walk RewriteRope chunks efficiently using MoveToNextPiece() instead of the
+  // character iterator.
+  for (RopePieceBTreeIterator I = begin(), E = end(); I != E;
+       I.MoveToNextPiece())
+    os << I.piece();
+  return os;
+}
+
+/// \brief Return true if this character is non-new-line whitespace:
+/// ' ', '\\t', '\\f', '\\v', '\\r'.
+static inline bool isWhitespace(unsigned char c) {
+  switch (c) {
+  case ' ':
+  case '\t':
+  case '\f':
+  case '\v':
+  case '\r':
+    return true;
+  default:
+    return false;
+  }
+}
+
+void RewriteBuffer::RemoveText(unsigned OrigOffset, unsigned Size,
+                               bool removeLineIfEmpty) {
+  // Nothing to remove, exit early.
+  if (Size == 0) return;
+
+  unsigned RealOffset = getMappedOffset(OrigOffset, true);
+  assert(RealOffset+Size < Buffer.size() && "Invalid location");
+
+  // Remove the dead characters.
+  Buffer.erase(RealOffset, Size);
+
+  // Add a delta so that future changes are offset correctly.
+  AddReplaceDelta(OrigOffset, -Size);
+
+  if (removeLineIfEmpty) {
+    // Find the line that the remove occurred and if it is completely empty
+    // remove the line as well.
+
+    iterator curLineStart = begin();
+    unsigned curLineStartOffs = 0;
+    iterator posI = begin();
+    for (unsigned i = 0; i != RealOffset; ++i) {
+      if (*posI == '\n') {
+        curLineStart = posI;
+        ++curLineStart;
+        curLineStartOffs = i + 1;
+      }
+      ++posI;
+    }
+  
+    unsigned lineSize = 0;
+    posI = curLineStart;
+    while (posI != end() && isWhitespace(*posI)) {
+      ++posI;
+      ++lineSize;
+    }
+    if (posI != end() && *posI == '\n') {
+      Buffer.erase(curLineStartOffs, lineSize + 1/* + '\n'*/);
+      AddReplaceDelta(curLineStartOffs, -(lineSize + 1/* + '\n'*/));
+    }
+  }
+}
+
+void RewriteBuffer::InsertText(unsigned OrigOffset, StringRef Str,
+                               bool InsertAfter) {
+
+  // Nothing to insert, exit early.
+  if (Str.empty()) return;
+
+  unsigned RealOffset = getMappedOffset(OrigOffset, InsertAfter);
+  Buffer.insert(RealOffset, Str.begin(), Str.end());
+
+  // Add a delta so that future changes are offset correctly.
+  AddInsertDelta(OrigOffset, Str.size());
+}
+
+/// ReplaceText - This method replaces a range of characters in the input
+/// buffer with a new string.  This is effectively a combined "remove+insert"
+/// operation.
+void RewriteBuffer::ReplaceText(unsigned OrigOffset, unsigned OrigLength,
+                                StringRef NewStr) {
+  unsigned RealOffset = getMappedOffset(OrigOffset, true);
+  Buffer.erase(RealOffset, OrigLength);
+  Buffer.insert(RealOffset, NewStr.begin(), NewStr.end());
+  if (OrigLength != NewStr.size())
+    AddReplaceDelta(OrigOffset, NewStr.size() - OrigLength);
+}
+
+
+//===----------------------------------------------------------------------===//
+// Rewriter class
+//===----------------------------------------------------------------------===//
+
+/// getRangeSize - Return the size in bytes of the specified range if they
+/// are in the same file.  If not, this returns -1.
+int Rewriter::getRangeSize(const CharSourceRange &Range,
+                           RewriteOptions opts) const {
+  if (!isRewritable(Range.getBegin()) ||
+      !isRewritable(Range.getEnd())) return -1;
+
+  FileID StartFileID, EndFileID;
+  unsigned StartOff, EndOff;
+
+  StartOff = getLocationOffsetAndFileID(Range.getBegin(), StartFileID);
+  EndOff   = getLocationOffsetAndFileID(Range.getEnd(), EndFileID);
+
+  if (StartFileID != EndFileID)
+    return -1;
+
+  // If edits have been made to this buffer, the delta between the range may
+  // have changed.
+  std::map<FileID, RewriteBuffer>::const_iterator I =
+    RewriteBuffers.find(StartFileID);
+  if (I != RewriteBuffers.end()) {
+    const RewriteBuffer &RB = I->second;
+    EndOff = RB.getMappedOffset(EndOff, opts.IncludeInsertsAtEndOfRange);
+    StartOff = RB.getMappedOffset(StartOff, !opts.IncludeInsertsAtBeginOfRange);
+  }
+
+
+  // Adjust the end offset to the end of the last token, instead of being the
+  // start of the last token if this is a token range.
+  if (Range.isTokenRange())
+    EndOff += Lexer::MeasureTokenLength(Range.getEnd(), *SourceMgr, *LangOpts);
+
+  return EndOff-StartOff;
+}
+
+int Rewriter::getRangeSize(SourceRange Range, RewriteOptions opts) const {
+  return getRangeSize(CharSourceRange::getTokenRange(Range), opts);
+}
+
+
+/// getRewrittenText - Return the rewritten form of the text in the specified
+/// range.  If the start or end of the range was unrewritable or if they are
+/// in different buffers, this returns an empty string.
+///
+/// Note that this method is not particularly efficient.
+///
+std::string Rewriter::getRewrittenText(SourceRange Range) const {
+  if (!isRewritable(Range.getBegin()) ||
+      !isRewritable(Range.getEnd()))
+    return "";
+
+  FileID StartFileID, EndFileID;
+  unsigned StartOff, EndOff;
+  StartOff = getLocationOffsetAndFileID(Range.getBegin(), StartFileID);
+  EndOff   = getLocationOffsetAndFileID(Range.getEnd(), EndFileID);
+
+  if (StartFileID != EndFileID)
+    return ""; // Start and end in different buffers.
+
+  // If edits have been made to this buffer, the delta between the range may
+  // have changed.
+  std::map<FileID, RewriteBuffer>::const_iterator I =
+    RewriteBuffers.find(StartFileID);
+  if (I == RewriteBuffers.end()) {
+    // If the buffer hasn't been rewritten, just return the text from the input.
+    const char *Ptr = SourceMgr->getCharacterData(Range.getBegin());
+
+    // Adjust the end offset to the end of the last token, instead of being the
+    // start of the last token.
+    EndOff += Lexer::MeasureTokenLength(Range.getEnd(), *SourceMgr, *LangOpts);
+    return std::string(Ptr, Ptr+EndOff-StartOff);
+  }
+
+  const RewriteBuffer &RB = I->second;
+  EndOff = RB.getMappedOffset(EndOff, true);
+  StartOff = RB.getMappedOffset(StartOff);
+
+  // Adjust the end offset to the end of the last token, instead of being the
+  // start of the last token.
+  EndOff += Lexer::MeasureTokenLength(Range.getEnd(), *SourceMgr, *LangOpts);
+
+  // Advance the iterators to the right spot, yay for linear time algorithms.
+  RewriteBuffer::iterator Start = RB.begin();
+  std::advance(Start, StartOff);
+  RewriteBuffer::iterator End = Start;
+  std::advance(End, EndOff-StartOff);
+
+  return std::string(Start, End);
+}
+
+unsigned Rewriter::getLocationOffsetAndFileID(SourceLocation Loc,
+                                              FileID &FID) const {
+  assert(Loc.isValid() && "Invalid location");
+  std::pair<FileID,unsigned> V = SourceMgr->getDecomposedLoc(Loc);
+  FID = V.first;
+  return V.second;
+}
+
+
+/// getEditBuffer - Get or create a RewriteBuffer for the specified FileID.
+///
+RewriteBuffer &Rewriter::getEditBuffer(FileID FID) {
+  std::map<FileID, RewriteBuffer>::iterator I =
+    RewriteBuffers.lower_bound(FID);
+  if (I != RewriteBuffers.end() && I->first == FID)
+    return I->second;
+  I = RewriteBuffers.insert(I, std::make_pair(FID, RewriteBuffer()));
+
+  StringRef MB = SourceMgr->getBufferData(FID);
+  I->second.Initialize(MB.begin(), MB.end());
+
+  return I->second;
+}
+
+/// InsertText - Insert the specified string at the specified location in the
+/// original buffer.
+bool Rewriter::InsertText(SourceLocation Loc, StringRef Str,
+                          bool InsertAfter, bool indentNewLines) {
+  if (!isRewritable(Loc)) return true;
+  FileID FID;
+  unsigned StartOffs = getLocationOffsetAndFileID(Loc, FID);
+
+  SmallString<128> indentedStr;
+  if (indentNewLines && Str.find('\n') != StringRef::npos) {
+    StringRef MB = SourceMgr->getBufferData(FID);
+
+    unsigned lineNo = SourceMgr->getLineNumber(FID, StartOffs) - 1;
+    const SrcMgr::ContentCache *
+        Content = SourceMgr->getSLocEntry(FID).getFile().getContentCache();
+    unsigned lineOffs = Content->SourceLineCache[lineNo];
+
+    // Find the whitespace at the start of the line.
+    StringRef indentSpace;
+    {
+      unsigned i = lineOffs;
+      while (isWhitespace(MB[i]))
+        ++i;
+      indentSpace = MB.substr(lineOffs, i-lineOffs);
+    }
+
+    SmallVector<StringRef, 4> lines;
+    Str.split(lines, "\n");
+
+    for (unsigned i = 0, e = lines.size(); i != e; ++i) {
+      indentedStr += lines[i];
+      if (i < e-1) {
+        indentedStr += '\n';
+        indentedStr += indentSpace;
+      }
+    }
+    Str = indentedStr.str();
+  }
+
+  getEditBuffer(FID).InsertText(StartOffs, Str, InsertAfter);
+  return false;
+}
+
+bool Rewriter::InsertTextAfterToken(SourceLocation Loc, StringRef Str) {
+  if (!isRewritable(Loc)) return true;
+  FileID FID;
+  unsigned StartOffs = getLocationOffsetAndFileID(Loc, FID);
+  RewriteOptions rangeOpts;
+  rangeOpts.IncludeInsertsAtBeginOfRange = false;
+  StartOffs += getRangeSize(SourceRange(Loc, Loc), rangeOpts);
+  getEditBuffer(FID).InsertText(StartOffs, Str, /*InsertAfter*/true);
+  return false;
+}
+
+/// RemoveText - Remove the specified text region.
+bool Rewriter::RemoveText(SourceLocation Start, unsigned Length,
+                          RewriteOptions opts) {
+  if (!isRewritable(Start)) return true;
+  FileID FID;
+  unsigned StartOffs = getLocationOffsetAndFileID(Start, FID);
+  getEditBuffer(FID).RemoveText(StartOffs, Length, opts.RemoveLineIfEmpty);
+  return false;
+}
+
+/// ReplaceText - This method replaces a range of characters in the input
+/// buffer with a new string.  This is effectively a combined "remove/insert"
+/// operation.
+bool Rewriter::ReplaceText(SourceLocation Start, unsigned OrigLength,
+                           StringRef NewStr) {
+  if (!isRewritable(Start)) return true;
+  FileID StartFileID;
+  unsigned StartOffs = getLocationOffsetAndFileID(Start, StartFileID);
+
+  getEditBuffer(StartFileID).ReplaceText(StartOffs, OrigLength, NewStr);
+  return false;
+}
+
+bool Rewriter::ReplaceText(SourceRange range, SourceRange replacementRange) {
+  if (!isRewritable(range.getBegin())) return true;
+  if (!isRewritable(range.getEnd())) return true;
+  if (replacementRange.isInvalid()) return true;
+  SourceLocation start = range.getBegin();
+  unsigned origLength = getRangeSize(range);
+  unsigned newLength = getRangeSize(replacementRange);
+  FileID FID;
+  unsigned newOffs = getLocationOffsetAndFileID(replacementRange.getBegin(),
+                                                FID);
+  StringRef MB = SourceMgr->getBufferData(FID);
+  return ReplaceText(start, origLength, MB.substr(newOffs, newLength));
+}
+
+/// ReplaceStmt - This replaces a Stmt/Expr with another, using the pretty
+/// printer to generate the replacement code.  This returns true if the input
+/// could not be rewritten, or false if successful.
+bool Rewriter::ReplaceStmt(Stmt *From, Stmt *To) {
+  assert(From != nullptr && To != nullptr && "Expected non-null Stmt's");
+
+  // Measaure the old text.
+  int Size = getRangeSize(From->getSourceRange());
+  if (Size == -1)
+    return true;
+
+  // Get the new text.
+  std::string SStr;
+  llvm::raw_string_ostream S(SStr);
+  To->printPretty(S, nullptr, PrintingPolicy(*LangOpts));
+  const std::string &Str = S.str();
+
+  ReplaceText(From->getLocStart(), Size, Str);
+  return false;
+}
+
+std::string Rewriter::ConvertToString(Stmt *From) {
+  assert(From != nullptr && "Expected non-null Stmt");
+  std::string SStr;
+  llvm::raw_string_ostream S(SStr);
+  From->printPretty(S, nullptr, PrintingPolicy(*LangOpts));
+  return S.str();
+}
+
+bool Rewriter::IncreaseIndentation(CharSourceRange range,
+                                   SourceLocation parentIndent) {
+  if (range.isInvalid()) return true;
+  if (!isRewritable(range.getBegin())) return true;
+  if (!isRewritable(range.getEnd())) return true;
+  if (!isRewritable(parentIndent)) return true;
+
+  FileID StartFileID, EndFileID, parentFileID;
+  unsigned StartOff, EndOff, parentOff;
+
+  StartOff = getLocationOffsetAndFileID(range.getBegin(), StartFileID);
+  EndOff   = getLocationOffsetAndFileID(range.getEnd(), EndFileID);
+  parentOff = getLocationOffsetAndFileID(parentIndent, parentFileID);
+
+  if (StartFileID != EndFileID || StartFileID != parentFileID)
+    return true;
+  if (StartOff > EndOff)
+    return true;
+
+  FileID FID = StartFileID;
+  StringRef MB = SourceMgr->getBufferData(FID);
+
+  unsigned parentLineNo = SourceMgr->getLineNumber(FID, parentOff) - 1;
+  unsigned startLineNo = SourceMgr->getLineNumber(FID, StartOff) - 1;
+  unsigned endLineNo = SourceMgr->getLineNumber(FID, EndOff) - 1;
+  
+  const SrcMgr::ContentCache *
+      Content = SourceMgr->getSLocEntry(FID).getFile().getContentCache();
+  
+  // Find where the lines start.
+  unsigned parentLineOffs = Content->SourceLineCache[parentLineNo];
+  unsigned startLineOffs = Content->SourceLineCache[startLineNo];
+
+  // Find the whitespace at the start of each line.
+  StringRef parentSpace, startSpace;
+  {
+    unsigned i = parentLineOffs;
+    while (isWhitespace(MB[i]))
+      ++i;
+    parentSpace = MB.substr(parentLineOffs, i-parentLineOffs);
+
+    i = startLineOffs;
+    while (isWhitespace(MB[i]))
+      ++i;
+    startSpace = MB.substr(startLineOffs, i-startLineOffs);
+  }
+  if (parentSpace.size() >= startSpace.size())
+    return true;
+  if (!startSpace.startswith(parentSpace))
+    return true;
+
+  StringRef indent = startSpace.substr(parentSpace.size());
+
+  // Indent the lines between start/end offsets.
+  RewriteBuffer &RB = getEditBuffer(FID);
+  for (unsigned lineNo = startLineNo; lineNo <= endLineNo; ++lineNo) {
+    unsigned offs = Content->SourceLineCache[lineNo];
+    unsigned i = offs;
+    while (isWhitespace(MB[i]))
+      ++i;
+    StringRef origIndent = MB.substr(offs, i-offs);
+    if (origIndent.startswith(startSpace))
+      RB.InsertText(offs, indent, /*InsertAfter=*/false);
+  }
+
+  return false;
+}
+
+namespace {
+// A wrapper for a file stream that atomically overwrites the target.
+//
+// Creates a file output stream for a temporary file in the constructor,
+// which is later accessible via getStream() if ok() return true.
+// Flushes the stream and moves the temporary file to the target location
+// in the destructor.
+class AtomicallyMovedFile {
+public:
+  AtomicallyMovedFile(DiagnosticsEngine &Diagnostics, StringRef Filename,
+                      bool &AllWritten)
+    : Diagnostics(Diagnostics), Filename(Filename), AllWritten(AllWritten) {
+    TempFilename = Filename;
+    TempFilename += "-%%%%%%%%";
+    int FD;
+    if (llvm::sys::fs::createUniqueFile(TempFilename.str(), FD, TempFilename)) {
+      AllWritten = false;
+      Diagnostics.Report(clang::diag::err_unable_to_make_temp)
+        << TempFilename;
+    } else {
+      FileStream.reset(new llvm::raw_fd_ostream(FD, /*shouldClose=*/true));
+    }
+  }
+
+  ~AtomicallyMovedFile() {
+    if (!ok()) return;
+
+    FileStream->flush();
+#ifdef LLVM_ON_WIN32
+    // Win32 does not allow rename/removing opened files.
+    FileStream.reset();
+#endif
+    if (std::error_code ec =
+            llvm::sys::fs::rename(TempFilename.str(), Filename)) {
+      AllWritten = false;
+      Diagnostics.Report(clang::diag::err_unable_to_rename_temp)
+        << TempFilename << Filename << ec.message();
+      // If the remove fails, there's not a lot we can do - this is already an
+      // error.
+      llvm::sys::fs::remove(TempFilename.str());
+    }
+  }
+
+  bool ok() { return (bool)FileStream; }
+  raw_ostream &getStream() { return *FileStream; }
+
+private:
+  DiagnosticsEngine &Diagnostics;
+  StringRef Filename;
+  SmallString<128> TempFilename;
+  std::unique_ptr<llvm::raw_fd_ostream> FileStream;
+  bool &AllWritten;
+};
+} // end anonymous namespace
+
+bool Rewriter::overwriteChangedFiles() {
+  bool AllWritten = true;
+  for (buffer_iterator I = buffer_begin(), E = buffer_end(); I != E; ++I) {
+    const FileEntry *Entry =
+        getSourceMgr().getFileEntryForID(I->first);
+    AtomicallyMovedFile File(getSourceMgr().getDiagnostics(), Entry->getName(),
+                             AllWritten);
+    if (File.ok()) {
+      I->second.write(File.getStream());
+    }
+  }
+  return !AllWritten;
+}