1 //===--- Rewriter.cpp - Code rewriting interface --------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 //  This file defines the Rewriter class, which is used for code
11 //  transformations.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang/Rewrite/Core/Rewriter.h"
16 #include "clang/Basic/Diagnostic.h"
17 #include "clang/Basic/DiagnosticIDs.h"
18 #include "clang/Basic/SourceManager.h"
19 #include "clang/Lex/Lexer.h"
20 #include "llvm/ADT/SmallString.h"
21 #include "llvm/Support/FileSystem.h"
22 #include "llvm/Support/raw_ostream.h"
23 using namespace clang;
24 
write(raw_ostream & os) const25 raw_ostream &RewriteBuffer::write(raw_ostream &os) const {
26   // Walk RewriteRope chunks efficiently using MoveToNextPiece() instead of the
27   // character iterator.
28   for (RopePieceBTreeIterator I = begin(), E = end(); I != E;
29        I.MoveToNextPiece())
30     os << I.piece();
31   return os;
32 }
33 
34 /// \brief Return true if this character is non-new-line whitespace:
35 /// ' ', '\\t', '\\f', '\\v', '\\r'.
isWhitespaceExceptNL(unsigned char c)36 static inline bool isWhitespaceExceptNL(unsigned char c) {
37   switch (c) {
38   case ' ':
39   case '\t':
40   case '\f':
41   case '\v':
42   case '\r':
43     return true;
44   default:
45     return false;
46   }
47 }
48 
RemoveText(unsigned OrigOffset,unsigned Size,bool removeLineIfEmpty)49 void RewriteBuffer::RemoveText(unsigned OrigOffset, unsigned Size,
50                                bool removeLineIfEmpty) {
51   // Nothing to remove, exit early.
52   if (Size == 0) return;
53 
54   unsigned RealOffset = getMappedOffset(OrigOffset, true);
55   assert(RealOffset+Size <= Buffer.size() && "Invalid location");
56 
57   // Remove the dead characters.
58   Buffer.erase(RealOffset, Size);
59 
60   // Add a delta so that future changes are offset correctly.
61   AddReplaceDelta(OrigOffset, -Size);
62 
63   if (removeLineIfEmpty) {
64     // Find the line that the remove occurred and if it is completely empty
65     // remove the line as well.
66 
67     iterator curLineStart = begin();
68     unsigned curLineStartOffs = 0;
69     iterator posI = begin();
70     for (unsigned i = 0; i != RealOffset; ++i) {
71       if (*posI == '\n') {
72         curLineStart = posI;
73         ++curLineStart;
74         curLineStartOffs = i + 1;
75       }
76       ++posI;
77     }
78 
79     unsigned lineSize = 0;
80     posI = curLineStart;
81     while (posI != end() && isWhitespaceExceptNL(*posI)) {
82       ++posI;
83       ++lineSize;
84     }
85     if (posI != end() && *posI == '\n') {
86       Buffer.erase(curLineStartOffs, lineSize + 1/* + '\n'*/);
87       AddReplaceDelta(curLineStartOffs, -(lineSize + 1/* + '\n'*/));
88     }
89   }
90 }
91 
InsertText(unsigned OrigOffset,StringRef Str,bool InsertAfter)92 void RewriteBuffer::InsertText(unsigned OrigOffset, StringRef Str,
93                                bool InsertAfter) {
94 
95   // Nothing to insert, exit early.
96   if (Str.empty()) return;
97 
98   unsigned RealOffset = getMappedOffset(OrigOffset, InsertAfter);
99   Buffer.insert(RealOffset, Str.begin(), Str.end());
100 
101   // Add a delta so that future changes are offset correctly.
102   AddInsertDelta(OrigOffset, Str.size());
103 }
104 
105 /// ReplaceText - This method replaces a range of characters in the input
106 /// buffer with a new string.  This is effectively a combined "remove+insert"
107 /// operation.
ReplaceText(unsigned OrigOffset,unsigned OrigLength,StringRef NewStr)108 void RewriteBuffer::ReplaceText(unsigned OrigOffset, unsigned OrigLength,
109                                 StringRef NewStr) {
110   unsigned RealOffset = getMappedOffset(OrigOffset, true);
111   Buffer.erase(RealOffset, OrigLength);
112   Buffer.insert(RealOffset, NewStr.begin(), NewStr.end());
113   if (OrigLength != NewStr.size())
114     AddReplaceDelta(OrigOffset, NewStr.size() - OrigLength);
115 }
116 
117 
118 //===----------------------------------------------------------------------===//
119 // Rewriter class
120 //===----------------------------------------------------------------------===//
121 
122 /// getRangeSize - Return the size in bytes of the specified range if they
123 /// are in the same file.  If not, this returns -1.
getRangeSize(const CharSourceRange & Range,RewriteOptions opts) const124 int Rewriter::getRangeSize(const CharSourceRange &Range,
125                            RewriteOptions opts) const {
126   if (!isRewritable(Range.getBegin()) ||
127       !isRewritable(Range.getEnd())) return -1;
128 
129   FileID StartFileID, EndFileID;
130   unsigned StartOff, EndOff;
131 
132   StartOff = getLocationOffsetAndFileID(Range.getBegin(), StartFileID);
133   EndOff   = getLocationOffsetAndFileID(Range.getEnd(), EndFileID);
134 
135   if (StartFileID != EndFileID)
136     return -1;
137 
138   // If edits have been made to this buffer, the delta between the range may
139   // have changed.
140   std::map<FileID, RewriteBuffer>::const_iterator I =
141     RewriteBuffers.find(StartFileID);
142   if (I != RewriteBuffers.end()) {
143     const RewriteBuffer &RB = I->second;
144     EndOff = RB.getMappedOffset(EndOff, opts.IncludeInsertsAtEndOfRange);
145     StartOff = RB.getMappedOffset(StartOff, !opts.IncludeInsertsAtBeginOfRange);
146   }
147 
148 
149   // Adjust the end offset to the end of the last token, instead of being the
150   // start of the last token if this is a token range.
151   if (Range.isTokenRange())
152     EndOff += Lexer::MeasureTokenLength(Range.getEnd(), *SourceMgr, *LangOpts);
153 
154   return EndOff-StartOff;
155 }
156 
getRangeSize(SourceRange Range,RewriteOptions opts) const157 int Rewriter::getRangeSize(SourceRange Range, RewriteOptions opts) const {
158   return getRangeSize(CharSourceRange::getTokenRange(Range), opts);
159 }
160 
161 
162 /// getRewrittenText - Return the rewritten form of the text in the specified
163 /// range.  If the start or end of the range was unrewritable or if they are
164 /// in different buffers, this returns an empty string.
165 ///
166 /// Note that this method is not particularly efficient.
167 ///
getRewrittenText(SourceRange Range) const168 std::string Rewriter::getRewrittenText(SourceRange Range) const {
169   if (!isRewritable(Range.getBegin()) ||
170       !isRewritable(Range.getEnd()))
171     return "";
172 
173   FileID StartFileID, EndFileID;
174   unsigned StartOff, EndOff;
175   StartOff = getLocationOffsetAndFileID(Range.getBegin(), StartFileID);
176   EndOff   = getLocationOffsetAndFileID(Range.getEnd(), EndFileID);
177 
178   if (StartFileID != EndFileID)
179     return ""; // Start and end in different buffers.
180 
181   // If edits have been made to this buffer, the delta between the range may
182   // have changed.
183   std::map<FileID, RewriteBuffer>::const_iterator I =
184     RewriteBuffers.find(StartFileID);
185   if (I == RewriteBuffers.end()) {
186     // If the buffer hasn't been rewritten, just return the text from the input.
187     const char *Ptr = SourceMgr->getCharacterData(Range.getBegin());
188 
189     // Adjust the end offset to the end of the last token, instead of being the
190     // start of the last token.
191     EndOff += Lexer::MeasureTokenLength(Range.getEnd(), *SourceMgr, *LangOpts);
192     return std::string(Ptr, Ptr+EndOff-StartOff);
193   }
194 
195   const RewriteBuffer &RB = I->second;
196   EndOff = RB.getMappedOffset(EndOff, true);
197   StartOff = RB.getMappedOffset(StartOff);
198 
199   // Adjust the end offset to the end of the last token, instead of being the
200   // start of the last token.
201   EndOff += Lexer::MeasureTokenLength(Range.getEnd(), *SourceMgr, *LangOpts);
202 
203   // Advance the iterators to the right spot, yay for linear time algorithms.
204   RewriteBuffer::iterator Start = RB.begin();
205   std::advance(Start, StartOff);
206   RewriteBuffer::iterator End = Start;
207   std::advance(End, EndOff-StartOff);
208 
209   return std::string(Start, End);
210 }
211 
getLocationOffsetAndFileID(SourceLocation Loc,FileID & FID) const212 unsigned Rewriter::getLocationOffsetAndFileID(SourceLocation Loc,
213                                               FileID &FID) const {
214   assert(Loc.isValid() && "Invalid location");
215   std::pair<FileID,unsigned> V = SourceMgr->getDecomposedLoc(Loc);
216   FID = V.first;
217   return V.second;
218 }
219 
220 
221 /// getEditBuffer - Get or create a RewriteBuffer for the specified FileID.
222 ///
getEditBuffer(FileID FID)223 RewriteBuffer &Rewriter::getEditBuffer(FileID FID) {
224   std::map<FileID, RewriteBuffer>::iterator I =
225     RewriteBuffers.lower_bound(FID);
226   if (I != RewriteBuffers.end() && I->first == FID)
227     return I->second;
228   I = RewriteBuffers.insert(I, std::make_pair(FID, RewriteBuffer()));
229 
230   StringRef MB = SourceMgr->getBufferData(FID);
231   I->second.Initialize(MB.begin(), MB.end());
232 
233   return I->second;
234 }
235 
236 /// InsertText - Insert the specified string at the specified location in the
237 /// original buffer.
InsertText(SourceLocation Loc,StringRef Str,bool InsertAfter,bool indentNewLines)238 bool Rewriter::InsertText(SourceLocation Loc, StringRef Str,
239                           bool InsertAfter, bool indentNewLines) {
240   if (!isRewritable(Loc)) return true;
241   FileID FID;
242   unsigned StartOffs = getLocationOffsetAndFileID(Loc, FID);
243 
244   SmallString<128> indentedStr;
245   if (indentNewLines && Str.find('\n') != StringRef::npos) {
246     StringRef MB = SourceMgr->getBufferData(FID);
247 
248     unsigned lineNo = SourceMgr->getLineNumber(FID, StartOffs) - 1;
249     const SrcMgr::ContentCache *
250         Content = SourceMgr->getSLocEntry(FID).getFile().getContentCache();
251     unsigned lineOffs = Content->SourceLineCache[lineNo];
252 
253     // Find the whitespace at the start of the line.
254     StringRef indentSpace;
255     {
256       unsigned i = lineOffs;
257       while (isWhitespaceExceptNL(MB[i]))
258         ++i;
259       indentSpace = MB.substr(lineOffs, i-lineOffs);
260     }
261 
262     SmallVector<StringRef, 4> lines;
263     Str.split(lines, "\n");
264 
265     for (unsigned i = 0, e = lines.size(); i != e; ++i) {
266       indentedStr += lines[i];
267       if (i < e-1) {
268         indentedStr += '\n';
269         indentedStr += indentSpace;
270       }
271     }
272     Str = indentedStr.str();
273   }
274 
275   getEditBuffer(FID).InsertText(StartOffs, Str, InsertAfter);
276   return false;
277 }
278 
InsertTextAfterToken(SourceLocation Loc,StringRef Str)279 bool Rewriter::InsertTextAfterToken(SourceLocation Loc, StringRef Str) {
280   if (!isRewritable(Loc)) return true;
281   FileID FID;
282   unsigned StartOffs = getLocationOffsetAndFileID(Loc, FID);
283   RewriteOptions rangeOpts;
284   rangeOpts.IncludeInsertsAtBeginOfRange = false;
285   StartOffs += getRangeSize(SourceRange(Loc, Loc), rangeOpts);
286   getEditBuffer(FID).InsertText(StartOffs, Str, /*InsertAfter*/true);
287   return false;
288 }
289 
290 /// RemoveText - Remove the specified text region.
RemoveText(SourceLocation Start,unsigned Length,RewriteOptions opts)291 bool Rewriter::RemoveText(SourceLocation Start, unsigned Length,
292                           RewriteOptions opts) {
293   if (!isRewritable(Start)) return true;
294   FileID FID;
295   unsigned StartOffs = getLocationOffsetAndFileID(Start, FID);
296   getEditBuffer(FID).RemoveText(StartOffs, Length, opts.RemoveLineIfEmpty);
297   return false;
298 }
299 
300 /// ReplaceText - This method replaces a range of characters in the input
301 /// buffer with a new string.  This is effectively a combined "remove/insert"
302 /// operation.
ReplaceText(SourceLocation Start,unsigned OrigLength,StringRef NewStr)303 bool Rewriter::ReplaceText(SourceLocation Start, unsigned OrigLength,
304                            StringRef NewStr) {
305   if (!isRewritable(Start)) return true;
306   FileID StartFileID;
307   unsigned StartOffs = getLocationOffsetAndFileID(Start, StartFileID);
308 
309   getEditBuffer(StartFileID).ReplaceText(StartOffs, OrigLength, NewStr);
310   return false;
311 }
312 
ReplaceText(SourceRange range,SourceRange replacementRange)313 bool Rewriter::ReplaceText(SourceRange range, SourceRange replacementRange) {
314   if (!isRewritable(range.getBegin())) return true;
315   if (!isRewritable(range.getEnd())) return true;
316   if (replacementRange.isInvalid()) return true;
317   SourceLocation start = range.getBegin();
318   unsigned origLength = getRangeSize(range);
319   unsigned newLength = getRangeSize(replacementRange);
320   FileID FID;
321   unsigned newOffs = getLocationOffsetAndFileID(replacementRange.getBegin(),
322                                                 FID);
323   StringRef MB = SourceMgr->getBufferData(FID);
324   return ReplaceText(start, origLength, MB.substr(newOffs, newLength));
325 }
326 
IncreaseIndentation(CharSourceRange range,SourceLocation parentIndent)327 bool Rewriter::IncreaseIndentation(CharSourceRange range,
328                                    SourceLocation parentIndent) {
329   if (range.isInvalid()) return true;
330   if (!isRewritable(range.getBegin())) return true;
331   if (!isRewritable(range.getEnd())) return true;
332   if (!isRewritable(parentIndent)) return true;
333 
334   FileID StartFileID, EndFileID, parentFileID;
335   unsigned StartOff, EndOff, parentOff;
336 
337   StartOff = getLocationOffsetAndFileID(range.getBegin(), StartFileID);
338   EndOff   = getLocationOffsetAndFileID(range.getEnd(), EndFileID);
339   parentOff = getLocationOffsetAndFileID(parentIndent, parentFileID);
340 
341   if (StartFileID != EndFileID || StartFileID != parentFileID)
342     return true;
343   if (StartOff > EndOff)
344     return true;
345 
346   FileID FID = StartFileID;
347   StringRef MB = SourceMgr->getBufferData(FID);
348 
349   unsigned parentLineNo = SourceMgr->getLineNumber(FID, parentOff) - 1;
350   unsigned startLineNo = SourceMgr->getLineNumber(FID, StartOff) - 1;
351   unsigned endLineNo = SourceMgr->getLineNumber(FID, EndOff) - 1;
352 
353   const SrcMgr::ContentCache *
354       Content = SourceMgr->getSLocEntry(FID).getFile().getContentCache();
355 
356   // Find where the lines start.
357   unsigned parentLineOffs = Content->SourceLineCache[parentLineNo];
358   unsigned startLineOffs = Content->SourceLineCache[startLineNo];
359 
360   // Find the whitespace at the start of each line.
361   StringRef parentSpace, startSpace;
362   {
363     unsigned i = parentLineOffs;
364     while (isWhitespaceExceptNL(MB[i]))
365       ++i;
366     parentSpace = MB.substr(parentLineOffs, i-parentLineOffs);
367 
368     i = startLineOffs;
369     while (isWhitespaceExceptNL(MB[i]))
370       ++i;
371     startSpace = MB.substr(startLineOffs, i-startLineOffs);
372   }
373   if (parentSpace.size() >= startSpace.size())
374     return true;
375   if (!startSpace.startswith(parentSpace))
376     return true;
377 
378   StringRef indent = startSpace.substr(parentSpace.size());
379 
380   // Indent the lines between start/end offsets.
381   RewriteBuffer &RB = getEditBuffer(FID);
382   for (unsigned lineNo = startLineNo; lineNo <= endLineNo; ++lineNo) {
383     unsigned offs = Content->SourceLineCache[lineNo];
384     unsigned i = offs;
385     while (isWhitespaceExceptNL(MB[i]))
386       ++i;
387     StringRef origIndent = MB.substr(offs, i-offs);
388     if (origIndent.startswith(startSpace))
389       RB.InsertText(offs, indent, /*InsertAfter=*/false);
390   }
391 
392   return false;
393 }
394 
395 namespace {
396 // A wrapper for a file stream that atomically overwrites the target.
397 //
398 // Creates a file output stream for a temporary file in the constructor,
399 // which is later accessible via getStream() if ok() return true.
400 // Flushes the stream and moves the temporary file to the target location
401 // in the destructor.
402 class AtomicallyMovedFile {
403 public:
AtomicallyMovedFile(DiagnosticsEngine & Diagnostics,StringRef Filename,bool & AllWritten)404   AtomicallyMovedFile(DiagnosticsEngine &Diagnostics, StringRef Filename,
405                       bool &AllWritten)
406     : Diagnostics(Diagnostics), Filename(Filename), AllWritten(AllWritten) {
407     TempFilename = Filename;
408     TempFilename += "-%%%%%%%%";
409     int FD;
410     if (llvm::sys::fs::createUniqueFile(TempFilename, FD, TempFilename)) {
411       AllWritten = false;
412       Diagnostics.Report(clang::diag::err_unable_to_make_temp)
413         << TempFilename;
414     } else {
415       FileStream.reset(new llvm::raw_fd_ostream(FD, /*shouldClose=*/true));
416     }
417   }
418 
~AtomicallyMovedFile()419   ~AtomicallyMovedFile() {
420     if (!ok()) return;
421 
422     // Close (will also flush) theFileStream.
423     FileStream->close();
424     if (std::error_code ec = llvm::sys::fs::rename(TempFilename, Filename)) {
425       AllWritten = false;
426       Diagnostics.Report(clang::diag::err_unable_to_rename_temp)
427         << TempFilename << Filename << ec.message();
428       // If the remove fails, there's not a lot we can do - this is already an
429       // error.
430       llvm::sys::fs::remove(TempFilename);
431     }
432   }
433 
ok()434   bool ok() { return (bool)FileStream; }
getStream()435   raw_ostream &getStream() { return *FileStream; }
436 
437 private:
438   DiagnosticsEngine &Diagnostics;
439   StringRef Filename;
440   SmallString<128> TempFilename;
441   std::unique_ptr<llvm::raw_fd_ostream> FileStream;
442   bool &AllWritten;
443 };
444 } // end anonymous namespace
445 
overwriteChangedFiles()446 bool Rewriter::overwriteChangedFiles() {
447   bool AllWritten = true;
448   for (buffer_iterator I = buffer_begin(), E = buffer_end(); I != E; ++I) {
449     const FileEntry *Entry =
450         getSourceMgr().getFileEntryForID(I->first);
451     AtomicallyMovedFile File(getSourceMgr().getDiagnostics(), Entry->getName(),
452                              AllWritten);
453     if (File.ok()) {
454       I->second.write(File.getStream());
455     }
456   }
457   return !AllWritten;
458 }
459