1//===- Rewriter.cpp - Code rewriting interface ----------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9//  This file defines the Rewriter class, which is used for code
10//  transformations.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/Rewrite/Core/Rewriter.h"
15#include "clang/Basic/Diagnostic.h"
16#include "clang/Basic/DiagnosticIDs.h"
17#include "clang/Basic/FileManager.h"
18#include "clang/Basic/SourceLocation.h"
19#include "clang/Basic/SourceManager.h"
20#include "clang/Lex/Lexer.h"
21#include "clang/Rewrite/Core/RewriteBuffer.h"
22#include "clang/Rewrite/Core/RewriteRope.h"
23#include "llvm/ADT/SmallString.h"
24#include "llvm/ADT/SmallVector.h"
25#include "llvm/ADT/StringRef.h"
26#include "llvm/Support/FileSystem.h"
27#include "llvm/Support/raw_ostream.h"
28#include <cassert>
29#include <iterator>
30#include <map>
31#include <memory>
32#include <system_error>
33#include <utility>
34
35using namespace clang;
36
37raw_ostream &RewriteBuffer::write(raw_ostream &os) const {
38  // Walk RewriteRope chunks efficiently using MoveToNextPiece() instead of the
39  // character iterator.
40  for (RopePieceBTreeIterator I = begin(), E = end(); I != E;
41       I.MoveToNextPiece())
42    os << I.piece();
43  return os;
44}
45
46/// Return true if this character is non-new-line whitespace:
47/// ' ', '\\t', '\\f', '\\v', '\\r'.
48static inline bool isWhitespaceExceptNL(unsigned char c) {
49  switch (c) {
50  case ' ':
51  case '\t':
52  case '\f':
53  case '\v':
54  case '\r':
55    return true;
56  default:
57    return false;
58  }
59}
60
61void RewriteBuffer::RemoveText(unsigned OrigOffset, unsigned Size,
62                               bool removeLineIfEmpty) {
63  // Nothing to remove, exit early.
64  if (Size == 0) return;
65
66  unsigned RealOffset = getMappedOffset(OrigOffset, true);
67  assert(RealOffset+Size <= Buffer.size() && "Invalid location");
68
69  // Remove the dead characters.
70  Buffer.erase(RealOffset, Size);
71
72  // Add a delta so that future changes are offset correctly.
73  AddReplaceDelta(OrigOffset, -Size);
74
75  if (removeLineIfEmpty) {
76    // Find the line that the remove occurred and if it is completely empty
77    // remove the line as well.
78
79    iterator curLineStart = begin();
80    unsigned curLineStartOffs = 0;
81    iterator posI = begin();
82    for (unsigned i = 0; i != RealOffset; ++i) {
83      if (*posI == '\n') {
84        curLineStart = posI;
85        ++curLineStart;
86        curLineStartOffs = i + 1;
87      }
88      ++posI;
89    }
90
91    unsigned lineSize = 0;
92    posI = curLineStart;
93    while (posI != end() && isWhitespaceExceptNL(*posI)) {
94      ++posI;
95      ++lineSize;
96    }
97    if (posI != end() && *posI == '\n') {
98      Buffer.erase(curLineStartOffs, lineSize + 1/* + '\n'*/);
99      // FIXME: Here, the offset of the start of the line is supposed to be
100      // expressed in terms of the original input not the "real" rewrite
101      // buffer.  How do we compute that reliably?  It might be tempting to use
102      // curLineStartOffs + OrigOffset - RealOffset, but that assumes the
103      // difference between the original and real offset is the same at the
104      // removed text and at the start of the line, but that's not true if
105      // edits were previously made earlier on the line.  This bug is also
106      // documented by a FIXME on the definition of
107      // clang::Rewriter::RewriteOptions::RemoveLineIfEmpty.  A reproducer for
108      // the implementation below is the test RemoveLineIfEmpty in
109      // clang/unittests/Rewrite/RewriteBufferTest.cpp.
110      AddReplaceDelta(curLineStartOffs, -(lineSize + 1/* + '\n'*/));
111    }
112  }
113}
114
115void RewriteBuffer::InsertText(unsigned OrigOffset, StringRef Str,
116                               bool InsertAfter) {
117  // Nothing to insert, exit early.
118  if (Str.empty()) return;
119
120  unsigned RealOffset = getMappedOffset(OrigOffset, InsertAfter);
121  Buffer.insert(RealOffset, Str.begin(), Str.end());
122
123  // Add a delta so that future changes are offset correctly.
124  AddInsertDelta(OrigOffset, Str.size());
125}
126
127/// ReplaceText - This method replaces a range of characters in the input
128/// buffer with a new string.  This is effectively a combined "remove+insert"
129/// operation.
130void RewriteBuffer::ReplaceText(unsigned OrigOffset, unsigned OrigLength,
131                                StringRef NewStr) {
132  unsigned RealOffset = getMappedOffset(OrigOffset, true);
133  Buffer.erase(RealOffset, OrigLength);
134  Buffer.insert(RealOffset, NewStr.begin(), NewStr.end());
135  if (OrigLength != NewStr.size())
136    AddReplaceDelta(OrigOffset, NewStr.size() - OrigLength);
137}
138
139//===----------------------------------------------------------------------===//
140// Rewriter class
141//===----------------------------------------------------------------------===//
142
143/// getRangeSize - Return the size in bytes of the specified range if they
144/// are in the same file.  If not, this returns -1.
145int Rewriter::getRangeSize(const CharSourceRange &Range,
146                           RewriteOptions opts) const {
147  if (!isRewritable(Range.getBegin()) ||
148      !isRewritable(Range.getEnd())) return -1;
149
150  FileID StartFileID, EndFileID;
151  unsigned StartOff = getLocationOffsetAndFileID(Range.getBegin(), StartFileID);
152  unsigned EndOff = getLocationOffsetAndFileID(Range.getEnd(), EndFileID);
153
154  if (StartFileID != EndFileID)
155    return -1;
156
157  // If edits have been made to this buffer, the delta between the range may
158  // have changed.
159  std::map<FileID, RewriteBuffer>::const_iterator I =
160    RewriteBuffers.find(StartFileID);
161  if (I != RewriteBuffers.end()) {
162    const RewriteBuffer &RB = I->second;
163    EndOff = RB.getMappedOffset(EndOff, opts.IncludeInsertsAtEndOfRange);
164    StartOff = RB.getMappedOffset(StartOff, !opts.IncludeInsertsAtBeginOfRange);
165  }
166
167  // Adjust the end offset to the end of the last token, instead of being the
168  // start of the last token if this is a token range.
169  if (Range.isTokenRange())
170    EndOff += Lexer::MeasureTokenLength(Range.getEnd(), *SourceMgr, *LangOpts);
171
172  return EndOff-StartOff;
173}
174
175int Rewriter::getRangeSize(SourceRange Range, RewriteOptions opts) const {
176  return getRangeSize(CharSourceRange::getTokenRange(Range), opts);
177}
178
179/// getRewrittenText - Return the rewritten form of the text in the specified
180/// range.  If the start or end of the range was unrewritable or if they are
181/// in different buffers, this returns an empty string.
182///
183/// Note that this method is not particularly efficient.
184std::string Rewriter::getRewrittenText(CharSourceRange Range) const {
185  if (!isRewritable(Range.getBegin()) ||
186      !isRewritable(Range.getEnd()))
187    return {};
188
189  FileID StartFileID, EndFileID;
190  unsigned StartOff, EndOff;
191  StartOff = getLocationOffsetAndFileID(Range.getBegin(), StartFileID);
192  EndOff   = getLocationOffsetAndFileID(Range.getEnd(), EndFileID);
193
194  if (StartFileID != EndFileID)
195    return {}; // Start and end in different buffers.
196
197  // If edits have been made to this buffer, the delta between the range may
198  // have changed.
199  std::map<FileID, RewriteBuffer>::const_iterator I =
200    RewriteBuffers.find(StartFileID);
201  if (I == RewriteBuffers.end()) {
202    // If the buffer hasn't been rewritten, just return the text from the input.
203    const char *Ptr = SourceMgr->getCharacterData(Range.getBegin());
204
205    // Adjust the end offset to the end of the last token, instead of being the
206    // start of the last token.
207    if (Range.isTokenRange())
208      EndOff +=
209          Lexer::MeasureTokenLength(Range.getEnd(), *SourceMgr, *LangOpts);
210    return std::string(Ptr, Ptr+EndOff-StartOff);
211  }
212
213  const RewriteBuffer &RB = I->second;
214  EndOff = RB.getMappedOffset(EndOff, true);
215  StartOff = RB.getMappedOffset(StartOff);
216
217  // Adjust the end offset to the end of the last token, instead of being the
218  // start of the last token.
219  if (Range.isTokenRange())
220    EndOff += Lexer::MeasureTokenLength(Range.getEnd(), *SourceMgr, *LangOpts);
221
222  // Advance the iterators to the right spot, yay for linear time algorithms.
223  RewriteBuffer::iterator Start = RB.begin();
224  std::advance(Start, StartOff);
225  RewriteBuffer::iterator End = Start;
226  std::advance(End, EndOff-StartOff);
227
228  return std::string(Start, End);
229}
230
231unsigned Rewriter::getLocationOffsetAndFileID(SourceLocation Loc,
232                                              FileID &FID) const {
233  assert(Loc.isValid() && "Invalid location");
234  std::pair<FileID, unsigned> V = SourceMgr->getDecomposedLoc(Loc);
235  FID = V.first;
236  return V.second;
237}
238
239/// getEditBuffer - Get or create a RewriteBuffer for the specified FileID.
240RewriteBuffer &Rewriter::getEditBuffer(FileID FID) {
241  std::map<FileID, RewriteBuffer>::iterator I =
242    RewriteBuffers.lower_bound(FID);
243  if (I != RewriteBuffers.end() && I->first == FID)
244    return I->second;
245  I = RewriteBuffers.insert(I, std::make_pair(FID, RewriteBuffer()));
246
247  StringRef MB = SourceMgr->getBufferData(FID);
248  I->second.Initialize(MB.begin(), MB.end());
249
250  return I->second;
251}
252
253/// InsertText - Insert the specified string at the specified location in the
254/// original buffer.
255bool Rewriter::InsertText(SourceLocation Loc, StringRef Str,
256                          bool InsertAfter, bool indentNewLines) {
257  if (!isRewritable(Loc)) return true;
258  FileID FID;
259  unsigned StartOffs = getLocationOffsetAndFileID(Loc, FID);
260
261  SmallString<128> indentedStr;
262  if (indentNewLines && Str.find('\n') != StringRef::npos) {
263    StringRef MB = SourceMgr->getBufferData(FID);
264
265    unsigned lineNo = SourceMgr->getLineNumber(FID, StartOffs) - 1;
266    const SrcMgr::ContentCache *
267        Content = SourceMgr->getSLocEntry(FID).getFile().getContentCache();
268    unsigned lineOffs = Content->SourceLineCache[lineNo];
269
270    // Find the whitespace at the start of the line.
271    StringRef indentSpace;
272    {
273      unsigned i = lineOffs;
274      while (isWhitespaceExceptNL(MB[i]))
275        ++i;
276      indentSpace = MB.substr(lineOffs, i-lineOffs);
277    }
278
279    SmallVector<StringRef, 4> lines;
280    Str.split(lines, "\n");
281
282    for (unsigned i = 0, e = lines.size(); i != e; ++i) {
283      indentedStr += lines[i];
284      if (i < e-1) {
285        indentedStr += '\n';
286        indentedStr += indentSpace;
287      }
288    }
289    Str = indentedStr.str();
290  }
291
292  getEditBuffer(FID).InsertText(StartOffs, Str, InsertAfter);
293  return false;
294}
295
296bool Rewriter::InsertTextAfterToken(SourceLocation Loc, StringRef Str) {
297  if (!isRewritable(Loc)) return true;
298  FileID FID;
299  unsigned StartOffs = getLocationOffsetAndFileID(Loc, FID);
300  RewriteOptions rangeOpts;
301  rangeOpts.IncludeInsertsAtBeginOfRange = false;
302  StartOffs += getRangeSize(SourceRange(Loc, Loc), rangeOpts);
303  getEditBuffer(FID).InsertText(StartOffs, Str, /*InsertAfter*/true);
304  return false;
305}
306
307/// RemoveText - Remove the specified text region.
308bool Rewriter::RemoveText(SourceLocation Start, unsigned Length,
309                          RewriteOptions opts) {
310  if (!isRewritable(Start)) return true;
311  FileID FID;
312  unsigned StartOffs = getLocationOffsetAndFileID(Start, FID);
313  getEditBuffer(FID).RemoveText(StartOffs, Length, opts.RemoveLineIfEmpty);
314  return false;
315}
316
317/// ReplaceText - This method replaces a range of characters in the input
318/// buffer with a new string.  This is effectively a combined "remove/insert"
319/// operation.
320bool Rewriter::ReplaceText(SourceLocation Start, unsigned OrigLength,
321                           StringRef NewStr) {
322  if (!isRewritable(Start)) return true;
323  FileID StartFileID;
324  unsigned StartOffs = getLocationOffsetAndFileID(Start, StartFileID);
325
326  getEditBuffer(StartFileID).ReplaceText(StartOffs, OrigLength, NewStr);
327  return false;
328}
329
330bool Rewriter::ReplaceText(SourceRange range, SourceRange replacementRange) {
331  if (!isRewritable(range.getBegin())) return true;
332  if (!isRewritable(range.getEnd())) return true;
333  if (replacementRange.isInvalid()) return true;
334  SourceLocation start = range.getBegin();
335  unsigned origLength = getRangeSize(range);
336  unsigned newLength = getRangeSize(replacementRange);
337  FileID FID;
338  unsigned newOffs = getLocationOffsetAndFileID(replacementRange.getBegin(),
339                                                FID);
340  StringRef MB = SourceMgr->getBufferData(FID);
341  return ReplaceText(start, origLength, MB.substr(newOffs, newLength));
342}
343
344bool Rewriter::IncreaseIndentation(CharSourceRange range,
345                                   SourceLocation parentIndent) {
346  if (range.isInvalid()) return true;
347  if (!isRewritable(range.getBegin())) return true;
348  if (!isRewritable(range.getEnd())) return true;
349  if (!isRewritable(parentIndent)) return true;
350
351  FileID StartFileID, EndFileID, parentFileID;
352  unsigned StartOff, EndOff, parentOff;
353
354  StartOff = getLocationOffsetAndFileID(range.getBegin(), StartFileID);
355  EndOff   = getLocationOffsetAndFileID(range.getEnd(), EndFileID);
356  parentOff = getLocationOffsetAndFileID(parentIndent, parentFileID);
357
358  if (StartFileID != EndFileID || StartFileID != parentFileID)
359    return true;
360  if (StartOff > EndOff)
361    return true;
362
363  FileID FID = StartFileID;
364  StringRef MB = SourceMgr->getBufferData(FID);
365
366  unsigned parentLineNo = SourceMgr->getLineNumber(FID, parentOff) - 1;
367  unsigned startLineNo = SourceMgr->getLineNumber(FID, StartOff) - 1;
368  unsigned endLineNo = SourceMgr->getLineNumber(FID, EndOff) - 1;
369
370  const SrcMgr::ContentCache *
371      Content = SourceMgr->getSLocEntry(FID).getFile().getContentCache();
372
373  // Find where the lines start.
374  unsigned parentLineOffs = Content->SourceLineCache[parentLineNo];
375  unsigned startLineOffs = Content->SourceLineCache[startLineNo];
376
377  // Find the whitespace at the start of each line.
378  StringRef parentSpace, startSpace;
379  {
380    unsigned i = parentLineOffs;
381    while (isWhitespaceExceptNL(MB[i]))
382      ++i;
383    parentSpace = MB.substr(parentLineOffs, i-parentLineOffs);
384
385    i = startLineOffs;
386    while (isWhitespaceExceptNL(MB[i]))
387      ++i;
388    startSpace = MB.substr(startLineOffs, i-startLineOffs);
389  }
390  if (parentSpace.size() >= startSpace.size())
391    return true;
392  if (!startSpace.startswith(parentSpace))
393    return true;
394
395  StringRef indent = startSpace.substr(parentSpace.size());
396
397  // Indent the lines between start/end offsets.
398  RewriteBuffer &RB = getEditBuffer(FID);
399  for (unsigned lineNo = startLineNo; lineNo <= endLineNo; ++lineNo) {
400    unsigned offs = Content->SourceLineCache[lineNo];
401    unsigned i = offs;
402    while (isWhitespaceExceptNL(MB[i]))
403      ++i;
404    StringRef origIndent = MB.substr(offs, i-offs);
405    if (origIndent.startswith(startSpace))
406      RB.InsertText(offs, indent, /*InsertAfter=*/false);
407  }
408
409  return false;
410}
411
412namespace {
413
414// A wrapper for a file stream that atomically overwrites the target.
415//
416// Creates a file output stream for a temporary file in the constructor,
417// which is later accessible via getStream() if ok() return true.
418// Flushes the stream and moves the temporary file to the target location
419// in the destructor.
420class AtomicallyMovedFile {
421public:
422  AtomicallyMovedFile(DiagnosticsEngine &Diagnostics, StringRef Filename,
423                      bool &AllWritten)
424      : Diagnostics(Diagnostics), Filename(Filename), AllWritten(AllWritten) {
425    TempFilename = Filename;
426    TempFilename += "-%%%%%%%%";
427    int FD;
428    if (llvm::sys::fs::createUniqueFile(TempFilename, FD, TempFilename)) {
429      AllWritten = false;
430      Diagnostics.Report(clang::diag::err_unable_to_make_temp)
431        << TempFilename;
432    } else {
433      FileStream.reset(new llvm::raw_fd_ostream(FD, /*shouldClose=*/true));
434    }
435  }
436
437  ~AtomicallyMovedFile() {
438    if (!ok()) return;
439
440    // Close (will also flush) theFileStream.
441    FileStream->close();
442    if (std::error_code ec = llvm::sys::fs::rename(TempFilename, Filename)) {
443      AllWritten = false;
444      Diagnostics.Report(clang::diag::err_unable_to_rename_temp)
445        << TempFilename << Filename << ec.message();
446      // If the remove fails, there's not a lot we can do - this is already an
447      // error.
448      llvm::sys::fs::remove(TempFilename);
449    }
450  }
451
452  bool ok() { return (bool)FileStream; }
453  raw_ostream &getStream() { return *FileStream; }
454
455private:
456  DiagnosticsEngine &Diagnostics;
457  StringRef Filename;
458  SmallString<128> TempFilename;
459  std::unique_ptr<llvm::raw_fd_ostream> FileStream;
460  bool &AllWritten;
461};
462
463} // namespace
464
465bool Rewriter::overwriteChangedFiles() {
466  bool AllWritten = true;
467  for (buffer_iterator I = buffer_begin(), E = buffer_end(); I != E; ++I) {
468    const FileEntry *Entry =
469        getSourceMgr().getFileEntryForID(I->first);
470    AtomicallyMovedFile File(getSourceMgr().getDiagnostics(), Entry->getName(),
471                             AllWritten);
472    if (File.ok()) {
473      I->second.write(File.getStream());
474    }
475  }
476  return !AllWritten;
477}
478