[LibTooling] Add function to translate and validate source range for editing

Summary:
Adds the function `getRangeForEdit` to validate that a given source range is
editable and, if needed, translate it into a range in the source file (for
example, if it's sourced in macro expansions).

Reviewers: ilya-biryukov

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D64924

llvm-svn: 366469

1 files changed, 34 insertions, 0 deletions

diff --git a/clang/lib/Tooling/Refactoring/SourceCode.cpp b/clang/lib/Tooling/Refactoring/SourceCode.cpp
index 3a97e178bbd..cee8f43f3e6 100644
--- a/clang/lib/Tooling/Refactoring/SourceCode.cpp
+++ b/clang/lib/Tooling/Refactoring/SourceCode.cpp
@@ -29,3 +29,37 @@ CharSourceRange clang::tooling::maybeExtendRange(CharSourceRange Range,
     return Range;
   return CharSourceRange::getTokenRange(Range.getBegin(), Tok->getLocation());
 }
+
+llvm::Optional<CharSourceRange>
+clang::tooling::getRangeForEdit(const CharSourceRange &EditRange,
+                                const SourceManager &SM,
+                                const LangOptions &LangOpts) {
+  // FIXME: makeFileCharRange() has the disadvantage of stripping off "identity"
+  // macros. For example, if we're looking to rewrite the int literal 3 to 6,
+  // and we have the following definition:
+  //    #define DO_NOTHING(x) x
+  // then
+  //    foo(DO_NOTHING(3))
+  // will be rewritten to
+  //    foo(6)
+  // rather than the arguably better
+  //    foo(DO_NOTHING(6))
+  // Decide whether the current behavior is desirable and modify if not.
+  CharSourceRange Range = Lexer::makeFileCharRange(EditRange, SM, LangOpts);
+  if (Range.isInvalid())
+    return None;
+
+  if (Range.getBegin().isMacroID() || Range.getEnd().isMacroID())
+    return None;
+  if (SM.isInSystemHeader(Range.getBegin()) ||
+      SM.isInSystemHeader(Range.getEnd()))
+    return None;
+
+  std::pair<FileID, unsigned> BeginInfo = SM.getDecomposedLoc(Range.getBegin());
+  std::pair<FileID, unsigned> EndInfo = SM.getDecomposedLoc(Range.getEnd());
+  if (BeginInfo.first != EndInfo.first ||
+      BeginInfo.second > EndInfo.second)
+    return None;
+
+  return Range;
+}