Add CharSourceRange -- a half-open character range, which will be used in IDE

integration

Motivation: libIDE clients should be simple, and they should not have to
translate token-based SourceRanges to character locations.

This also allows us to remove the dependency of DiagnosticConsumer on the
Lexer.  Now the DiagnosticEngine translates the diagnostics to CharSourceRanges
and passes character-based ranges to the DiagnosticConsumer.


Swift SVN r7173

lib/Basic/SourceLoc.cpp

@@ -36,6 +36,19 @@ unsigned SourceManager::getLocOffsetInBuffer(SourceLoc Loc,
   return Loc.Value.getPointer() - Buffer->getBuffer().begin();
 }
 
+unsigned SourceManager::getByteDistance(SourceLoc Start, SourceLoc End) const {
+#ifndef NDEBUG
+  unsigned BufferID = findBufferContainingLoc(Start);
+  auto *Buffer = LLVMSourceMgr.getMemoryBuffer(BufferID);
+  assert(End.Value.getPointer() >= Buffer->getBuffer().begin() &&
+         End.Value.getPointer() <= Buffer->getBuffer().end() &&
+         "End location is not from the same buffer");
+#endif
+  // When we have a rope buffer, could be implemented in terms of
+  // getLocOffsetInBuffer().
+  return End.Value.getPointer() - Start.Value.getPointer();
+}
+
 void SourceLoc::printLineAndColumn(raw_ostream &OS,
                                    const SourceManager &SM) const {
   if (isInvalid()) {
@@ -93,3 +106,12 @@ void SourceRange::dump(const SourceManager &SM) const {
   print(llvm::errs(), SM);
 }
 
+CharSourceRange::CharSourceRange(SourceManager &SM, SourceLoc Start,
+                                 SourceLoc End)
+    : Start(Start) {
+  assert(Start.isValid() == End.isValid() &&
+         "Start and end should either both be valid or both be invalid!");
+  if (Start.isValid())
+    ByteLength = SM.getByteDistance(Start, End);
+}
+