documentation parsing. Patch to do typo correction for

documentation commands. Patch was reviewed, along with
great suggestions for improvement, by Doug. 
// rdar://12381408

llvm-svn: 181458

2 files changed, 39 insertions, 2 deletions

diff --git a/clang/lib/AST/CommentCommandTraits.cpp b/clang/lib/AST/CommentCommandTraits.cpp
index e24d542c962..e4cc84afb78 100644
--- a/clang/lib/AST/CommentCommandTraits.cpp
+++ b/clang/lib/AST/CommentCommandTraits.cpp
@@ -43,6 +43,33 @@ const CommandInfo *CommandTraits::getCommandInfo(unsigned CommandID) const {
   return getRegisteredCommandInfo(CommandID);
 }
 
+const CommandInfo *
+CommandTraits::getTypoCorrectCommandInfo(StringRef Typo) const {
+  const unsigned MaxEditDistance = 1;
+  unsigned BestEditDistance = MaxEditDistance + 1;
+  SmallVector<const CommandInfo *, 2> BestCommand;
+  
+  int NumOfCommands = sizeof(Commands) / sizeof(CommandInfo);
+  for (int i = 0; i < NumOfCommands; i++) {
+    StringRef Name = Commands[i].Name;
+    unsigned MinPossibleEditDistance = abs((int)Name.size() - (int)Typo.size());
+    if (MinPossibleEditDistance > 0 &&
+        Typo.size() / MinPossibleEditDistance < 1)
+      continue;
+    unsigned EditDistance = Typo.edit_distance(Name, true, MaxEditDistance);
+    if (EditDistance > MaxEditDistance)
+      continue;
+    if (EditDistance == BestEditDistance)
+      BestCommand.push_back(&Commands[i]);
+    else if (EditDistance < BestEditDistance) {
+      BestCommand.clear();
+      BestCommand.push_back(&Commands[i]);
+      BestEditDistance = EditDistance;
+    }
+  }
+  return (BestCommand.size() != 1) ? NULL : BestCommand[0];
+}
+
 CommandInfo *CommandTraits::createCommandInfoWithName(StringRef CommandName) {
   char *Name = Allocator.Allocate<char>(CommandName.size() + 1);
   memcpy(Name, CommandName.data(), CommandName.size());
diff --git a/clang/lib/AST/CommentLexer.cpp b/clang/lib/AST/CommentLexer.cpp
index 70410d61085..a59badaeaf1 100644
--- a/clang/lib/AST/CommentLexer.cpp
+++ b/clang/lib/AST/CommentLexer.cpp
@@ -265,6 +265,7 @@ const char *findCCommentEnd(const char *BufferPtr, const char *BufferEnd) {
   }
   llvm_unreachable("buffer end hit before '*/' was seen");
 }
+    
 } // unnamed namespace
 
 void Lexer::lexCommentText(Token &T) {
@@ -354,8 +355,17 @@ void Lexer::lexCommentText(Token &T) {
         if (!Info) {
           formTokenWithChars(T, TokenPtr, tok::unknown_command);
           T.setUnknownCommandName(CommandName);
-          Diag(T.getLocation(), diag::warn_unknown_comment_command_name);
-          return;
+          if (Info = Traits.getTypoCorrectCommandInfo(CommandName)) {
+            StringRef CorrectedName = Info->Name;
+            SourceRange CommandRange(T.getLocation().getLocWithOffset(1),
+                                     T.getEndLocation());
+            Diag(T.getLocation(), diag::warn_correct_comment_command_name)
+              << CommandName << CorrectedName
+              << FixItHint::CreateReplacement(CommandRange, CorrectedName);
+          } else {
+            Diag(T.getLocation(), diag::warn_unknown_comment_command_name);
+            return;
+          }
         }
         if (Info->IsVerbatimBlockCommand) {
           setupAndLexVerbatimBlock(T, TokenPtr, *BufferPtr, Info);