1 files changed, 27 insertions, 49 deletions

diff --git a/clang-tools-extra/clangd/Selection.cpp b/clang-tools-extra/clangd/Selection.cpp
index 4dae2f73539..ffa48f3a57d 100644
--- a/clang-tools-extra/clangd/Selection.cpp
+++ b/clang-tools-extra/clangd/Selection.cpp
@@ -142,11 +142,6 @@ void update(SelectionTree::Selection &Result, SelectionTree::Selection New) {
     Result = SelectionTree::Partial;
 }
 
-// As well as comments, don't count semicolons as real tokens.
-// They're not properly claimed as expr-statement is missing from the AST.
-bool shouldIgnore(const syntax::Token &Tok) {
-  return Tok.kind() == tok::comment || Tok.kind() == tok::semi;
-}
 
 // SelectionTester can determine whether a range of tokens from the PP-expanded
 // stream (corresponding to an AST node) is considered selected.
@@ -177,7 +172,9 @@ public:
         });
     // Precompute selectedness and offset for selected spelled tokens.
     for (const syntax::Token *T = SelFirst; T < SelLimit; ++T) {
-      if (shouldIgnore(*T))
+      // As well as comments, don't count semicolons as real tokens.
+      // They're not properly claimed as expr-statement is missing from the AST.
+      if (T->kind() == tok::comment || T->kind() == tok::semi)
         continue;
       SpelledTokens.emplace_back();
       Tok &S = SpelledTokens.back();
@@ -653,49 +650,24 @@ std::string SelectionTree::Node::kind() const {
   return std::move(OS.str());
 }
 
-// Decide which selections emulate a "point" query in between characters.
-// If it's ambiguous (the neighboring characters are selectable tokens), returns
-// both possibilities in preference order.
-// Always returns at least one range - if no tokens touched, and empty range.
-static llvm::SmallVector<std::pair<unsigned, unsigned>, 2>
-pointBounds(unsigned Offset, const syntax::TokenBuffer &Tokens) {
-  const auto &SM = Tokens.sourceManager();
-  SourceLocation Loc = SM.getComposedLoc(SM.getMainFileID(), Offset);
-  llvm::SmallVector<std::pair<unsigned, unsigned>, 2> Result;
-  // Prefer right token over left.
-  for (const syntax::Token &Tok :
-       llvm::reverse(spelledTokensTouching(Loc, Tokens))) {
-    if (shouldIgnore(Tok))
-      continue;
-    unsigned Offset = Tokens.sourceManager().getFileOffset(Tok.location());
-    Result.emplace_back(Offset, Offset + Tok.length());
-  }
-  if (Result.empty())
-    Result.emplace_back(Offset, Offset);
-  return Result;
-}
-
-bool SelectionTree::createEach(ASTContext &AST,
-                               const syntax::TokenBuffer &Tokens,
-                               unsigned Begin, unsigned End,
-                               llvm::function_ref<bool(SelectionTree)> Func) {
-  if (Begin != End)
-    return Func(SelectionTree(AST, Tokens, Begin, End));
-  for (std::pair<unsigned, unsigned> Bounds : pointBounds(Begin, Tokens))
-    if (Func(SelectionTree(AST, Tokens, Bounds.first, Bounds.second)))
-      return true;
-  return false;
-}
-
-SelectionTree SelectionTree::createRight(ASTContext &AST,
-                                         const syntax::TokenBuffer &Tokens,
-                                         unsigned int Begin, unsigned int End) {
-  llvm::Optional<SelectionTree> Result;
-  createEach(AST, Tokens, Begin, End, [&](SelectionTree T) {
-    Result = std::move(T);
-    return true;
-  });
-  return std::move(*Result);
+// Decide which selection emulates a "point" query in between characters.
+static std::pair<unsigned, unsigned> pointBounds(unsigned Offset, FileID FID,
+                                                 ASTContext &AST) {
+  StringRef Buf = AST.getSourceManager().getBufferData(FID);
+  // Edge-cases where the choice is forced.
+  if (Buf.size() == 0)
+    return {0, 0};
+  if (Offset == 0)
+    return {0, 1};
+  if (Offset == Buf.size())
+    return {Offset - 1, Offset};
+  // We could choose either this byte or the previous. Usually we prefer the
+  // character on the right of the cursor (or under a block cursor).
+  // But if that's whitespace/semicolon, we likely want the token on the left.
+  auto IsIgnoredChar = [](char C) { return isWhitespace(C) || C == ';'; };
+  if (IsIgnoredChar(Buf[Offset]) && !IsIgnoredChar(Buf[Offset - 1]))
+    return {Offset - 1, Offset};
+  return {Offset, Offset + 1};
 }
 
 SelectionTree::SelectionTree(ASTContext &AST, const syntax::TokenBuffer &Tokens,
@@ -705,6 +677,8 @@ SelectionTree::SelectionTree(ASTContext &AST, const syntax::TokenBuffer &Tokens,
   // but that's all clangd has needed so far.
   const SourceManager &SM = AST.getSourceManager();
   FileID FID = SM.getMainFileID();
+  if (Begin == End)
+    std::tie(Begin, End) = pointBounds(Begin, FID, AST);
   PrintPolicy.TerseOutput = true;
   PrintPolicy.IncludeNewlines = false;
 
@@ -716,6 +690,10 @@ SelectionTree::SelectionTree(ASTContext &AST, const syntax::TokenBuffer &Tokens,
   dlog("Built selection tree\n{0}", *this);
 }
 
+SelectionTree::SelectionTree(ASTContext &AST, const syntax::TokenBuffer &Tokens,
+                             unsigned Offset)
+    : SelectionTree(AST, Tokens, Offset, Offset) {}
+
 const Node *SelectionTree::commonAncestor() const {
   const Node *Ancestor = Root;
   while (Ancestor->Children.size() == 1 && !Ancestor->Selected)