[clang-tools-extra] [clangd] Implement fold range for #pragma region (PR #168177)

[Nathan Ridge via cfe-commits]

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@@ -163,6 +164,66 @@ llvm::Expected<SelectionRange> getSemanticRanges(ParsedAST &AST, Position Pos) {
   return std::move(Head);
 }
 
+class PragmaRegionFinder {
+  // Record the token range of a region:
+  //
+  //   #pragma region [[name
+  //   ...
+  //   ]]#pragma region
+  std::vector<Token::Range> &Ranges;
+  const TokenStream &Code;
+  // Stack of starting token (the name of the region) indices for nested #pragma
+  // region.
+  std::vector<unsigned> Stack;
+
+public:
+  PragmaRegionFinder(std::vector<Token::Range> &Ranges, const TokenStream &Code)
+      : Ranges(Ranges), Code(Code) {}
+
+  void walk(const DirectiveTree &T) {
+    for (const auto &C : T.Chunks)
+      std::visit(*this, C);
+  }
+
+  void operator()(const DirectiveTree::Code &C) {}
+
+  void operator()(const DirectiveTree::Directive &D) {
+    // Get the tokens that make up this directive.
+    auto Tokens = Code.tokens(D.Tokens);
+    if (Tokens.empty())
+      return;
+    const Token &HashToken = Tokens.front();
+    assert(HashToken.Kind == tok::hash);
+    const Token &Pragma = HashToken.nextNC();
+    if (Pragma.text() != "pragma")
+      return;
+    const Token &Value = Pragma.nextNC();
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HighCommander4 wrote:

If there can be a comment between `pragma` and `region`...

https://github.com/llvm/llvm-project/pull/168177