Commit 9d212e83 authored by Jonathan Coe's avatar Jonathan Coe
Browse files

[clang-format] Handle quotes and escaped braces in C# interpolated strings 

Summary:
This addresses issues raised in https://bugs.llvm.org/show_bug.cgi?id=44454.

There are outstanding issues with multi-line verbatim strings in C# that will be addressed in a follow-up PR.

Reviewers: krasimir, MyDeveloperDay

Reviewed By: krasimir, MyDeveloperDay

Subscribers: MyDeveloperDay

Tags: #clang-format

Differential Revision: https://reviews.llvm.org/D73492
parent e916c8df

clang/lib/Format/FormatTokenLexer.cpp

+56 −6
Original line number Diff line number Diff line
@@ -74,7 +74,7 @@ void FormatTokenLexer::tryMergePreviousTokens() { 
  if (Style.isCSharp()) {

    if (tryMergeCSharpKeywordVariables())

      return;

    if (tryMergeCSharpVerbatimStringLiteral())

    if (tryMergeCSharpStringLiteral())

      return;

    if (tryMergeCSharpDoubleQuestion())

      return;
@@ -181,18 +181,68 @@ bool FormatTokenLexer::tryMergeJSPrivateIdentifier() { 
// Search for verbatim or interpolated string literals @"ABC" or

// $"aaaaa{abc}aaaaa" i and mark the token as TT_CSharpStringLiteral, and to

// prevent splitting of @, $ and ".

bool FormatTokenLexer::tryMergeCSharpVerbatimStringLiteral() {

bool FormatTokenLexer::tryMergeCSharpStringLiteral() {

  if (Tokens.size() < 2)

    return false;



  auto &String = *(Tokens.end() - 1);

  if (!String->is(tok::string_literal))

    return false;

  auto &CSharpStringLiteral = *(Tokens.end() - 2);



  // Interpolated strings could contain { } with " characters inside.

  // $"{x ?? "null"}"

  // should not be split into $"{x ?? ", null, "}" but should treated as a

  // single string-literal.

  //

  // We opt not to try and format expressions inside {} within a C#

  // interpolated string. Formatting expressions within an interpolated string

  // would require similar work as that done for JavaScript template strings

  // in `handleTemplateStrings()`.

  auto &CSharpInterpolatedString = *(Tokens.end() - 2);

  if (CSharpInterpolatedString->Type == TT_CSharpStringLiteral &&

      (CSharpInterpolatedString->TokenText.startswith(R"($")") ||

       CSharpInterpolatedString->TokenText.startswith(R"($@")"))) {

    int UnmatchedOpeningBraceCount = 0;



    auto TokenTextSize = CSharpInterpolatedString->TokenText.size();

    for (size_t Index = 0; Index < TokenTextSize; ++Index) {

      char C = CSharpInterpolatedString->TokenText[Index];

      if (C == '{') {

        // "{{"  inside an interpolated string is an escaped '{' so skip it.

        if (Index + 1 < TokenTextSize &&

            CSharpInterpolatedString->TokenText[Index + 1] == '{') {

          ++Index;

          continue;

        }

        ++UnmatchedOpeningBraceCount;

      } else if (C == '}') {

        // "}}"  inside an interpolated string is an escaped '}' so skip it.

        if (Index + 1 < TokenTextSize &&

            CSharpInterpolatedString->TokenText[Index + 1] == '}') {

          ++Index;

          continue;

        }

        --UnmatchedOpeningBraceCount;

      }

    }



    if (UnmatchedOpeningBraceCount > 0) {

      auto &NextToken = *(Tokens.end() - 1);

      CSharpInterpolatedString->TokenText =

          StringRef(CSharpInterpolatedString->TokenText.begin(),

                    NextToken->TokenText.end() -

                        CSharpInterpolatedString->TokenText.begin());

      CSharpInterpolatedString->ColumnWidth += NextToken->ColumnWidth;

      Tokens.erase(Tokens.end() - 1);

      return true;

    }

  }



  // verbatim strings could contain "" which C# sees as an escaped ".

  // @"""Hello""" will have been tokenized as @"" "Hello" "" and needs

  // merging into a single string literal.

  auto &CSharpStringLiteral = *(Tokens.end() - 2);

  auto &String = *(Tokens.end() - 1);

  if (!String->is(tok::string_literal))

    return false;



  if (CSharpStringLiteral->Type == TT_CSharpStringLiteral &&

      (CSharpStringLiteral->TokenText.startswith(R"(@")") ||

       CSharpStringLiteral->TokenText.startswith(R"($@")"))) {

clang/lib/Format/FormatTokenLexer.h

+1 −1
Original line number Diff line number Diff line
@@ -49,7 +49,7 @@ private: 
  bool tryMergeLessLess();

  bool tryMergeNSStringLiteral();

  bool tryMergeJSPrivateIdentifier();

  bool tryMergeCSharpVerbatimStringLiteral();

  bool tryMergeCSharpStringLiteral();

  bool tryMergeCSharpKeywordVariables();

  bool tryMergeCSharpNullConditionals();

  bool tryMergeCSharpDoubleQuestion();

clang/unittests/Format/FormatTestCSharp.cpp

+8 −0
Original line number Diff line number Diff line
@@ -417,5 +417,13 @@ TEST_F(FormatTestCSharp, CSharpEscapedQuotesInVerbatimStrings) { 
  verifyFormat(R"(string str = $@"""Hello {friend}""")", Style);

}



TEST_F(FormatTestCSharp, CSharpQuotesInInterpolatedStrings) {

  FormatStyle Style = getGoogleStyle(FormatStyle::LK_CSharp);



  verifyFormat(R"(string str1 = $"{null ?? "null"}";)", Style);

  verifyFormat(R"(string str2 = $"{{{braceCount} braces";)", Style);

  verifyFormat(R"(string str3 = $"{braceCount}}} braces";)", Style);

}



} // namespace format

} // end namespace clang