[PATCH] D142804: [clang-format] Support clang-format on/off line comments as prefixes

[Alex via Phabricator via cfe-commits]

alexolog added inline comments.


================
Comment at: clang/lib/Format/Format.cpp:3893
 
+bool isClangFormatOn(StringRef Comment) {
+  if (Comment == "/* clang-format on */")
----------------
Here's my attempt at something flexible:
Disclaimer: this is my first time looking at the LLVM codebase, so don't expect 
production quality.

```
////////////////////////////////////////////////////////////////////////////////////////////////////

// Implementation detail, hide in a namespace and/or take out of the header
bool isClangFormatMarked(StringRef Comment, StringRef Mark) {
  // Quick heuristics: minimum length and starts with a slash (comment)
  // Shortest tag: "//clang-format on", 17 characters
  static constexpr StringLiteral clangFormatStr("clang-format ");
  if (Comment.size() < clangFormatStr.size() + 4 || Comment[0] != '/')
    return false;

  // check if it's a comment starting with "//" or "/*"
  bool CloseNeeded = false;
  if (Comment[1] == '*')
    CloseNeeded = true;
  else if (Comment[1] != '/')
    return false;

  // Remove the comment start and all following whitespace
  Comment = Comment.substr(2).ltrim();

  // Check for the actual command, a piece at a time
  if (!Comment.consume_front(clangFormatStr) || !Comment.consume_front(Mark))
    return false;

  // Are we there yet?
  if (!CloseNeeded && Comment.empty() ||
      CloseNeeded && Comment.starts_with("*/"))
    return true;

  // For a trailer, restrict the next character
  // (currently spaces and tabs, but can include a colon, etc.)
  static constexpr StringLiteral Separator(" \t");
  if (!Separator.contains(Comment[0]))
    return false;
  
  // Verify comment is properly terminated
  if (!CloseNeeded || Comment.contains("*/"))
    return true;

  return false; // Everything else
}

////////////////////////////////////////////////////////////////////////////////////////////////////

bool isClangFormatOn(StringRef Comment) {
  return isClangFormatMarked(Comment, "on");
}

bool isClangFormatOff(StringRef Comment) {
  return isClangFormatMarked(Comment, "off");
}

////////////////////////////////////////////////////////////////////////////////////////////////////

  EXPECT_TRUE(isClangFormatOn("//clang-format on"));
  EXPECT_TRUE(isClangFormatOn("// clang-format on"));
  EXPECT_TRUE(isClangFormatOn("//clang-format on "));
  EXPECT_TRUE(isClangFormatOn("//clang-format on and off"));
  EXPECT_TRUE(isClangFormatOn("/*clang-format on*/"));
  EXPECT_TRUE(isClangFormatOn("/* clang-format on*/"));
  EXPECT_TRUE(isClangFormatOn("/*clang-format on */"));
  EXPECT_TRUE(isClangFormatOn("/*clang-format on*/int i{0};"));

  EXPECT_FALSE(isClangFormatOn("//clang-format  on"));
  EXPECT_FALSE(isClangFormatOn("//clang-format o"));
  EXPECT_FALSE(isClangFormatOn("//     clang-format o"));
  EXPECT_FALSE(isClangFormatOn("//clang-format ontario"));
  EXPECT_FALSE(isClangFormatOn("//clang-format off"));
  EXPECT_FALSE(isClangFormatOn("/*clang-format onwards*/"));

////////////////////////////////////////////////////////////////////////////////////////////////////
```


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D142804/new/

https://reviews.llvm.org/D142804

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