[clang] [clang-format] Add an option to format integer and float literal case (PR #151590)

[Björn Schäpers via cfe-commits]

================
@@ -0,0 +1,190 @@
+//===--- NumericLiteralCaseFixer.cpp -----------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file implements NumericLiteralCaseFixer that standardizes character
+/// case within numeric literal constants.
+///
+//===----------------------------------------------------------------------===//
+
+#include "NumericLiteralCaseFixer.h"
+#include "NumericLiteralInfo.h"
+
+#include "llvm/ADT/StringExtras.h"
+
+#include <algorithm>
+
+namespace clang {
+namespace format {
+
+static std::string
+transformComponent(StringRef Component,
+                   FormatStyle::NumericLiteralComponentStyle ConfigValue) {
+  switch (ConfigValue) {
+  case FormatStyle::NLCS_Upper:
+    return Component.upper();
+  case FormatStyle::NLCS_Lower:
+    return Component.lower();
+  case FormatStyle::NLCS_Leave:
+  default:
+    return Component.str();
+  }
+}
+
+/// @brief Test if Suffix matches a C++ literal reserved by the library.
+/// Matches against all suffixes reserved in the C++23 standard
+static bool matchesReservedSuffix(StringRef Suffix) {
+  static constexpr std::array<StringRef, 11> SortedReservedSuffixes = {
+      "d", "h", "i", "if", "il", "min", "ms", "ns", "s", "us", "y"};
+
+  // This can be static_assert when we have access to constexpr is_sorted in
+  // C++ 20.
+  assert(llvm::is_sorted(SortedReservedSuffixes) &&
+         "Must be sorted as precondition for lower_bound().");
+
+  auto entry = llvm::lower_bound(SortedReservedSuffixes, Suffix);
+  if (entry == SortedReservedSuffixes.cend())
+    return false;
+  return *entry == Suffix;
+}
+
+static std::optional<std::string> formatIfNeeded(StringRef IntegerLiteral,
+                                                 const FormatStyle &Style) {
+  char Separator;
+  switch (Style.Language) {
+  case FormatStyle::LK_CSharp:
+  case FormatStyle::LK_Java:
+  case FormatStyle::LK_JavaScript:
+    Separator = '_';
+    break;
+  case FormatStyle::LK_C:
+  case FormatStyle::LK_Cpp:
+  case FormatStyle::LK_ObjC:
+  default:
+    Separator = '\'';
+  }
+  const NumericLiteralInfo N{IntegerLiteral, Separator};
+
+  std::string Formatted{""};
+
+  if (N.BaseLetterPos != llvm::StringRef::npos) {
+    Formatted +=
+        transformComponent(IntegerLiteral.take_front(1 + N.BaseLetterPos),
+                           Style.NumericLiteralCase.Prefix);
+  }
+  // reformat this slice as HexDigit whether or not the digit has hexadecimal
+  // characters because binary/decimal/octal digits are unchanged
----------------
HazardyKnusperkeks wrote:

```suggestion
  // Reformat this slice as HexDigit whether or not the digit has hexadecimal
  // characters because binary/decimal/octal digits are unchanged.
```

https://github.com/llvm/llvm-project/pull/151590