StringUtil: Backport helper functions

src/common/string_util.cpp

@@ -162,6 +162,20 @@ std::size_t StringUtil::Strlcpy(char* dst, const std::string_view src, std::size
   return len;
 }
 
+std::string StringUtil::StripControlCharacters(std::string_view str)
+{
+  std::string out;
+  out.reserve(str.length());
+  for (size_t i = 0; i < str.length();)
+  {
+    char32_t ch;
+    i += StringUtil::DecodeUTF8(str, i, &ch);
+    ch = (ch < 0x20) ? '_' : ch;
+    StringUtil::EncodeAndAppendUTF8(out, ch);
+  }
+  return out;
+}
+
 u8 StringUtil::DecodeHexDigit(char ch)
 {
   if (ch >= '0' && ch <= '9')
@@ -321,6 +335,17 @@ std::string StringUtil::EncodeBase64(const std::span<u8> data)
   return ret;
 }
 
+size_t StringUtil::CountChar(const std::string_view str, char ch)
+{
+  return std::count(str.begin(), str.end(), ch);
+}
+
+size_t StringUtil::CountCharNoCase(const std::string_view str, char ch)
+{
+  ch = ToLower(ch);
+  return std::count_if(str.begin(), str.end(), [ch](char och) { return (ch == ToLower(och)); });
+}
+
 std::string_view StringUtil::StripWhitespace(const std::string_view str)
 {
   std::string_view::size_type start = 0;

src/common/string_util.h

@@ -267,6 +267,9 @@ ALWAYS_INLINE bool IsWhitespace(char ch)
           ch == 0x20);                  // space
 }
 
+/// Removes control characters from the given string.
+std::string StripControlCharacters(std::string_view str);
+
 /// Encode/decode hexadecimal byte buffers
 u8 DecodeHexDigit(char ch);
 size_t DecodeHex(std::span<u8> dest, const std::string_view str);
@@ -347,6 +350,10 @@ ALWAYS_INLINE bool EndsWithNoCase(const std::string_view str, const std::string_
           Strncasecmp(str.data() + (str.length() - suffix_length), suffix.data(), suffix_length) == 0);
 }
 
+/// Returns the number of occurrences of the given character in the string.
+size_t CountChar(const std::string_view str, char ch);
+size_t CountCharNoCase(const std::string_view str, char ch);
+
 /// Strip whitespace from the start/end of the string.
 std::string_view StripWhitespace(const std::string_view str);
 void StripWhitespace(std::string* str);