AK: Implement StringView::find_all()

This implements the StringView::find_all() method by re-implemeting the
current method existing for String in StringUtils, and using that
implementation for both String and StringView.

The rewrite uses memmem() instead of strstr(), so the String::find_all()
argument type has been changed from String to StringView, as the null
byte is no longer required.

AK/String.cpp

@@ -293,23 +293,6 @@ bool String::equals_ignoring_case(const StringView& other) const
  return StringUtils::equals_ignoring_case(view(), other);
 }
 
-Vector<size_t> String::find_all(const String& needle) const
-{
- Vector<size_t> positions;
- size_t start = 0, pos;
- for (;;) {
- const char* ptr = strstr(characters() + start, needle.characters());
- if (!ptr)
- break;
-
- pos = ptr - characters();
- positions.append(pos);
-
- start = pos + 1;
- }
- return positions;
-}
-
 int String::replace(const String& needle, const String& replacement, bool all_occurrences)
 {
  if (is_empty())

AK/String.h

@@ -143,6 +143,7 @@ class String {
 
  [[nodiscard]] Optional<size_t> find(char, size_t start = 0) const;
  [[nodiscard]] Optional<size_t> find(StringView const&, size_t start = 0) const;
+ [[nodiscard]] Vector<size_t> find_all(StringView const& needle) const { return StringUtils::find_all(*this, needle); }
 
  [[nodiscard]] String substring(size_t start) const;
  [[nodiscard]] String substring(size_t start, size_t length) const;
@@ -279,7 +280,6 @@ class String {
 
  int replace(const String& needle, const String& replacement, bool all_occurrences = false);
  size_t count(const String& needle) const;
- Vector<size_t> find_all(const String& needle) const;
  [[nodiscard]] String reverse() const;
 
  template<typename... Ts>

AK/StringUtils.cpp

@@ -362,6 +362,22 @@ Optional<size_t> find_last(StringView const& haystack, char needle)
  return {};
 }
 
+Vector<size_t> find_all(StringView const& haystack, StringView const& needle)
+{
+ Vector<size_t> positions;
+ size_t current_position = 0;
+ while (current_position <= haystack.length()) {
+ auto maybe_position = AK::memmem_optional(
+ haystack.characters_without_null_termination() + current_position, haystack.length() - current_position,
+ needle.characters_without_null_termination(), needle.length());
+ if (!maybe_position.has_value())
+ break;
+ positions.append(current_position + *maybe_position);
+ current_position += *maybe_position + 1;
+ }
+ return positions;
+}
+
 String to_snakecase(const StringView& str)
 {
  auto should_insert_underscore = [&](auto i, auto current_char) {

AK/StringView.h

@@ -91,6 +91,8 @@ class StringView {
  [[nodiscard]] Optional<size_t> find_last(char needle) const { return StringUtils::find_last(*this, needle); }
  // FIXME: Implement find_last(StringView const&) for API symmetry.
 
+ [[nodiscard]] Vector<size_t> find_all(StringView const& needle) const { return StringUtils::find_all(*this, needle); }
+
  [[nodiscard]] Optional<size_t> find_first_of(StringView const&) const;
  [[nodiscard]] Optional<size_t> find_last_of(StringView const&) const;