AK: Add DeprecatedStringCodePointIterator

This is a safe iterator over the underlying code points. It will be used
in Jakt to assist in the migration away from DeprecatedString.

AK/DeprecatedString.cpp

@@ -11,6 +11,7 @@
 #include <AK/Function.h>
 #include <AK/StdLibExtras.h>
 #include <AK/StringView.h>
+#include <AK/Utf8View.h>
 #include <AK/Vector.h>
 
 namespace AK {
@@ -449,4 +450,9 @@ Vector<size_t> DeprecatedString::find_all(StringView needle) const
     return StringUtils::find_all(*this, needle);
 }
 
+DeprecatedStringCodePointIterator DeprecatedString::code_points() const
+{
+    return DeprecatedStringCodePointIterator(*this);
+}
+
 }

AK/DeprecatedString.h

@@ -129,6 +129,8 @@ public:
 
     [[nodiscard]] bool is_whitespace() const { return StringUtils::is_whitespace(*this); }
 
+    [[nodiscard]] DeprecatedStringCodePointIterator code_points() const;
+
     [[nodiscard]] DeprecatedString trim(StringView characters, TrimMode mode = TrimMode::Both) const
     {
         auto trimmed_view = StringUtils::trim(view(), characters, mode);

AK/Forward.h

@@ -30,6 +30,7 @@ class JsonValue;
 class StackInfo;
 class DeprecatedFlyString;
 class DeprecatedString;
+class DeprecatedStringCodePointIterator;
 class StringBuilder;
 class StringImpl;
 class StringView;
@@ -156,6 +157,7 @@ using AK::CircularBuffer;
 using AK::CircularQueue;
 using AK::DeprecatedFlyString;
 using AK::DeprecatedString;
+using AK::DeprecatedStringCodePointIterator;
 using AK::DoublyLinkedList;
 using AK::Error;
 using AK::ErrorOr;

AK/Utf8View.h

@@ -130,9 +130,32 @@ private:
     mutable bool m_have_length { false };
 };
 
+class DeprecatedStringCodePointIterator {
+public:
+    Optional<u32> next()
+    {
+        if (m_it.done())
+            return {};
+        auto value = *m_it;
+        ++m_it;
+        return value;
+    }
+
+    DeprecatedStringCodePointIterator(DeprecatedString string)
+        : m_string(move(string))
+        , m_it(Utf8View(m_string).begin())
+    {
+    }
+
+private:
+    DeprecatedString m_string;
+    Utf8CodePointIterator m_it;
+};
+
 }
 
 #if USING_AK_GLOBALLY
+using AK::DeprecatedStringCodePointIterator;
 using AK::Utf8CodePointIterator;
 using AK::Utf8View;
 #endif