AK: Implement a method to split a UTF-16 string

Author: https://github.com/trflynn89
Commit: baddac5155
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5610

AK/Utf16StringBase.h

@@ -225,6 +225,21 @@ public:
     [[nodiscard]] ALWAYS_INLINE bool starts_with(Utf16View const& needle) const { return utf16_view().starts_with(needle); }
     [[nodiscard]] ALWAYS_INLINE bool ends_with(Utf16View const& needle) const { return utf16_view().ends_with(needle); }
 
+    [[nodiscard]] ALWAYS_INLINE Vector<Utf16View> split_view(char16_t needle, SplitBehavior split_behavior) const { return utf16_view().split_view(needle, split_behavior); }
+    [[nodiscard]] ALWAYS_INLINE Vector<Utf16View> split_view(Utf16View const& needle, SplitBehavior split_behavior) const { return utf16_view().split_view(needle, split_behavior); }
+
+    template<typename Callback>
+    ALWAYS_INLINE void for_each_split_view(char16_t separator, SplitBehavior split_behavior, Callback&& callback) const
+    {
+        utf16_view().for_each_split_view(separator, split_behavior, forward<Callback>(callback));
+    }
+
+    template<typename Callback>
+    ALWAYS_INLINE void for_each_split_view(Utf16View const& separator, SplitBehavior split_behavior, Callback&& callback) const
+    {
+        utf16_view().for_each_split_view(separator, split_behavior, forward<Callback>(callback));
+    }
+
     // This is primarily interesting to unit tests.
     [[nodiscard]] constexpr bool has_short_ascii_storage() const
     {

AK/Utf16View.cpp

@@ -254,6 +254,24 @@ Utf16View Utf16View::unicode_substring_view(size_t code_point_offset, size_t cod
     VERIFY_NOT_REACHED();
 }
 
+Vector<Utf16View> Utf16View::split_view(char16_t separator, SplitBehavior split_behavior) const
+{
+    Utf16View seperator_view { &separator, 1 };
+    return split_view(seperator_view, split_behavior);
+}
+
+Vector<Utf16View> Utf16View::split_view(Utf16View const& separator, SplitBehavior split_behavior) const
+{
+    Vector<Utf16View> parts;
+
+    for_each_split_view(separator, split_behavior, [&](auto const& part) {
+        parts.append(part);
+        return IterationDecision::Continue;
+    });
+
+    return parts;
+}
+
 size_t Utf16View::calculate_length_in_code_points() const
 {
     ASSERT(!has_ascii_storage());

AK/Utf16View.h

@@ -10,6 +10,7 @@
 #include <AK/Error.h>
 #include <AK/Format.h>
 #include <AK/Forward.h>
+#include <AK/IterationDecision.h>
 #include <AK/MemMem.h>
 #include <AK/Optional.h>
 #include <AK/Span.h>
@@ -515,6 +516,46 @@ public:
         return substring_view(length_in_code_units() - needle_length, needle_length) == needle;
     }
 
+    [[nodiscard]] Vector<Utf16View> split_view(char16_t, SplitBehavior) const;
+    [[nodiscard]] Vector<Utf16View> split_view(Utf16View const&, SplitBehavior) const;
+
+    template<typename Callback>
+    constexpr void for_each_split_view(char16_t separator, SplitBehavior split_behavior, Callback&& callback) const
+    {
+        Utf16View seperator_view { &separator, 1 };
+        for_each_split_view(seperator_view, split_behavior, forward<Callback>(callback));
+    }
+
+    template<typename Callback>
+    constexpr void for_each_split_view(Utf16View const& separator, SplitBehavior split_behavior, Callback&& callback) const
+    {
+        VERIFY(!separator.is_empty());
+
+        if (is_empty())
+            return;
+
+        bool keep_empty = has_flag(split_behavior, SplitBehavior::KeepEmpty);
+        bool keep_separator = has_flag(split_behavior, SplitBehavior::KeepTrailingSeparator);
+
+        auto view { *this };
+
+        for (auto index = view.find_code_unit_offset(separator); index.has_value(); index = view.find_code_unit_offset(separator)) {
+            if (keep_empty || *index > 0) {
+                auto part = keep_separator
+                    ? view.substring_view(0, *index + separator.length_in_code_units())
+                    : view.substring_view(0, *index);
+
+                if (callback(part) == IterationDecision::Break)
+                    return;
+            }
+
+            view = view.substring_view(*index + separator.length_in_code_units());
+        }
+
+        if (keep_empty || !view.is_empty())
+            callback(view);
+    }
+
     // https://infra.spec.whatwg.org/#code-unit-less-than
     [[nodiscard]] constexpr bool is_code_unit_less_than(Utf16View const& other) const
     {

Tests/AK/TestUtf16View.cpp

@@ -634,6 +634,47 @@ TEST_CASE(ends_with)
     EXPECT(!emoji.ends_with(u"😀"sv));
 }
 
+TEST_CASE(split_view)
+{
+    {
+        auto test = u"axxbxcxd"sv;
+
+        EXPECT_EQ(test.split_view('x', SplitBehavior::Nothing), Vector({ u"a"sv, u"b"sv, u"c"sv, u"d"sv }));
+        EXPECT_EQ(test.split_view("x"sv, SplitBehavior::Nothing), Vector({ u"a"sv, u"b"sv, u"c"sv, u"d"sv }));
+
+        EXPECT_EQ(test.split_view('x', SplitBehavior::KeepEmpty), Vector({ u"a"sv, u""sv, u"b"sv, u"c"sv, u"d"sv }));
+        EXPECT_EQ(test.split_view("x"sv, SplitBehavior::KeepEmpty), Vector({ u"a"sv, u""sv, u"b"sv, u"c"sv, u"d"sv }));
+    }
+    {
+        auto test = u"axxbx"sv;
+
+        EXPECT_EQ(test.split_view('x', SplitBehavior::Nothing), Vector({ u"a"sv, u"b"sv }));
+        EXPECT_EQ(test.split_view("x"sv, SplitBehavior::Nothing), Vector({ u"a"sv, u"b"sv }));
+
+        EXPECT_EQ(test.split_view('x', SplitBehavior::KeepEmpty), Vector({ u"a"sv, u""sv, u"b"sv, u""sv }));
+        EXPECT_EQ(test.split_view("x"sv, SplitBehavior::KeepEmpty), Vector({ u"a"sv, u""sv, u"b"sv, u""sv }));
+    }
+    {
+        auto test = u"axxbcxxdxx"sv;
+        EXPECT_EQ(test.split_view(u"xx"sv, SplitBehavior::Nothing), Vector({ u"a"sv, u"bc"sv, u"d"sv }));
+        EXPECT_EQ(test.split_view(u"xx"sv, SplitBehavior::KeepEmpty), Vector({ u"a"sv, u"bc"sv, u"d"sv, u""sv }));
+    }
+    {
+        auto test = u"a,,,b"sv;
+        EXPECT_EQ(test.split_view(u","sv, SplitBehavior::KeepEmpty), Vector({ u"a"sv, u""sv, u""sv, u"b"sv }));
+        EXPECT_EQ(test.split_view(u","sv, SplitBehavior::KeepTrailingSeparator), Vector({ u"a,"sv, u"b"sv }));
+        EXPECT_EQ(test.split_view(u","sv, SplitBehavior::KeepTrailingSeparator | SplitBehavior::KeepEmpty), Vector({ u"a,"sv, u","sv, u","sv, u"b"sv }));
+    }
+    {
+        auto test = u"foo bar baz"sv;
+        EXPECT_EQ(test.split_view(u" "sv, SplitBehavior::Nothing), Vector({ u"foo"sv, u"bar"sv, u"baz"sv }));
+    }
+    {
+        auto test = u"ωΣ2ωΣω"sv;
+        EXPECT_EQ(test.split_view(0x03A3u, SplitBehavior::Nothing), Vector({ u"ω"sv, u"2ω"sv, u"ω"sv }));
+    }
+}
+
 TEST_CASE(find_code_unit_offset)
 {
     auto conversion_result = Utf16String::from_utf8("😀foo😀bar"sv);