LibRegex: Add RegexStringView wrapper to support utf8 and utf32 views

Libraries/LibRegex/RegexMatch.h

@@ -31,11 +31,196 @@
 #include "AK/FlyString.h"
 #include "AK/HashMap.h"
 #include "AK/String.h"
+#include "AK/StringBuilder.h"
 #include "AK/StringView.h"
+#include "AK/Utf32View.h"
 #include "AK/Vector.h"
 
 namespace regex {
 
+class RegexStringView {
+public:
+    RegexStringView(const char* chars)
+        : m_u8view(chars)
+    {
+    }
+
+    RegexStringView(const String& string)
+        : m_u8view(string)
+    {
+    }
+
+    RegexStringView(const StringView view)
+        : m_u8view(view)
+    {
+    }
+    RegexStringView(const Utf32View view)
+        : m_u32view(view)
+    {
+    }
+
+    bool is_u8_view() const { return m_u8view.has_value(); }
+    bool is_u32_view() const { return m_u32view.has_value(); }
+
+    const StringView& u8view() const
+    {
+        ASSERT(m_u8view.has_value());
+        return m_u8view.value();
+    };
+
+    const Utf32View& u32view() const
+    {
+        ASSERT(m_u32view.has_value());
+        return m_u32view.value();
+    };
+
+    bool is_empty() const
+    {
+        if (is_u8_view())
+            return m_u8view.value().is_empty();
+        else
+            return m_u32view.value().is_empty();
+    }
+
+    bool is_null() const
+    {
+        if (is_u8_view())
+            return m_u8view.value().is_null();
+        else
+            return m_u32view.value().code_points() == nullptr;
+    }
+
+    size_t length() const
+    {
+        if (is_u8_view())
+            return m_u8view.value().length();
+        else
+            return m_u32view.value().length();
+    }
+
+    Vector<RegexStringView> lines() const
+    {
+        if (is_u8_view()) {
+            auto views = u8view().lines(false);
+            Vector<RegexStringView> new_views;
+            for (auto& view : views)
+                new_views.append(move(view));
+            return new_views;
+        }
+
+        // FIXME: line splitting for Utf32View needed
+        Vector<RegexStringView> views;
+        views.append(m_u32view.value());
+        return views;
+    }
+
+    RegexStringView substring_view(size_t offset, size_t length) const
+    {
+        if (is_u8_view()) {
+            return u8view().substring_view(offset, length);
+        }
+        return u32view().substring_view(offset, length);
+    }
+
+    String to_string() const
+    {
+        if (is_u8_view()) {
+            return u8view().to_string();
+        }
+
+        StringBuilder builder;
+        builder.append(u32view());
+        return builder.to_string();
+    }
+
+    u32 operator[](size_t index) const
+    {
+        if (is_u8_view()) {
+            return u8view()[index];
+        }
+        return u32view().code_points()[index];
+    }
+
+    bool operator==(const char* cstring) const
+    {
+        if (is_u8_view())
+            return u8view() == cstring;
+
+        return to_string() == cstring;
+    }
+
+    bool operator!=(const char* cstring) const
+    {
+        return !(*this == cstring);
+    }
+
+    bool operator==(const String& string) const
+    {
+        if (is_u8_view())
+            return u8view() == string;
+
+        return to_string() == string;
+    }
+
+    bool operator==(const StringView& other) const
+    {
+        if (is_u8_view())
+            return u8view() == other;
+
+        return false;
+    }
+
+    bool operator!=(const StringView& other) const
+    {
+        return !(*this == other);
+    }
+
+    bool operator==(const Utf32View& other) const
+    {
+        if (is_u32_view()) {
+            StringBuilder builder;
+            builder.append(other);
+            return to_string() == builder.to_string();
+        }
+
+        return false;
+    }
+
+    bool operator!=(const Utf32View& other) const
+    {
+        return !(*this == other);
+    }
+
+    const char* characters_without_null_termination() const
+    {
+        if(is_u8_view())
+            return u8view().characters_without_null_termination();
+
+        return to_string().characters(); // FIXME: it contains the null termination, does that actually matter?
+    }
+
+    bool starts_with(const StringView& str) const
+    {
+        if(is_u32_view())
+            return false;
+        return u8view().starts_with(str);
+    }
+
+    bool starts_with(const Utf32View& str) const
+    {
+        if(is_u8_view())
+            return false;
+
+        StringBuilder builder;
+        builder.append(str);
+        return to_string().starts_with(builder.to_string());
+    }
+
+private:
+    Optional<StringView> m_u8view;
+    Optional<Utf32View> m_u32view;
+};
+
 class Match final {
 private:
     Optional<FlyString> string;
@@ -44,7 +229,7 @@ public:
     Match() = default;
     ~Match() = default;
 
-    Match(const StringView view_, const size_t line_, const size_t column_, const size_t global_offset_)
+    Match(const RegexStringView view_, const size_t line_, const size_t column_, const size_t global_offset_)
         : view(view_)
         , line(line_)
         , column(column_)
@@ -63,7 +248,7 @@ public:
     {
     }
 
-    StringView view { nullptr };
+    RegexStringView view { nullptr };
     size_t line { 0 };
     size_t column { 0 };
     size_t global_offset { 0 };
@@ -74,14 +259,14 @@ public:
 };
 
 struct MatchInput {
-    StringView view { nullptr };
+    RegexStringView view { nullptr };
     AllOptions regex_options {};
 
     size_t match_index { 0 };
     size_t line { 0 };
     size_t column { 0 };
 
-    size_t global_offset { 0 }; // For multiline matching, knowning the offset from start could be important
+    size_t global_offset { 0 }; // For multiline matching, knowing the offset from start could be important
 };
 
 struct MatchState {
@@ -98,3 +283,5 @@ struct MatchOutput {
 };
 
 }
+
+using regex::RegexStringView;