1 files changed, 163 insertions, 0 deletions
diff --git a/Userland/Libraries/LibJS/Runtime/PropertyName.h b/Userland/Libraries/LibJS/Runtime/PropertyName.h
new file mode 100644
index 0000000000..bbd6a0c640
--- /dev/null
+++ b/Userland/Libraries/LibJS/Runtime/PropertyName.h
@@ -0,0 +1,163 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/FlyString.h>
+#include <LibJS/Runtime/StringOrSymbol.h>
+
+namespace JS {
+
+class PropertyName {
+public:
+    enum class Type {
+        Invalid,
+        Number,
+        String,
+        Symbol,
+    };
+
+    static PropertyName from_value(GlobalObject& global_object, Value value)
+    {
+        if (value.is_empty())
+            return {};
+        if (value.is_symbol())
+            return &value.as_symbol();
+        if (value.is_integer() && value.as_i32() >= 0)
+            return value.as_i32();
+        auto string = value.to_string(global_object);
+        if (string.is_null())
+            return {};
+        return string;
+    }
+
+    PropertyName() { }
+
+    PropertyName(i32 index)
+        : m_type(Type::Number)
+        , m_number(index)
+    {
+        ASSERT(index >= 0);
+    }
+
+    PropertyName(const char* chars)
+        : m_type(Type::String)
+        , m_string(FlyString(chars))
+    {
+    }
+
+    PropertyName(const String& string)
+        : m_type(Type::String)
+        , m_string(FlyString(string))
+    {
+        ASSERT(!string.is_null());
+    }
+
+    PropertyName(const FlyString& string)
+        : m_type(Type::String)
+        , m_string(string)
+    {
+        ASSERT(!string.is_null());
+    }
+
+    PropertyName(Symbol* symbol)
+        : m_type(Type::Symbol)
+        , m_symbol(symbol)
+    {
+        ASSERT(symbol);
+    }
+
+    PropertyName(const StringOrSymbol& string_or_symbol)
+    {
+        if (string_or_symbol.is_string()) {
+            m_string = string_or_symbol.as_string();
+            m_type = Type::String;
+        } else if (string_or_symbol.is_symbol()) {
+            m_symbol = const_cast<Symbol*>(string_or_symbol.as_symbol());
+            m_type = Type::Symbol;
+        }
+    }
+
+    bool is_valid() const { return m_type != Type::Invalid; }
+    bool is_number() const { return m_type == Type::Number; }
+    bool is_string() const { return m_type == Type::String; }
+    bool is_symbol() const { return m_type == Type::Symbol; }
+
+    i32 as_number() const
+    {
+        ASSERT(is_number());
+        return m_number;
+    }
+
+    const FlyString& as_string() const
+    {
+        ASSERT(is_string());
+        return m_string;
+    }
+
+    const Symbol* as_symbol() const
+    {
+        ASSERT(is_symbol());
+        return m_symbol;
+    }
+
+    String to_string() const
+    {
+        ASSERT(is_valid());
+        ASSERT(!is_symbol());
+        if (is_string())
+            return as_string();
+        return String::number(as_number());
+    }
+
+    StringOrSymbol to_string_or_symbol() const
+    {
+        ASSERT(is_valid());
+        ASSERT(!is_number());
+        if (is_string())
+            return StringOrSymbol(as_string());
+        return StringOrSymbol(as_symbol());
+    }
+
+    Value to_value(VM& vm) const
+    {
+        if (is_string())
+            return js_string(vm, m_string);
+        if (is_number())
+            return Value(m_number);
+        if (is_symbol())
+            return m_symbol;
+        return js_undefined();
+    }
+
+private:
+    Type m_type { Type::Invalid };
+    FlyString m_string;
+    Symbol* m_symbol { nullptr };
+    u32 m_number { 0 };
+};
+
+}