LibJS: Implement abstract equality and inequality

Author: https://github.com/0xtechnobabble
Commit: https://github.com/SerenityOS/serenity/commit/dfbaa8e5432
Pull-request: https://github.com/SerenityOS/serenity/pull/1470
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/oriko1010

Base/home/anon/js/type-play.js

@@ -0,0 +1,12 @@
+const object = {};
+
+print(true == 1);
+print(null == undefined);
+print("12" == 12);
+print(1 + "12");
+print(12 / "12" == true);
+print(2 * "12");
+print(~"24");
+print(~true);
+print(2*2 + "4");
+print(object == "[object Object]");

Libraries/LibJS/AST.cpp

@@ -155,7 +155,11 @@ Value BinaryExpression::execute(Interpreter& interpreter) const
     case BinaryOp::TypedEquals:
         return typed_eq(lhs_result, rhs_result);
     case BinaryOp::TypedInequals:
-        return Value(!typed_eq(lhs_result, rhs_result).to_boolean());
+        return Value(!typed_eq(lhs_result, rhs_result).as_bool());
+    case BinaryOp::AbstractEquals:
+        return eq(lhs_result, rhs_result);
+    case BinaryOp::AbstractInequals:
+        return Value(!eq(lhs_result, rhs_result).as_bool());
     case BinaryOp::GreaterThan:
         return greater_than(lhs_result, rhs_result);
     case BinaryOp::GreaterThanEquals:
@@ -247,6 +251,12 @@ void BinaryExpression::dump(int indent) const
     case BinaryOp::TypedInequals:
         op_string = "!==";
         break;
+    case BinaryOp::AbstractEquals:
+        op_string = "==";
+        break;
+    case BinaryOp::AbstractInequals:
+        op_string = "!=";
+        break;
     case BinaryOp::GreaterThan:
         op_string = ">";
         break;

Libraries/LibJS/AST.h

@@ -248,6 +248,8 @@ enum class BinaryOp {
     Slash,
     TypedEquals,
     TypedInequals,
+    AbstractEquals,
+    AbstractInequals,
     GreaterThan,
     GreaterThanEquals,
     LessThan,

Libraries/LibJS/Parser.cpp

@@ -334,6 +334,12 @@ NonnullOwnPtr<Expression> Parser::parse_secondary_expression(NonnullOwnPtr<Expre
     case TokenType::ExclamationMarkEqualsEquals:
         consume();
         return make<BinaryExpression>(BinaryOp::TypedInequals, move(lhs), parse_expression(min_precedence, associativity));
+    case TokenType::EqualsEquals:
+        consume();
+        return make<BinaryExpression>(BinaryOp::AbstractEquals, move(lhs), parse_expression(min_precedence, associativity));
+    case TokenType::ExclamationMarkEquals:
+        consume();
+        return make<BinaryExpression>(BinaryOp::AbstractInequals, move(lhs), parse_expression(min_precedence, associativity));
     case TokenType::ParenOpen:
         return parse_call_expression(move(lhs));
     case TokenType::Equals:
@@ -543,6 +549,8 @@ bool Parser::match_secondary_expression() const
         || type == TokenType::Equals
         || type == TokenType::EqualsEqualsEquals
         || type == TokenType::ExclamationMarkEqualsEquals
+        || type == TokenType::EqualsEquals
+        || type == TokenType::ExclamationMarkEquals
         || type == TokenType::GreaterThan
         || type == TokenType::GreaterThanEquals
         || type == TokenType::LessThan

Libraries/LibJS/Value.cpp

@@ -209,7 +209,7 @@ Value typed_eq(Value lhs, Value rhs)
     case Value::Type::Number:
         return Value(lhs.as_double() == rhs.as_double());
     case Value::Type::String:
-        return Value(lhs.as_string() == rhs.as_string());
+        return Value(lhs.as_string()->string() == rhs.as_string()->string());
     case Value::Type::Boolean:
         return Value(lhs.as_bool() == rhs.as_bool());
     case Value::Type::Object:
@@ -219,6 +219,35 @@ Value typed_eq(Value lhs, Value rhs)
     ASSERT_NOT_REACHED();
 }
 
+Value eq(Value lhs, Value rhs)
+{
+    if (lhs.type() == rhs.type())
+        return typed_eq(lhs, rhs);
+
+    if ((lhs.is_undefined() || lhs.is_null()) && (rhs.is_undefined() || rhs.is_null()))
+        return Value(true);
+
+    if (lhs.is_object() && rhs.is_boolean())
+        return eq(lhs.as_object()->to_primitive(), rhs.to_number());
+
+    if (lhs.is_boolean() && rhs.is_object())
+        return eq(lhs.to_number(), rhs.as_object()->to_primitive());
+
+    if (lhs.is_object())
+        return eq(lhs.as_object()->to_primitive(), rhs);
+
+    if (rhs.is_object())
+        return eq(lhs, rhs.as_object()->to_primitive());
+
+    if (lhs.is_number() || rhs.is_number())
+        return Value(lhs.to_number().as_double() == rhs.to_number().as_double());
+
+    if ((lhs.is_string() && rhs.is_boolean()) || (lhs.is_string() && rhs.is_boolean()))
+        return Value(lhs.to_number().as_double() == rhs.to_number().as_double());
+
+    return Value(false);
+}
+
 const LogStream& operator<<(const LogStream& stream, const Value& value)
 {
     return stream << value.to_string();

Libraries/LibJS/Value.h

@@ -174,6 +174,7 @@ Value add(Value lhs, Value rhs);
 Value sub(Value lhs, Value rhs);
 Value mul(Value lhs, Value rhs);
 Value div(Value lhs, Value rhs);
+Value eq(Value lhs, Value rhs);
 Value typed_eq(Value lhs, Value rhs);
 
 const LogStream& operator<<(const LogStream&, const Value&);