LibJS: Parse dynamic import calls 'import()' and 'import.meta'

For now both just throw when executing but this can be implemented when
modules are implemented :^).

Userland/Libraries/LibJS/AST.cpp

@@ -2880,17 +2880,39 @@ void MetaProperty::dump(int indent) const
     outln("{} {}", class_name(), name);
 }
 
-Value MetaProperty::execute(Interpreter& interpreter, GlobalObject&) const
+Value MetaProperty::execute(Interpreter& interpreter, GlobalObject& global_object) const
 {
     InterpreterNodeScope node_scope { interpreter, *this };
 
     if (m_type == MetaProperty::Type::NewTarget)
         return interpreter.vm().get_new_target().value_or(js_undefined());
-    if (m_type == MetaProperty::Type::ImportMeta)
-        TODO();
+    if (m_type == MetaProperty::Type::ImportMeta) {
+        interpreter.vm().throw_exception<InternalError>(global_object, ErrorType::NotImplemented, "'import.meta' in modules");
+        return {};
+    }
+
     VERIFY_NOT_REACHED();
 }
 
+void ImportCall::dump(int indent) const
+{
+    ASTNode::dump(indent);
+    print_indent(indent);
+    outln("(Specifier)");
+    m_specifier->dump(indent + 1);
+    if (m_options) {
+        outln("(Options)");
+        m_options->dump(indent + 1);
+    }
+}
+
+Value ImportCall::execute(Interpreter& interpreter, GlobalObject& global_object) const
+{
+    InterpreterNodeScope node_scope { interpreter, *this };
+    interpreter.vm().throw_exception<InternalError>(global_object, ErrorType::NotImplemented, "'import(...)' in modules");
+    return {};
+}
+
 Value StringLiteral::execute(Interpreter& interpreter, GlobalObject&) const
 {
     InterpreterNodeScope node_scope { interpreter, *this };

Userland/Libraries/LibJS/AST.h

@@ -1671,6 +1671,23 @@ private:
     Type m_type;
 };
 
+class ImportCall final : public Expression {
+public:
+    ImportCall(SourceRange source_range, NonnullRefPtr<Expression> specifier, RefPtr<Expression> options)
+        : Expression(source_range)
+        , m_specifier(move(specifier))
+        , m_options(move(options))
+    {
+    }
+
+    virtual void dump(int indent) const override;
+    virtual Value execute(Interpreter&, GlobalObject&) const override;
+
+private:
+    NonnullRefPtr<Expression> m_specifier;
+    RefPtr<Expression> m_options;
+};
+
 class ConditionalExpression final : public Expression {
 public:
     ConditionalExpression(SourceRange source_range, NonnullRefPtr<Expression> test, NonnullRefPtr<Expression> consequent, NonnullRefPtr<Expression> alternate)

Userland/Libraries/LibJS/Parser.cpp

@@ -874,6 +874,63 @@ RefPtr<MetaProperty> Parser::try_parse_new_target_expression()
     return create_ast_node<MetaProperty>({ m_state.current_token.filename(), rule_start.position(), position() }, MetaProperty::Type::NewTarget);
 }
 
+RefPtr<MetaProperty> Parser::try_parse_import_meta_expression()
+{
+    // Optimization which skips the save/load state.
+    if (next_token().type() != TokenType::Period)
+        return {};
+
+    save_state();
+    auto rule_start = push_start();
+    ArmedScopeGuard state_rollback_guard = [&] {
+        load_state();
+    };
+
+    consume(TokenType::Import);
+    consume(TokenType::Period);
+    if (!match(TokenType::Identifier))
+        return {};
+    // The string 'meta' cannot have escapes so we check original value.
+    if (consume().original_value() != "meta"sv)
+        return {};
+
+    state_rollback_guard.disarm();
+    discard_saved_state();
+    return create_ast_node<MetaProperty>({ m_state.current_token.filename(), rule_start.position(), position() }, MetaProperty::Type::ImportMeta);
+}
+
+NonnullRefPtr<ImportCall> Parser::parse_import_call()
+{
+    auto rule_start = push_start();
+
+    // We use the extended definition:
+    //  ImportCall[Yield, Await]:
+    //      import(AssignmentExpression[+In, ?Yield, ?Await] ,opt)
+    //      import(AssignmentExpression[+In, ?Yield, ?Await] ,AssignmentExpression[+In, ?Yield, ?Await] ,opt)
+    // From https://tc39.es/proposal-import-assertions/#sec-evaluate-import-call
+
+    consume(TokenType::Import);
+    consume(TokenType::ParenOpen);
+    auto argument = parse_expression(2);
+
+    RefPtr<Expression> options;
+    if (match(TokenType::Comma)) {
+        consume(TokenType::Comma);
+
+        if (!match(TokenType::ParenClose)) {
+            options = parse_expression(2);
+
+            // Second optional comma
+            if (match(TokenType::Comma))
+                consume(TokenType::Comma);
+        }
+    }
+
+    consume(TokenType::ParenClose);
+
+    return create_ast_node<ImportCall>({ m_state.current_token.filename(), rule_start.position(), position() }, move(argument), move(options));
+}
+
 NonnullRefPtr<ClassDeclaration> Parser::parse_class_declaration()
 {
     auto rule_start = push_start();
@@ -1305,6 +1362,19 @@ Parser::PrimaryExpressionParseResult Parser::parse_primary_expression()
         }
         return { parse_new_expression() };
     }
+    case TokenType::Import: {
+        auto lookahead_token = next_token();
+        VERIFY(lookahead_token.type() == TokenType::Period || lookahead_token.type() == TokenType::ParenOpen);
+        if (lookahead_token.type() == TokenType::ParenOpen)
+            return { parse_import_call() };
+
+        if (auto import_meta = try_parse_import_meta_expression()) {
+            if (m_program_type != Program::Type::Module)
+                syntax_error("import.meta is only allowed in modules");
+            return { import_meta.release_nonnull() };
+        }
+        break;
+    }
     case TokenType::Yield:
         if (!m_state.in_generator_function_context)
             goto read_as_identifier;
@@ -1321,10 +1391,11 @@ Parser::PrimaryExpressionParseResult Parser::parse_primary_expression()
     default:
         if (match_identifier_name())
             goto read_as_identifier;
-        expected("primary expression");
-        consume();
-        return { create_ast_node<ErrorExpression>({ m_state.current_token.filename(), rule_start.position(), position() }) };
+        break;
     }
+    expected("primary expression");
+    consume();
+    return { create_ast_node<ErrorExpression>({ m_state.current_token.filename(), rule_start.position(), position() }) };
 }
 
 NonnullRefPtr<RegExpLiteral> Parser::parse_regexp_literal()
@@ -2115,6 +2186,8 @@ NonnullRefPtr<NewExpression> Parser::parse_new_expression()
     consume(TokenType::New);
 
     auto callee = parse_expression(g_operator_precedence.get(TokenType::New), Associativity::Right, { TokenType::ParenOpen, TokenType::QuestionMarkPeriod });
+    if (is<ImportCall>(*callee))
+        syntax_error("Cannot call new on dynamic import", callee->source_range().start);
 
     Vector<CallExpression::Argument> arguments;
 
@@ -3343,6 +3416,11 @@ bool Parser::match(TokenType type) const
 bool Parser::match_expression() const
 {
     auto type = m_state.current_token.type();
+    if (type == TokenType::Import) {
+        auto lookahead_token = next_token();
+        return lookahead_token.type() == TokenType::Period || lookahead_token.type() == TokenType::ParenOpen;
+    }
+
     return type == TokenType::BoolLiteral
         || type == TokenType::NumericLiteral
         || type == TokenType::BigIntLiteral

Userland/Libraries/LibJS/Parser.h

@@ -122,6 +122,8 @@ public:
     RefPtr<FunctionExpression> try_parse_arrow_function_expression(bool expect_parens, bool is_async = false);
     RefPtr<Statement> try_parse_labelled_statement(AllowLabelledFunction allow_function);
     RefPtr<MetaProperty> try_parse_new_target_expression();
+    RefPtr<MetaProperty> try_parse_import_meta_expression();
+    NonnullRefPtr<ImportCall> parse_import_call();
 
     Vector<CallExpression::Argument> parse_arguments();