LibJS: Add Function() and Function.prototype

Libraries/LibJS/Runtime/FunctionConstructor.cpp

@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2020, Linus Groh <mail@linusgroh.de>
+ * 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.
+ */
+
+#include <AK/StringBuilder.h>
+#include <LibJS/AST.h>
+#include <LibJS/Interpreter.h>
+#include <LibJS/Parser.h>
+#include <LibJS/Runtime/Error.h>
+#include <LibJS/Runtime/FunctionConstructor.h>
+#include <LibJS/Runtime/ScriptFunction.h>
+
+namespace JS {
+
+FunctionConstructor::FunctionConstructor()
+{
+    put("prototype", interpreter().function_prototype());
+    put("length", Value(1));
+}
+
+FunctionConstructor::~FunctionConstructor()
+{
+}
+
+Value FunctionConstructor::call(Interpreter& interpreter)
+{
+    return construct(interpreter);
+}
+
+Value FunctionConstructor::construct(Interpreter& interpreter)
+{
+    String parameters_source = "";
+    String body_source = "";
+    if (interpreter.argument_count() == 1)
+        body_source = interpreter.argument(0).to_string();
+    if (interpreter.argument_count() > 1) {
+        Vector<String> parameters;
+        for (size_t i = 0; i < interpreter.argument_count() - 1; ++i)
+            parameters.append(interpreter.argument(i).to_string());
+        StringBuilder parameters_builder;
+        parameters_builder.join(',', parameters);
+        parameters_source = parameters_builder.build();
+        body_source = interpreter.argument(interpreter.argument_count() - 1).to_string();
+    }
+    auto source = String::format("function (%s) { %s }", parameters_source.characters(), body_source.characters());
+    auto parser = Parser(Lexer(source));
+    auto function_expression = parser.parse_function_node<FunctionExpression>();
+    if (parser.has_errors()) {
+        // FIXME: The parser should expose parsing error strings rather than just fprintf()'ing them
+        return interpreter.heap().allocate<Error>("SyntaxError", "");
+    }
+    return function_expression->execute(interpreter);
+}
+
+}