Implement String copy to guest std::string, fix Dictionary string bug

program/cpp/api/string.cpp

@@ -59,3 +59,9 @@ String &String::operator=(String &&other) {
 	m_idx = other.m_idx;
 	return *this;
 }
+
+String::operator std::string() const {
+	std::string str;
+	sys_string_ops(String_Op::TO_STD_STRING, m_idx, 0, (Variant *)&str);
+	return str;
+}

program/cpp/api/string.hpp

@@ -32,6 +32,8 @@ struct String {
 	String operator[](int idx) const;
 	String at(int idx) const { return (*this)[idx]; }
 
+	operator std::string() const;
+
 	// String size
 	int size() const;
 
@@ -48,10 +50,16 @@ inline Variant::Variant(const String &s) {
 }
 
 inline Variant::operator String() const {
+	if (m_type != STRING) {
+		api_throw("std::bad_cast", "Failed to cast Variant to String", this);
+	}
 	return String::from_variant_index(v.i);
 }
 
 inline String Variant::as_string() const {
+	if (m_type != STRING) {
+		api_throw("std::bad_cast", "Failed to cast Variant to String", this);
+	}
 	return String::from_variant_index(v.i);
 }
 

program/cpp/api/syscalls.h

@@ -146,4 +146,5 @@ enum class String_Op {
 	INSERT,
 	FIND,
 	ERASE,
+	TO_STD_STRING,
 };

src/syscalls.cpp

@@ -52,11 +52,16 @@ APICALL(api_print) {
 	auto [array, len] = machine.sysargs<gaddr_t, gaddr_t>();
 	auto &emu = riscv::emu(machine);
 
+	if (len >= 64) {
+		ERR_PRINT("print(): Too many Variants to print");
+		throw std::runtime_error("print(): Too many Variants to print");
+	}
 	const GuestVariant *array_ptr = emu.machine().memory.memarray<GuestVariant>(array, len);
 
 	// We really want print_internal to be a public function.
 	for (gaddr_t i = 0; i < len; i++) {
 		auto &var = array_ptr[i];
+		//printf("Variant[%lu]: type=%d\n", i, var.type);
 		UtilityFunctions::print(var.toVariant(emu));
 	}
 }
@@ -793,7 +798,7 @@ APICALL(api_dict_ops) {
 			auto *vp = emu.machine().memory.memarray<GuestVariant>(vaddr, 1);
 			// TODO: Check if the value is already scoped?
 			auto v = dict[key->toVariant(emu)];
-			vp->set(emu, v, true); // Implicit trust, as we are returning engine-provided result.
+			vp->create(emu, std::move(v));
 			break;
 		}
 		case Dictionary_Op::SET: {
@@ -859,6 +864,13 @@ APICALL(api_string_ops) {
 		case String_Op::GET_LENGTH:
 			machine.set_result(str.length());
 			break;
+		case String_Op::TO_STD_STRING: {
+			// Get the string as a std::string.
+			auto utf8 = str.utf8();
+			auto *gstr = emu.machine().memory.memarray<GuestStdString>(vaddr, 1);
+			gstr->set_string(emu.machine(), vaddr, utf8.ptr(), utf8.length());
+			break;
+		}
 		default:
 			ERR_PRINT("Invalid String operation");
 			throw std::runtime_error("Invalid String operation");