2.7 Rusty_v8


V8 and Deno operate at their cores in different programming languages: V8 is crafted using C++, while Deno is constructed using Rust. Bridging the gap between these two languages, the ingenious "rusty_v8" was conceived. This ingenious library, rusty_v8, serves the pivotal role of establishing robust Rust bindings to the intricate C++ APIs of V8. Notably, rusty_v8 excels in efficiency, managing to maintain seamless integration without imposing any extra call overhead.
When delving into the realm of APIs, rusty_v8 goes to great lengths to harmonize with V8's own APIs. This synchronization is often a straightforward process, involving a simple translation of functionalities. Remarkably, rusty_v8 is able to preserve its efficiency without adding any unnecessary burdens in the form of additional call overhead.
In essence, the creation of rusty_v8 showcases the marriage of languages and technologies, enabling the dynamic interaction between V8's C++ foundation and Deno's Rust infrastructure. This intricate connection not only underscores the compatibility of these distinct programming languages but also emphasizes the commitment to efficiency and seamless integration within the Deno ecosystem.


Let's take a look at a few code examples to enhance our understanding of rusty_v8. We can gain better insight into rusty_v8 by examining its practical applications. One area to explore is within the String implementation of rusty_v8.
pub fn length(&self) -> usize {
unsafe { v8__String__Length(self) as usize }
This function is a component of the implementation of the String class in Rust programming language. When the "length" function is invoked, it triggers the execution of "v8__String__Length." This is a piece of C++ code responsible for determining and providing the length of the v8 string data type. The relationship between the function and the code is quite straightforward, operating as a direct and simple one-to-one mapping. This means that the function and the code correspond closely, ensuring a clear and direct connection between the Rust String class and v8's string data type.
int v8__String__Length(const v8::String& self) {
return self.Length(); }
Let's explore another example within the rusty_v8 module, specifically the 'parse' function:
pub fn parse<'s>(
scope: &mut HandleScope<'s>,
json_string: Local<'_, String>,
) -> Option<Local<'s, Value>> {
unsafe {
.cast_local(|sd| v8__JSON__Parse(sd.get_current_context(), &*json_string))
Rusty_v8 includes a parse function which corresponds to v8__JSON__Parse. This parse function is coded in C++ and serves as a bridge to connect with the equivalent function in the v8 library. This linkage allows Rusty_v8 to leverage the capabilities of v8 for handling JSON parsing tasks.
const v8::Value* v8__JSON__Parse(const v8::Context& context,
const v8::String& json_string) {
return maybe_local_to_ptr(
v8::JSON::Parse(ptr_to_local(&context), ptr_to_local(&json_string)));
In the majority of situations, rusty_v8 essentially corresponds to the v8 API. To find out more about rusty_v8, you can head over to their GitHub page: https://github.com/denoland/rusty_v8. Now, let's delve into the topic of tokio, a tool that imparts full asynchronicity to Deno's workings. This means that Deno can efficiently handle tasks without getting stuck on one task, thus enhancing its overall performance and responsiveness.