Boa 0.5.1

Boa is a Javascript lexer, parser and Just-in-Time compiler written in Rust. Currently, it has support for some of the language.
Documentation 
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#![forbid(
    //missing_docs,
    //warnings,
    anonymous_parameters,
    unused_extern_crates,
    unused_import_braces,
    missing_copy_implementations,
    //trivial_casts,
    variant_size_differences,
    missing_debug_implementations,
    trivial_numeric_casts
)]
// Debug trait derivation will show an error if forbidden.
#![deny(unused_qualifications)]
#![deny(clippy::all)]
#![warn(
    // clippy::pedantic,
    clippy::restriction,
    clippy::cognitive_complexity,
    //missing_docs
)]
#![allow(
    clippy::missing_docs_in_private_items,
    clippy::missing_inline_in_public_items,
    clippy::implicit_return,
    clippy::wildcard_enum_match_arm,
    clippy::cognitive_complexity,
    clippy::module_name_repetitions,
    clippy::print_stdout,
    clippy::cast_possible_truncation,
    clippy::cast_possible_wrap,
    clippy::non_ascii_literal,
    clippy::float_arithmetic
)]

pub mod builtins;
pub mod environment;
pub mod exec;
pub mod realm;
pub mod syntax;

use crate::{
    builtins::value::ResultValue,
    exec::{Executor, Interpreter},
    realm::Realm,
    syntax::{ast::expr::Expr, lexer::Lexer, parser::Parser},
};
use wasm_bindgen::prelude::*;

fn parser_expr(src: &str) -> Expr {
    let mut lexer = Lexer::new(src);
    lexer.lex().expect("lexing failed");
    let tokens = lexer.tokens;
    Parser::new(tokens).parse_all().expect("parsing failed")
}

/// Execute the code using an existing Interpreter
/// The str is consumed and the state of the Interpreter is changed
pub fn forward(engine: &mut Interpreter, src: &str) -> String {
    // Setup executor
    let expr = parser_expr(src);
    let result = engine.run(&expr);
    match result {
        Ok(v) => v.to_string(),
        Err(v) => format!("{}: {}", "Error", v.to_string()),
    }
}

/// Execute the code using an existing Interpreter.
/// The str is consumed and the state of the Interpreter is changed
/// Similar to `forward`, except the current value is returned instad of the string
/// If the interpreter fails parsing an error value is returned instead (error object)
pub fn forward_val(engine: &mut Interpreter, src: &str) -> ResultValue {
    // Setup executor
    let expr = parser_expr(src);
    engine.run(&expr)
}

/// Create a clean Interpreter and execute the code
pub fn exec(src: &str) -> String {
    // Create new Realm
    let realm = Realm::create();
    let mut engine: Interpreter = Executor::new(realm);
    forward(&mut engine, src)
}

// WASM
#[wasm_bindgen]
extern "C" {
    // Use `js_namespace` here to bind `console.log(..)` instead of just
    // `log(..)`
    #[wasm_bindgen(js_namespace = console)]
    fn log(s: &str);
}

#[wasm_bindgen]
pub fn evaluate(src: &str) -> String {
    let mut lexer = Lexer::new(&src);
    match lexer.lex() {
        Ok(_v) => (),
        Err(v) => log(&v.to_string()),
    }

    let tokens = lexer.tokens;

    // Setup executor
    let expr: Expr;

    match Parser::new(tokens).parse_all() {
        Ok(v) => {
            expr = v;
        }
        Err(_v) => {
            log("parsing fail");
            return String::from("parsing failed");
        }
    }
    // Create new Realm
    let realm = Realm::create();
    let mut engine: Interpreter = Executor::new(realm);
    let result = engine.run(&expr);
    log("test2");
    match result {
        Ok(v) => v.to_string(),
        Err(v) => format!("{}: {}", "error", v.to_string()),
    }
}