boa_engine 0.19.0

Boa is a Javascript lexer, parser and compiler written in Rust. Currently, it has support for some of the language.
Documentation 
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use crate::{
    vm::{opcode::Operation, CompletionType},
    Context, JsResult,
};

/// `Pop` implements the Opcode Operation for `Opcode::Pop`
///
/// Operation:
///  - Pop the top value from the stack.
#[derive(Debug, Clone, Copy)]
pub(crate) struct Pop;

impl Operation for Pop {
    const NAME: &'static str = "Pop";
    const INSTRUCTION: &'static str = "INST - Pop";
    const COST: u8 = 1;

    fn execute(context: &mut Context) -> JsResult<CompletionType> {
        let _val = context.vm.pop();
        Ok(CompletionType::Normal)
    }
}

/// `PopEnvironment` implements the Opcode Operation for `Opcode::PopEnvironment`
///
/// Operation:
///  - Pop the current environment.
#[derive(Debug, Clone, Copy)]
pub(crate) struct PopEnvironment;

impl Operation for PopEnvironment {
    const NAME: &'static str = "PopEnvironment";
    const INSTRUCTION: &'static str = "INST - PopEnvironment";
    const COST: u8 = 1;

    fn execute(context: &mut Context) -> JsResult<CompletionType> {
        context.vm.environments.pop();
        Ok(CompletionType::Normal)
    }
}