boa_engine 0.17.0

use crate::{
    vm::{call_frame::EnvStackEntry, opcode::Operation, CompletionType},
    Context, JsResult,
};

/// `TryStart` implements the Opcode Operation for `Opcode::TryStart`
///
/// Operation:
///  - Start of a try block.
#[derive(Debug, Clone, Copy)]
pub(crate) struct TryStart;

impl Operation for TryStart {
    const NAME: &'static str = "TryStart";
    const INSTRUCTION: &'static str = "INST - TryStart";

    fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
        let catch = context.vm.read::<u32>();
        let finally = context.vm.read::<u32>();

        // If a finally exists, push the env to the stack before the try.
        if finally != u32::MAX {
            context.vm.frame_mut().env_stack.push(
                EnvStackEntry::default()
                    .with_finally_flag()
                    .with_start_address(finally),
            );
        }

        let fp = context.vm.stack.len() as u32;

        context
            .vm
            .frame_mut()
            .env_stack
            .push(EnvStackEntry::new(catch, finally).with_try_flag(fp));

        Ok(CompletionType::Normal)
    }
}

/// `TryEnd` implements the Opcode Operation for `Opcode::TryEnd`
///
/// Operation:
///  - End of a try block
#[derive(Debug, Clone, Copy)]
pub(crate) struct TryEnd;

impl Operation for TryEnd {
    const NAME: &'static str = "TryEnd";
    const INSTRUCTION: &'static str = "INST - TryEnd";

    fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
        let mut envs_to_pop = 0_usize;
        while let Some(env_entry) = context.vm.frame_mut().env_stack.pop() {
            envs_to_pop += env_entry.env_num();

            if env_entry.is_try_env() {
                break;
            }
        }

        let env_truncation_len = context.vm.environments.len().saturating_sub(envs_to_pop);
        context.vm.environments.truncate(env_truncation_len);

        Ok(CompletionType::Normal)
    }
}