You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: gramatron.rs
    path of file: ./repos/LibAFL/libafl/src/generators
    
    the code of the file until where you have to start completion: //! Gramatron generator
use alloc::{string::String, vec::Vec};
use core::marker::PhantomData;

use libafl_bolts::rands::Rand;
use serde::{Deserialize, Serialize};

use crate::{
    generators::Generator,
    inputs::{GramatronInput, Terminal},
    state::HasRand,
    Error,
};

/// A trigger
#[derive(Serialize, Deserialize, Clone, Debug, PartialEq, Eq)]
pub struct Trigger {
    /// the destination
    pub dest: usize,
    /// the term
    pub term: String,
}

/// The [`Automaton`]
#[derive(Serialize, Deserialize, Clone, Debug, PartialEq, Eq)]
pub struct Automaton {
    /// final state
    pub final_state: usize,
    /// init state
    pub init_state: usize,
    /// pda of [`Trigger`]s
    pub pda: Vec<Vec<Trigger>>,
}

#[derive(Clone, Debug)]
/// Generates random inputs from a
    
    pub fn append_generated_terminals(&self, input: &mut GramatronInput, state: &mut S) -> usize {
        let mut counter = 0;
        let final_state = self.automaton.final_state;
        let mut current_state =
            input
                .terminals()
                .last()
                .map_or(self.automaton.init_state, |last| {
                    let triggers = &self.automaton.pda[last.state];
                    let idx = state.rand_mut().below(triggers.len() as u64) as usize;
                    triggers[idx].dest
                });

        while current_state != final_state {
            let triggers = &self.automaton.pda[current_state];
            let idx = state.rand_mut().below(triggers.len() as u64) as usize;
            let trigger = &triggers[idx];
            input
                .terminals_mut()
                .push(Terminal::new(current_state, idx, trigger.term.clone()));
            current_state = trigger.dest;
            counter += 1;
        }

        counter
    }