ContextoExecucaoImperativa.java

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package plp.imperative1.memory;

import java.util.HashMap;
import java.util.Stack;

import plp.expressions2.expression.Id;
import plp.expressions2.expression.Valor;
import plp.expressions2.memory.ContextoExecucao;
import plp.expressions2.memory.VariavelNaoDeclaradaException;

public class ContextoExecucaoImperativa extends ContextoExecucao 
        implements AmbienteExecucaoImperativa {

    private ListaValor entrada;
 
    private ListaValor saida;

    public ContextoExecucaoImperativa(ListaValor entrada){
        super();
        this.entrada = entrada;
        this.saida = new ListaValor();        
    }
   
    public Valor read() throws EntradaVaziaException {
        if(entrada == null || entrada.getHead() == null) {
            throw new EntradaVaziaException();
        }
        Valor aux =  entrada.getHead();
        entrada = (ListaValor) entrada.getTail();
        return aux;
    }
   
    public ListaValor getSaida() {
        return saida;    
    }
     
    public void write(Valor v){
        saida = new ListaValor(v, saida);
    }

    public void changeValor(Id idArg, Valor valorId) 
                throws VariavelNaoDeclaradaException {   
        
        Object result = null;
                Stack<HashMap<Id,Valor>> auxStack = new Stack<HashMap<Id,Valor>>();
                Stack<HashMap<Id,Valor>> stack = this.getPilha();
                
                while (result == null && !stack.empty()) {
                        HashMap<Id,Valor> aux = stack.pop();
                        auxStack.push(aux);
                        result = aux.get(idArg);
                        if (result != null) {
                                aux.put(idArg, valorId);
                        }
                }
                while (!auxStack.empty()) {
                        stack.push(auxStack.pop());
                }
                if (result == null) {
                        throw new VariavelNaoDeclaradaException(idArg);
                }
    }
}

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