Contexto.java

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package plp.expressions2.memory;

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

import plp.expressions2.expression.Id;

public class Contexto<T> {
        private Stack<HashMap<Id, T>> pilha;

        public Contexto() {
                pilha = new Stack<HashMap<Id, T>>();
        }

        public void incrementa() {
                pilha.push(new HashMap<Id, T>());
        }

        public void restaura() {
                pilha.pop();
        }

        public void map(Id idArg, T valorId) throws VariavelJaDeclaradaException {
                try {
                        HashMap<Id, T> aux = pilha.peek();
                        if (aux.put(idArg, valorId) != null)
                                throw new IdentificadorJaDeclaradoException();
                } catch (IdentificadorJaDeclaradoException e) {
                        throw new VariavelJaDeclaradaException(idArg);
                }
        }

        public T get(Id idArg) throws VariavelNaoDeclaradaException {
                try {
                        T result = null;
                        Stack<HashMap<Id, T>> auxStack = new Stack<HashMap<Id, T>>();
                        while (result == null && !pilha.empty()) {
                                HashMap<Id, T> aux = pilha.pop();
                                auxStack.push(aux);
                                result = aux.get(idArg);
                        }
                        while (!auxStack.empty()) {
                                pilha.push(auxStack.pop());
                        }
                        if (result == null)
                                throw new IdentificadorNaoDeclaradoException();

                        return result;
                } catch (IdentificadorNaoDeclaradoException e) {
                        throw new VariavelNaoDeclaradaException(idArg);
                }
        }

        protected Stack<HashMap<Id, T>> getPilha() {
                return pilha;
        }

        protected void setPilha(Stack<HashMap<Id, T>> pilha) {
                this.pilha = pilha;
        }

}

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