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 {
                        HashMap<Id,T> aux =  pilha.peek();
                if (aux.put(idArg, valorId) != null) {
                        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 = (T) 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);
                }
        }

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

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

}

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