package data;

import java.util.HashMap;

import java.util.Map;

import syntaxtree.Identifier;

public class Env{

private Env outerEnv;

private Map<Identifier,Addr> entries;

public Env() {

outerEnv = null;

entries = new HashMap<Identifier,Addr>();

}

private Map<Identifier,Addr> getEntries(){

return entries;

}

public Env(Env e){

entries = new HashMap<Identifier,Addr>(e.getEntries());

}

private void setOuterEnv(Env e){

outerEnv = e;

}

private Env getOuterEnv(){

return outerEnv;

}

public Env extendEnv(){

Env newEnv = new Env();

newEnv.setOuterEnv(this);

return newEnv;

}

public Addr lookup(Identifier key){

Addr addr;

addr = entries.get(key);

if ( addr == null ) {

Env oEnv = getOuterEnv();

if (oEnv == null ) return null;

return oEnv.lookup(key);

}

return addr;

}

public Env getTopEnv(){

Env e = this;

while(e.getOuterEnv() != null){

e = e.getOuterEnv();

}

return e;

}

public void putTopEnv(Identifier key, Addr addr){

getTopEnv().put(key, addr);

}

public void put(Identifier key, Addr addr){

entries.put(key, addr);

}

public String toString(){

return entries.toString();

}

public int hashCode(){

final int PRIME = 31;

int result = 1;

result = PRIME * result + ( (entries == null) ? 0 : entries.hashCode());

return result;

}

public boolean equals(Object o){

if (this == o ) return true;

if (o == null) return false;

if (getClass() != o.getClass()) return false;

Env e = (Env) o;

if ( outerEnv == null || e.getOuterEnv() == null ){

if ( outerEnv != e.getOuterEnv() ) return false;

} else if ( ! outerEnv.equals(e.getOuterEnv()) ) return false;

return entries.equals(e.getEntries());

}

public static void main(String[] args){

Env e1 = new Env();

Contour c1 = new Contour();

Bind b1 = new Bind(new Identifier("bbb"),c1.tick(22, 1) );

Bind b2 = new Bind(new Identifier("bbb"),c1.tick(22, 1) );

e1.put(new Identifier("a"), b1);

Env e2 = e1.extendEnv();

e2.put(new Identifier("b"),b2);

System.out.println(e1.equals(e2));

Bind b3 = new Bind(new Identifier("bbb"),c1.tick(22, 1) );

Bind b4 = new Bind(new Identifier("bbb"),c1.tick(22, 1) );

Env e3 = new Env();

e3.put(new Identifier("a"), b1);

Env e4 = e3.extendEnv();

e4.put(new Identifier("b"),b2);

System.out.println(e2.lookup(new Identifier("a")));

System.out.println(e4.getTopEnv());

}

}