private CCCons Index(CCIdentifier exp, CCCons env, int i)
{
if (env == null)
{
return null;
}
else
{
var j = Index2(exp, env.car as CCCons, 1);
if (j == null)
{
return Index(exp, env.cdr as CCCons, i + 1);
}
else
{
return new CCCons(new CCInt() { value = i }, j);
}
}
}
private CCObject Index2(CCIdentifier exp, CCCons env, int j)
{
if (env == null || env.car == null)
{
return null;
}
else
{
if(env.car.GetType() == typeof(CCCons)) // function or macro
{
if (env.caar.ToString() == exp.ToString())
{
return new CCCons(new CCInt() { value = j }, env.cdar);
}
else
{
return Index2(exp, env.cdr as CCCons, j + 1);
}
}
else // atom
{
if (env.car.ToString() == exp.ToString())
{
return new CCInt() { value = j };
}
else
{
return Index2(exp, env.cdr as CCCons, j + 1);
}
}
}
}
private CCCons Index(CCIdentifier exp, CCCons env)
{
return Index(exp, env, 1);
}