public Object eval(Env env)
{
DynamicEnv olddenv = DynamicEnv.current();
try
{
for (int i = 0; i < binds.Length; i++)
{
DynamicEnv.extend(binds[i].dvar.sym,
binds[i].expr.eval(env));
}
return(body.eval(env));
}
catch (BacktraceException bex)
{
throw bex;
}
catch (Exception ex)
{
throw BacktraceException.push(ex, new BacktraceFrame(loc, "set", null), interpreter);
}
finally
{
DynamicEnv.restore(olddenv);
}
}
internal static void extend(Symbol sym, Object val)
{
if (!sym.isDynamic)
{
throw new Exception("Dynamic vars must have prefix *");
}
denv = new DynamicEnv(sym, val, denv);
}
public void setval(Object val, Env env)
{
DynamicEnv d = DynamicEnv.find(sym);
if (d != null)
{
d.val = val;
}
sym.setGlobalValue(val);
}
public Object eval(Env env)
{
DynamicEnv d = DynamicEnv.find(sym);
if (d != null)
{
return(d.val);
}
return(sym.getGlobalValue());
}
internal static DynamicEnv find(Symbol s)
{
for (DynamicEnv d = denv; d != null; d = d.next)
{
if (d.sym == s)
{
return(d);
}
}
return(null);
}
private DynamicEnv(Symbol sym, Object val, DynamicEnv next)
{
this.sym = sym;
this.val = val;
this.next = next;
}
internal static void restore(DynamicEnv olddenv)
{
denv = olddenv;
}
private DynamicEnv(Symbol sym,Object val, DynamicEnv next)
{
this.sym = sym;
this.val = val;
this.next = next;
}
internal static void extend(Symbol sym, Object val)
{
if(!sym.isDynamic)
throw new Exception("Dynamic vars must have prefix *");
denv = new DynamicEnv(sym,val,denv);
}
internal static void restore(DynamicEnv olddenv)
{
denv = olddenv;
}
