Assignment.java

package calculator.interpreter.ast.vars;

import calculator.interpreter.Environment;
import calculator.interpreter.EvalException;
import calculator.interpreter.ast.InfixOp;

/**
 * Execute assignment operator
 */
public class Assignment extends InfixOp {
  @Override
  public Object eval(Environment env) {
    String name;
    if (first instanceof Name) {
      name = ((Name) first).name();
    } else {
      throw new EvalException(first,
          "Left hand side of assignment must be an identifier");
    }
    Object value = second.eval(env);
    return env.findDefined(location, name).bind(location, value);
  }
}