package org.hamcrest.core;

import org.hamcrest.BaseMatcher;
import org.hamcrest.Description;
import org.hamcrest.Matcher;

import static org.hamcrest.core.IsNot.not;

/**
 
* Is the value null?
 
*/

public class IsNull<T> extends BaseMatcher<T> {
    
@Override
    
public boolean matches(Object o) {
        
return o == null;
    
}

    
@Override
    
public void describeTo(Description description) {
        
description.appendText("null");
    
}

    
/**
     
* Creates a matcher that matches if examined object is <code>null</code>.
     
* For example:
     
* <pre>assertThat(cheese, is(nullValue())</pre>
     
*
 

     
*/

    
public static Matcher<Object> nullValue() {
        
return new IsNull<Object>();
    
}

    
/**
     
* A shortcut to the frequently used <code>not(nullValue())</code>.
     
* For example:
     
* <pre>assertThat(cheese, is(notNullValue()))</pre>
     
* instead of:
     
* <pre>assertThat(cheese, is(not(nullValue())))</pre>
     
*
 

     
*/

    
public static Matcher<Object> notNullValue() {
        
return not(nullValue());
    
}

    
/**
     
* Creates a matcher that matches if examined object is <code>null</code>. Accepts a
     
* single dummy argument to facilitate type inference.
     
* For example:
     
* <pre>assertThat(cheese, is(nullValue(Cheese.class))</pre>
     
*
 

     
* @param type
     
*dummy parameter used to infer the generic type of the returned matcher
     
*/

    
public static <T> Matcher<T> nullValue(Class<T> type) {
        
return new IsNull<T>();
    
}

    
/**
     
* A shortcut to the frequently used <code>not(nullValue(X.class)). Accepts a
     
* single dummy argument to facilitate type inference.</code>.
     
* For example:
     
* <pre>assertThat(cheese, is(notNullValue(X.class)))</pre>
     
* instead of:
     
* <pre>assertThat(cheese, is(not(nullValue(X.class))))</pre>
     
*
 

     
* @param type
     
*dummy parameter used to infer the generic type of the returned matcher
     
*
  

     
*/

    
public static <T> Matcher<T> notNullValue(Class<T> type) {
        
return not(nullValue(type));
    
}
}