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The class hierarchy for types distinguishes basic from wrapped types, with wrapped types providing additional information for basic types. For each basic type, this class provides isName() and toName() methods to replace instanceof tests and casts, respectively. For each wrapped type, this class additionally provides a hasName() method, which identifies instances of the wrapped type even if they are wrapped inside another (wrapped) type. In other words, invocations of hasName() are forwarded across wrapped types while invocations of isName() only apply to the outermost type object. For wrapped types, invocations of toName() are also forwarded across (other) wrapped types.

As an example, consider an int type wrapped in an annotated type and an alias type:

 Type i = NumberT.INT;
 Type j = new AnnotatedT(i);
 Type k = new AliasT("alias", j);
 

 k.isAlias()        ⇒ true
 k.hasAlias()       ⇒ true
 k.toAlias()        ⇒ k
 k.isAnnotated()    ⇒ false
 k.hasAnnotated()   ⇒ true
 k.toAnnotated()    ⇒ j
 k.isInteger()      ⇒ false
 k.toInteger()      ⇒ error
 

 Type r = k.resolve();
 r.isAlias()        ⇒ false
 r.isAnnotated()    ⇒ false
 r.isInteger()      ⇒ true
 r.toInteger()      ⇒ i
 

The Tag enumeration also identifies particular types. A type's tag can be accessed through Type.tag() , which is forwarded across wrapped types, and through Type.wtag() , which is not forwarded across wrapped types. As a result, tag() identifies basic types independent of whether they are wrapped or not, while wtag() always identifies the outermost type:

 k.tag()            ⇒ Tag.INTEGER
 k.wtag()           ⇒ Tag.ALIAS
 i.tag()            ⇒ Tag.INTEGER
 i.tag()            ⇒ Tag.INTEGER
 

Each type can have one or more of the following annotations:

• Its source location represented as a Location .
• Its source language represented as a Language tag.
• Its scope represented as a String .
• Its constant value represented as a Constant .
• Its memory shape represented as a Reference . Only lvalues can have a shape.
• Its attributes represented as a list of Attribute values.

 t.getAttribute(name, true)
 

 t.getConstant(true)
 

 t.getLanguage(true)
 

 t.getLocation(true)
 

 t.getScope(true)
 

 t.getShape(true)
 

 t.hasAttribute(att, true)
 

 null != t.getAttribute(name, true)
 

 null != t.getAttribute(name, forward)
 

 t.hasConstant(true)
 

 Type.Tag.Error == tag()
 

 t.hasLanguage(true)
 

 t.hasLocation(true)
 

 t.hasScope(true)
 

 t.hasShape(true)
 

 tag == t.tag()
 

 tag == wtag()
 

 public Type seal() {
 if (! isSealed()) {
 super.seal();
 type.seal();
 }
 return this;
 }