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1 package com.github.javaparser.resolution.declarations;
2 
3 import com.github.javaparser.ast.Node;
4 
5 import java.util.Optional;
6 
7 /**
8  * A declaration that can be potentially associated with an AST node.
9  * @param <N> type of AST Node that can be associated
10  */
11 public interface AssociableToAST<N extends Node> {
12 
13     /**
14      * If the declaration is associated to an AST node return it, otherwise it return empty.
15      * Declaration based on source code have an AST node associated while others don't. Example
16      * of other declarations are declarations coming from reflection or JARs.
17      *
18      * You may wonder how this method is different from the various getWrappedNode.
19      * The difference is that toAst is present in all Resolved* declarations (such as
20      * ResolvedAnnotationDeclaration), while getWrappedNode is present
21      * only on the subclasses of the Resolved* declarations that derive from JP AST nodes (such as
22      * JavaParserClassDeclaration). Therefore one
23      * which has a Resolved* declaration need to do a downcast before being able to use getWrappedNode.
24      *
25      * Now, this means that toAst could potentially replace getWrappedNode (but not the other way around!).
26      * However toAst return an Optional, which is less convenient than getting the direct node. Also,
27      * toAst sometimes have to return a more generic node. This is the case for subclasses of
28      * ResolvedClassDeclaration. In those cases toAst return a Node. Why? Because both anonymous
29      * class declarations and standard class declarations are subclasses of that. In one case the
30      * underlying AST node is an ObjectCreationExpr, while in the other case it is ClassOrInterfaceDeclaration.
31      * In these cases getWrappedNode is particularly nice because it returns the right type of AST node,
32      * not just a Node.
33      */
toAst()34     default Optional<N> toAst() {
35         throw new UnsupportedOperationException();
36     }
37 }
38