lang-api/src/com/intellij/psi/PsiChildLink.java

   1 /*
   2  * Copyright (c) 2000-2005 by JetBrains s.r.o. All Rights Reserved.
   3  * Use is subject to license terms.
   4  */
   5 package com.intellij.psi;
   6
   7 import org.jetbrains.annotations.NotNull;
   8 import org.jetbrains.annotations.Nullable;
   9
  10 /**
  11  * @author peter
  12  */
  13 public abstract class PsiChildLink<Parent extends PsiElement, Child extends PsiElement> implements PsiRefElementCreator<Parent, Child> {
  14
  15   @Nullable public abstract Child findLinkedChild(@Nullable Parent parent);
  16
  17   @NotNull
  18   public final PsiRef<Child> createChildRef(@NotNull Parent parent) {
  19     final Child existing = findLinkedChild(parent);
  20     if (existing != null) {
  21       return PsiRef.real(existing);
  22     }
  23     return PsiRef.imaginary(PsiRef.real(parent), this);
  24   }
  25
  26   @NotNull
  27   public final PsiRef<Child> createChildRef(@NotNull PsiRef<? extends Parent> parentRef) {
  28     final Parent parent = parentRef.getPsiElement();
  29     if (parent != null) {
  30       final Child existing = findLinkedChild(parent);
  31       if (existing != null) {
  32         return PsiRef.real(existing);
  33       }
  34     }
  35     return PsiRef.imaginary(parentRef, this);
  36   }
  37
  38 }