[platform] add new GotoDeclarationProvider and NavigationTarget APIs (IDEA-198180)

platform/core-api/src/com/intellij/navigation/NavigationTarget.java

@@ -0,0 +1,42 @@
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package com.intellij.navigation;
+
+import com.intellij.pom.Navigatable;
+import org.jetbrains.annotations.ApiStatus.Experimental;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+@Experimental
+public interface NavigationTarget {
+
+  /**
+   * @return {@code true} if it's safe to call other methods of this instance
+   */
+  boolean isValid();
+
+  /**
+   * This method is called only if {@link #isValid()} returns {@code true}.
+   *
+   * @return navigatable instance to use when this target is selected
+   */
+  @Nullable
+  Navigatable getNavigatable();
+
+  /**
+   * This method is called only if {@link #isValid()} returns {@code true}.
+   *
+   * @return presentation to render this target in navigation popup
+   */
+  @NotNull
+  TargetPresentation getTargetPresentation();
+
+  /**
+   * Two different symbols may have the same navigation target.
+   * #equals and #hashCode are used to filter out same targets to hide them in navigation popup.
+   */
+  @Override
+  boolean equals(Object obj);
+
+  @Override
+  int hashCode();
+}

platform/lang-impl/src/com/intellij/codeInsight/navigation/GotoDeclarationProvider.java

@@ -0,0 +1,20 @@
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package com.intellij.codeInsight.navigation;
+
+import com.intellij.navigation.NavigationTarget;
+import com.intellij.openapi.editor.Editor;
+import com.intellij.openapi.project.Project;
+import com.intellij.psi.PsiFile;
+import org.jetbrains.annotations.ApiStatus.Experimental;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.function.Consumer;
+
+@Experimental
+public interface GotoDeclarationProvider {
+
+  void collectTargets(@NotNull Project project,
+                      @NotNull Editor editor,
+                      @NotNull PsiFile file,
+                      @NotNull Consumer<? super NavigationTarget> consumer);
+}

platform/platform-resources/src/META-INF/LangExtensionPoints.xml

@@ -601,6 +601,8 @@
                     interface="com.intellij.codeInsight.navigation.actions.TypeDeclarationProvider"/>
     <extensionPoint name="gotoTargetRendererProvider"
                     interface="com.intellij.codeInsight.navigation.GotoTargetRendererProvider"/>
+    <extensionPoint name="gotoDeclaration"
+                    interface="com.intellij.codeInsight.navigation.GotoDeclarationProvider"/>
 
     <extensionPoint name="navbar" interface="com.intellij.ide.navigationToolbar.NavBarModelExtension"/>