API for quickly checking if external doc is available for an element

java/java-impl/src/com/intellij/lang/java/JavaDocumentationProvider.java

@@ -26,6 +26,7 @@ import com.intellij.lang.CodeDocumentationAwareCommenter;
 import com.intellij.lang.LangBundle;
 import com.intellij.lang.LanguageCommenters;
 import com.intellij.lang.documentation.CodeDocumentationProvider;
+import com.intellij.lang.documentation.CompositeDocumentationProvider;
 import com.intellij.lang.documentation.ExternalDocumentationProvider;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.module.Module;
@@ -675,6 +676,11 @@ public class JavaDocumentationProvider implements CodeDocumentationProvider, Ext
     return fetchExternalJavadoc(element, project, docUrls);
   }
 
+  @Override
+  public boolean hasDocumentationFor(PsiElement element, PsiElement originalElement) {
+    return CompositeDocumentationProvider.hasUrlsFor(this, element, originalElement);
+  }
+
   public static String fetchExternalJavadoc(PsiElement element, final Project project, final List<String> docURLs) {
     final JavaDocExternalFilter docFilter = new JavaDocExternalFilter(project);
 

platform/lang-api/src/com/intellij/lang/documentation/CompositeDocumentationProvider.java

@@ -134,4 +134,23 @@ public class CompositeDocumentationProvider implements DocumentationProvider, Ex
     }
     return null;
   }
+
+  @Override
+  public boolean hasDocumentationFor(PsiElement element, PsiElement originalElement) {
+    for (DocumentationProvider provider : myProviders) {
+      if (provider instanceof ExternalDocumentationProvider) {
+        if (((ExternalDocumentationProvider) provider).hasDocumentationFor(element, originalElement)) return true;
+      }
+      else {
+        if (hasUrlsFor(provider, element, originalElement)) return true;
+      }
+    }
+    return false;
+  }
+
+  public static boolean hasUrlsFor(DocumentationProvider provider, PsiElement element, PsiElement originalElement) {
+    final List<String> urls = provider.getUrlFor(element, originalElement);
+    if (urls != null && !urls.isEmpty()) return true;
+    return false;
+  }
 }

platform/lang-api/src/com/intellij/lang/documentation/ExternalDocumentationProvider.java

@@ -29,4 +29,14 @@ import java.util.List;
 public interface ExternalDocumentationProvider {
   @Nullable
   String fetchExternalDocumentation(final Project project, PsiElement element, final List<String> docUrls);
+
+  /**
+   * Quick check for existence of external documentation for specified element. Called from action update, so must be fast.
+   * If not implemented, update check is performed by calling {@link DocumentationProvider#getUrlFor(com.intellij.psi.PsiElement, com.intellij.psi.PsiElement)}.
+   *
+   * @param element the element to check for existence of documentation
+   * @param originalElement the element at caret (on which the action was invoked)
+   * @return true if the external documentation action should be enabled, false otherwise.
+   */
+  boolean hasDocumentationFor(PsiElement element, PsiElement originalElement);
 }

platform/lang-impl/src/com/intellij/ide/actions/ExternalJavaDocAction.java

@@ -18,9 +18,10 @@ package com.intellij.ide.actions;
 
 import com.intellij.codeInsight.documentation.DocumentationManager;
 import com.intellij.ide.BrowserUtil;
-import com.intellij.ide.IdeBundle;
 import com.intellij.ide.DataManager;
+import com.intellij.ide.IdeBundle;
 import com.intellij.lang.documentation.DocumentationProvider;
+import com.intellij.lang.documentation.ExternalDocumentationProvider;
 import com.intellij.openapi.actionSystem.*;
 import com.intellij.openapi.editor.Editor;
 import com.intellij.openapi.project.Project;
@@ -33,8 +34,8 @@ import com.intellij.psi.PsiFile;
 import com.intellij.util.ArrayUtil;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.List;
 import java.util.HashSet;
+import java.util.List;
 
 public class ExternalJavaDocAction extends AnAction {
 
@@ -100,8 +101,14 @@ public class ExternalJavaDocAction extends AnAction {
     final PsiElement originalElement = getOriginalElement(LangDataKeys.PSI_FILE.getData(dataContext), editor);
     DocumentationManager.storeOriginalElement(PlatformDataKeys.PROJECT.getData(dataContext), originalElement, element);
     final DocumentationProvider provider = DocumentationManager.getProviderFromElement(element);
-    final List<String> urls = provider.getUrlFor(element, originalElement);
-    boolean enabled = urls != null && !urls.isEmpty();
+    boolean enabled;
+    if (provider instanceof ExternalDocumentationProvider) {
+      enabled = ((ExternalDocumentationProvider) provider).hasDocumentationFor(element, originalElement);
+    }
+    else {
+      final List<String> urls = provider.getUrlFor(element, originalElement);
+      enabled = urls != null && !urls.isEmpty();
+    }
     if (editor != null) {
       presentation.setEnabled(enabled);
       if (event.getPlace().equals(ActionPlaces.MAIN_MENU)) {

plugins/android/src/org/jetbrains/android/AndroidDocumentationProvider.java

@@ -18,6 +18,7 @@ package org.jetbrains.android;
 import com.android.sdklib.SdkConstants;
 import com.intellij.codeInsight.javadoc.JavaDocExternalFilter;
 import com.intellij.facet.ProjectFacetManager;
+import com.intellij.lang.documentation.CompositeDocumentationProvider;
 import com.intellij.lang.documentation.DocumentationProvider;
 import com.intellij.lang.documentation.ExternalDocumentationProvider;
 import com.intellij.lang.java.JavaDocumentationProvider;
@@ -79,6 +80,11 @@ public class AndroidDocumentationProvider implements DocumentationProvider, Exte
            null;
   }
 
+  @Override
+  public boolean hasDocumentationFor(PsiElement element, PsiElement originalElement) {
+    return false;
+  }
+
   private static boolean isMyContext(@NotNull final PsiElement element, @NotNull final Project project) {
     if (element instanceof PsiClass) {
       return ApplicationManager.getApplication().runReadAction(new Computable<Boolean>() {

plugins/groovy/src/org/jetbrains/plugins/groovy/lang/documentation/GroovyDocumentationProvider.java

@@ -21,6 +21,7 @@ import com.intellij.codeInsight.javadoc.JavaDocUtil;
 import com.intellij.lang.CodeDocumentationAwareCommenter;
 import com.intellij.lang.LanguageCommenters;
 import com.intellij.lang.documentation.CodeDocumentationProvider;
+import com.intellij.lang.documentation.CompositeDocumentationProvider;
 import com.intellij.lang.documentation.ExternalDocumentationProvider;
 import com.intellij.lang.java.JavaDocumentationProvider;
 import com.intellij.openapi.project.Project;
@@ -292,6 +293,11 @@ public class GroovyDocumentationProvider implements CodeDocumentationProvider, E
     return JavaDocumentationProvider.fetchExternalJavadoc(element, project, docUrls);
   }
 
+  @Override
+  public boolean hasDocumentationFor(PsiElement element, PsiElement originalElement) {
+    return CompositeDocumentationProvider.hasUrlsFor(this, element, originalElement);
+  }
+
   private static String getMethodCandidateInfo(GrReferenceExpression expr) {
     final GroovyResolveResult[] candidates = expr.multiResolve(false);
     final String text = expr.getText();