avoid expensive isSchemaFile()

json/src/com/intellij/json/JsonUtil.java

+// Copyright 2000-2018 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.json;
 
 import com.intellij.json.psi.*;
+import com.intellij.openapi.fileTypes.FileType;
+import com.intellij.openapi.fileTypes.LanguageFileType;
 import com.intellij.openapi.util.text.StringUtil;
+import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.psi.PsiElement;
 import com.intellij.util.ObjectUtils;
 import org.jetbrains.annotations.NotNull;
@@ -82,4 +86,9 @@ public class JsonUtil {
     }
     return -1;
   }
+
+  public static boolean isJsonFile(@NotNull VirtualFile file) {
+    FileType type = file.getFileType();
+    return type instanceof LanguageFileType && ((LanguageFileType)type).getLanguage() instanceof JsonLanguage;
+  }
 }

json/src/com/jetbrains/jsonSchema/ide/JsonSchemaService.java

 // Copyright 2000-2018 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.jetbrains.jsonSchema.ide;
 
-
 import com.intellij.openapi.components.ServiceManager;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.ModificationTracker;
@@ -27,7 +26,7 @@ public interface JsonSchemaService {
   static boolean isSchemaFile(@NotNull PsiFile psiFile) {
     final VirtualFile file = psiFile.getViewProvider().getVirtualFile();
     JsonSchemaService service = Impl.get(psiFile.getProject());
-    return service.isApplicableToFile(file) && service.isSchemaFile(file);
+    return service.isSchemaFile(file) && service.isApplicableToFile(file);
   }
 
   boolean isSchemaFile(@NotNull VirtualFile file);

json/src/com/jetbrains/jsonSchema/impl/JsonSchemaInJsonFilesEnabler.java

 // Copyright 2000-2018 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.jetbrains.jsonSchema.impl;
 
-import com.intellij.json.JsonLanguage;
-import com.intellij.openapi.fileTypes.FileType;
-import com.intellij.openapi.fileTypes.LanguageFileType;
+import com.intellij.json.JsonUtil;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.jetbrains.jsonSchema.extension.JsonSchemaEnabler;
 
 public class JsonSchemaInJsonFilesEnabler implements JsonSchemaEnabler {
   @Override
   public boolean isEnabledForFile(VirtualFile file) {
-    FileType type = file.getFileType();
-    return type instanceof LanguageFileType && ((LanguageFileType)type).getLanguage() instanceof JsonLanguage;
+    return JsonUtil.isJsonFile(file);
   }
 }

json/src/com/jetbrains/jsonSchema/impl/JsonSchemaServiceImpl.java

@@ -2,6 +2,7 @@
 package com.jetbrains.jsonSchema.impl;
 
 import com.intellij.codeInsight.daemon.DaemonCodeAnalyzer;
+import com.intellij.json.JsonUtil;
 import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.project.Project;
@@ -258,9 +259,9 @@ public class JsonSchemaServiceImpl implements JsonSchemaService {
 
   @Override
   public boolean isSchemaFile(@NotNull VirtualFile file) {
-    return isMappedSchema(file)
-           || isSchemaByProvider(file)
-           || hasSchemaSchema(file);
+    return JsonUtil.isJsonFile(file) && (isMappedSchema(file)
+                                         || isSchemaByProvider(file)
+                                         || hasSchemaSchema(file));
   }
 
   public boolean isMappedSchema(@NotNull VirtualFile file) {

json/src/com/jetbrains/jsonSchema/widget/JsonSchemaStatusWidget.java

@@ -178,10 +178,8 @@ class JsonSchemaStatusWidget extends EditorBasedStatusBarPopup {
     });
   }
 
-  private boolean isValidSchemaFile(VirtualFile schemaFile) {
-    if (schemaFile == null || !myService.isApplicableToFile(schemaFile) || !myService.isSchemaFile(schemaFile)) return false;
-    FileType type = schemaFile.getFileType();
-    return type instanceof LanguageFileType && ((LanguageFileType)type).getLanguage() instanceof JsonLanguage;
+  private boolean isValidSchemaFile(@Nullable VirtualFile schemaFile) {
+    return schemaFile != null && myService.isSchemaFile(schemaFile) && myService.isApplicableToFile(schemaFile);
   }
 
   @Nullable