Add API allowing to register a language extension for a group of languages matching a certain criteria

platform/core-api/src/com/intellij/lang/LanguageExtension.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2017 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,12 +21,12 @@ package com.intellij.lang;
 
 import com.intellij.openapi.util.Key;
 import com.intellij.openapi.util.KeyedExtensionCollector;
-import com.intellij.util.containers.ContainerUtil;
 import gnu.trove.THashSet;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Set;
 
@@ -55,20 +55,33 @@ public class LanguageExtension<T> extends KeyedExtensionCollector<T, Language> {
     T cached = l.getUserData(IN_LANGUAGE_CACHE);
     if (cached != null) return cached;
 
-    List<T> extensions = forKey(l);
-    T result;
-    if (extensions.isEmpty()) {
-      Language base = l.getBaseLanguage();
-      result = base == null ? myDefaultImplementation : forLanguage(base);
-    }
-    else {
-      result = extensions.get(0);
-    }
+    T result = findForLanguage(l);
     if (result == null) return null;
     result = l.putUserDataIfAbsent(IN_LANGUAGE_CACHE, result);
     return result;
   }
 
+  protected T findForLanguage(@NotNull Language l) {
+    List<T> extensions = forKey(l);
+    if (!extensions.isEmpty()) {
+      return extensions.get(0);
+    }
+
+    Language base = l.getBaseLanguage();
+    if (base != null) {
+      return forLanguage(base);
+    }
+
+    for (MetaLanguage metaLanguage: MetaLanguage.all()) {
+      if (metaLanguage.matchesLanguage(l)) {
+        T result = forLanguage(metaLanguage);
+        if (result != null) break;
+      }
+    }
+
+    return myDefaultImplementation;
+  }
+
   /**
    *  @see #allForLanguageOrAny(Language)
    */
@@ -86,9 +99,17 @@ public class LanguageExtension<T> extends KeyedExtensionCollector<T, Language> {
 
   @NotNull
   public List<T> allForLanguageOrAny(@NotNull Language l) {
-    List<T> providers = allForLanguage(l);
-    if (l == Language.ANY) return providers;
-    return ContainerUtil.concat(providers, allForLanguage(Language.ANY));
+    List<T> providers = new ArrayList<T>(allForLanguage(l));
+    if (l != Language.ANY) {
+      providers.addAll(allForLanguage(Language.ANY));
+    }
+
+    if (!(l instanceof MetaLanguage)) {
+      for (MetaLanguage metaLanguage : MetaLanguage.all()) {
+        providers.addAll(allForLanguage(metaLanguage));
+      }
+    }
+    return providers;
   }
 
   protected T getDefaultImplementation() {
@@ -108,6 +129,9 @@ public class LanguageExtension<T> extends KeyedExtensionCollector<T, Language> {
       key = key.getBaseLanguage();
     }
     allowed.add("any");
+    for (MetaLanguage metaLanguage : MetaLanguage.all()) {
+      allowed.add(metaLanguage.getID());
+    }
     return allowed;
   }
 

platform/core-api/src/com/intellij/lang/MetaLanguage.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2000-2017 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.lang;
+
+import com.intellij.openapi.extensions.ExtensionPointName;
+import com.intellij.openapi.extensions.Extensions;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Allows to register a language extension for a group of languages defined by a certain criterion.
+ * To use this, specify the ID of a meta-language in the "language" attribute of an extension in plugin.xml.
+ *
+ * @author yole
+ */
+public abstract class MetaLanguage extends Language {
+  public static final ExtensionPointName<MetaLanguage> EP_NAME = ExtensionPointName.create("com.intellij.metaLanguage");
+
+  protected MetaLanguage(@NotNull String ID) {
+    super(ID);
+  }
+
+  public static MetaLanguage[] all() {
+    return Extensions.getExtensions(EP_NAME);
+  }
+
+  /**
+   * Checks if the given language matches the criterion of this meta-language.
+   */
+  public abstract boolean matchesLanguage(Language language);
+}

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

@@ -901,6 +901,7 @@
                     interface="com.intellij.execution.testframework.sm.runner.history.ImportTestOutputExtension"/>
 
     <extensionPoint name="sdkEditorAdditionalOptionsProvider" interface="com.intellij.openapi.SdkEditorAdditionalOptionsProvider"/>
+    <extensionPoint name="metaLanguage" interface="com.intellij.lang.MetaLanguage"/>
   </extensionPoints>
 </idea-plugin>