[command-completion] IDEA-388842 Add "explain regexp" in command completion

GitOrigin-RevId: 6054df6bf2405a51ca3ebe062689340514353720

RegExpSupport/src/org/intellij/lang/regexp/intention/ExplainRegExpCommandCompletionProvider.java

@@ -0,0 +1,72 @@
+// Copyright 2000-2026 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package org.intellij.lang.regexp.intention;
+
+import com.intellij.codeInsight.completion.command.CommandCompletionProviderContext;
+import com.intellij.codeInsight.completion.command.CommandProvider;
+import com.intellij.codeInsight.completion.command.CompletionCommand;
+import com.intellij.codeInsight.intention.impl.ShowIntentionActionsHandler;
+import com.intellij.lang.injection.InjectedLanguageManager;
+import com.intellij.openapi.application.ModalityState;
+import com.intellij.openapi.application.ReadAction;
+import com.intellij.openapi.editor.Editor;
+import com.intellij.openapi.util.Pair;
+import com.intellij.openapi.util.TextRange;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiFile;
+import com.intellij.psi.PsiLanguageInjectionHost;
+import com.intellij.psi.util.PsiTreeUtil;
+import com.intellij.util.concurrency.AppExecutorUtil;
+import org.intellij.lang.regexp.RegExpFile;
+import org.jetbrains.annotations.Nls;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+
+public final class ExplainRegExpCommandCompletionProvider implements CommandProvider {
+  @Override
+  public @NotNull List<@NotNull CompletionCommand> getCommands(@NotNull CommandCompletionProviderContext context) {
+    if (findInjectedRegexpFile(context.getPsiFile(), context.getOffset()) == null) return List.of();
+    ExplainRegExpIntention intention = new ExplainRegExpIntention();
+    return List.of(new CompletionCommand() {
+      @Override
+      public @Nls @NotNull String getPresentableName() {
+        return intention.getFamilyName();
+      }
+
+      @Override
+      public void execute(int offset, @NotNull PsiFile psiFile, @Nullable Editor editor) {
+        ReadAction.nonBlocking(() -> findInjectedRegexpFile(psiFile, offset))
+          .finishOnUiThread(ModalityState.nonModal(), regexpContext -> {
+            if (regexpContext == null || editor == null) return;
+            editor.getCaretModel()
+              .moveToOffset(
+                regexpContext.injectionHost.getTextRange().getStartOffset() + regexpContext.regexpInsideHostRange.getStartOffset());
+            ShowIntentionActionsHandler.chooseActionAndInvoke(psiFile, editor, intention, intention.getFamilyName());
+            editor.getCaretModel()
+              .moveToOffset(regexpContext.injectionHost.getTextRange().getEndOffset());
+          })
+          .submit(AppExecutorUtil.getAppExecutorService());
+      }
+    });
+  }
+
+  private static @Nullable RegexpContext findInjectedRegexpFile(@NotNull PsiFile psiFile, int offset) {
+    PsiElement element = psiFile.findElementAt(offset - 1);
+    if (element == null) return null;
+    PsiLanguageInjectionHost injectionHost = PsiTreeUtil.getParentOfType(element, PsiLanguageInjectionHost.class, false);
+    if (injectionHost == null) return null;
+    InjectedLanguageManager injectedLanguageManager = InjectedLanguageManager.getInstance(psiFile.getProject());
+    List<Pair<PsiElement, TextRange>> files = injectedLanguageManager.getInjectedPsiFiles(injectionHost);
+    if (files == null) return null;
+    if (files.size() != 1) return null;
+    Pair<PsiElement, TextRange> pair = files.getFirst();
+    PsiElement psiElement = pair.first;
+    if (!(psiElement instanceof RegExpFile regExpFile)) return null;
+    return new RegexpContext(regExpFile, injectionHost, pair.second);
+  }
+
+  private record RegexpContext(@NotNull RegExpFile regExpFile, @NotNull PsiLanguageInjectionHost injectionHost,
+                               @NotNull TextRange regexpInsideHostRange) {
+  }
+}

java/java-backend/resources/META-INF/JavaPlugin.xml

@@ -1200,6 +1200,7 @@
     <!--<codeInsight.completion.command.provider language="JAVA" implementationClass="com.intellij.codeInsight.completion.command.commands.SimpleRunMarkerCommandProvider" />-->
     <codeInsight.completion.command.provider language="JAVA" implementationClass="com.intellij.codeInsight.completion.command.commands.DirectIntentionCommandProvider" order="last"/>
     <codeInsight.completion.command.provider language="JAVA" implementationClass="com.intellij.codeInsight.completion.commands.impl.JavaGenerateCommandCompletion" />
+    <codeInsight.completion.command.provider language="JAVA" implementationClass="org.intellij.lang.regexp.intention.ExplainRegExpCommandCompletionProvider" />
     <codeInsight.completion.command.provider language="JAVA" implementationClass="com.intellij.codeInsight.completion.commands.impl.JavaInlineVariableCompletionCommandProvider" />
     <codeInsight.completion.command.provider language="JAVA" implementationClass="com.intellij.codeInsight.completion.commands.impl.JavaGoToDeclarationCommandCompletionProvider" />
     <codeInsight.completion.command.provider language="JAVA"

plugins/kotlin/completion/impl-k2/resources/intellij.kotlin.completion.impl.xml

@@ -91,5 +91,6 @@
     <codeInsight.completion.command.provider language="kotlin" implementationClass="org.jetbrains.kotlin.idea.completion.impl.k2.contributors.commands.KotlinSafeDeleteCompletionCommandProvider" order="last"/>
     <codeInsight.completion.command.provider language="kotlin" implementationClass="org.jetbrains.kotlin.idea.completion.impl.k2.contributors.commands.KotlinParameterInfoCompletionCommand" order="last"/>
     <codeInsight.completion.command.provider language="kotlin" implementationClass="com.intellij.codeInsight.completion.command.commands.InsertLiveTemplateCompletionCommandProvider" order="last"/>
+    <codeInsight.completion.command.provider language="kotlin" implementationClass="org.intellij.lang.regexp.intention.ExplainRegExpCommandCompletionProvider" />
   </extensions>
 </idea-plugin>