From b0651337f98ada40bdbd7ae3df6b6f7aaec23532 Mon Sep 17 00:00:00 2001
From: Bas Leijdekkers <basleijdekkers@gmail.com>
Date: Tue, 3 Jan 2023 17:04:16 +0100
Subject: [PATCH] RegExp: fall back to Java regex evaluation if JS is not
 available (IDEA-261269)

GitOrigin-RevId: 7997dfe4a0f74d4a304285a3c1e0b17585e5649d
---
 .../lang/regexp/RegExpMatcherProvider.java    | 20 +++----------------
 .../EcmaScriptRegExpMatcherProvider.java      | 12 ++++++++---
 2 files changed, 12 insertions(+), 20 deletions(-)

diff --git a/RegExpSupport/src/org/intellij/lang/regexp/RegExpMatcherProvider.java b/RegExpSupport/src/org/intellij/lang/regexp/RegExpMatcherProvider.java
index 296db34678e6..c43adbfbcb8e 100644
--- a/RegExpSupport/src/org/intellij/lang/regexp/RegExpMatcherProvider.java
+++ b/RegExpSupport/src/org/intellij/lang/regexp/RegExpMatcherProvider.java
@@ -1,25 +1,11 @@
-/*
- * Copyright 2000-2016 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.
- */
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package org.intellij.lang.regexp;
 
 import com.intellij.lang.LanguageExtension;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
-import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * Use an RegExpMatcherProvider implementation to replace the regexp matcher used for the Check RegExp intention.
@@ -41,7 +27,7 @@ public interface RegExpMatcherProvider {
    *                       (see e.g. {@link StringUtil#newBombedCharSequence(java.lang.CharSequence, long)}
    * @return the result of the match
    */
-  @NotNull
+  @Nullable
   RegExpMatchResult matches(String regExp,
                             PsiFile regExpFile,
                             PsiElement elementInHost,
diff --git a/RegExpSupport/src/org/intellij/lang/regexp/ecmascript/EcmaScriptRegExpMatcherProvider.java b/RegExpSupport/src/org/intellij/lang/regexp/ecmascript/EcmaScriptRegExpMatcherProvider.java
index fb76b1a61d33..3c16ea4ae643 100644
--- a/RegExpSupport/src/org/intellij/lang/regexp/ecmascript/EcmaScriptRegExpMatcherProvider.java
+++ b/RegExpSupport/src/org/intellij/lang/regexp/ecmascript/EcmaScriptRegExpMatcherProvider.java
@@ -1,6 +1,7 @@
-// Copyright 2000-2020 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.
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package org.intellij.lang.regexp.ecmascript;
 
+import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
@@ -11,7 +12,7 @@ import org.intellij.lang.regexp.RegExpMatch;
 import org.intellij.lang.regexp.RegExpMatchResult;
 import org.intellij.lang.regexp.RegExpMatcherProvider;
 import org.intellij.lang.regexp.intention.CheckRegExpForm;
-import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import javax.script.ScriptEngine;
 import javax.script.ScriptEngineManager;
@@ -22,8 +23,9 @@ import java.util.List;
  * @author Bas Leijdekkers
  */
 public class EcmaScriptRegExpMatcherProvider implements RegExpMatcherProvider {
+  private static final Logger LOG = Logger.getInstance(EcmaScriptRegExpMatcherProvider.class);
 
-  @NotNull
+  @Nullable
   @Override
   public RegExpMatchResult matches(String regExp, PsiFile regExpFile, PsiElement elementInHost, String sampleText, long timeoutMillis) {
     String modifiers = "";
@@ -43,6 +45,10 @@ public class EcmaScriptRegExpMatcherProvider implements RegExpMatcherProvider {
       }
     }
     final ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
+    if (engine == null) {
+      LOG.warn("Nashorn JS scripting engine not found, falling back to Java regex evaluation");
+      return null;
+    }
     try {
       @Language("Nashorn JS")
       final String script =