[SPARK-57173][SQL] Simplify regexp pattern-compile codegen by extracting a static Java helper

sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/ExpressionImplUtils.java

@@ -25,6 +25,8 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Locale;
+import java.util.regex.Pattern;
+import java.util.regex.PatternSyntaxException;
 import javax.crypto.Cipher;
 import javax.crypto.spec.GCMParameterSpec;
 import javax.crypto.spec.IvParameterSpec;
@@ -342,4 +344,19 @@ public static UTF8String quote(UTF8String str) {
     String sp = str.toString().replaceAll(qtChar, qtCharRep);
     return UTF8String.fromString(qtChar + sp + qtChar);
   }
+
+  /**
+   * Compiles {@code regex} with the given {@code flags} for the regexp expression
+   * family, translating a {@link PatternSyntaxException} into the user-facing
+   * INVALID_PARAMETER_VALUE.PATTERN error. Shared by the regexp eval and codegen
+   * paths so the generated Java is a single call instead of an inline try/catch
+   * around {@code Pattern.compile}.
+   */
+  public static Pattern compileRegexPattern(String regex, int flags, String funcName) {
+    try {
+      return Pattern.compile(regex, flags);
+    } catch (PatternSyntaxException e) {
+      throw QueryExecutionErrors.invalidPatternError(funcName, e.getPattern(), e);
+    }
+  }
 }

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala

@@ -1253,17 +1253,15 @@ object RegExpUtils {
     val termLastRegex = ctx.addMutableState("UTF8String", "lastRegex")
     val termPattern = ctx.addMutableState(classNamePattern, "pattern")
     val collationRegexFlags = CollationSupport.collationAwareRegexFlags(collationId)
+    val utils = classOf[ExpressionImplUtils].getName
 
     s"""
        |if (!$regexp.equals($termLastRegex)) {
        |  // regex value changed
-       |  try {
-       |    UTF8String r = $regexp.clone();
-       |    $termPattern = $classNamePattern.compile(r.toString(), $collationRegexFlags);
-       |    $termLastRegex = r;
-       |  } catch (java.util.regex.PatternSyntaxException e) {
-       |    throw QueryExecutionErrors.invalidPatternError("$prettyName", e.getPattern(), e);
-       |  }
+       |  UTF8String r = $regexp.clone();
+       |  $termPattern =
+       |    $utils.compileRegexPattern(r.toString(), $collationRegexFlags, "$prettyName");
+       |  $termLastRegex = r;
        |}
        |java.util.regex.Matcher $matcher = $termPattern.matcher($subject.toString());
        |""".stripMargin
@@ -1272,12 +1270,8 @@ object RegExpUtils {
   def getPatternAndLastRegex(p: Any, prettyName: String, collationId: Int): (Pattern, UTF8String) =
   {
     val r = p.asInstanceOf[UTF8String].clone()
-    val pattern = try {
-      Pattern.compile(r.toString, CollationSupport.collationAwareRegexFlags(collationId))
-    } catch {
-      case e: PatternSyntaxException =>
-        throw QueryExecutionErrors.invalidPatternError(prettyName, e.getPattern, e)
-    }
+    val pattern = ExpressionImplUtils.compileRegexPattern(
+      r.toString, CollationSupport.collationAwareRegexFlags(collationId), prettyName)
     (pattern, r)
   }
 }