[SPARK-50641][SQL] Move GetJsonObjectEvaluator to JsonExpressionEvalUtils

### What changes were proposed in this pull request?
The pr aims to move `GetJsonObjectEvaluator` to `JsonExpressionEvalUtils`.

### Why are the changes needed?
Make code clearly.

### Does this PR introduce _any_ user-facing change?
No.

### How was this patch tested?
- Pass GA
- Manually test.

### Was this patch authored or co-authored using generative AI tooling?
No.

Closes #49259 from panbingkun/SPARK-50641.

Authored-by: panbingkun <[email protected]>
Signed-off-by: panbingkun <[email protected]>

Author: panbingkun

sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/json/JsonExpressionUtils.java

@@ -24,7 +24,6 @@
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.core.JsonToken;
 
-import org.apache.spark.sql.catalyst.expressions.SharedFactory;
 import org.apache.spark.sql.catalyst.json.CreateJacksonParser;
 import org.apache.spark.sql.catalyst.util.GenericArrayData;
 import org.apache.spark.unsafe.types.UTF8String;

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/json/JsonExpressionEvalUtils.scala

@@ -16,13 +16,16 @@
  */
 package org.apache.spark.sql.catalyst.expressions.json
 
-import java.io.{ByteArrayOutputStream, CharArrayWriter}
+import java.io.{ByteArrayOutputStream, CharArrayWriter, StringWriter}
+
+import scala.util.parsing.combinator.RegexParsers
 
 import com.fasterxml.jackson.core._
+import com.fasterxml.jackson.core.json.JsonReadFeature
 
 import org.apache.spark.SparkException
 import org.apache.spark.sql.catalyst.InternalRow
-import org.apache.spark.sql.catalyst.expressions.{ExprUtils, GenericInternalRow, SharedFactory}
+import org.apache.spark.sql.catalyst.expressions.{ExprUtils, GenericInternalRow}
 import org.apache.spark.sql.catalyst.expressions.variant.VariantExpressionEvalUtils
 import org.apache.spark.sql.catalyst.json.{CreateJacksonParser, JacksonGenerator, JacksonParser, JsonInferSchema, JSONOptions}
 import org.apache.spark.sql.catalyst.util.{ArrayData, FailFastMode, FailureSafeParser, MapData, PermissiveMode}
@@ -32,6 +35,79 @@ import org.apache.spark.sql.types.{ArrayType, DataType, MapType, StructField, St
 import org.apache.spark.unsafe.types.{UTF8String, VariantVal}
 import org.apache.spark.util.Utils
 
+private[this] sealed trait PathInstruction
+private[this] object PathInstruction {
+  private[expressions] case object Subscript extends PathInstruction
+  private[expressions] case object Wildcard extends PathInstruction
+  private[expressions] case object Key extends PathInstruction
+  private[expressions] case class Index(index: Long) extends PathInstruction
+  private[expressions] case class Named(name: String) extends PathInstruction
+}
+
+private[this] sealed trait WriteStyle
+private[this] object WriteStyle {
+  private[expressions] case object RawStyle extends WriteStyle
+  private[expressions] case object QuotedStyle extends WriteStyle
+  private[expressions] case object FlattenStyle extends WriteStyle
+}
+
+private[this] object JsonPathParser extends RegexParsers {
+  import PathInstruction._
+
+  def root: Parser[Char] = '$'
+
+  def long: Parser[Long] = "\\d+".r ^? {
+    case x => x.toLong
+  }
+
+  // parse `[*]` and `[123]` subscripts
+  def subscript: Parser[List[PathInstruction]] =
+    for {
+      operand <- '[' ~> ('*' ^^^ Wildcard | long ^^ Index) <~ ']'
+    } yield {
+      Subscript :: operand :: Nil
+    }
+
+  // parse `.name` or `['name']` child expressions
+  def named: Parser[List[PathInstruction]] =
+    for {
+      name <- '.' ~> "[^\\.\\[]+".r | "['" ~> "[^\\']+".r <~ "']"
+    } yield {
+      Key :: Named(name) :: Nil
+    }
+
+  // child wildcards: `..`, `.*` or `['*']`
+  def wildcard: Parser[List[PathInstruction]] =
+    (".*" | "['*']") ^^^ List(Wildcard)
+
+  def node: Parser[List[PathInstruction]] =
+    wildcard |
+      named |
+      subscript
+
+  val expression: Parser[List[PathInstruction]] = {
+    phrase(root ~> rep(node) ^^ (x => x.flatten))
+  }
+
+  def parse(str: String): Option[List[PathInstruction]] = {
+    this.parseAll(expression, str) match {
+      case Success(result, _) =>
+        Some(result)
+
+      case _ =>
+        None
+    }
+  }
+}
+
+private[this] object SharedFactory {
+  val jsonFactory: JsonFactory = new JsonFactoryBuilder()
+    // The two options below enabled for Hive compatibility
+    .enable(JsonReadFeature.ALLOW_UNESCAPED_CONTROL_CHARS)
+    .enable(JsonReadFeature.ALLOW_SINGLE_QUOTES)
+    .build()
+}
+
 case class JsonToStructsEvaluator(
     options: Map[String, String],
     nullableSchema: DataType,
@@ -278,3 +354,225 @@ case class JsonTupleEvaluator(foldableFieldNames: Array[Option[String]]) {
     }
   }
 }
+
+/**
+ * The expression `GetJsonObject` will utilize it to support codegen.
+ */
+case class GetJsonObjectEvaluator(cachedPath: UTF8String) {
+  import com.fasterxml.jackson.core.JsonToken._
+  import PathInstruction._
+  import SharedFactory._
+  import WriteStyle._
+
+  def this() = this(null)
+
+  @transient
+  private lazy val parsedPath: Option[List[PathInstruction]] = parsePath(cachedPath)
+
+  @transient
+  private var jsonStr: UTF8String = _
+
+  @transient
+  private var pathStr: UTF8String = _
+
+  def setJson(arg: UTF8String): Unit = {
+    jsonStr = arg
+  }
+
+  def setPath(arg: UTF8String): Unit = {
+    pathStr = arg
+  }
+
+  def evaluate(): Any = {
+    if (jsonStr == null) return null
+
+    val parsed = if (cachedPath != null) {
+      parsedPath
+    } else {
+      parsePath(pathStr)
+    }
+
+    if (parsed.isDefined) {
+      try {
+        /* We know the bytes are UTF-8 encoded. Pass a Reader to avoid having Jackson
+          detect character encoding which could fail for some malformed strings */
+        Utils.tryWithResource(CreateJacksonParser.utf8String(jsonFactory, jsonStr)) { parser =>
+          val output = new ByteArrayOutputStream()
+          val matched = Utils.tryWithResource(
+            jsonFactory.createGenerator(output, JsonEncoding.UTF8)) { generator =>
+            parser.nextToken()
+            evaluatePath(parser, generator, RawStyle, parsed.get)
+          }
+          if (matched) {
+            UTF8String.fromBytes(output.toByteArray)
+          } else {
+            null
+          }
+        }
+      } catch {
+        case _: JsonProcessingException => null
+      }
+    } else {
+      null
+    }
+  }
+
+  private def parsePath(path: UTF8String): Option[List[PathInstruction]] = {
+    if (path != null) {
+      JsonPathParser.parse(path.toString)
+    } else {
+      None
+    }
+  }
+
+  // advance to the desired array index, assumes to start at the START_ARRAY token
+  private def arrayIndex(p: JsonParser, f: () => Boolean): Long => Boolean = {
+    case _ if p.getCurrentToken == END_ARRAY =>
+      // terminate, nothing has been written
+      false
+
+    case 0 =>
+      // we've reached the desired index
+      val dirty = f()
+
+      while (p.nextToken() != END_ARRAY) {
+        // advance the token stream to the end of the array
+        p.skipChildren()
+      }
+
+      dirty
+
+    case i if i > 0 =>
+      // skip this token and evaluate the next
+      p.skipChildren()
+      p.nextToken()
+      arrayIndex(p, f)(i - 1)
+  }
+
+  /**
+   * Evaluate a list of JsonPath instructions, returning a bool that indicates if any leaf nodes
+   * have been written to the generator
+   */
+  private def evaluatePath(
+      p: JsonParser,
+      g: JsonGenerator,
+      style: WriteStyle,
+      path: List[PathInstruction]): Boolean = {
+    (p.getCurrentToken, path) match {
+      case (VALUE_STRING, Nil) if style == RawStyle =>
+        // there is no array wildcard or slice parent, emit this string without quotes
+        if (p.hasTextCharacters) {
+          g.writeRaw(p.getTextCharacters, p.getTextOffset, p.getTextLength)
+        } else {
+          g.writeRaw(p.getText)
+        }
+        true
+
+      case (START_ARRAY, Nil) if style == FlattenStyle =>
+        // flatten this array into the parent
+        var dirty = false
+        while (p.nextToken() != END_ARRAY) {
+          dirty |= evaluatePath(p, g, style, Nil)
+        }
+        dirty
+
+      case (_, Nil) =>
+        // general case: just copy the child tree verbatim
+        g.copyCurrentStructure(p)
+        true
+
+      case (START_OBJECT, Key :: xs) =>
+        var dirty = false
+        while (p.nextToken() != END_OBJECT) {
+          if (dirty) {
+            // once a match has been found we can skip other fields
+            p.skipChildren()
+          } else {
+            dirty = evaluatePath(p, g, style, xs)
+          }
+        }
+        dirty
+
+      case (START_ARRAY, Subscript :: Wildcard :: Subscript :: Wildcard :: xs) =>
+        // special handling for the non-structure preserving double wildcard behavior in Hive
+        var dirty = false
+        g.writeStartArray()
+        while (p.nextToken() != END_ARRAY) {
+          dirty |= evaluatePath(p, g, FlattenStyle, xs)
+        }
+        g.writeEndArray()
+        dirty
+
+      case (START_ARRAY, Subscript :: Wildcard :: xs) if style != QuotedStyle =>
+        // retain Flatten, otherwise use Quoted... cannot use Raw within an array
+        val nextStyle = style match {
+          case RawStyle => QuotedStyle
+          case FlattenStyle => FlattenStyle
+          case QuotedStyle => throw SparkException.internalError("Unexpected the quoted style.")
+        }
+
+        // temporarily buffer child matches, the emitted json will need to be
+        // modified slightly if there is only a single element written
+        val buffer = new StringWriter()
+
+        var dirty = 0
+        Utils.tryWithResource(jsonFactory.createGenerator(buffer)) { flattenGenerator =>
+          flattenGenerator.writeStartArray()
+
+          while (p.nextToken() != END_ARRAY) {
+            // track the number of array elements and only emit an outer array if
+            // we've written more than one element, this matches Hive's behavior
+            dirty += (if (evaluatePath(p, flattenGenerator, nextStyle, xs)) 1 else 0)
+          }
+          flattenGenerator.writeEndArray()
+        }
+
+        val buf = buffer.getBuffer
+        if (dirty > 1) {
+          g.writeRawValue(buf.toString)
+        } else if (dirty == 1) {
+          // remove outer array tokens
+          g.writeRawValue(buf.substring(1, buf.length() - 1))
+        } // else do not write anything
+
+        dirty > 0
+
+      case (START_ARRAY, Subscript :: Wildcard :: xs) =>
+        var dirty = false
+        g.writeStartArray()
+        while (p.nextToken() != END_ARRAY) {
+          // wildcards can have multiple matches, continually update the dirty count
+          dirty |= evaluatePath(p, g, QuotedStyle, xs)
+        }
+        g.writeEndArray()
+
+        dirty
+
+      case (START_ARRAY, Subscript :: Index(idx) :: (xs@Subscript :: Wildcard :: _)) =>
+        p.nextToken()
+        // we're going to have 1 or more results, switch to QuotedStyle
+        arrayIndex(p, () => evaluatePath(p, g, QuotedStyle, xs))(idx)
+
+      case (START_ARRAY, Subscript :: Index(idx) :: xs) =>
+        p.nextToken()
+        arrayIndex(p, () => evaluatePath(p, g, style, xs))(idx)
+
+      case (FIELD_NAME, Named(name) :: xs) if p.currentName == name =>
+        // exact field match
+        if (p.nextToken() != JsonToken.VALUE_NULL) {
+          evaluatePath(p, g, style, xs)
+        } else {
+          false
+        }
+
+      case (FIELD_NAME, Wildcard :: xs) =>
+        // wildcard field match
+        p.nextToken()
+        evaluatePath(p, g, style, xs)
+
+      case _ =>
+        p.skipChildren()
+        false
+    }
+  }
+}