[SPARK-16318][SQL] Implement all remaining xpath functions

sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/xml/UDFXPathUtil.java

@@ -43,7 +43,7 @@ public class UDFXPathUtil {
   private XPathExpression expression = null;
   private String oldPath = null;
 
-  public Object eval(String xml, String path, QName qname) {
+  public Object eval(String xml, String path, QName qname) throws XPathExpressionException {
     if (xml == null || path == null || qname == null) {
       return null;
     }
@@ -56,7 +56,7 @@ public Object eval(String xml, String path, QName qname) {
       try {
         expression = xpath.compile(path);
       } catch (XPathExpressionException e) {
-        expression = null;
+        throw new RuntimeException("Invalid XPath '" + path + "'" + e.getMessage(), e);
       }
       oldPath = path;
     }
@@ -66,31 +66,30 @@ public Object eval(String xml, String path, QName qname) {
     }
 
     reader.set(xml);
-
     try {
       return expression.evaluate(inputSource, qname);
     } catch (XPathExpressionException e) {
-      throw new RuntimeException("Invalid expression '" + oldPath + "'", e);
+      throw new RuntimeException("Invalid XML document: " + e.getMessage() + "\n" + xml, e);
     }
   }
 
-  public Boolean evalBoolean(String xml, String path) {
+  public Boolean evalBoolean(String xml, String path) throws XPathExpressionException {
     return (Boolean) eval(xml, path, XPathConstants.BOOLEAN);
   }
 
-  public String evalString(String xml, String path) {
+  public String evalString(String xml, String path) throws XPathExpressionException {
     return (String) eval(xml, path, XPathConstants.STRING);
   }
 
-  public Double evalNumber(String xml, String path) {
+  public Double evalNumber(String xml, String path) throws XPathExpressionException {
     return (Double) eval(xml, path, XPathConstants.NUMBER);
   }
 
-  public Node evalNode(String xml, String path) {
+  public Node evalNode(String xml, String path) throws XPathExpressionException {
     return (Node) eval(xml, path, XPathConstants.NODE);
   }
 
-  public NodeList evalNodeList(String xml, String path) {
+  public NodeList evalNodeList(String xml, String path) throws XPathExpressionException {
     return (NodeList) eval(xml, path, XPathConstants.NODESET);
   }
 

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/FunctionRegistry.scala

@@ -310,7 +310,15 @@ object FunctionRegistry {
     expression[UnBase64]("unbase64"),
     expression[Unhex]("unhex"),
     expression[Upper]("upper"),
+    expression[XPathList]("xpath"),
     expression[XPathBoolean]("xpath_boolean"),
+    expression[XPathDouble]("xpath_double"),
+    expression[XPathDouble]("xpath_number"),
+    expression[XPathFloat]("xpath_float"),
+    expression[XPathInt]("xpath_int"),
+    expression[XPathLong]("xpath_long"),
+    expression[XPathShort]("xpath_short"),
+    expression[XPathString]("xpath_string"),
 
     // datetime functions
     expression[AddMonths]("add_months"),

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/xml/xpath.scala

@@ -0,0 +1,174 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.spark.sql.catalyst.expressions.xml
+
+import org.apache.spark.sql.catalyst.analysis.TypeCheckResult
+import org.apache.spark.sql.catalyst.analysis.TypeCheckResult.TypeCheckFailure
+import org.apache.spark.sql.catalyst.expressions._
+import org.apache.spark.sql.catalyst.expressions.codegen.CodegenFallback
+import org.apache.spark.sql.catalyst.util.GenericArrayData
+import org.apache.spark.sql.types._
+import org.apache.spark.unsafe.types.UTF8String
+
+/**
+ * Base class for xpath_boolean, xpath_double, xpath_int, etc.
+ *
+ * This is not the world's most efficient implementation due to type conversion, but works.
+ */
+abstract class XPathExtract extends BinaryExpression with ExpectsInputTypes with CodegenFallback {
+  override def left: Expression = xml
+  override def right: Expression = path
+
+  /** XPath expressions are always nullable, e.g. if the xml string is empty. */
+  override def nullable: Boolean = true
+
+  override def inputTypes: Seq[AbstractDataType] = Seq(StringType, StringType)
+
+  override def checkInputDataTypes(): TypeCheckResult = {
+    if (!path.foldable) {
+      TypeCheckFailure("path should be a string literal")
+    } else {
+      super.checkInputDataTypes()
+    }
+  }
+
+  @transient protected lazy val xpathUtil = new UDFXPathUtil
+  @transient protected lazy val pathString: String = path.eval().asInstanceOf[UTF8String].toString
+
+  /** Concrete implementations need to override the following three methods. */
+  def xml: Expression
+  def path: Expression
+}
+
+@ExpressionDescription(
+  usage = "_FUNC_(xml, xpath) - Evaluates a boolean xpath expression.",
+  extended = "> SELECT _FUNC_('<a><b>1</b></a>','a/b');\ntrue")
+case class XPathBoolean(xml: Expression, path: Expression) extends XPathExtract {
+
+  override def prettyName: String = "xpath_boolean"
+  override def dataType: DataType = BooleanType
+
+  override def nullSafeEval(xml: Any, path: Any): Any = {
+    xpathUtil.evalBoolean(xml.asInstanceOf[UTF8String].toString, pathString)
+  }
+}
+
+@ExpressionDescription(
+  usage = "_FUNC_(xml, xpath) - Returns a short value that matches the xpath expression",
+  extended = "> SELECT _FUNC_('<a><b>1</b><b>2</b></a>','sum(a/b)');\n3")
+case class XPathShort(xml: Expression, path: Expression) extends XPathExtract {
+  override def prettyName: String = "xpath_int"
+  override def dataType: DataType = ShortType
+
+  override def nullSafeEval(xml: Any, path: Any): Any = {
+    val ret = xpathUtil.evalNumber(xml.asInstanceOf[UTF8String].toString, pathString)
+    if (ret eq null) null else ret.shortValue()
+  }
+}
+
+@ExpressionDescription(
+  usage = "_FUNC_(xml, xpath) - Returns an integer value that matches the xpath expression",
+  extended = "> SELECT _FUNC_('<a><b>1</b><b>2</b></a>','sum(a/b)');\n3")
+case class XPathInt(xml: Expression, path: Expression) extends XPathExtract {
+  override def prettyName: String = "xpath_int"
+  override def dataType: DataType = IntegerType
+
+  override def nullSafeEval(xml: Any, path: Any): Any = {
+    val ret = xpathUtil.evalNumber(xml.asInstanceOf[UTF8String].toString, pathString)
+    if (ret eq null) null else ret.intValue()
+  }
+}
+
+@ExpressionDescription(
+  usage = "_FUNC_(xml, xpath) - Returns a long value that matches the xpath expression",
+  extended = "> SELECT _FUNC_('<a><b>1</b><b>2</b></a>','sum(a/b)');\n3")
+case class XPathLong(xml: Expression, path: Expression) extends XPathExtract {
+  override def prettyName: String = "xpath_long"
+  override def dataType: DataType = LongType
+
+  override def nullSafeEval(xml: Any, path: Any): Any = {
+    val ret = xpathUtil.evalNumber(xml.asInstanceOf[UTF8String].toString, pathString)
+    if (ret eq null) null else ret.longValue()
+  }
+}
+
+@ExpressionDescription(
+  usage = "_FUNC_(xml, xpath) - Returns a float value that matches the xpath expression",
+  extended = "> SELECT _FUNC_('<a><b>1</b><b>2</b></a>','sum(a/b)');\n3.0")
+case class XPathFloat(xml: Expression, path: Expression) extends XPathExtract {
+  override def prettyName: String = "xpath_float"
+  override def dataType: DataType = FloatType
+
+  override def nullSafeEval(xml: Any, path: Any): Any = {
+    val ret = xpathUtil.evalNumber(xml.asInstanceOf[UTF8String].toString, pathString)
+    if (ret eq null) null else ret.floatValue()
+  }
+}
+
+@ExpressionDescription(
+  usage = "_FUNC_(xml, xpath) - Returns a double value that matches the xpath expression",
+  extended = "> SELECT _FUNC_('<a><b>1</b><b>2</b></a>','sum(a/b)');\n3.0")
+case class XPathDouble(xml: Expression, path: Expression) extends XPathExtract {
+  override def prettyName: String = "xpath_float"
+  override def dataType: DataType = DoubleType
+
+  override def nullSafeEval(xml: Any, path: Any): Any = {
+    val ret = xpathUtil.evalNumber(xml.asInstanceOf[UTF8String].toString, pathString)
+    if (ret eq null) null else ret.doubleValue()
+  }
+}
+
+// scalastyle:off line.size.limit
+@ExpressionDescription(
+  usage = "_FUNC_(xml, xpath) - Returns the text contents of the first xml node that matches the xpath expression",
+  extended = "> SELECT _FUNC_('<a><b>b</b><c>cc</c></a>','a/c');\ncc")
+// scalastyle:on line.size.limit
+case class XPathString(xml: Expression, path: Expression) extends XPathExtract {
+  override def prettyName: String = "xpath_string"
+  override def dataType: DataType = StringType
+
+  override def nullSafeEval(xml: Any, path: Any): Any = {
+    val ret = xpathUtil.evalString(xml.asInstanceOf[UTF8String].toString, pathString)
+    UTF8String.fromString(ret)
+  }
+}
+
+// scalastyle:off line.size.limit
+@ExpressionDescription(
+  usage = "_FUNC_(xml, xpath) - Returns a string array of values within xml nodes that match the xpath expression",
+  extended = "> SELECT _FUNC_('<a><b>b1</b><b>b2</b><b>b3</b><c>c1</c><c>c2</c></a>','a/b/text()');\n['b1','b2','b3']")
+// scalastyle:on line.size.limit
+case class XPathList(xml: Expression, path: Expression) extends XPathExtract {
+  override def prettyName: String = "xpath"
+  override def dataType: DataType = ArrayType(StringType, containsNull = false)
+
+  override def nullSafeEval(xml: Any, path: Any): Any = {
+    val nodeList = xpathUtil.evalNodeList(xml.asInstanceOf[UTF8String].toString, pathString)
+    if (nodeList ne null) {
+      val ret = new Array[UTF8String](nodeList.getLength)
+      var i = 0
+      while (i < nodeList.getLength) {
+        ret(i) = UTF8String.fromString(nodeList.item(i).getNodeValue)
+        i += 1
+      }
+      new GenericArrayData(ret)
+    } else {
+      null
+    }
+  }
+}

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/xml/UDFXPathUtilSuite.scala

@@ -43,8 +43,9 @@ class UDFXPathUtilSuite extends SparkFunSuite {
     assert(util.eval("<a><b>b1</b><b>b2</b><b>b3</b><c>c1</c><c>c2</c></a>", "", STRING) == null)
 
     // wrong expression:
-    assert(
-      util.eval("<a><b>b1</b><b>b2</b><b>b3</b><c>c1</c><c>c2</c></a>", "a/text(", STRING) == null)
+    intercept[RuntimeException] {
+      util.eval("<a><b>b1</b><b>b2</b><b>b3</b><c>c1</c><c>c2</c></a>", "a/text(", STRING)
+    }
   }
 
   test("generic eval") {