move getDictionary to DictionaryPage

Author: pyckle

parquet-column/src/main/java/org/apache/parquet/column/impl/ColumnReaderBase.java

@@ -37,6 +37,7 @@
 import org.apache.parquet.column.page.DataPage;
 import org.apache.parquet.column.page.DataPageV1;
 import org.apache.parquet.column.page.DataPageV2;
+import org.apache.parquet.column.page.DictionaryPage;
 import org.apache.parquet.column.page.PageReader;
 import org.apache.parquet.column.values.RequiresPreviousReader;
 import org.apache.parquet.column.values.ValuesReader;
@@ -451,7 +452,8 @@ void writeValue() {
     this.converter = Objects.requireNonNull(converter, "converter cannot be null");
     this.writerVersion = writerVersion;
     this.maxDefinitionLevel = path.getMaxDefinitionLevel();
-    this.dictionary = pageReader.getDictionary(path);
+    DictionaryPage dictionaryPage = pageReader.readDictionaryPage();
+    this.dictionary = dictionaryPage == null ? null : dictionaryPage.getDictionary(path);
     if (dictionary != null && converter.hasDictionarySupport()) {
       converter.setDictionary(dictionary);
     }

parquet-column/src/main/java/org/apache/parquet/column/page/DictionaryPage.java

@@ -21,7 +21,10 @@
 import java.io.IOException;
 import java.util.Objects;
 import org.apache.parquet.bytes.BytesInput;
+import org.apache.parquet.column.ColumnDescriptor;
+import org.apache.parquet.column.Dictionary;
 import org.apache.parquet.column.Encoding;
+import org.apache.parquet.io.ParquetDecodingException;
 
 /**
  * Data for a dictionary page
@@ -74,6 +77,17 @@ public DictionaryPage copy() throws IOException {
     return new DictionaryPage(BytesInput.copy(bytes), getUncompressedSize(), dictionarySize, encoding);
   }
 
+  /**
+   * @return the decoded dictionary
+   */
+  public Dictionary getDictionary(ColumnDescriptor path) {
+    try {
+      return getEncoding().initDictionary(path, this);
+    } catch (IOException e) {
+      throw new ParquetDecodingException("could not decode the dictionary for " + path, e);
+    }
+  }
+
   @Override
   public String toString() {
     return "Page [bytes.size=" + bytes.size() + ", entryCount=" + dictionarySize + ", uncompressedSize="

parquet-column/src/main/java/org/apache/parquet/column/page/PageReader.java

@@ -18,11 +18,6 @@
  */
 package org.apache.parquet.column.page;
 
-import java.io.IOException;
-import org.apache.parquet.column.ColumnDescriptor;
-import org.apache.parquet.column.Dictionary;
-import org.apache.parquet.io.ParquetDecodingException;
-
 /**
  * Reader for a sequence a page from a given column chunk
  */
@@ -33,22 +28,6 @@ public interface PageReader {
    */
   DictionaryPage readDictionaryPage();
 
-  /**
-   * @return the dictionary in this page or null if none
-   */
-  default Dictionary getDictionary(ColumnDescriptor path) {
-    Dictionary dictionary = null;
-    DictionaryPage dictionaryPage = readDictionaryPage();
-    if (dictionaryPage != null) {
-      try {
-        dictionary = dictionaryPage.getEncoding().initDictionary(path, dictionaryPage);
-      } catch (IOException e) {
-        throw new ParquetDecodingException("could not decode the dictionary for " + path, e);
-      }
-    }
-    return dictionary;
-  }
-
   /**
    * @return the total number of values in the column chunk
    */