Friendly stringing of py list wrapper (#1520)

deephaven · Nov 2, 2021 · 606585a · 606585a
1 parent c605f72
commit 606585a
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Showing 3 changed files with 42 additions and 3 deletions.
diff --git a/DB/src/main/java/io/deephaven/db/tables/remote/preview/ArrayPreview.java b/DB/src/main/java/io/deephaven/db/tables/remote/preview/ArrayPreview.java
@@ -2,6 +2,7 @@
 
 import io.deephaven.db.tables.dbarrays.DbArrayBase;
 import io.deephaven.db.v2.sources.chunk.ChunkType;
+import org.jpy.PyListWrapper;
 
 /**
  * A Preview Type for Arrays and DbArray. Converts long arrays to a String "[1, 2, 3, 4, 5...]"
@@ -10,14 +11,14 @@ public class ArrayPreview implements PreviewType {
     private static final int ARRAY_SIZE_CUTOFF = 5;
     private final String displayString;
 
-    public static ArrayPreview fromDbArray(DbArrayBase dbArray) {
+    public static ArrayPreview fromDbArray(final DbArrayBase<?> dbArray) {
         if (dbArray == null) {
             return null;
         }
         return new ArrayPreview(dbArray.toString(ARRAY_SIZE_CUTOFF));
     }
 
-    public static ArrayPreview fromArray(Object array) {
+    public static ArrayPreview fromArray(final Object array) {
         if (array == null) {
             return null;
         }
@@ -28,6 +29,13 @@ public static ArrayPreview fromArray(Object array) {
                 .toString(ARRAY_SIZE_CUTOFF));
     }
 
+    public static ArrayPreview fromPyListWrapper(final PyListWrapper list) {
+        if (list == null) {
+            return null;
+        }
+        return new ArrayPreview(list.toString(ARRAY_SIZE_CUTOFF));
+    }
+
     private ArrayPreview(String displayString) {
         this.displayString = displayString;
 

diff --git a/DB/src/main/java/io/deephaven/db/tables/remote/preview/ColumnPreviewManager.java b/DB/src/main/java/io/deephaven/db/tables/remote/preview/ColumnPreviewManager.java
@@ -10,6 +10,7 @@
 import io.deephaven.db.v2.sources.ColumnSource;
 import io.deephaven.util.type.TypeUtils;
 import org.apache.commons.lang3.StringUtils;
+import org.jpy.PyListWrapper;
 
 import java.util.*;
 import java.util.function.Function;
@@ -27,6 +28,8 @@ public class ColumnPreviewManager {
             new PreviewColumnFactory<>(Object.class, ArrayPreview.class, ArrayPreview::fromArray);
     private static final PreviewColumnFactory<DbArrayBase, ArrayPreview> dbArrayPreviewFactory =
             new PreviewColumnFactory<>(DbArrayBase.class, ArrayPreview.class, ArrayPreview::fromDbArray);
+    private static final PreviewColumnFactory<PyListWrapper, ArrayPreview> pyListWrapperPreviewFactory =
+            new PreviewColumnFactory<>(PyListWrapper.class, ArrayPreview.class, ArrayPreview::fromPyListWrapper);
 
     // Factory for non-serializable types
     private static final PreviewColumnFactory<Object, DisplayWrapper> nonDisplayableFactory =
@@ -87,6 +90,10 @@ public static Table applyPreview(final Table table) {
                 // Always wrap DbArrays
                 selectColumns.add(dbArrayPreviewFactory.makeColumn(name));
                 originalTypes.put(name, type.getName());
+            } else if (PyListWrapper.class.isAssignableFrom(type)) {
+                // Always wrap PyListWrapper
+                selectColumns.add(pyListWrapperPreviewFactory.makeColumn(name));
+                originalTypes.put(name, type.getName());
             } else if (type.isArray()) {
                 // Always wrap arrays
                 selectColumns.add(arrayPreviewFactory.makeColumn(name));

diff --git a/py/jpy/src/main/java/org/jpy/PyListWrapper.java b/py/jpy/src/main/java/org/jpy/PyListWrapper.java
@@ -23,7 +23,7 @@
 /**
  * A simple wrapper around a Python List object that implements a java List of PyObjects.
  */
-class PyListWrapper implements List<PyObject> {
+public class PyListWrapper implements List<PyObject> {
     // todo: https://docs.python.org/3/c-api/list.html vs https://docs.python.org/3/c-api/sequence.html
     private PyObject pyObject;
 
@@ -235,4 +235,28 @@ public ListIterator<PyObject> listIterator(int index) {
     public List<PyObject> subList(int fromIndex, int toIndex) {
         throw new UnsupportedOperationException();
     }
+
+    /**
+     * Return a summarized preview of this list.
+     *
+     * @param prefixLength The maximum prefix of the array to convert
+     * @return The String representation of array
+     */
+    public String toString(final int prefixLength) {
+        if (isEmpty()) {
+            return "[]";
+        }
+        final StringBuilder builder = new StringBuilder("[");
+        final int displaySize = Math.min(size(), prefixLength);
+        builder.append(get(0).str());
+        for (int ei = 1; ei < displaySize; ++ei) {
+            builder.append(", ").append(get(ei).str());
+        }
+        if (displaySize == size()) {
+            builder.append(']');
+        } else {
+            builder.append(", ...]");
+        }
+        return builder.toString();
+    }
 }