ARROW-1031: [GLib] Support pretty print

c_glib/arrow-glib/array.cpp

@@ -24,9 +24,11 @@
 #include <arrow-glib/array.hpp>
 #include <arrow-glib/buffer.hpp>
 #include <arrow-glib/data-type.hpp>
+#include <arrow-glib/error.hpp>
 #include <arrow-glib/type.hpp>
 
 #include <iostream>
+#include <sstream>
 
 G_BEGIN_DECLS
 
@@ -395,6 +397,31 @@ garrow_array_slice(GArrowArray *array,
   return garrow_array_new_raw(&arrow_sub_array);
 }
 
+/**
+ * garrow_array_to_string:
+ * @array: A #GArrowArray.
+ * @error: (nullable): Return location for a #GError or %NULL.
+ *
+ * Returns: (nullable): The formatted array content or %NULL on error.
+ *
+ *   The returned string should be freed when with g_free() when no
+ *   longer needed.
+ *
+ * Since: 0.4.0
+ */
+gchar *
+garrow_array_to_string(GArrowArray *array, GError **error)
+{
+  const auto arrow_array = garrow_array_get_raw(array);
+  std::stringstream sink;
+  auto status = arrow::PrettyPrint(*arrow_array, 0, &sink);
+  if (garrow_error_check(error, status, "[array][to-string]")) {
+    return g_strdup(sink.str().c_str());
+  } else {
+    return NULL;
+  }
+}
+
 
 G_DEFINE_TYPE(GArrowNullArray,               \
               garrow_null_array,             \

c_glib/arrow-glib/array.h

@@ -79,6 +79,8 @@ GArrowType     garrow_array_get_value_type(GArrowArray *array);
 GArrowArray   *garrow_array_slice       (GArrowArray *array,
                                          gint64 offset,
                                          gint64 length);
+gchar         *garrow_array_to_string   (GArrowArray *array,
+                                         GError **error);
 
 #define GARROW_TYPE_NULL_ARRAY                  \
   (garrow_null_array_get_type())

c_glib/arrow-glib/record-batch.cpp

@@ -22,9 +22,12 @@
 #endif
 
 #include <arrow-glib/array.hpp>
+#include <arrow-glib/error.hpp>
 #include <arrow-glib/record-batch.hpp>
 #include <arrow-glib/schema.hpp>
 
+#include <sstream>
+
 G_BEGIN_DECLS
 
 /**
@@ -286,6 +289,32 @@ garrow_record_batch_slice(GArrowRecordBatch *record_batch,
   return garrow_record_batch_new_raw(&arrow_sub_record_batch);
 }
 
+/**
+ * garrow_record_batch_to_string:
+ * @record_batch: A #GArrowRecordBatch.
+ * @error: (nullable): Return location for a #GError or %NULL.
+ *
+ * Returns: (nullable): The formatted record batch content or %NULL on error.
+ *
+ *   The returned string should be freed when with g_free() when no
+ *   longer needed.
+ *
+ * Since: 0.4.0
+ */
+gchar *
+garrow_record_batch_to_string(GArrowRecordBatch *record_batch, GError **error)
+{
+  const auto arrow_record_batch = garrow_record_batch_get_raw(record_batch);
+  std::stringstream sink;
+  auto status = arrow::PrettyPrint(*arrow_record_batch, 0, &sink);
+  if (garrow_error_check(error, status, "[record-batch][to-string]")) {
+    return g_strdup(sink.str().c_str());
+  } else {
+    return NULL;
+  }
+}
+
+
 G_END_DECLS
 
 GArrowRecordBatch *

c_glib/arrow-glib/record-batch.h

@@ -85,4 +85,7 @@ GArrowRecordBatch *garrow_record_batch_slice     (GArrowRecordBatch *record_batc
                                                   gint64 offset,
                                                   gint64 length);
 
+gchar        *garrow_record_batch_to_string      (GArrowRecordBatch *record_batch,
+                                                  GError **error);
+
 G_END_DECLS

c_glib/arrow-glib/table.h

@@ -86,4 +86,6 @@ GArrowTable    *garrow_table_remove_column (GArrowTable *table,
                                             guint i,
                                             GError **error);
 
+gchar          *garrow_table_to_string     (GArrowTable *table);
+
 G_END_DECLS

c_glib/test/test-array.rb

@@ -96,4 +96,9 @@ def test_slice
     assert_equal([false, true],
                  sub_array.length.times.collect {|i| sub_array.get_value(i)})
   end
+
+  def test_to_s
+    assert_equal("[true, false, true]",
+                 build_boolean_array([true, false, true]).to_s)
+  end
 end

c_glib/test/test-record-batch.rb

@@ -91,5 +91,12 @@ def test_slice
       assert_equal([false, true],
                    sub_visible_values)
     end
+
+    def test_to_s
+      assert_equal(<<-PRETTY_PRINT, @record_batch.to_s)
+visible: [true, false, true, false, true, false]
+valid: [false, true, false, true, false]
+      PRETTY_PRINT
+    end
   end
 end