all util file

Author: GE-fighting

src/util/mod.rs

@@ -0,0 +1,34 @@
+pub mod util;
+
+use arrow::record_batch::RecordBatch;
+use arrow::datatypes::{DataType, Field, Schema, SchemaRef};
+use arrow::error::ArrowError;
+
+pub fn record_batch_to_string(batch: &RecordBatch) -> Result<String, ArrowError> {
+    let mut output = String::new();
+    for row in 0..batch.num_rows() {
+        for col in 0..batch.num_columns() {
+            if col != 0 {
+                output.push(' ');
+            }
+            let column = batch.column(col);
+
+            // NULL values are rendered as "NULL".
+            if column.is_null(row) {
+                output.push_str("NULL");
+                continue;
+            }
+            let string = array_value_to_string(column, row)?;
+
+            // Empty strings are rendered as "(empty)".
+            if *column.data_type() == DataType::Utf8 && string.is_empty() {
+                output.push_str("(empty)");
+                continue;
+            }
+            output.push_str(&string);
+        }
+        output.push('\n');
+    }
+
+    Ok(output)
+}