add tests for string_view type

src/common/arrow/src/arrow/array/binview/from.rs

@@ -0,0 +1,24 @@
+// Copyright 2021 Datafuse Labs
+//
+// Licensed 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.
+
+use crate::arrow::array::BinaryViewArrayGeneric;
+use crate::arrow::array::MutableBinaryViewArray;
+use crate::arrow::array::ViewType;
+
+impl<T: ViewType + ?Sized, P: AsRef<T>> FromIterator<Option<P>> for BinaryViewArrayGeneric<T> {
+    #[inline]
+    fn from_iter<I: IntoIterator<Item=Option<P>>>(iter: I) -> Self {
+        MutableBinaryViewArray::<T>::from_iter(iter).into()
+    }
+}

src/common/arrow/src/arrow/array/binview/mod.rs

@@ -15,6 +15,7 @@
 
 mod ffi;
 pub(crate) mod fmt;
+mod from;
 mod iterator;
 mod mutable;
 mod view;
@@ -23,6 +24,7 @@ mod private {
     pub trait Sealed: Send + Sync {}
 
     impl Sealed for str {}
+
     impl Sealed for [u8] {}
 }
 
@@ -157,6 +159,7 @@ impl<T: ViewType + ?Sized> Clone for BinaryViewArrayGeneric<T> {
 }
 
 unsafe impl<T: ViewType + ?Sized> Send for BinaryViewArrayGeneric<T> {}
+
 unsafe impl<T: ViewType + ?Sized> Sync for BinaryViewArrayGeneric<T> {}
 
 fn buffers_into_raw<T>(buffers: &[Buffer<T>]) -> Arc<[(*const T, usize)]> {
@@ -254,6 +257,12 @@ impl<T: ViewType + ?Sized> BinaryViewArrayGeneric<T> {
         }
     }
 
+    /// Returns a new [`BinaryViewArrayGeneric`] from a slice of `&T`.
+    // Note: this can't be `impl From` because Rust does not allow double `AsRef` on it.
+    pub fn from<V: AsRef<T>, P: AsRef<[Option<V>]>>(slice: P) -> Self {
+        MutableBinaryViewArray::<T>::from(slice).into()
+    }
+
     /// Creates an empty [`BinaryViewArrayGeneric`], i.e. whose `.len` is zero.
     #[inline]
     pub fn new_empty(data_type: DataType) -> Self {
@@ -323,7 +332,7 @@ impl<T: ViewType + ?Sized> BinaryViewArrayGeneric<T> {
         BinaryViewValueIter::new(self)
     }
 
-    pub fn len_iter(&self) -> impl Iterator<Item = u32> + '_ {
+    pub fn len_iter(&self) -> impl Iterator<Item=u32> + '_ {
         self.views.iter().map(|v| v.length)
     }
 

src/common/arrow/src/arrow/array/binview/mutable.rs

@@ -175,8 +175,16 @@ impl<T: ViewType + ?Sized> MutableBinaryViewArray<T> {
         payload[0..4].copy_from_slice(&len.to_le_bytes());
 
         if len <= 12 {
+            // |   len   |  prefix  |  remaining(zero-padded)  |
+            //     ^          ^             ^
+            // | 4 bytes | 4 bytes |      8 bytes              |
             payload[4..4 + bytes.len()].copy_from_slice(bytes);
         } else {
+            // |   len   |  prefix  |  buffer |  offsets  |
+            //     ^          ^          ^         ^
+            // | 4 bytes | 4 bytes | 4 bytes |  4 bytes  |
+            //
+            // buffer index + offset -> real binary data
             self.total_buffer_len += bytes.len();
             let required_cap = self.in_progress_buffer.len() + bytes.len();
             if self.in_progress_buffer.capacity() < required_cap {
@@ -192,6 +200,7 @@ impl<T: ViewType + ?Sized> MutableBinaryViewArray<T> {
             let offset = self.in_progress_buffer.len() as u32;
             self.in_progress_buffer.extend_from_slice(bytes);
 
+            // set prefix
             unsafe { payload[4..8].copy_from_slice(bytes.get_unchecked(0..4)) };
             let buffer_idx: u32 = self.completed_buffers.len().try_into().unwrap();
             payload[8..12].copy_from_slice(&buffer_idx.to_le_bytes());
@@ -347,12 +356,13 @@ impl<T: ViewType + ?Sized> MutableBinaryViewArray<T> {
         let len = v.length;
 
         // view layout:
+        // for no-inlined layout:
         // length: 4 bytes
         // prefix: 4 bytes
         // buffer_index: 4 bytes
         // offset: 4 bytes
 
-        // inlined layout:
+        // for inlined layout:
         // length: 4 bytes
         // data: 12 bytes
         let bytes = if len <= 12 {

src/common/arrow/tests/it/arrow/array/binview/mod.rs

@@ -0,0 +1,130 @@
+// Copyright 2021 Datafuse Labs
+//
+// Licensed 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.
+
+use databend_common_arrow::arrow::array::Array;
+use databend_common_arrow::arrow::array::BinaryViewArray;
+use databend_common_arrow::arrow::array::Utf8ViewArray;
+use databend_common_arrow::arrow::bitmap::Bitmap;
+use databend_common_arrow::arrow::datatypes::DataType;
+
+#[test]
+fn basics_string_view() {
+    let data = vec![
+        Some("hello"),
+        None,
+        // larger than 12 bytes.
+        Some("Databend Cloud is a Cost-Effective alternative to Snowflake."),
+    ];
+
+    let array: Utf8ViewArray = data.into_iter().collect();
+
+    assert_eq!(array.value(0), "hello");
+    assert_eq!(array.value(1), "");
+    assert_eq!(
+        array.value(2),
+        "Databend Cloud is a Cost-Effective alternative to Snowflake."
+    );
+    assert_eq!(
+        unsafe { array.value_unchecked(2) },
+        "Databend Cloud is a Cost-Effective alternative to Snowflake."
+    );
+    assert_eq!(
+        array.validity(),
+        Some(&Bitmap::from_u8_slice([0b00000101], 3))
+    );
+    assert!(array.is_valid(0));
+    assert!(!array.is_valid(1));
+    assert!(array.is_valid(2));
+
+    let array2 = Utf8ViewArray::new_unchecked(
+        DataType::Utf8View,
+        array.views().clone(),
+        array.data_buffers().clone(),
+        array.validity().cloned(),
+        array.total_bytes_len(),
+        array.total_buffer_len(),
+    );
+
+    assert_eq!(array, array2);
+
+    let array = array.sliced(1, 2);
+
+    assert_eq!(array.value(0), "");
+    assert_eq!(
+        array.value(1),
+        "Databend Cloud is a Cost-Effective alternative to Snowflake."
+    );
+}
+
+#[test]
+fn basics_binary_view() {
+    let data = vec![
+        Some(b"hello".to_vec()),
+        None,
+        // larger than 12 bytes.
+        Some(b"Databend Cloud is a Cost-Effective alternative to Snowflake.".to_vec()),
+    ];
+
+    let array: BinaryViewArray = data.into_iter().collect();
+
+    assert_eq!(array.value(0), b"hello");
+    assert_eq!(array.value(1), b"");
+    assert_eq!(
+        array.value(2),
+        b"Databend Cloud is a Cost-Effective alternative to Snowflake."
+    );
+    assert_eq!(
+        unsafe { array.value_unchecked(2) },
+        b"Databend Cloud is a Cost-Effective alternative to Snowflake."
+    );
+    assert_eq!(
+        array.validity(),
+        Some(&Bitmap::from_u8_slice([0b00000101], 3))
+    );
+    assert!(array.is_valid(0));
+    assert!(!array.is_valid(1));
+    assert!(array.is_valid(2));
+
+    let array2 = BinaryViewArray::new_unchecked(
+        DataType::Utf8View,
+        array.views().clone(),
+        array.data_buffers().clone(),
+        array.validity().cloned(),
+        array.total_bytes_len(),
+        array.total_buffer_len(),
+    );
+
+    assert_eq!(array, array2);
+
+    let array = array.sliced(1, 2);
+
+    assert_eq!(array.value(0), b"");
+    assert_eq!(
+        array.value(1),
+        b"Databend Cloud is a Cost-Effective alternative to Snowflake."
+    );
+}
+
+#[test]
+fn from() {
+    let array = Utf8ViewArray::from([Some("hello"), Some(" "), None]);
+
+    let a = array.validity().unwrap();
+    assert_eq!(a, &Bitmap::from([true, true, false]));
+
+    let array = BinaryViewArray::from([Some(b"hello".to_vec()), Some(b" ".to_vec()), None]);
+
+    let a = array.validity().unwrap();
+    assert_eq!(a, &Bitmap::from([true, true, false]));
+}

src/common/arrow/tests/it/arrow/array/mod.rs

@@ -14,6 +14,7 @@
 // limitations under the License.
 
 mod binary;
+mod binview;
 mod boolean;
 mod dictionary;
 mod equal;