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https://issues.apache.org/jira/browse/ARROW-2440?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16432848#comment-16432848
]
ASF GitHub Bot commented on ARROW-2440:
---------------------------------------
pitrou closed pull request #1876: ARROW-2440: [Rust] Implement ListBuilder<T>
URL: https://github.com/apache/arrow/pull/1876
This is a PR merged from a forked repository.
As GitHub hides the original diff on merge, it is displayed below for
the sake of provenance:
As this is a foreign pull request (from a fork), the diff is supplied
below (as it won't show otherwise due to GitHub magic):
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index 6ab3daabb..e0c14db87 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -28,4 +28,5 @@ pub mod builder;
pub mod datatypes;
pub mod error;
pub mod list;
+pub mod list_builder;
pub mod memory;
diff --git a/rust/src/list.rs b/rust/src/list.rs
index a7b11a628..fad0ed372 100644
--- a/rust/src/list.rs
+++ b/rust/src/list.rs
@@ -17,9 +17,8 @@
use std::str;
-use bytes::{BufMut, BytesMut};
-
use super::buffer::Buffer;
+use super::list_builder::ListBuilder;
pub struct List<T> {
pub data: Buffer<T>,
@@ -40,19 +39,11 @@ impl<T> List<T> {
impl From<Vec<String>> for List<u8> {
fn from(v: Vec<String>) -> Self {
- let mut offsets: Vec<i32> = Vec::with_capacity(v.len() + 1);
- let mut buf = BytesMut::with_capacity(v.len() * 32);
- offsets.push(0_i32);
+ let mut b: ListBuilder<u8> = ListBuilder::with_capacity(v.len());
v.iter().for_each(|s| {
- let slice = s.as_bytes();
- buf.reserve(slice.len());
- buf.put(slice);
- offsets.push(buf.len() as i32);
+ b.push(s.as_bytes());
});
- List {
- data: Buffer::from(buf.freeze()),
- offsets: Buffer::from(offsets),
- }
+ b.finish()
}
}
diff --git a/rust/src/list_builder.rs b/rust/src/list_builder.rs
new file mode 100644
index 000000000..0122e680e
--- /dev/null
+++ b/rust/src/list_builder.rs
@@ -0,0 +1,66 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you 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 super::builder::*;
+use super::list::List;
+
+pub struct ListBuilder<T> {
+ data: Builder<T>,
+ offsets: Builder<i32>,
+}
+
+impl<T> ListBuilder<T> {
+ pub fn new() -> Self {
+ ListBuilder::with_capacity(64)
+ }
+
+ pub fn with_capacity(n: usize) -> Self {
+ let data = Builder::with_capacity(n);
+ let mut offsets = Builder::with_capacity(n);
+ offsets.push(0_i32);
+ ListBuilder { data, offsets }
+ }
+
+ pub fn push(&mut self, slice: &[T]) {
+ self.data.push_slice(slice);
+ self.offsets.push(self.data.len() as i32);
+ }
+
+ pub fn finish(&mut self) -> List<T> {
+ List {
+ data: self.data.finish(),
+ offsets: self.offsets.finish(),
+ }
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn test_list_u8() {
+ let mut b: ListBuilder<u8> = ListBuilder::new();
+ b.push("Hello, ".as_bytes());
+ b.push("World!".as_bytes());
+ let buffer = b.finish();
+
+ assert_eq!(2, buffer.len());
+ assert_eq!("Hello, ".as_bytes(), buffer.slice(0));
+ assert_eq!("World!".as_bytes(), buffer.slice(1));
+ }
+}
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> [Rust] Implement ListBuilder<T>
> -------------------------------
>
> Key: ARROW-2440
> URL: https://issues.apache.org/jira/browse/ARROW-2440
> Project: Apache Arrow
> Issue Type: New Feature
> Components: Rust
> Reporter: Andy Grove
> Assignee: Andy Grove
> Priority: Major
> Labels: pull-request-available
> Fix For: 0.10.0
>
>
> Implement ListBuilder<T>
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