datafusion_functions/string/
bit_length.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership.  The ASF licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License.  You may obtain a copy of the License at
8//
9//   http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18use arrow::compute::kernels::length::bit_length;
19use arrow::datatypes::DataType;
20use std::any::Any;
21
22use crate::utils::utf8_to_int_type;
23use datafusion_common::{utils::take_function_args, Result, ScalarValue};
24use datafusion_expr::{ColumnarValue, Documentation, Volatility};
25use datafusion_expr::{ScalarFunctionArgs, ScalarUDFImpl, Signature};
26use datafusion_macros::user_doc;
27
28#[user_doc(
29    doc_section(label = "String Functions"),
30    description = "Returns the bit length of a string.",
31    syntax_example = "bit_length(str)",
32    sql_example = r#"```sql
33> select bit_length('datafusion');
34+--------------------------------+
35| bit_length(Utf8("datafusion")) |
36+--------------------------------+
37| 80                             |
38+--------------------------------+
39```"#,
40    standard_argument(name = "str", prefix = "String"),
41    related_udf(name = "length"),
42    related_udf(name = "octet_length")
43)]
44#[derive(Debug)]
45pub struct BitLengthFunc {
46    signature: Signature,
47}
48
49impl Default for BitLengthFunc {
50    fn default() -> Self {
51        Self::new()
52    }
53}
54
55impl BitLengthFunc {
56    pub fn new() -> Self {
57        Self {
58            signature: Signature::string(1, Volatility::Immutable),
59        }
60    }
61}
62
63impl ScalarUDFImpl for BitLengthFunc {
64    fn as_any(&self) -> &dyn Any {
65        self
66    }
67
68    fn name(&self) -> &str {
69        "bit_length"
70    }
71
72    fn signature(&self) -> &Signature {
73        &self.signature
74    }
75
76    fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
77        utf8_to_int_type(&arg_types[0], "bit_length")
78    }
79
80    fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
81        let [array] = take_function_args(self.name(), &args.args)?;
82
83        match array {
84            ColumnarValue::Array(v) => Ok(ColumnarValue::Array(bit_length(v.as_ref())?)),
85            ColumnarValue::Scalar(v) => match v {
86                ScalarValue::Utf8(v) => Ok(ColumnarValue::Scalar(ScalarValue::Int32(
87                    v.as_ref().map(|x| (x.len() * 8) as i32),
88                ))),
89                ScalarValue::LargeUtf8(v) => Ok(ColumnarValue::Scalar(
90                    ScalarValue::Int64(v.as_ref().map(|x| (x.len() * 8) as i64)),
91                )),
92                ScalarValue::Utf8View(v) => Ok(ColumnarValue::Scalar(
93                    ScalarValue::Int32(v.as_ref().map(|x| (x.len() * 8) as i32)),
94                )),
95                _ => unreachable!("bit length"),
96            },
97        }
98    }
99
100    fn documentation(&self) -> Option<&Documentation> {
101        self.doc()
102    }
103}
datafusion_functions/string/bit_length.rs

datafusion_functions/string/
bit_length.rs
