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::types::logical_string;
24use datafusion_common::utils::take_function_args;
25use datafusion_common::{Result, ScalarValue};
26use datafusion_expr::{
27    Coercion, ColumnarValue, Documentation, ScalarFunctionArgs, ScalarUDFImpl, Signature,
28    TypeSignatureClass, Volatility,
29};
30use datafusion_macros::user_doc;
31
32#[user_doc(
33    doc_section(label = "String Functions"),
34    description = "Returns the bit length of a string.",
35    syntax_example = "bit_length(str)",
36    sql_example = r#"```sql
37> select bit_length('datafusion');
38+--------------------------------+
39| bit_length(Utf8("datafusion")) |
40+--------------------------------+
41| 80                             |
42+--------------------------------+
43```"#,
44    standard_argument(name = "str", prefix = "String"),
45    related_udf(name = "length"),
46    related_udf(name = "octet_length")
47)]
48#[derive(Debug)]
49pub struct BitLengthFunc {
50    signature: Signature,
51}
52
53impl Default for BitLengthFunc {
54    fn default() -> Self {
55        Self::new()
56    }
57}
58
59impl BitLengthFunc {
60    pub fn new() -> Self {
61        Self {
62            signature: Signature::coercible(
63                vec![Coercion::new_exact(TypeSignatureClass::Native(
64                    logical_string(),
65                ))],
66                Volatility::Immutable,
67            ),
68        }
69    }
70}
71
72impl ScalarUDFImpl for BitLengthFunc {
73    fn as_any(&self) -> &dyn Any {
74        self
75    }
76
77    fn name(&self) -> &str {
78        "bit_length"
79    }
80
81    fn signature(&self) -> &Signature {
82        &self.signature
83    }
84
85    fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
86        utf8_to_int_type(&arg_types[0], "bit_length")
87    }
88
89    fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
90        let [array] = take_function_args(self.name(), &args.args)?;
91
92        match array {
93            ColumnarValue::Array(v) => Ok(ColumnarValue::Array(bit_length(v.as_ref())?)),
94            ColumnarValue::Scalar(v) => match v {
95                ScalarValue::Utf8(v) => Ok(ColumnarValue::Scalar(ScalarValue::Int32(
96                    v.as_ref().map(|x| (x.len() * 8) as i32),
97                ))),
98                ScalarValue::LargeUtf8(v) => Ok(ColumnarValue::Scalar(
99                    ScalarValue::Int64(v.as_ref().map(|x| (x.len() * 8) as i64)),
100                )),
101                ScalarValue::Utf8View(v) => Ok(ColumnarValue::Scalar(
102                    ScalarValue::Int32(v.as_ref().map(|x| (x.len() * 8) as i32)),
103                )),
104                _ => unreachable!("bit length"),
105            },
106        }
107    }
108
109    fn documentation(&self) -> Option<&Documentation> {
110        self.doc()
111    }
112}
datafusion_functions/string/bit_length.rs

datafusion_functions/string/
bit_length.rs
