1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138

// 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.

//! [`ScalarUDFImpl`] definitions for cardinality function.

use crate::utils::make_scalar_function;
use arrow_array::{
    Array, ArrayRef, GenericListArray, MapArray, OffsetSizeTrait, UInt64Array,
};
use arrow_schema::DataType;
use arrow_schema::DataType::{FixedSizeList, LargeList, List, Map, UInt64};
use datafusion_common::cast::{as_large_list_array, as_list_array, as_map_array};
use datafusion_common::Result;
use datafusion_common::{exec_err, plan_err};
use datafusion_expr::{
    ArrayFunctionSignature, ColumnarValue, ScalarUDFImpl, Signature, TypeSignature,
    Volatility,
};
use std::any::Any;
use std::sync::Arc;

make_udf_expr_and_func!(
    Cardinality,
    cardinality,
    array,
    "returns the total number of elements in the array or map.",
    cardinality_udf
);

impl Cardinality {
    pub fn new() -> Self {
        Self {
            signature: Signature::one_of(
                vec![
                    TypeSignature::ArraySignature(ArrayFunctionSignature::Array),
                    TypeSignature::ArraySignature(ArrayFunctionSignature::MapArray),
                ],
                Volatility::Immutable,
            ),
            aliases: vec![],
        }
    }
}

#[derive(Debug)]
pub(super) struct Cardinality {
    signature: Signature,
    aliases: Vec<String>,
}
impl ScalarUDFImpl for Cardinality {
    fn as_any(&self) -> &dyn Any {
        self
    }
    fn name(&self) -> &str {
        "cardinality"
    }

    fn signature(&self) -> &Signature {
        &self.signature
    }

    fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
        Ok(match arg_types[0] {
            List(_) | LargeList(_) | FixedSizeList(_, _) | Map(_, _) => UInt64,
            _ => {
                return plan_err!("The cardinality function can only accept List/LargeList/FixedSizeList/Map.");
            }
        })
    }

    fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> {
        make_scalar_function(cardinality_inner)(args)
    }

    fn aliases(&self) -> &[String] {
        &self.aliases
    }
}

/// Cardinality SQL function
pub fn cardinality_inner(args: &[ArrayRef]) -> Result<ArrayRef> {
    if args.len() != 1 {
        return exec_err!("cardinality expects one argument");
    }

    match &args[0].data_type() {
        List(_) => {
            let list_array = as_list_array(&args[0])?;
            generic_list_cardinality::<i32>(list_array)
        }
        LargeList(_) => {
            let list_array = as_large_list_array(&args[0])?;
            generic_list_cardinality::<i64>(list_array)
        }
        Map(_, _) => {
            let map_array = as_map_array(&args[0])?;
            generic_map_cardinality(map_array)
        }
        other => {
            exec_err!("cardinality does not support type '{:?}'", other)
        }
    }
}

fn generic_map_cardinality(array: &MapArray) -> Result<ArrayRef> {
    let result: UInt64Array = array
        .iter()
        .map(|opt_arr| opt_arr.map(|arr| arr.len() as u64))
        .collect();
    Ok(Arc::new(result))
}

fn generic_list_cardinality<O: OffsetSizeTrait>(
    array: &GenericListArray<O>,
) -> Result<ArrayRef> {
    let result = array
        .iter()
        .map(|arr| match crate::utils::compute_array_dims(arr)? {
            Some(vector) => Ok(Some(vector.iter().map(|x| x.unwrap()).product::<u64>())),
            None => Ok(None),
        })
        .collect::<Result<UInt64Array>>()?;
    Ok(Arc::new(result) as ArrayRef)
}