risingwave_common/types/
successor.rs

1// Copyright 2025 RisingWave Labs
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15use chrono::Duration;
16
17use super::{Date, ScalarImpl, Timestamp};
18
19/// A successor is a term that comes right after a particular value. Suppose n is a number (where n
20/// belongs to any whole number), then the successor of n is 'n+1'. The other terminologies used for
21/// a successor are just after, immediately after, and next value.
22pub trait Successor {
23    /// Returns the successor of the current value if it exists, otherwise returns None.
24    fn successor(&self) -> Option<Self>
25    where
26        Self: Sized,
27    {
28        None
29    }
30}
31
32impl Successor for i16 {
33    fn successor(&self) -> Option<Self> {
34        self.checked_add(1)
35    }
36}
37
38impl Successor for i32 {
39    fn successor(&self) -> Option<Self> {
40        self.checked_add(1)
41    }
42}
43
44impl Successor for i64 {
45    fn successor(&self) -> Option<Self> {
46        self.checked_add(1)
47    }
48}
49
50impl Successor for Timestamp {
51    fn successor(&self) -> Option<Self> {
52        self.0
53            .checked_add_signed(Duration::nanoseconds(1))
54            .map(Timestamp)
55    }
56}
57
58impl Successor for Date {
59    fn successor(&self) -> Option<Self> {
60        self.0.checked_add_signed(Duration::days(1)).map(Date)
61    }
62}
63
64impl ScalarImpl {
65    /// Returns the successor of the current value if it exists.
66    ///
67    /// See also [`Successor`].
68    ///
69    /// The function may return None when:
70    /// 1. The current value is the maximum value of the type.
71    /// 2. The successor value of the type is not well-defined.
72    pub fn successor(&self) -> Option<Self> {
73        match self {
74            ScalarImpl::Int16(v) => v.successor().map(ScalarImpl::Int16),
75            ScalarImpl::Int32(v) => v.successor().map(ScalarImpl::Int32),
76            ScalarImpl::Int64(v) => v.successor().map(ScalarImpl::Int64),
77            ScalarImpl::Timestamp(v) => v.successor().map(ScalarImpl::Timestamp),
78            ScalarImpl::Date(v) => v.successor().map(ScalarImpl::Date),
79            _ => None,
80        }
81    }
82}
risingwave_common/types/successor.rs

risingwave_common/types/
successor.rs
