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
139
140
141
142
143
144
145
146

// Copyright Materialize, Inc. and contributors. All rights reserved.
//
// Use of this software is governed by the Business Source License
// included in the LICENSE file.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0.

use std::error::Error;
use std::fmt;

use anyhow::bail;
use mz_lowertest::MzReflect;
use mz_ore::cast::CastFrom;
use mz_proto::{RustType, TryFromProtoError};
use proptest::arbitrary::Arbitrary;
use proptest::strategy::{BoxedStrategy, Strategy};
use serde::{Deserialize, Serialize};

include!(concat!(env!("OUT_DIR"), "/mz_repr.adt.varchar.rs"));

// https://github.com/postgres/postgres/blob/REL_14_0/src/include/access/htup_details.h#L577-L584
pub const MAX_MAX_LENGTH: u32 = 10_485_760;

/// A marker type indicating that a Rust string should be interpreted as a
/// [`ScalarType::VarChar`].
///
/// [`ScalarType::VarChar`]: crate::ScalarType::VarChar
#[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub struct VarChar<S: AsRef<str>>(pub S);

/// The `max_length` of a [`ScalarType::VarChar`].
///
/// This newtype wrapper ensures that the length is within the valid range.
///
/// [`ScalarType::VarChar`]: crate::ScalarType::VarChar
#[derive(
    Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash, Serialize, Deserialize, MzReflect,
)]
pub struct VarCharMaxLength(pub(crate) u32);

impl VarCharMaxLength {
    /// Consumes the newtype wrapper, returning the inner `u32`.
    pub fn into_u32(self) -> u32 {
        self.0
    }
}

impl TryFrom<i64> for VarCharMaxLength {
    type Error = InvalidVarCharMaxLengthError;

    fn try_from(max_length: i64) -> Result<Self, Self::Error> {
        match u32::try_from(max_length) {
            Ok(max_length) if max_length > 0 && max_length < MAX_MAX_LENGTH => {
                Ok(VarCharMaxLength(max_length))
            }
            _ => Err(InvalidVarCharMaxLengthError),
        }
    }
}

impl RustType<ProtoVarCharMaxLength> for VarCharMaxLength {
    fn into_proto(&self) -> ProtoVarCharMaxLength {
        ProtoVarCharMaxLength { value: self.0 }
    }

    fn from_proto(proto: ProtoVarCharMaxLength) -> Result<Self, TryFromProtoError> {
        Ok(VarCharMaxLength(proto.value))
    }
}

impl Arbitrary for VarCharMaxLength {
    type Parameters = ();
    type Strategy = BoxedStrategy<VarCharMaxLength>;

    fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy {
        proptest::arbitrary::any::<u32>()
            // We cap the maximum VarCharMaxLength to prevent generating
            // massive strings which can greatly slow down tests and are
            // relatively uninteresting.
            .prop_map(|len| VarCharMaxLength(len % 300))
            .boxed()
    }
}

/// The error returned when constructing a [`VarCharMaxLength`] from an invalid
/// value.
#[derive(Debug, Clone)]
pub struct InvalidVarCharMaxLengthError;

impl fmt::Display for InvalidVarCharMaxLengthError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(
            f,
            "length for type character varying must be between 1 and {}",
            MAX_MAX_LENGTH
        )
    }
}

impl Error for InvalidVarCharMaxLengthError {}

pub fn format_str(
    s: &str,
    length: Option<VarCharMaxLength>,
    fail_on_len: bool,
) -> Result<&str, anyhow::Error> {
    Ok(match length {
        // Note that length is 1-indexed, so finding `None` means the string's
        // characters don't exceed the length, while finding `Some` means it
        // does.
        Some(l) => {
            let l = usize::cast_from(l.into_u32());
            match s.char_indices().nth(l) {
                None => s,
                Some((idx, _)) => {
                    if !fail_on_len || s[idx..].chars().all(|c| c.is_ascii_whitespace()) {
                        &s[..idx]
                    } else {
                        bail!("{} exceeds maximum length of {}", s, l)
                    }
                }
            }
        }
        None => s,
    })
}

#[cfg(test)]
mod tests {
    use mz_ore::assert_ok;
    use mz_proto::protobuf_roundtrip;
    use proptest::prelude::*;

    use super::*;

    proptest! {
        #[mz_ore::test]
        fn var_char_max_length_protobuf_roundtrip(expect in any::<VarCharMaxLength>()) {
            let actual = protobuf_roundtrip::<_, ProtoVarCharMaxLength>(&expect);
            assert_ok!(actual);
            assert_eq!(actual.unwrap(), expect);
        }
    }
}