odbc_api/
fixed_sized.rs

1use crate::{
2    buffers::{FetchRowMember, Indicator},
3    handles::{CData, CDataMut, DataType, HasDataType},
4    parameter::{CElement, OutputParameter},
5};
6use odbc_sys::{CDataType, Date, Numeric, Time, Timestamp};
7use std::{
8    ffi::c_void,
9    ptr::{null, null_mut},
10};
11
12/// New type wrapping u8 and binding as SQL_BIT.
13///
14/// If rust would guarantee the representation of `bool` to be an `u8`, `bool` would be the obvious
15/// choice instead. Alas it is not and someday on some platform `bool` might be something else than
16/// a `u8` so let's use this new type instead.
17#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Ord, PartialOrd)]
18pub struct Bit(pub u8);
19
20impl Bit {
21    /// Maps `true` to `1` and `false` to `0`.
22    ///
23    /// ```
24    /// use odbc_api::Bit;
25    ///
26    /// assert_eq!(Bit(0), Bit::from_bool(false));
27    /// assert_eq!(Bit(1), Bit::from_bool(true));
28    /// ```
29    pub fn from_bool(boolean: bool) -> Self {
30        if boolean { Bit(1) } else { Bit(0) }
31    }
32
33    /// Maps `1` to `true`, `0` to `false`. Panics if `Bit` should be invalid (not `0` or `1`).
34    pub fn as_bool(self) -> bool {
35        match self.0 {
36            0 => false,
37            1 => true,
38            _ => panic!("Invalid boolean representation in Bit."),
39        }
40    }
41}
42
43/// A plain old data type. With an associated C Type. Must be completely stack allocated without any
44/// external references. In addition to that the buffer size must be known to ODBC in advance.
45///
46/// # Safety
47///
48/// A type implementing this trait, must be a fixed sized type. The information in the `C_DATA_TYPE`
49/// constant must be enough to determine both the size and the buffer length of an Instance.
50pub unsafe trait Pod: Default + Copy + CElement + CDataMut + 'static {
51    /// ODBC C Data type used to bind instances to a statement.
52    const C_DATA_TYPE: CDataType;
53}
54
55macro_rules! impl_pod {
56    ($t:ident, $c_data_type:expr) => {
57        unsafe impl CData for $t {
58            fn cdata_type(&self) -> CDataType {
59                $c_data_type
60            }
61
62            fn indicator_ptr(&self) -> *const isize {
63                // Fixed sized types do not require a length indicator.
64                null()
65            }
66
67            fn value_ptr(&self) -> *const c_void {
68                self as *const $t as *const c_void
69            }
70
71            fn buffer_length(&self) -> isize {
72                0
73            }
74        }
75
76        unsafe impl CDataMut for $t {
77            /// Indicates the length of variable sized types. May be zero for fixed sized types.
78            fn mut_indicator_ptr(&mut self) -> *mut isize {
79                null_mut()
80            }
81
82            /// Pointer to a value corresponding to the one described by `cdata_type`.
83            fn mut_value_ptr(&mut self) -> *mut c_void {
84                self as *mut $t as *mut c_void
85            }
86        }
87
88        unsafe impl CElement for $t {
89            /// Fixed sized types are always complete
90            fn assert_completness(&self) {}
91        }
92
93        unsafe impl Pod for $t {
94            const C_DATA_TYPE: CDataType = $c_data_type;
95        }
96
97        unsafe impl FetchRowMember for $t {
98            fn indicator(&self) -> Option<Indicator> {
99                None
100            }
101        }
102    };
103}
104
105impl_pod!(f64, CDataType::Double);
106impl_pod!(f32, CDataType::Float);
107impl_pod!(Date, CDataType::TypeDate);
108impl_pod!(Timestamp, CDataType::TypeTimestamp);
109impl_pod!(Time, CDataType::TypeTime);
110impl_pod!(Numeric, CDataType::Numeric);
111impl_pod!(i16, CDataType::SShort);
112impl_pod!(u16, CDataType::UShort);
113impl_pod!(i32, CDataType::SLong);
114impl_pod!(u32, CDataType::ULong);
115impl_pod!(i8, CDataType::STinyInt);
116impl_pod!(u8, CDataType::UTinyInt);
117impl_pod!(Bit, CDataType::Bit);
118impl_pod!(i64, CDataType::SBigInt);
119impl_pod!(u64, CDataType::UBigInt);
120
121// While the C-Type is independent of the Data (SQL) Type in the source, there are often DataTypes
122// which are a natural match for the C-Type in question. These can be used to spare the user to
123// specify that an i32 is supposed to be bound as an SQL Integer.
124
125macro_rules! impl_input_fixed_sized {
126    ($t:ident, $data_type:expr) => {
127        impl HasDataType for $t {
128            fn data_type(&self) -> DataType {
129                $data_type
130            }
131        }
132
133        unsafe impl OutputParameter for $t {}
134    };
135}
136
137impl_input_fixed_sized!(f64, DataType::Double);
138impl_input_fixed_sized!(f32, DataType::Real);
139impl_input_fixed_sized!(Date, DataType::Date);
140impl_input_fixed_sized!(i16, DataType::SmallInt);
141impl_input_fixed_sized!(i32, DataType::Integer);
142impl_input_fixed_sized!(i8, DataType::TinyInt);
143impl_input_fixed_sized!(Bit, DataType::Bit);
144impl_input_fixed_sized!(i64, DataType::BigInt);
145
146// Support for fixed size types, which are not unsigned. Time, Date and timestamp types could be
147// supported, implementation DataType would need to take an instance into account.
148
149#[cfg(test)]
150mod tests {
151
152    use super::Bit;
153
154    /// `as_bool` should panic if bit is neither 0 or 1.
155    #[test]
156    #[should_panic(expected = "Invalid boolean representation in Bit.")]
157    fn invalid_bit() {
158        let bit = Bit(2);
159        bit.as_bool();
160    }
161}
odbc_api/fixed_sized.rs

odbc_api/
fixed_sized.rs
