pth/
transitive.rs

1/// Define a private namespace for all its items.
2mod private
3{
4  // xxx : move to derive_tools
5
6  // qqq : write tests, lool into example
7  //
8  // impl< Initial > TransitiveTryFrom< AbsolutePath, PathError, Initial >
9  // for CrateDir
10  // where
11  //   AbsolutePath : TryFrom< Initial >,
12  //   PathError : From< < AbsolutePath as TryFrom< Initial > >::Error >,
13  // {
14  // }
15
16  // qqq : implement transitive_from
17  // qqq : implement transitive_into
18
19  // qqq : move to derive_tools
20  // qqq : write tests, look into example
21  //
22  // impl< Initial > TransitiveTryFrom< AbsolutePath, PathError, Initial >
23  // for CrateDir
24  // where
25  //   AbsolutePath : TryFrom< Initial >,
26  //   PathError : From< < AbsolutePath as TryFrom< Initial > >::Error >,
27  // {
28  // }
29  // qqq : implement transitive_try_into
30  // qqq : implement transitive_from
31  // qqq : implement transitive_into
32
33  /// A trait to perform a transitive `try_from` conversion.
34  ///
35  /// This trait allows for a two-step conversion process where an initial type `Initial`
36  /// is first converted to an intermediate type `Transitive`, and then to the final type `Self`.
37  ///
38  /// # Type Parameters
39  ///
40  /// - `Error`: The error type that can be produced during the conversion.
41  /// - `Initial`: The initial type from which the conversion starts.
42  ///
43  /// # Requirements
44  ///
45  /// - `Transitive` must implement `TryFrom<Initial>`.
46  /// - `Self` must implement `TryFrom<Transitive>` with the same error type.
47  /// - `Error` must implement `From<<Transitive as TryFrom<Initial>>::Error>`.
48  ///
49  /// # Example
50  ///
51  /// ```rust
52  /// use pth::TransitiveTryFrom;
53  /// use std::convert::TryFrom;
54  ///
55  /// struct InitialType;
56  /// struct IntermediateType;
57  /// struct FinalType;
58  /// struct ConversionError;
59  ///
60  /// impl TryFrom< InitialType > for IntermediateType
61  /// {
62  ///   type Error = ConversionError;
63  ///   fn try_from( value : InitialType ) -> Result<  Self, Self::Error  >
64  ///   {
65  ///     // Conversion logic here
66  ///     Ok( IntermediateType )
67  ///   }
68  /// }
69  ///
70  /// impl TryFrom< IntermediateType > for FinalType
71  /// {
72  ///   type Error = ConversionError;
73  ///   fn try_from( value : IntermediateType ) -> Result<  Self, Self::Error  >
74  ///   {
75  ///     // Conversion logic here
76  ///     Ok( FinalType )
77  ///   }
78  /// }
79  ///
80  /// let initial = InitialType;
81  /// let final_result : Result<  FinalType, ConversionError  > = FinalType::transitive_try_from::< IntermediateType >( initial );
82  /// ```
83  pub trait TransitiveTryFrom< Error, Initial >
84  {
85    /// Performs a transitive `try_from` conversion.
86    ///
87    /// This method first converts the `src` of type `Initial` to the intermediate type `Transitive`,
88    /// and then converts the intermediate type to the final type `Self`.
89    ///
90    /// # Arguments
91    ///
92    /// - `src`: The initial value to be converted.
93    ///
94    /// # Returns
95    ///
96    /// - `Ok(Self)`: If both conversions succeed.
97    /// - `Err(Error)`: If either conversion fails.
98    ///
99    /// # Example
100    ///
101    /// See the trait-level documentation for an example.
102    ///
103    /// # Errors
104    /// qqq: doc
105    #[ inline( always ) ]
106    fn transitive_try_from< Transitive >( src : Initial ) -> Result<  Self, Error  >
107    where
108      Transitive : TryFrom< Initial >,
109      Self : TryFrom< Transitive, Error = Error >,
110      Error : From< < Transitive as TryFrom< Initial > >::Error >,
111    {
112      let src2 = TryFrom::< Initial >::try_from( src )?;
113      TryFrom::< Transitive >::try_from( src2 )
114    }
115  }
116
117  impl< Initial, Error, Final > TransitiveTryFrom< Error, Initial > for Final {}
118
119  /// A trait to perform a transitive `try_into` conversion.
120  ///
121  /// This trait allows for a two-step conversion process where an initial type `Self`
122  /// is first converted to an intermediate type `Transitive`, and then to the final type `Final`.
123  ///
124  /// # Type Parameters
125  ///
126  /// - `Error`: The error type that can be produced during the conversion.
127  /// - `Final`: The final type to which `Transitive` is converted.
128  ///
129  /// # Requirements
130  ///
131  /// - `Self` must implement `TryInto<Transitive>`.
132  /// - `Transitive` must implement `TryInto<Final>` with the same error type.
133  /// - `Error` must implement `From<<Self as TryInto<Transitive>>::Error>`.
134  ///
135  /// # Example
136  ///
137  /// ```rust
138  /// use pth::TransitiveTryInto;
139  /// use std::convert::TryInto;
140  ///
141  /// struct InitialType;
142  /// struct IntermediateType;
143  /// struct FinalType;
144  /// struct ConversionError;
145  ///
146  /// impl TryInto< IntermediateType > for InitialType
147  /// {
148  ///   type Error = ConversionError;
149  ///   fn try_into( self ) -> Result<  IntermediateType, Self::Error  >
150  ///   {
151  ///     // Conversion logic here
152  ///     Ok( IntermediateType )
153  ///   }
154  /// }
155  ///
156  /// impl TryInto< FinalType > for IntermediateType
157  /// {
158  ///   type Error = ConversionError;
159  ///   fn try_into( self ) -> Result<  FinalType, Self::Error  >
160  ///   {
161  ///     // Conversion logic here
162  ///     Ok( FinalType )
163  ///   }
164  /// }
165  ///
166  /// let initial = InitialType;
167  /// let final_result : Result<  FinalType, ConversionError  > = initial.transitive_try_into::< IntermediateType >();
168  /// ```
169  pub trait TransitiveTryInto< Error, Final > : Sized
170  {
171    /// Performs a transitive `try_into` conversion.
172    ///
173    /// This method first converts `self` to the intermediate type `Transitive`,
174    /// and then converts the intermediate type to the final type `Final`.
175    ///
176    /// # Returns
177    ///
178    /// - `Ok(Final)`: If both conversions succeed.
179    /// - `Err(Error)`: If either conversion fails.
180    ///
181    /// # Example
182    ///
183    /// See the trait-level documentation for an example.
184    /// # Errors
185    /// qqq: doc
186    #[ inline( always ) ]
187    fn transitive_try_into< Transitive >( self ) -> Result<  Final, Error  >
188    where
189      Self : TryInto< Transitive >,
190      Transitive : TryInto< Final, Error = Error >,
191      Error : From< < Self as TryInto< Transitive > >::Error >,
192    {
193      let src2 = TryInto::< Transitive >::try_into( self )?;
194      TryInto::< Final >::try_into( src2 )
195    }
196  }
197
198  impl< Error, Final, Initial > TransitiveTryInto< Error, Final > for Initial {}
199
200}
201
202crate::mod_interface!
203{
204  exposed use TransitiveTryFrom;
205  exposed use TransitiveTryInto;
206}
pth/transitive.rs

pth/
transitive.rs
