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
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
//!
//! This module provides utilities to handle and manipulate generic arguments using the `syn` crate. It includes traits and functions for transforming, merging, and managing generic parameters within procedural macros, enabling seamless syntactic analysis and code generation.
//!
/// Internal namespace.
pub( crate ) mod private
{
/// A trait for converting a reference to an existing type into a `syn::AngleBracketedGenericArguments`.
///
/// This trait provides a mechanism to transform various types that represent generic parameters,
/// such as `syn::Generics`, into a uniform `syn::AngleBracketedGenericArguments`. This is particularly
/// useful when working with Rust syntax trees in procedural macros, allowing for the manipulation
/// and merging of generic parameters from different syntactic elements.
pub trait IntoGenericArgs
{
/// Converts a reference of the implementing type into `syn::AngleBracketedGenericArguments`.
///
/// This method should handle the conversion logic necessary to transform the implementing
/// type's generic parameter representations into the structured format required by
/// `syn::AngleBracketedGenericArguments`, which is commonly used to represent generic parameters
/// enclosed in angle brackets.
///
/// # Returns
/// A new instance of `syn::AngleBracketedGenericArguments` representing the generic parameters
/// of the original type.
fn into_generic_args( &self ) -> syn::AngleBracketedGenericArguments;
}
impl IntoGenericArgs for syn::Generics
{
fn into_generic_args( &self ) -> syn::AngleBracketedGenericArguments
{
let args = self.params.iter().map( | param |
{
match param
{
syn::GenericParam::Type( ty ) => syn::GenericArgument::Type( syn::Type::Path( syn::TypePath
{
qself: None,
path: ty.ident.clone().into(),
})),
syn::GenericParam::Lifetime( lifetime ) => syn::GenericArgument::Lifetime( lifetime.lifetime.clone() ),
syn::GenericParam::Const( const_param ) => syn::GenericArgument::Const( syn::Expr::Path( syn::ExprPath
{
attrs: vec![],
qself: None,
path: const_param.ident.clone().into(),
})),
}
}).collect();
syn::AngleBracketedGenericArguments
{
colon2_token: None,
lt_token: syn::token::Lt::default(),
args,
gt_token: syn::token::Gt::default(),
}
}
}
/// Merges two `syn::AngleBracketedGenericArguments` instances into a new one,
/// prioritizing lifetime parameters before other types of generic arguments.
///
/// This function takes two references to `syn::AngleBracketedGenericArguments` and
/// categorizes their arguments into lifetimes and other types. It then combines
/// them such that all lifetimes from both instances precede any other arguments in the
/// resulting `syn::AngleBracketedGenericArguments` instance. This is particularly useful
/// for ensuring that the merged generics conform to typical Rust syntax requirements where
/// lifetimes are declared before other generic parameters.
///
/// # Arguments
///
/// * `a` - A reference to the first `syn::AngleBracketedGenericArguments` instance, containing one or more generic arguments.
/// * `b` - A reference to the second `syn::AngleBracketedGenericArguments` instance, containing one or more generic arguments.
///
/// # Returns
///
/// Returns a new `syn::AngleBracketedGenericArguments` instance containing the merged
/// arguments from both `a` and `b`, with lifetimes appearing first.
///
/// # Examples
///
/// ```
/// use macro_tools::{
/// generic_args,
/// syn::{parse_quote, AngleBracketedGenericArguments},
/// };
///
/// let a: AngleBracketedGenericArguments = parse_quote! { <'a, T: Clone, U: Default> };
/// let b: AngleBracketedGenericArguments = parse_quote! { <'b, V: core::fmt::Debug> };
/// let merged = generic_args::merge(&a, &b);
///
/// let expected: AngleBracketedGenericArguments = parse_quote! { <'a, 'b, T: Clone, U: Default, V: core::fmt::Debug> };
/// assert_eq!(merged, expected);
/// ```
///
/// This example demonstrates how lifetimes `'a` and `'b` are placed before other generic parameters
/// like `T`, `U`, and `V` in the merged result, adhering to the expected syntax order in Rust generics.
pub fn merge
(
a : &syn::AngleBracketedGenericArguments,
b : &syn::AngleBracketedGenericArguments
) -> syn::AngleBracketedGenericArguments
{
let mut lifetimes : syn::punctuated::Punctuated< syn::GenericArgument, syn::token::Comma > = syn::punctuated::Punctuated::new();
let mut others : syn::punctuated::Punctuated< syn::GenericArgument, syn::token::Comma > = syn::punctuated::Punctuated::new();
// Function to categorize and collect arguments into lifetimes and others
let mut categorize_and_collect = |args : &syn::punctuated::Punctuated<syn::GenericArgument, syn::token::Comma>|
{
for arg in args.iter()
{
match arg
{
syn::GenericArgument::Lifetime( _ ) => lifetimes.push( arg.clone() ),
_ => others.push( arg.clone() ),
}
}
};
// Categorize and collect from both input arguments
categorize_and_collect( &a.args );
categorize_and_collect( &b.args );
// Combine lifetimes and other arguments into final merged arguments
let mut args = syn::punctuated::Punctuated::new();
args.extend( lifetimes );
args.extend( others );
syn::AngleBracketedGenericArguments
{
colon2_token: None, // Adjust if needed based on context
lt_token: syn::token::Lt::default(),
args,
gt_token: syn::token::Gt::default(),
}
}
}
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
pub use protected::*;
/// Protected namespace of the module.
pub mod protected
{
//!
//! This module provides utilities to handle and manipulate generic arguments using the `syn` crate. It includes traits and functions for transforming, merging, and managing generic parameters within procedural macros, enabling seamless syntactic analysis and code generation.
//!
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
pub use super::orphan::*;
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
pub use super::private::
{
merge,
};
}
/// Orphan namespace of the module.
pub mod orphan
{
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
pub use super::exposed::*;
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
pub use super::private::
{
IntoGenericArgs,
};
}
/// Exposed namespace of the module.
pub mod exposed
{
pub use super::protected as generic_args;
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
pub use super::
{
prelude::*,
};
}
/// Prelude to use essentials: `use my_module::prelude::*`.
pub mod prelude
{
}