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//!
//! Attributes analyzys and manipulation.
//!
/// Internal namespace.
pub( crate ) mod private
{
use crate::*;
/// Checks if the given iterator of attributes contains an attribute named `debug`.
///
/// This function iterates over an input sequence of `syn::Attribute`, typically associated with a struct,
/// enum, or other item in a Rust Abstract Syntax Tree ( AST ), and determines whether any of the attributes
/// is exactly named `debug`.
///
/// # Parameters
/// - `attrs` : An iterator over `syn::Attribute`. This could be obtained from parsing Rust code
/// with the `syn` crate, where the iterator represents attributes applied to a Rust item ( like a struct or function ).
///
/// # Returns
/// - `Ok( true )` if the `debug` attribute is present.
/// - `Ok( false )` if the `debug` attribute is not found.
/// - `Err( syn::Error )` if an unknown or improperly formatted attribute is encountered.
///
/// # Example
///
/// Suppose you have the following struct definition in a procedural macro input:
///
/// ```rust, ignore
/// #[ derive( SomeDerive ) ]
/// #[ debug ]
/// struct MyStruct
/// {
/// field : i32,
/// }
/// ```
///
/// You can use `has_debug` to check for the presence of the `debug` attribute:
///
/// ```rust
/// use macro_tools::exposed::*;
///
/// // Example struct attribute
/// let attrs : Vec< syn::Attribute > = vec![ syn::parse_quote!( #[ debug ] ) ];
///
/// // Checking for 'debug' attribute
/// let contains_debug = attr::has_debug( ( &attrs ).into_iter() ).unwrap();
///
/// assert!( contains_debug, "Expected to find 'debug' attribute" );
/// ```
///
pub fn has_debug< 'a >( attrs : impl Iterator< Item = &'a syn::Attribute > ) -> Result< bool >
{
for attr in attrs
{
if let Some( ident ) = attr.path().get_ident()
{
let ident_string = format!( "{}", ident );
if ident_string == "debug"
{
return Ok( true )
}
}
else
{
return_syn_err!( "Unknown structure attribute:\n{}", qt!{ attr } );
}
}
return Ok( false )
}
/// Checks if the given attribute name is a standard Rust attribute.
///
/// Standard Rust attributes are those which are recognized and processed
/// directly by the Rust compiler. They influence various aspects of compilation,
/// including but not limited to conditional compilation, optimization hints,
/// code visibility, and procedural macro behavior.
///
/// This function is useful when developing tools that need to interact with or
/// understand the significance of specific attributes in Rust source code, such
/// as linters, code analyzers, or procedural macros.
///
/// This function does not cover all possible attributes but includes many of the
/// common ones that are relevant to most Rust projects. Developers are encouraged
/// to update this function as needed to suit more specialized needs, especially
/// when dealing with nightly-only compiler attributes or deprecated ones.
///
/// # Parameters
/// - `attr_name`: A string slice that holds the name of the attribute to check.
///
/// # Returns
/// Returns `true` if `attr_name` is a recognized standard Rust attribute. Otherwise,
/// returns `false`.
///
/// # Examples
///
/// Standard attributes:
///
/// ```
/// assert_eq!( macro_tools::attr::is_standard( "cfg" ), true );
/// assert_eq!( macro_tools::attr::is_standard( "inline" ), true );
/// assert_eq!( macro_tools::attr::is_standard( "derive" ), true );
/// ```
///
/// Non-standard or custom attributes:
///
/// ```
/// assert_eq!( macro_tools::attr::is_standard( "custom_attr" ), false );
/// assert_eq!( macro_tools::attr::is_standard( "my_attribute" ), false );
/// ```
///
pub fn is_standard<'a>( attr_name : &'a str ) -> bool
{
match attr_name
{
// Conditional compilation
"cfg" | "cfg_attr" => true,
// Compiler instructions and optimizations
"inline" | "repr" | "derive" | "allow" | "warn" | "deny" | "forbid" => true,
// Testing attributes
"test" | "bench" => true,
// Documentation attributes
"doc" => true,
// Visibility and accessibility
"pub" => true, // This would typically need context to be accurate
// Safety and ABI
"unsafe" | "no_mangle" | "extern" => true,
// Module and Crate configuration
"path" | "macro_use" | "crate_type" | "crate_name" => true,
// Linking
"link" | "link_name" | "link_section" => true,
// Usage warnings
"must_use" => true,
// Other attributes
"cold" | "export_name" | "global_allocator" => true,
// Module handling
"used" | "unused" => true,
// Procedural macros and hygiene
"proc_macro" | "proc_macro_derive" | "proc_macro_attribute" => true,
// Stability attributes
"stable" | "unstable" | "rustc_const_unstable" | "rustc_const_stable" |
"rustc_diagnostic_item" | "rustc_deprecated" | "rustc_legacy_const_generics" => true,
// Special compiler attributes
"feature" | "non_exhaustive" => true,
// Future compatibility
"rustc_paren_sugar" | "rustc_insignificant_dtor" => true,
// Type system extensions
"opaque" => true,
// Miscellaneous
"track_caller" => true,
// Default case
_ => false,
}
}
///
/// Attribute which is inner.
///
/// For example: `// #![ deny( missing_docs ) ]`.
///
#[ derive( Debug, PartialEq, Eq, Clone, Default ) ]
pub struct AttributesInner( pub Vec< syn::Attribute > );
impl From< Vec< syn::Attribute > > for AttributesInner
{
#[ inline( always ) ]
fn from( src : Vec< syn::Attribute > ) -> Self
{
Self( src )
}
}
impl From< AttributesInner > for Vec< syn::Attribute >
{
#[ inline( always ) ]
fn from( src : AttributesInner ) -> Self
{
src.0
}
}
impl AttributesInner
{
/// Iterator
pub fn iter( &self ) -> core::slice::Iter< '_, syn::Attribute >
{
self.0.iter()
}
}
impl syn::parse::Parse
for AttributesInner
{
fn parse( input : ParseStream< '_ > ) -> Result< Self >
{
// let mut result : Self = from!();
let mut result : Self = Default::default();
loop
{
if !input.peek( Token![ # ] ) || !input.peek2( Token![ ! ] )
{
break;
}
let input2;
let element = syn::Attribute
{
pound_token : input.parse()?,
style : syn::AttrStyle::Inner( input.parse()? ),
bracket_token : bracketed!( input2 in input ),
// path : input2.call( syn::Path::parse_mod_style )?,
// tokens : input2.parse()?,
meta : input2.parse()?,
};
result.0.push( element );
}
Ok( result )
}
}
impl quote::ToTokens
for AttributesInner
{
fn to_tokens( &self, tokens : &mut proc_macro2::TokenStream )
{
use crate::quote::TokenStreamExt;
tokens.append_all( self.0.iter() );
}
}
/// Represents a collection of outer attributes.
///
/// This struct wraps a `Vec< syn::Attribute >`, providing utility methods for parsing,
/// converting, and iterating over outer attributes. Outer attributes are those that
/// appear outside of an item, such as `#[ ... ]` annotations in Rust.
///
#[ derive( Debug, PartialEq, Eq, Clone, Default ) ]
pub struct AttributesOuter( pub Vec< syn::Attribute > );
impl From< Vec< syn::Attribute > > for AttributesOuter
{
#[ inline( always ) ]
fn from( src : Vec< syn::Attribute > ) -> Self
{
Self( src )
}
}
impl From< AttributesOuter > for Vec< syn::Attribute >
{
#[ inline( always ) ]
fn from( src : AttributesOuter ) -> Self
{
src.0
}
}
impl AttributesOuter
{
/// Iterator
pub fn iter( &self ) -> core::slice::Iter< '_, syn::Attribute >
{
self.0.iter()
}
}
impl syn::parse::Parse
for AttributesOuter
{
fn parse( input : ParseStream< '_ > ) -> Result< Self >
{
let mut result : Self = Default::default();
loop
{
if !input.peek( Token![ # ] ) || input.peek2( Token![ ! ] )
{
break;
}
let input2;
let element = syn::Attribute
{
pound_token : input.parse()?,
style : syn::AttrStyle::Outer,
bracket_token : bracketed!( input2 in input ),
// path : input2.call( syn::Path::parse_mod_style )?,
// tokens : input2.parse()?,
meta : input2.parse()?,
};
result.0.push( element );
}
Ok( result )
}
}
impl quote::ToTokens
for AttributesOuter
{
fn to_tokens( &self, tokens : &mut proc_macro2::TokenStream )
{
use crate::quote::TokenStreamExt;
tokens.append_all( self.0.iter() );
}
}
/// Trait for components of a structure aggregating attributes that can be constructed from a meta attribute.
///
/// The `AttributeComponent` trait defines the interface for components that can be created
/// from a `syn::Attribute` meta item. Implementors of this trait are required to define
/// a constant `KEYWORD` that identifies the type of the component and a method `from_meta`
/// that handles the construction of the component from the given attribute.
///
/// This trait is designed to facilitate modular and reusable parsing of attributes applied
/// to structs, enums, or other constructs. By implementing this trait, you can create specific
/// components from attributes and then aggregate these components into a larger structure.
///
/// # Example
///
/// ```rust
/// use macro_tools::{ AttributeComponent, Result };
/// use syn::{ Attribute, Error };
///
/// struct MyComponent;
///
/// impl AttributeComponent for MyComponent
/// {
/// const KEYWORD : &'static str = "my_component";
///
/// fn from_meta( attr : &Attribute ) -> Result<Self>
/// {
/// // Parsing logic here
/// // Return Ok(MyComponent) if parsing is successful
/// // Return Err(Error::new_spanned(attr, "error message")) if parsing fails
/// Ok( MyComponent )
/// }
/// }
/// ```
///
/// # Parameters
///
/// - `attr` : A reference to the `syn::Attribute` from which the component is to be constructed.
///
/// # Returns
///
/// A `Result` containing the constructed component if successful, or an error if the parsing fails.
///
pub trait AttributeComponent
where
Self : Sized,
{
/// The keyword that identifies the component.
///
/// This constant is used to match the attribute to the corresponding component.
/// Each implementor of this trait must provide a unique keyword for its type.
const KEYWORD : &'static str;
/// Constructs the component from the given meta attribute.
///
/// This method is responsible for parsing the provided `syn::Attribute` and
/// returning an instance of the component. If the attribute cannot be parsed
/// into the component, an error should be returned.
///
/// # Parameters
///
/// - `attr` : A reference to the `syn::Attribute` from which the component is to be constructed.
///
/// # Returns
///
/// A `Result` containing the constructed component if successful, or an error if the parsing fails.
fn from_meta( attr : &syn::Attribute ) -> Result< Self >;
}
/// Trait for properties of an attribute component that can be identified by a keyword.
///
/// The `AttributePropertyComponent` trait defines the interface for attribute properties
/// that can be identified by a specific keyword. Implementors of this trait are required
/// to define a constant `KEYWORD` that identifies the type of the property.
///
/// This trait is useful in scenarios where attributes may have multiple properties
/// that need to be parsed and handled separately. By defining a unique keyword for each property,
/// the parsing logic can accurately identify and process each property.
///
/// # Example
///
/// ```rust
/// use macro_tools::AttributePropertyComponent;
///
/// struct MyProperty;
///
/// impl AttributePropertyComponent for MyProperty
/// {
/// const KEYWORD : &'static str = "my_property";
/// }
/// ```
///
pub trait AttributePropertyComponent
where
Self : Sized,
{
/// The keyword that identifies the component.
///
/// This constant is used to match the attribute to the corresponding property.
/// Each implementor of this trait must provide a unique keyword for its type.
const KEYWORD : &'static str;
}
}
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
pub use protected::*;
/// Protected namespace of the module.
pub mod protected
{
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
pub use super::orphan::*;
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
pub use super::private::
{
// equation,
has_debug,
is_standard,
};
}
/// Orphan namespace of the module.
pub mod orphan
{
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
pub use super::exposed::*;
}
/// Exposed namespace of the module.
pub mod exposed
{
pub use super::protected as attr;
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
pub use super::prelude::*;
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
pub use super::private::
{
AttributesInner,
AttributesOuter,
AttributeComponent,
AttributePropertyComponent,
};
}
/// Prelude to use essentials: `use my_module::prelude::*`.
pub mod prelude
{
}