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//!
//! Advanced syntax elements.
//!
/// Internal namespace.
pub( crate ) mod private
{
use crate::*;
use interval_adapter::BoundExt;
/// Check is the rightmost item of path refering a type is specified type.
///
/// Good to verify `core::option::Option< i32 >` is optional.
/// Good to verify `alloc::vec::Vec< i32 >` is vector.
///
/// ### Basic use-case.
/// ```rust
/// use macro_tools::exposed::*;
///
/// let code = qt!( core::option::Option< i32 > );
/// let tree_type = syn::parse2::< syn::Type >( code ).unwrap();
/// let got = typ::type_rightmost( &tree_type );
/// assert_eq!( got, Some( "Option".to_string() ) );
/// ```
pub fn type_rightmost( ty : &syn::Type ) -> Option< String >
{
if let syn::Type::Path( path ) = ty
{
let last = &path.path.segments.last();
if last.is_none()
{
return None;
}
return Some( last.unwrap().ident.to_string() );
}
None
}
/// Return the specified number of parameters of the type.
///
/// Good to getting `i32` from `core::option::Option< i32 >` or `alloc::vec::Vec< i32 >`
///
/// ### Basic use-case.
/// ```
/// use macro_tools::{ typ, qt };
///
/// let code = qt!( core::option::Option< i8, i16, i32, i64 > );
/// let tree_type = syn::parse2::< syn::Type >( code ).unwrap();
/// let got = typ::type_parameters( &tree_type, 0..=2 );
/// got.iter().for_each( | e | println!( "{}", qt!( #e ) ) );
/// // < i8
/// // < i16
/// // < i32
/// ```
pub fn type_parameters( ty : &syn::Type, range : impl NonIterableInterval ) -> Vec< &syn::Type >
{
if let syn::Type::Path( syn::TypePath{ path : syn::Path { ref segments, .. }, .. } ) = ty
{
let last = &segments.last();
if last.is_none()
{
return vec![ ty ]
}
let args = &last.unwrap().arguments;
if let syn::PathArguments::AngleBracketed( ref args2 ) = args
{
let args3 = &args2.args;
let left = range.left().into_left_closed();
let mut right = range.right().into_right_closed();
let len = args3.len();
if right == isize::MAX
{
right = len as isize;
}
// dbg!( left );
// dbg!( right );
// dbg!( len );
let selected : Vec< &syn::Type > = args3
.iter()
.skip_while( | e | !matches!( e, syn::GenericArgument::Type( _ ) ) )
.skip( usize::try_from( left.max( 0 ) ).unwrap() )
.take( usize::try_from( ( right - left + 1 ).min( len as isize - left ).max( 0 ) ).unwrap() )
.map( | e | if let syn::GenericArgument::Type( ty ) = e { ty } else { unreachable!( "Expects Type" ) } )
.collect();
return selected;
}
}
vec![ ty ]
}
// /// Extract generics from a type.
// pub fn all_type_parameters( type_example : &syn::Type )
// ->
// Option< syn::punctuated::Punctuated< syn::GenericArgument, syn::token::Comma > >
// {
// if let syn::Type::Path( type_path ) = type_example
// {
// let segments = &type_path.path.segments;
// let last_segment = segments.last()?;
//
// if let syn::PathArguments::AngleBracketed( generics ) = &last_segment.arguments
// {
// return Some( generics.args.clone() );
// }
// }
// None
// }
/// Checks if a given [`syn::Type`] is an `Option` type.
///
/// This function examines a type to determine if it represents an `Option`.
/// It is useful for scenarios where type-specific behavior needs to be conditional
/// on whether the type is optional or not.
///
/// # Example
///
/// ```rust
/// let type_string = "Option< i32 >";
/// let parsed_type : syn::Type = syn::parse_str( type_string ).expect( "Type should parse correctly" );
/// assert!( macro_tools::typ::is_optional( &parsed_type ) );
/// ```
///
pub fn is_optional( ty : &syn::Type ) -> bool
{
typ::type_rightmost( ty ) == Some( "Option".to_string() )
}
/// Extracts the first generic parameter from a given `syn::Type` if any exists.
///
/// This function is designed to analyze a type and retrieve its first generic parameter.
/// It is particularly useful when working with complex types in macro expansions and needs
/// to extract specific type information for further processing.
///
///
/// # Example
/// ```rust
/// let type_string = "Result< Option< i32 >, Error >";
/// let parsed_type : syn::Type = syn::parse_str( type_string ).expect( "Type should parse correctly" );
/// let first_param = macro_tools::typ::parameter_first( &parsed_type ).expect( "Should have at least one parameter" );
/// // Option< i32 >
/// ```
pub fn parameter_first( ty : &syn::Type ) -> Result< &syn::Type >
{
typ::type_parameters( ty, 0 ..= 0 )
.first()
.copied()
.ok_or_else( || syn_err!( ty, "Expects at least one parameter here:\n {}", qt!{ #ty } ) )
}
}
#[ 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::
{
type_rightmost,
type_parameters,
// all_type_parameters,
is_optional,
parameter_first,
};
}
/// 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 typ;
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
pub use super::prelude::*;
}
/// Prelude to use essentials: `use my_module::prelude::*`.
pub mod prelude
{
}