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//!
//! Advanced syntax elements.
//!
/// Define a private namespace for all its items.
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() ) );
/// ```
/// # Panics
/// qqq: doc
#[ must_use ]
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
/// ```
/// # Panics
/// qqq: doc
#[ allow( clippy ::cast_possible_wrap, clippy ::needless_pass_by_value ) ]
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]
}
/// 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 ) );
/// ```
///
#[ must_use ]
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 >
/// ```
/// # Errors
/// qqq: docs
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 own :: *;
/// Own namespace of the module.
#[ allow( unused_imports ) ]
pub mod own
{
use super :: *;
#[ doc( inline ) ]
pub use orphan :: *;
#[ doc( inline ) ]
pub use private :: { type_rightmost, type_parameters, is_optional, parameter_first };
}
/// Orphan namespace of the module.
#[ allow( unused_imports ) ]
pub mod orphan
{
use super :: *;
#[ doc( inline ) ]
pub use exposed :: *;
}
/// Exposed namespace of the module.
#[ allow( unused_imports ) ]
pub mod exposed
{
use super :: *;
pub use super ::super ::typ;
// pub use super ::own as typ;
#[ doc( inline ) ]
pub use prelude :: *;
}
/// Prelude to use essentials: `use my_module ::prelude :: *`.
#[ allow( unused_imports ) ]
pub mod prelude
{
use super :: *;
}