easy_proc_common 0.4.0

Common code for `easy_proc` and `easy_proc_derive`
Documentation 
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#![warn(
    missing_docs,
    unused_import_braces,
    clippy::pedantic,
    missing_debug_implementations
)]

//! Common code for [`easy_proc`](https://docs.rs/easy_proc/latest/easy_proc/) and [`easy_proc_derive`](https://docs.rs/easy_proc_derive/latest/easy_proc_derive/).

use proc_macro_error2::abort;
use std::iter::Filter;
use syn::{Attribute, Ident};

/// Finds an attribute from a list with ident `ident`
pub fn find_attr<T: PathIsIdent>(attrs: impl IntoIterator<Item = T>, ident: &Ident) -> Option<T> {
    let mut attrs = find_attrs(attrs, ident);
    let found = attrs.next();
    if let Some(attr) = attrs.next() {
        attr.abort_with_span(format!("Multiple `{ident}` attributes found"))
    }
    found
}
/// The input's path is a given ident. Used for [`find_attr`] and [`find_attrs`]. Implemented for [`Attribute`] and [`&Attribute`](Attribute).
pub trait PathIsIdent {
    /// Returns true if the path is a given ident
    fn path_is_ident(&self, ident: &Ident) -> bool;
    /// Aborts with a given message on self's span
    fn abort_with_span(self, message: String) -> !;
}
impl PathIsIdent for Attribute {
    fn path_is_ident(&self, ident: &Ident) -> bool {
        self.path().is_ident(ident)
    }

    fn abort_with_span(self, message: String) -> ! {
        abort!(self, "{}", message)
    }
}
impl PathIsIdent for &Attribute {
    fn path_is_ident(&self, ident: &Ident) -> bool {
        self.path().is_ident(ident)
    }

    fn abort_with_span(self, message: String) -> ! {
        abort!(self, "{}", message)
    }
}
impl PathIsIdent for &mut Attribute {
    fn path_is_ident(&self, ident: &Ident) -> bool {
        self.path().is_ident(ident)
    }

    fn abort_with_span(self, message: String) -> ! {
        abort!(self, "{}", message)
    }
}

/// Finds all attributes from a list with ident `ident`
pub fn find_attrs<'a, T: PathIsIdent, I: 'a + IntoIterator<Item = T>>(
    attrs: I,
    ident: &'a Ident,
) -> Filter<I::IntoIter, impl FnMut(&T) -> bool + 'a> {
    attrs
        .into_iter()
        .filter(move |attr| attr.path_is_ident(ident))
}