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use proc_macro2::TokenStream;
use proc_macro_error::{abort, ResultExt};
use quote::{quote, ToTokens};
use syn::{
parenthesized,
parse::{Parse, ParseStream},
punctuated::Punctuated,
spanned::Spanned,
Attribute, Expr, Ident, LitStr, Token,
};
use crate::spanned::Sp;
#[derive(Clone)]
pub struct IniAttr {
pub kind: Sp<AttrKind>,
pub name: Ident,
pub magic: Option<MagicAttrName>,
pub value: Option<AttrValue>,
}
impl IniAttr {
pub fn parse_all(all_attrs: &[Attribute]) -> Vec<Self> {
all_attrs
.iter()
.filter_map(|attr| {
let kind = if attr.path.is_ident("key") {
Some(Sp::new(AttrKind::Key, attr.path.span()))
} else {
None
};
kind.map(|k| (k, attr))
})
.flat_map(|(k, attr)| {
attr.parse_args_with(Punctuated::<IniAttr, Token![,]>::parse_terminated)
.unwrap_or_abort()
.into_iter()
.map(move |mut a| {
a.kind = k;
a
})
})
.collect()
}
pub fn value_or_abort(&self) -> &AttrValue {
self.value
.as_ref()
.unwrap_or_else(|| abort!(self.name, "attribute `{}` requires a value", self.name))
}
pub fn lit_str_or_abort(&self) -> &LitStr {
let value = self.value_or_abort();
match value {
AttrValue::LitStr(tokens) => tokens,
AttrValue::Expr(_) | AttrValue::Call(_) => {
abort!(
self.name,
"attribute `{}` can only accept string literals",
self.name
)
}
}
}
}
impl Parse for IniAttr {
fn parse(input: ParseStream) -> syn::Result<Self> {
let name: Ident = input.parse()?;
let name_str = name.to_string();
let magic = match name_str.as_str() {
"name" => Some(MagicAttrName::Name),
"default" => Some(MagicAttrName::Default),
"parse_with" => Some(MagicAttrName::ParseWith),
_ => None,
};
let value = if input.peek(Token![=]) {
// `name = value` attributes.
let assign_token = input.parse::<Token![=]>()?; // skip '='
if input.peek(LitStr) {
let lit: LitStr = input.parse()?;
Some(AttrValue::LitStr(lit))
} else {
match input.parse::<Expr>() {
Ok(expr) => Some(AttrValue::Expr(expr)),
Err(_) => abort! {
assign_token,
"expected `string literal` or `expression` after `=`"
},
}
}
} else if input.peek(syn::token::Paren) {
// `name(...)` attributes.
let nested;
parenthesized!(nested in input);
let method_args: Punctuated<_, Token![,]> = nested.parse_terminated(Expr::parse)?;
Some(AttrValue::Call(Vec::from_iter(method_args)))
} else {
None
};
Ok(Self {
kind: Sp::new(AttrKind::Ini, name.span()),
name,
magic,
value,
})
}
}
#[derive(Copy, Clone, PartialEq, Eq)]
pub enum MagicAttrName {
Name,
Default,
ParseWith,
}
#[derive(Clone)]
#[allow(clippy::large_enum_variant)]
pub enum AttrValue {
LitStr(LitStr),
Expr(Expr),
Call(Vec<Expr>),
}
impl ToTokens for AttrValue {
fn to_tokens(&self, tokens: &mut TokenStream) {
match self {
Self::LitStr(t) => t.to_tokens(tokens),
Self::Expr(t) => t.to_tokens(tokens),
Self::Call(t) => {
let t = quote!(#(#t),*);
t.to_tokens(tokens)
}
}
}
}
#[derive(Copy, Clone, PartialEq, Eq)]
pub enum AttrKind {
Key,
}
impl AttrKind {
pub fn as_str(&self) -> &'static str {
match self {
Self::Key => "key",
}
}
}
|
