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use syn::parse::{Parse, Result, ParseBuffer};
use syn::{Path, Lit};
use syn::ext::IdentExt;
use proc_macro2::{Ident, TokenStream};
use quote::ToTokens;
use crate::ArgValue;
pub enum MetaArgs {
Literal(Lit),
Path(Path),
NameValue(MetaArgNameValue),
}
impl Parse for MetaArgs {
fn parse(input: &ParseBuffer) -> Result<Self> {
if input.peek2(Token![=]) {
input.parse().map(MetaArgs::NameValue)
} else if input.peek(Ident::peek_any)
|| input.peek(Token![::]) && input.peek3(Ident::peek_any)
{
input.parse().map(MetaArgs::Path)
} else {
input.parse().map(MetaArgs::Literal)
}
}
}
impl ToTokens for MetaArgs {
fn to_tokens(&self, tokens: &mut TokenStream) {
match self {
MetaArgs::Literal(lit) => lit.to_tokens(tokens),
MetaArgs::Path(path) => path.to_tokens(tokens),
MetaArgs::NameValue(meta) => meta.to_tokens(tokens),
}
}
}
pub struct MetaArgNameValue {
pub name: Ident,
pub eq_token: Token![=],
pub value: ArgValue,
}
impl Parse for MetaArgNameValue {
fn parse(input: &ParseBuffer) -> Result<Self> {
Ok(MetaArgNameValue {
name: input.parse()?,
eq_token: input.parse()?,
value: input.parse()?,
})
}
}
impl ToTokens for MetaArgNameValue {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.name.to_tokens(tokens);
self.eq_token.to_tokens(tokens);
self.value.to_tokens(tokens);
}
}