use proc_macro2::TokenStream;
use quote::quote;
use syn::{
parenthesized,
parse::{Parse, ParseStream},
Fields, Token,
};
use crate::{
diagnostic::{DiagnosticConcreteArgs, DiagnosticDef},
utils::{display_pat_members, gen_all_variants_with},
};
use crate::{
fmt::{self, Display},
forward::WhichFn,
};
pub struct Help {
pub display: Display,
}
impl Parse for Help {
fn parse(input: ParseStream) -> syn::Result<Self> {
let ident = input.parse::<syn::Ident>()?;
if ident == "help" {
let la = input.lookahead1();
if la.peek(syn::token::Paren) {
let content;
parenthesized!(content in input);
let fmt = content.parse()?;
let args = if content.is_empty() {
TokenStream::new()
} else {
fmt::parse_token_expr(&content, false)?
};
let display = Display {
fmt,
args,
has_bonus_display: false,
};
Ok(Help { display })
} else {
input.parse::<Token![=]>()?;
Ok(Help {
display: Display {
fmt: input.parse()?,
args: TokenStream::new(),
has_bonus_display: false,
},
})
}
} else {
Err(syn::Error::new(ident.span(), "not a help"))
}
}
}
impl Help {
pub(crate) fn gen_enum(variants: &[DiagnosticDef]) -> Option<TokenStream> {
gen_all_variants_with(
variants,
WhichFn::Help,
|ident, fields, DiagnosticConcreteArgs { help, .. }| {
let (display_pat, display_members) = display_pat_members(fields);
let display = &help.as_ref()?.display;
let (fmt, args) = display.expand_shorthand_cloned(&display_members);
Some(quote! {
Self::#ident #display_pat => std::option::Option::Some(std::boxed::Box::new(format!(#fmt #args))),
})
},
)
}
pub(crate) fn gen_struct(&self, fields: &Fields) -> Option<TokenStream> {
let (display_pat, display_members) = display_pat_members(fields);
let (fmt, args) = self.display.expand_shorthand_cloned(&display_members);
Some(quote! {
fn help<'a>(&'a self) -> std::option::Option<std::boxed::Box<dyn std::fmt::Display + 'a>> {
#[allow(unused_variables, deprecated)]
let Self #display_pat = self;
std::option::Option::Some(std::boxed::Box::new(format!(#fmt #args)))
}
})
}
}