miette/miette-derive/src/diagnostic.rs

276 lines
10 KiB
Rust

use proc_macro2::TokenStream;
use quote::{format_ident, quote};
use syn::{punctuated::Punctuated, DeriveInput, Token};
use crate::code::Code;
use crate::diagnostic_arg::DiagnosticArg;
use crate::help::Help;
use crate::severity::Severity;
use crate::snippets::Snippets;
use crate::url::Url;
pub enum Diagnostic {
Struct {
generics: syn::Generics,
ident: syn::Ident,
fields: syn::Fields,
args: DiagnosticDefArgs,
},
Enum {
ident: syn::Ident,
generics: syn::Generics,
variants: Vec<DiagnosticDef>,
},
}
pub struct DiagnosticDef {
pub ident: syn::Ident,
pub fields: syn::Fields,
pub args: DiagnosticDefArgs,
}
pub enum DiagnosticDefArgs {
Transparent,
Concrete(DiagnosticConcreteArgs),
}
#[derive(Default)]
pub struct DiagnosticConcreteArgs {
pub code: Option<Code>,
pub severity: Option<Severity>,
pub help: Option<Help>,
pub snippets: Option<Snippets>,
pub url: Option<Url>,
}
impl DiagnosticConcreteArgs {
fn parse(
_ident: &syn::Ident,
fields: &syn::Fields,
attr: &syn::Attribute,
args: impl Iterator<Item = DiagnosticArg>,
) -> Result<Self, syn::Error> {
let mut code = None;
let mut severity = None;
let mut help = None;
let mut url = None;
for arg in args {
match arg {
DiagnosticArg::Transparent => {
return Err(syn::Error::new_spanned(attr, "transparent not allowed"));
}
DiagnosticArg::Code(new_code) => {
// TODO: error on multiple?
code = Some(new_code);
}
DiagnosticArg::Severity(sev) => {
severity = Some(sev);
}
DiagnosticArg::Help(hl) => {
help = Some(hl);
}
DiagnosticArg::Url(u) => {
url = Some(u);
}
}
}
let snippets = Snippets::from_fields(fields)?;
let concrete = DiagnosticConcreteArgs {
code,
help,
severity,
snippets,
url,
};
Ok(concrete)
}
}
impl DiagnosticDefArgs {
fn parse(
ident: &syn::Ident,
fields: &syn::Fields,
attr: &syn::Attribute,
allow_transparent: bool,
) -> Result<Self, syn::Error> {
let args =
attr.parse_args_with(Punctuated::<DiagnosticArg, Token![,]>::parse_terminated)?;
if allow_transparent
&& args.len() == 1
&& matches!(args.first(), Some(DiagnosticArg::Transparent))
{
return Ok(Self::Transparent);
} else if args.iter().any(|x| matches!(x, DiagnosticArg::Transparent)) {
return Err(syn::Error::new_spanned(
attr,
if allow_transparent {
"diagnostic(transparent) not allowed in combination with other args"
} else {
"diagnostic(transparent) not allowed here"
},
));
}
let args = args
.into_iter()
.filter(|x| !matches!(x, DiagnosticArg::Transparent));
let concrete = DiagnosticConcreteArgs::parse(ident, fields, attr, args)?;
Ok(DiagnosticDefArgs::Concrete(concrete))
}
}
impl Diagnostic {
pub fn from_derive_input(input: DeriveInput) -> Result<Self, syn::Error> {
Ok(match input.data {
syn::Data::Struct(data_struct) => {
if let Some(attr) = input.attrs.iter().find(|x| x.path.is_ident("diagnostic")) {
let args =
DiagnosticDefArgs::parse(&input.ident, &data_struct.fields, attr, true)?;
Diagnostic::Struct {
fields: data_struct.fields,
ident: input.ident,
generics: input.generics,
args,
}
} else {
Diagnostic::Struct {
fields: data_struct.fields,
ident: input.ident,
generics: input.generics,
args: DiagnosticDefArgs::Concrete(Default::default()),
}
}
}
syn::Data::Enum(syn::DataEnum { variants, .. }) => {
let mut vars = Vec::new();
for var in variants {
if let Some(attr) = var.attrs.iter().find(|x| x.path.is_ident("diagnostic")) {
let args = DiagnosticDefArgs::parse(&var.ident, &var.fields, attr, true)?;
vars.push(DiagnosticDef {
ident: var.ident,
fields: var.fields,
args,
});
}
}
Diagnostic::Enum {
ident: input.ident,
generics: input.generics,
variants: vars,
}
}
syn::Data::Union(_) => {
return Err(syn::Error::new(
input.ident.span(),
"Can't derive Diagnostic for Unions",
))
}
})
}
pub fn gen(&self) -> TokenStream {
match self {
Self::Struct {
ident,
fields,
generics,
args,
} => {
let (impl_generics, ty_generics, where_clause) = &generics.split_for_impl();
match args {
DiagnosticDefArgs::Transparent => {
if fields.iter().len() != 1 {
return quote! {
compile_error!("you can only use #[diagnostic(transparent)] on a struct with exactly one field");
};
}
let field = fields
.iter()
.next()
.expect("MIETTE BUG: thought we knew we had exactly one field");
let field_name = field
.ident
.clone()
.unwrap_or_else(|| format_ident!("unnamed"));
let matcher = match fields {
syn::Fields::Named(_) => quote! { let Self { #field_name } = self; },
syn::Fields::Unnamed(_) => quote! { let Self(#field_name) = self; },
syn::Fields::Unit => {
unreachable!("MIETTE BUG: thought we knew we had exactly one field")
}
};
quote! {
impl #impl_generics miette::Diagnostic for #ident #ty_generics #where_clause {
fn code<'a>(&'a self) -> std::option::Option<std::boxed::Box<dyn std::fmt::Display + 'a>> {
#matcher
#field_name.code()
}
fn help<'a>(&'a self) -> std::option::Option<std::boxed::Box<dyn std::fmt::Display + 'a>> {
#matcher
#field_name.help()
}
fn url<'a>(&'a self) -> std::option::Option<std::boxed::Box<dyn std::fmt::Display + 'a>> {
#matcher
#field_name.url()
}
fn severity(&self) -> std::option::Option<miette::Severity> {
#matcher
#field_name.severity()
}
fn snippets(&self) -> std::option::Option<std::boxed::Box<dyn std::iter::Iterator<Item = miette::DiagnosticSnippet> + '_>> {
#matcher
#field_name.snippets()
}
}
}
}
DiagnosticDefArgs::Concrete(concrete) => {
let code_body = concrete.code.as_ref().and_then(|x| x.gen_struct());
let help_body = concrete.help.as_ref().and_then(|x| x.gen_struct(fields));
let sev_body = concrete.severity.as_ref().and_then(|x| x.gen_struct());
let snip_body = concrete
.snippets
.as_ref()
.and_then(|x| x.gen_struct(fields));
let url_body = concrete
.url
.as_ref()
.and_then(|x| x.gen_struct(ident, fields));
quote! {
impl #impl_generics miette::Diagnostic for #ident #ty_generics #where_clause {
#code_body
#help_body
#sev_body
#snip_body
#url_body
}
}
}
}
}
Self::Enum {
ident,
generics,
variants,
} => {
let (impl_generics, ty_generics, where_clause) = &generics.split_for_impl();
let code_body = Code::gen_enum(variants);
let help_body = Help::gen_enum(variants);
let sev_body = Severity::gen_enum(variants);
let snip_body = Snippets::gen_enum(variants);
let url_body = Url::gen_enum(ident, variants);
quote! {
impl #impl_generics miette::Diagnostic for #ident #ty_generics #where_clause {
#code_body
#help_body
#sev_body
#snip_body
#url_body
}
}
}
}
}
}