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|
use crate::file;
use anyhow::Result;
use proc_macro2::{Ident, Span, TokenStream};
use quote::quote;
use syn::Index;
use syn_codegen::{Data, Definitions, Node, Type};
const DEBUG_SRC: &str = "../tests/debug/gen.rs";
fn rust_type(ty: &Type) -> TokenStream {
match ty {
Type::Syn(ty) => {
let ident = Ident::new(ty, Span::call_site());
quote!(syn::#ident)
}
Type::Std(ty) => {
let ident = Ident::new(ty, Span::call_site());
quote!(#ident)
}
Type::Ext(ty) => {
let ident = Ident::new(ty, Span::call_site());
quote!(proc_macro2::#ident)
}
Type::Token(ty) | Type::Group(ty) => {
let ident = Ident::new(ty, Span::call_site());
quote!(syn::token::#ident)
}
Type::Punctuated(ty) => {
let element = rust_type(&ty.element);
let punct = Ident::new(&ty.punct, Span::call_site());
quote!(syn::punctuated::Punctuated<#element, #punct>)
}
Type::Option(ty) => {
let inner = rust_type(ty);
quote!(Option<#inner>)
}
Type::Box(ty) => {
let inner = rust_type(ty);
quote!(Box<#inner>)
}
Type::Vec(ty) => {
let inner = rust_type(ty);
quote!(Vec<#inner>)
}
Type::Tuple(ty) => {
let inner = ty.iter().map(rust_type);
quote!((#(#inner,)*))
}
}
}
fn is_printable(ty: &Type) -> bool {
match ty {
Type::Ext(name) => name != "Span",
Type::Box(ty) => is_printable(ty),
Type::Tuple(ty) => ty.iter().any(is_printable),
Type::Token(_) | Type::Group(_) => false,
Type::Syn(name) => name != "Reserved",
Type::Std(_) | Type::Punctuated(_) | Type::Option(_) | Type::Vec(_) => true,
}
}
fn format_field(val: &TokenStream, ty: &Type) -> Option<TokenStream> {
if !is_printable(ty) {
return None;
}
let format = match ty {
Type::Option(ty) => {
let inner = quote!(_val);
let format = format_field(&inner, ty).map(|format| {
quote! {
formatter.write_str("(")?;
Debug::fmt(#format, formatter)?;
formatter.write_str(")")?;
}
});
let ty = rust_type(ty);
quote!({
#[derive(RefCast)]
#[repr(transparent)]
struct Print(Option<#ty>);
impl Debug for Print {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
match &self.0 {
Some(#inner) => {
formatter.write_str("Some")?;
#format
Ok(())
}
None => formatter.write_str("None"),
}
}
}
Print::ref_cast(#val)
})
}
Type::Tuple(ty) => {
let printable: Vec<TokenStream> = ty
.iter()
.enumerate()
.filter_map(|(i, ty)| {
let index = Index::from(i);
let val = quote!(&#val.#index);
format_field(&val, ty)
})
.collect();
if printable.len() == 1 {
printable.into_iter().next().unwrap()
} else {
quote! {
&(#(#printable),*)
}
}
}
_ => quote! { Lite(#val) },
};
Some(format)
}
fn syntax_tree_enum<'a>(outer: &str, inner: &str, fields: &'a [Type]) -> Option<&'a str> {
if fields.len() != 1 {
return None;
}
const WHITELIST: &[&str] = &["PathArguments", "Visibility"];
match &fields[0] {
Type::Syn(ty) if WHITELIST.contains(&outer) || outer.to_owned() + inner == *ty => Some(ty),
_ => None,
}
}
fn lookup<'a>(defs: &'a Definitions, name: &str) -> &'a Node {
for node in &defs.types {
if node.ident == name {
return node;
}
}
panic!("not found: {}", name)
}
fn expand_impl_body(defs: &Definitions, node: &Node, name: &str) -> TokenStream {
let ident = Ident::new(&node.ident, Span::call_site());
match &node.data {
Data::Enum(variants) => {
let arms = variants.iter().map(|(v, fields)| {
let variant = Ident::new(v, Span::call_site());
if fields.is_empty() {
quote! {
syn::#ident::#variant => formatter.write_str(#v),
}
} else if let Some(inner) = syntax_tree_enum(name, v, fields) {
let path = format!("{}::{}", name, v);
let format = expand_impl_body(defs, lookup(defs, inner), &path);
quote! {
syn::#ident::#variant(_val) => {
#format
}
}
} else if fields.len() == 1 {
let ty = &fields[0];
let val = quote!(_val);
let format = format_field(&val, ty).map(|format| {
quote! {
formatter.write_str("(")?;
Debug::fmt(#format, formatter)?;
formatter.write_str(")")?;
}
});
quote! {
syn::#ident::#variant(_val) => {
formatter.write_str(#v)?;
#format
Ok(())
}
}
} else {
let pats = (0..fields.len())
.map(|i| Ident::new(&format!("_v{}", i), Span::call_site()));
let fields = fields.iter().enumerate().filter_map(|(i, ty)| {
let index = Ident::new(&format!("_v{}", i), Span::call_site());
let val = quote!(#index);
let format = format_field(&val, ty)?;
Some(quote! {
formatter.field(#format);
})
});
quote! {
syn::#ident::#variant(#(#pats),*) => {
let mut formatter = formatter.debug_tuple(#v);
#(#fields)*
formatter.finish()
}
}
}
});
let nonexhaustive = if node.exhaustive {
None
} else {
Some(quote!(_ => unreachable!()))
};
quote! {
match _val {
#(#arms)*
#nonexhaustive
}
}
}
Data::Struct(fields) => {
let fields = fields.iter().filter_map(|(f, ty)| {
let ident = Ident::new(f, Span::call_site());
if let Type::Option(ty) = ty {
let inner = quote!(_val);
let format = format_field(&inner, ty).map(|format| {
quote! {
let #inner = &self.0;
formatter.write_str("(")?;
Debug::fmt(#format, formatter)?;
formatter.write_str(")")?;
}
});
let ty = rust_type(ty);
Some(quote! {
if let Some(val) = &_val.#ident {
#[derive(RefCast)]
#[repr(transparent)]
struct Print(#ty);
impl Debug for Print {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str("Some")?;
#format
Ok(())
}
}
formatter.field(#f, Print::ref_cast(val));
}
})
} else {
let val = quote!(&_val.#ident);
let format = format_field(&val, ty)?;
let mut call = quote! {
formatter.field(#f, #format);
};
if let Type::Vec(_) | Type::Punctuated(_) = ty {
call = quote! {
if !_val.#ident.is_empty() {
#call
}
};
}
Some(call)
}
});
quote! {
let mut formatter = formatter.debug_struct(#name);
#(#fields)*
formatter.finish()
}
}
Data::Private => {
if node.ident == "LitInt" || node.ident == "LitFloat" {
quote! {
write!(formatter, "{}", _val)
}
} else {
quote! {
write!(formatter, "{:?}", _val.value())
}
}
}
}
}
fn expand_impl(defs: &Definitions, node: &Node) -> TokenStream {
if node.ident == "Reserved" {
return TokenStream::new();
}
let ident = Ident::new(&node.ident, Span::call_site());
let body = expand_impl_body(defs, node, &node.ident);
quote! {
impl Debug for Lite<syn::#ident> {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
let _val = &self.value;
#body
}
}
}
}
pub fn generate(defs: &Definitions) -> Result<()> {
let mut impls = TokenStream::new();
for node in &defs.types {
impls.extend(expand_impl(&defs, node));
}
file::write(
DEBUG_SRC,
quote! {
use super::{Lite, RefCast};
use std::fmt::{self, Debug};
#impls
},
)?;
Ok(())
}
|
