diff options
Diffstat (limited to 'syn/codegen/src/debug.rs')
| -rw-r--r-- | syn/codegen/src/debug.rs | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/syn/codegen/src/debug.rs b/syn/codegen/src/debug.rs new file mode 100644 index 0000000..9193881 --- /dev/null +++ b/syn/codegen/src/debug.rs @@ -0,0 +1,308 @@ +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(()) +} |