// This file is part of ICU4X. For terms of use, please see the file // called LICENSE at the top level of the ICU4X source tree // (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ). use crate::utils::{self, FieldInfo}; use proc_macro2::Span; use proc_macro2::TokenStream as TokenStream2; use quote::{quote, ToTokens}; use syn::spanned::Spanned; use syn::{ parse_quote, AttributeArgs, Data, DeriveInput, Error, Field, Fields, GenericArgument, Ident, Lifetime, PathArguments, Type, }; pub fn make_varule_impl(attr: AttributeArgs, mut input: DeriveInput) -> TokenStream2 { if input.generics.type_params().next().is_some() || input.generics.const_params().next().is_some() || input.generics.lifetimes().count() > 1 { return Error::new( input.generics.span(), "#[make_varule] must be applied to a struct without any type or const parameters and at most one lifetime", ) .to_compile_error(); } let sp = input.span(); let attrs = match utils::extract_attributes_common(&mut input.attrs, sp, true) { Ok(val) => val, Err(e) => return e.to_compile_error(), }; let lt = input.generics.lifetimes().next(); if let Some(lt) = lt { if lt.colon_token.is_some() || !lt.bounds.is_empty() { return Error::new( input.generics.span(), "#[make_varule] must be applied to a struct without lifetime bounds", ) .to_compile_error(); } } let lt = lt.map(|l| &l.lifetime); if attr.len() != 1 { return Error::new( input.span(), "#[make_ule] takes one argument for the name of the ULE type it produces", ) .to_compile_error(); } let arg = &attr[0]; let ule_name: Ident = parse_quote!(#arg); let name = &input.ident; let fields = match input.data { Data::Struct(ref s) => &s.fields, _ => { return Error::new(input.span(), "#[make_varule] must be applied to a struct") .to_compile_error(); } }; if fields.is_empty() { return Error::new( input.span(), "#[make_varule] must be applied to a struct with at least one field", ) .to_compile_error(); } let mut sized_fields = vec![]; let mut unsized_fields = vec![]; for (i, field) in fields.iter().enumerate() { match UnsizedField::new(field, i) { Ok(o) => unsized_fields.push(o), Err(_) => sized_fields.push(FieldInfo::new_for_field(field, i)), } } if unsized_fields.is_empty() { let last_field = fields.iter().next_back().unwrap(); let e = UnsizedField::new(last_field, fields.len() - 1).unwrap_err(); return Error::new(last_field.span(), e).to_compile_error(); } if unsized_fields[0].field.index != fields.len() - unsized_fields.len() && unsized_fields[0].field.field.ident.is_none() { return Error::new( unsized_fields.first().unwrap().field.field.span(), "#[make_varule] requires its unsized fields to be at the end for tuple structs", ) .to_compile_error(); } let unsized_field_info = UnsizedFields::new(unsized_fields); let mut field_inits = crate::ule::make_ule_fields(&sized_fields); let last_field_ule = unsized_field_info.varule_ty(); let setter = unsized_field_info.varule_setter(); let vis = &unsized_field_info.varule_vis(); field_inits.push(quote!(#vis #setter #last_field_ule)); let semi = utils::semi_for(fields); let repr_attr = utils::repr_for(fields); let field_inits = utils::wrap_field_inits(&field_inits, fields); let vis = &input.vis; let doc = format!("[`VarULE`](zerovec::ule::VarULE) type for {name}"); let varule_struct: DeriveInput = parse_quote!( #[repr(#repr_attr)] #[derive(PartialEq, Eq)] #[doc = #doc] #vis struct #ule_name #field_inits #semi ); let derived = crate::varule::derive_impl(&varule_struct, unsized_field_info.varule_validator()); let maybe_lt_bound = lt.as_ref().map(|lt| quote!(<#lt>)); let encode_impl = make_encode_impl( &sized_fields, &unsized_field_info, name, &ule_name, &maybe_lt_bound, ); let zf_impl = make_zf_impl( &sized_fields, &unsized_field_info, fields, name, &ule_name, lt, input.span(), ); let zerofrom_fq_path = quote!(<#name as zerovec::__zerovec_internal_reexport::ZeroFrom<#ule_name>>); let maybe_ord_impls = if attrs.skip_ord { quote!() } else { quote!( impl core::cmp::PartialOrd for #ule_name { fn partial_cmp(&self, other: &Self) -> Option { let this = #zerofrom_fq_path::zero_from(self); let other = #zerofrom_fq_path::zero_from(other); <#name as core::cmp::PartialOrd>::partial_cmp(&this, &other) } } impl core::cmp::Ord for #ule_name { fn cmp(&self, other: &Self) -> core::cmp::Ordering { let this = #zerofrom_fq_path::zero_from(self); let other = #zerofrom_fq_path::zero_from(other); <#name as core::cmp::Ord>::cmp(&this, &other) } } ) }; let maybe_debug = if attrs.debug { quote!( impl core::fmt::Debug for #ule_name { fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result { let this = #zerofrom_fq_path::zero_from(self); <#name as core::fmt::Debug>::fmt(&this, f) } } ) } else { quote!() }; let zmkv = if attrs.skip_kv { quote!() } else { quote!( impl<'a> zerovec::maps::ZeroMapKV<'a> for #ule_name { type Container = zerovec::VarZeroVec<'a, #ule_name>; type Slice = zerovec::VarZeroSlice<#ule_name>; type GetType = #ule_name; type OwnedType = zerovec::__zerovec_internal_reexport::boxed::Box<#ule_name>; } ) }; let serde_path = quote!(zerovec::__zerovec_internal_reexport::serde); let maybe_ser = if attrs.serialize { quote!( impl #serde_path::Serialize for #ule_name { fn serialize(&self, serializer: S) -> Result where S: #serde_path::Serializer { let this = #zerofrom_fq_path::zero_from(self); <#name as #serde_path::Serialize>::serialize(&this, serializer) } } ) } else { quote!() }; let maybe_de = if attrs.deserialize { quote!( impl<'de> #serde_path::Deserialize<'de> for zerovec::__zerovec_internal_reexport::boxed::Box<#ule_name> { fn deserialize(deserializer: D) -> Result where D: #serde_path::Deserializer<'de> { let this = <#name as #serde_path::Deserialize>::deserialize(deserializer)?; Ok(zerovec::ule::encode_varule_to_box(&this)) } } ) } else { quote!() }; quote!( #input #varule_struct #encode_impl #zf_impl #derived #maybe_ord_impls #zmkv #maybe_ser #maybe_de #maybe_debug ) } fn make_zf_impl( sized_fields: &[FieldInfo], unsized_field_info: &UnsizedFields, fields: &Fields, name: &Ident, ule_name: &Ident, maybe_lt: Option<&Lifetime>, span: Span, ) -> TokenStream2 { if !unsized_field_info.has_zf() { return quote!(); } let lt = if let Some(ref lt) = maybe_lt { lt } else { return Error::new( span, "Can only generate ZeroFrom impls for types with lifetimes", ) .to_compile_error(); }; let mut field_inits = sized_fields .iter() .map(|f| { let ty = &f.field.ty; let accessor = &f.accessor; let setter = f.setter(); quote!(#setter <#ty as zerovec::ule::AsULE>::from_unaligned(other.#accessor)) }) .collect::>(); unsized_field_info.push_zf_setters(lt, &mut field_inits); let field_inits = utils::wrap_field_inits(&field_inits, fields); let zerofrom_trait = quote!(zerovec::__zerovec_internal_reexport::ZeroFrom); quote!( impl <#lt> #zerofrom_trait <#lt, #ule_name> for #name <#lt> { fn zero_from(other: &#lt #ule_name) -> Self { Self #field_inits } } ) } fn make_encode_impl( sized_fields: &[FieldInfo], unsized_field_info: &UnsizedFields, name: &Ident, ule_name: &Ident, maybe_lt_bound: &Option, ) -> TokenStream2 { let mut lengths = vec![]; for field in sized_fields { let ty = &field.field.ty; lengths.push(quote!(::core::mem::size_of::<<#ty as zerovec::ule::AsULE>::ULE>())); } let (encoders, remaining_offset) = utils::generate_per_field_offsets( sized_fields, true, |field, prev_offset_ident, size_ident| { let ty = &field.field.ty; let accessor = &field.accessor; quote!( #[allow(clippy::indexing_slicing)] // generate_per_field_offsets produces valid indices let out = &mut dst[#prev_offset_ident .. #prev_offset_ident + #size_ident]; let unaligned = zerovec::ule::AsULE::to_unaligned(self.#accessor); let unaligned_slice = &[unaligned]; let src = <<#ty as zerovec::ule::AsULE>::ULE as zerovec::ule::ULE>::as_byte_slice(unaligned_slice); out.copy_from_slice(src); ) }, ); let last_encode_len = unsized_field_info.encode_len(); let last_encode_write = unsized_field_info.encode_write(quote!(out)); quote!( unsafe impl #maybe_lt_bound zerovec::ule::EncodeAsVarULE<#ule_name> for #name #maybe_lt_bound { // Safety: unimplemented as the other two are implemented fn encode_var_ule_as_slices(&self, cb: impl FnOnce(&[&[u8]]) -> R) -> R { unreachable!("other two methods implemented") } // Safety: returns the total length of the ULE form by adding up the lengths of each element's ULE forms fn encode_var_ule_len(&self) -> usize { #(#lengths +)* #last_encode_len } // Safety: converts each element to ULE form and writes them in sequence fn encode_var_ule_write(&self, mut dst: &mut [u8]) { debug_assert_eq!(self.encode_var_ule_len(), dst.len()); #encoders #[allow(clippy::indexing_slicing)] // generate_per_field_offsets produces valid remainder let out = &mut dst[#remaining_offset..]; #last_encode_write } } // This second impl exists to allow for using EncodeAsVarULE without cloning // // A blanket impl cannot exist without coherence issues unsafe impl #maybe_lt_bound zerovec::ule::EncodeAsVarULE<#ule_name> for &'_ #name #maybe_lt_bound { // Safety: unimplemented as the other two are implemented fn encode_var_ule_as_slices(&self, cb: impl FnOnce(&[&[u8]]) -> R) -> R { unreachable!("other two methods implemented") } // Safety: returns the total length of the ULE form by adding up the lengths of each element's ULE forms fn encode_var_ule_len(&self) -> usize { (**self).encode_var_ule_len() } // Safety: converts each element to ULE form and writes them in sequence fn encode_var_ule_write(&self, mut dst: &mut [u8]) { (**self).encode_var_ule_write(dst) } } ) } /// Represents a VarULE-compatible type that would typically /// be found behind a `Cow<'a, _>` in the last field, and is represented /// roughly the same in owned and borrowed versions #[derive(Copy, Clone, Debug)] enum OwnULETy<'a> { /// [T] where T: AsULE Slice(&'a Type), /// str Str, } /// Represents the type of the last field of the struct #[derive(Copy, Clone, Debug)] enum UnsizedFieldKind<'a> { Cow(OwnULETy<'a>), ZeroVec(&'a Type), VarZeroVec(&'a Type), // Generally you should be using the above ones for maximum zero-copy, but these will still work Growable(OwnULETy<'a>), Boxed(OwnULETy<'a>), Ref(OwnULETy<'a>), } #[derive(Clone, Debug)] struct UnsizedField<'a> { kind: UnsizedFieldKind<'a>, field: FieldInfo<'a>, } struct UnsizedFields<'a> { fields: Vec>, } impl<'a> UnsizedFields<'a> { fn new(fields: Vec>) -> Self { assert!(!fields.is_empty(), "Must have at least one unsized field"); Self { fields } } // Get the corresponding VarULE type that can store all of these fn varule_ty(&self) -> TokenStream2 { if self.fields.len() == 1 { self.fields[0].kind.varule_ty() } else { quote!(zerovec::ule::MultiFieldsULE) } } // Get the accessor field name in the VarULE type fn varule_accessor(&self) -> TokenStream2 { if self.fields.len() == 1 { self.fields[0].field.accessor.clone() } else if self.fields[0].field.field.ident.is_some() { quote!(unsized_fields) } else { // first unsized field self.fields[0].field.accessor.clone() } } // Get the setter for this type for use in struct definition/creation syntax fn varule_setter(&self) -> TokenStream2 { if self.fields.len() == 1 { self.fields[0].field.setter() } else if self.fields[0].field.field.ident.is_some() { quote!(unsized_fields: ) } else { quote!() } } fn varule_vis(&self) -> TokenStream2 { if self.fields.len() == 1 { self.fields[0].field.field.vis.to_token_stream() } else { // Always private quote!() } } // Check if the type has a ZeroFrom impl fn has_zf(&self) -> bool { self.fields.iter().all(|f| f.kind.has_zf()) } // Takes all unsized fields on self and encodes them into a byte slice `out` fn encode_write(&self, out: TokenStream2) -> TokenStream2 { if self.fields.len() == 1 { self.fields[0].encode_func(quote!(encode_var_ule_write), quote!(#out)) } else { let mut lengths = vec![]; let mut writers = vec![]; for (i, field) in self.fields.iter().enumerate() { lengths.push(field.encode_func(quote!(encode_var_ule_len), quote!())); let (encodeable_ty, encodeable) = field.encodeable_tokens(); let varule_ty = field.kind.varule_ty(); writers .push(quote!(multi.set_field_at::<#varule_ty, #encodeable_ty>(#i, #encodeable))) } quote!( let lengths = [#(#lengths),*]; let mut multi = zerovec::ule::MultiFieldsULE::new_from_lengths_partially_initialized(&lengths, #out); unsafe { #(#writers;)* } ) } } // Takes all unsized fields on self and returns the length needed for encoding into a byte slice fn encode_len(&self) -> TokenStream2 { if self.fields.len() == 1 { self.fields[0].encode_func(quote!(encode_var_ule_len), quote!()) } else { let mut lengths = vec![]; for field in self.fields.iter() { lengths.push(field.encode_func(quote!(encode_var_ule_len), quote!())); } quote!(zerovec::ule::MultiFieldsULE::compute_encoded_len_for(&[#(#lengths),*])) } } /// Constructs ZeroFrom setters for each field of the stack type fn push_zf_setters(&self, lt: &Lifetime, field_inits: &mut Vec) { let zerofrom_trait = quote!(zerovec::__zerovec_internal_reexport::ZeroFrom); if self.fields.len() == 1 { let accessor = self.fields[0].field.accessor.clone(); let setter = self.fields[0].field.setter(); let last_field_ty = &self.fields[0].field.field.ty; let last_field_ule_ty = self.fields[0].kind.varule_ty(); field_inits.push(quote!(#setter <#last_field_ty as #zerofrom_trait <#lt, #last_field_ule_ty>>::zero_from(&other.#accessor) )); } else { let multi_accessor = self.varule_accessor(); for (i, field) in self.fields.iter().enumerate() { let setter = field.field.setter(); let field_ty = &field.field.field.ty; let field_ule_ty = field.kind.varule_ty(); field_inits.push(quote!(#setter unsafe { <#field_ty as #zerofrom_trait <#lt, #field_ule_ty>>::zero_from(&other.#multi_accessor.get_field::<#field_ule_ty>(#i)) })); } } } /// In case this needs custom validation code, return it /// /// The code will validate a variable known as `last_field_bytes` fn varule_validator(&self) -> Option { if self.fields.len() == 1 { None } else { let mut validators = vec![]; for (i, field) in self.fields.iter().enumerate() { let varule_ty = field.kind.varule_ty(); validators.push(quote!(multi.validate_field::<#varule_ty>(#i)?;)); } Some(quote!( let multi = zerovec::ule::MultiFieldsULE::parse_byte_slice(last_field_bytes)?; unsafe { #(#validators)* } )) } } } impl<'a> UnsizedField<'a> { fn new(field: &'a Field, index: usize) -> Result { Ok(UnsizedField { kind: UnsizedFieldKind::new(&field.ty)?, field: FieldInfo::new_for_field(field, index), }) } /// Call `>::#method(self.accessor #additional_args)` after adjusting /// Self and self.accessor to be the right types fn encode_func(&self, method: TokenStream2, additional_args: TokenStream2) -> TokenStream2 { let encodeas_trait = quote!(zerovec::ule::EncodeAsVarULE); let (encodeable_ty, encodeable) = self.encodeable_tokens(); let varule_ty = self.kind.varule_ty(); quote!(<#encodeable_ty as #encodeas_trait<#varule_ty>>::#method(#encodeable, #additional_args)) } /// Returns (encodeable_ty, encodeable) fn encodeable_tokens(&self) -> (TokenStream2, TokenStream2) { let accessor = self.field.accessor.clone(); let value = quote!(self.#accessor); let encodeable = self.kind.encodeable_value(value); let encodeable_ty = self.kind.encodeable_ty(); (encodeable_ty, encodeable) } } impl<'a> UnsizedFieldKind<'a> { /// Construct a UnsizedFieldKind for the type of a UnsizedFieldKind if possible fn new(ty: &'a Type) -> Result, String> { static PATH_TYPE_IDENTITY_ERROR: &str = "Can only automatically detect corresponding VarULE types for path types \ that are Cow, ZeroVec, VarZeroVec, Box, String, or Vec"; static PATH_TYPE_GENERICS_ERROR: &str = "Can only automatically detect corresponding VarULE types for path \ types with at most one lifetime and at most one generic parameter. VarZeroVecFormat types are not currently supported"; match *ty { Type::Reference(ref tyref) => OwnULETy::new(&tyref.elem, "reference").map(UnsizedFieldKind::Ref), Type::Path(ref typath) => { if typath.path.segments.len() != 1 { return Err("Can only automatically detect corresponding VarULE types for \ path types with a single path segment".into()); } let segment = typath.path.segments.first().unwrap(); match segment.arguments { PathArguments::None => { if segment.ident == "String" { Ok(UnsizedFieldKind::Growable(OwnULETy::Str)) } else { Err(PATH_TYPE_IDENTITY_ERROR.into()) } } PathArguments::AngleBracketed(ref params) => { // At most one lifetime and exactly one generic parameter let mut lifetime = None; let mut generic = None; for param in ¶ms.args { match param { GenericArgument::Lifetime(ref lt) if lifetime.is_none() => { lifetime = Some(lt) } GenericArgument::Type(ref ty) if generic.is_none() => { generic = Some(ty) } _ => return Err(PATH_TYPE_GENERICS_ERROR.into()), } } // Must be exactly one generic parameter // (we've handled the zero generics case already) let generic = if let Some(g) = generic { g } else { return Err(PATH_TYPE_GENERICS_ERROR.into()); }; let ident = segment.ident.to_string(); if lifetime.is_some() { match &*ident { "ZeroVec" => Ok(UnsizedFieldKind::ZeroVec(generic)), "VarZeroVec" => Ok(UnsizedFieldKind::VarZeroVec(generic)), "Cow" => OwnULETy::new(generic, "Cow").map(UnsizedFieldKind::Cow), _ => Err(PATH_TYPE_IDENTITY_ERROR.into()), } } else { match &*ident { "Vec" => Ok(UnsizedFieldKind::Growable(OwnULETy::Slice(generic))), "Box" => OwnULETy::new(generic, "Box").map(UnsizedFieldKind::Boxed), _ => Err(PATH_TYPE_IDENTITY_ERROR.into()), } } } _ => Err("Can only automatically detect corresponding VarULE types for path types \ with none or angle bracketed generics".into()), } } _ => Err("Can only automatically detect corresponding VarULE types for path and reference types".into()), } } /// Get the tokens for the corresponding VarULE type fn varule_ty(&self) -> TokenStream2 { match *self { Self::Ref(ref inner) | Self::Cow(ref inner) | Self::Boxed(ref inner) | Self::Growable(ref inner) => { let inner_ule = inner.varule_ty(); quote!(#inner_ule) } Self::ZeroVec(ref inner) => quote!(zerovec::ZeroSlice<#inner>), Self::VarZeroVec(ref inner) => quote!(zerovec::VarZeroSlice<#inner>), } } // Takes expr `value` and returns it as a value that can be encoded via EncodeAsVarULE fn encodeable_value(&self, value: TokenStream2) -> TokenStream2 { match *self { Self::Ref(_) | Self::Cow(_) | Self::Growable(_) | Self::Boxed(_) => quote!(&*#value), Self::ZeroVec(_) => quote!(&*#value), Self::VarZeroVec(_) => quote!(&*#value), } } /// Returns the EncodeAsVarULE type this can be represented as, the same returned by encodeable_value() fn encodeable_ty(&self) -> TokenStream2 { match *self { Self::Ref(ref inner) | Self::Cow(ref inner) | Self::Growable(ref inner) | Self::Boxed(ref inner) => inner.varule_ty(), Self::ZeroVec(ty) => quote!(zerovec::ZeroSlice<#ty>), Self::VarZeroVec(ty) => quote!(zerovec::VarZeroSlice<#ty>), } } fn has_zf(&self) -> bool { matches!( *self, Self::Ref(_) | Self::Cow(_) | Self::ZeroVec(_) | Self::VarZeroVec(_) ) } } impl<'a> OwnULETy<'a> { fn new(ty: &'a Type, context: &str) -> Result { match *ty { Type::Slice(ref slice) => Ok(OwnULETy::Slice(&slice.elem)), Type::Path(ref typath) => { if typath.path.is_ident("str") { Ok(OwnULETy::Str) } else { Err(format!("Cannot automatically detect corresponding VarULE type for non-str path type inside a {context}")) } } _ => Err(format!("Cannot automatically detect corresponding VarULE type for non-slice/path type inside a {context}")), } } /// Get the tokens for the corresponding VarULE type fn varule_ty(&self) -> TokenStream2 { match *self { OwnULETy::Slice(s) => quote!([#s]), OwnULETy::Str => quote!(str), } } }