git.delta.rocks / jrsonnet / refs/commits / 906c620d4b95

1use proc_macro2::TokenStream;2use quote::quote;3use syn::{4	parenthesized,5	parse::{Parse, ParseStream},6	parse_macro_input,7	punctuated::Punctuated,8	spanned::Spanned,9	token::{self, Comma},10	Attribute, DeriveInput, Error, FnArg, GenericArgument, Ident, ItemFn, LitStr, Pat, Path,11	PathArguments, Result, ReturnType, Token, Type,12};1314fn parse_attr<A: Parse, I>(attrs: &[Attribute], ident: I) -> Result<Option<A>>15where16	Ident: PartialEq<I>,17{18	let attrs = attrs19		.iter()20		.filter(|a| a.path.is_ident(&ident))21		.collect::<Vec<_>>();22	if attrs.len() > 1 {23		return Err(Error::new(24			attrs[1].span(),25			"this attribute may be specified only once",26		));27	} else if attrs.is_empty() {28		return Ok(None);29	}30	let attr = attrs[0];31	let attr = attr.parse_args::<A>()?;3233	Ok(Some(attr))34}3536fn path_is(path: &Path, needed: &str) -> bool {37	path.leading_colon.is_none()38		&& !path.segments.is_empty()39		&& path.segments.iter().last().unwrap().ident == needed40}4142fn type_is_path<'ty>(ty: &'ty Type, needed: &str) -> Option<&'ty PathArguments> {43	match ty {44		Type::Path(path) if path.qself.is_none() && path_is(&path.path, needed) => {45			let args = &path.path.segments.iter().last().unwrap().arguments;46			Some(args)47		}48		_ => None,49	}50}5152fn extract_type_from_option(ty: &Type) -> Result<Option<&Type>> {53	let Some(args) = type_is_path(ty, "Option") else {54		return Ok(None);55	};56	// It should have only on angle-bracketed param ("<String>"):57	let PathArguments::AngleBracketed(params) = args else {58		return Err(Error::new(args.span(), "missing option generic"));59	};60	let generic_arg = params.args.iter().next().unwrap();61	// This argument must be a type:62	let GenericArgument::Type(ty) = generic_arg else {63		return Err(Error::new(64			generic_arg.span(),65			"option generic should be a type",66		));67	};68	Ok(Some(ty))69}7071struct Field {72	attrs: Vec<Attribute>,73	name: Ident,74	_colon: Token![:],75	ty: Type,76}77impl Parse for Field {78	fn parse(input: ParseStream) -> syn::Result<Self> {79		Ok(Self {80			attrs: input.call(Attribute::parse_outer)?,81			name: input.parse()?,82			_colon: input.parse()?,83			ty: input.parse()?,84		})85	}86}8788mod kw {89	syn::custom_keyword!(fields);90	syn::custom_keyword!(rename);91	syn::custom_keyword!(flatten);92	syn::custom_keyword!(add);93	syn::custom_keyword!(hide);94	syn::custom_keyword!(ok);95}9697struct EmptyAttr;98impl Parse for EmptyAttr {99	fn parse(_input: ParseStream) -> Result<Self> {100		Ok(Self)101	}102}103104struct BuiltinAttrs {105	fields: Vec<Field>,106}107impl Parse for BuiltinAttrs {108	fn parse(input: ParseStream) -> syn::Result<Self> {109		if input.is_empty() {110			return Ok(Self { fields: Vec::new() });111		}112		input.parse::<kw::fields>()?;113		let fields;114		parenthesized!(fields in input);115		let p = Punctuated::<Field, Comma>::parse_terminated(&fields)?;116		Ok(Self {117			fields: p.into_iter().collect(),118		})119	}120}121122enum ArgInfo {123	Normal {124		ty: Box<Type>,125		is_option: bool,126		name: Option<String>,127		cfg_attrs: Vec<Attribute>,128	},129	Lazy {130		is_option: bool,131		name: Option<String>,132	},133	Context,134	Location,135	This,136}137138impl ArgInfo {139	fn parse(name: &str, arg: &FnArg) -> Result<Self> {140		let FnArg::Typed(arg) = arg else {141			unreachable!()142		};143		let ident = match &arg.pat as &Pat {144			Pat::Ident(i) => Some(i.ident.clone()),145			_ => None,146		};147		let ty = &arg.ty;148		if type_is_path(ty, "Context").is_some() {149			return Ok(Self::Context);150		} else if type_is_path(ty, "CallLocation").is_some() {151			return Ok(Self::Location);152		} else if type_is_path(ty, "Thunk").is_some() {153			return Ok(Self::Lazy {154				is_option: false,155				name: ident.map(|v| v.to_string()),156			});157		}158159		match ty as &Type {160			Type::Reference(r) if type_is_path(&r.elem, name).is_some() => return Ok(Self::This),161			_ => {}162		}163164		let (is_option, ty) = if let Some(ty) = extract_type_from_option(ty)? {165			if type_is_path(ty, "Thunk").is_some() {166				return Ok(Self::Lazy {167					is_option: true,168					name: ident.map(|v| v.to_string()),169				});170			}171172			(true, Box::new(ty.clone()))173		} else {174			(false, ty.clone())175		};176177		let cfg_attrs = arg178			.attrs179			.iter()180			.filter(|a| a.path.is_ident("cfg"))181			.cloned()182			.collect();183184		Ok(Self::Normal {185			ty,186			is_option,187			name: ident.map(|v| v.to_string()),188			cfg_attrs,189		})190	}191}192193#[proc_macro_attribute]194pub fn builtin(195	attr: proc_macro::TokenStream,196	item: proc_macro::TokenStream,197) -> proc_macro::TokenStream {198	let attr = parse_macro_input!(attr as BuiltinAttrs);199	let item_fn = item.clone();200	let item_fn: ItemFn = parse_macro_input!(item_fn);201202	match builtin_inner(attr, item_fn, item.into()) {203		Ok(v) => v.into(),204		Err(e) => e.into_compile_error().into(),205	}206}207208fn builtin_inner(209	attr: BuiltinAttrs,210	fun: ItemFn,211	item: proc_macro2::TokenStream,212) -> syn::Result<TokenStream> {213	let ReturnType::Type(_, result) = &fun.sig.output else {214		return Err(Error::new(215			fun.sig.span(),216			"builtin should return something",217		));218	};219220	let name = fun.sig.ident.to_string();221	let args = fun222		.sig223		.inputs224		.iter()225		.map(|arg| ArgInfo::parse(&name, arg))226		.collect::<Result<Vec<_>>>()?;227228	let params_desc = args.iter().flat_map(|a| match a {229		ArgInfo::Normal {230			is_option,231			name,232			cfg_attrs,233			..234		} => {235			let name = name236				.as_ref()237				.map(|n| quote! {ParamName::new_static(#n)})238				.unwrap_or_else(|| quote! {None});239			Some(quote! {240				#(#cfg_attrs)*241				BuiltinParam::new(#name, #is_option),242			})243		}244		ArgInfo::Lazy { is_option, name } => {245			let name = name246				.as_ref()247				.map(|n| quote! {ParamName::new_static(#n)})248				.unwrap_or_else(|| quote! {None});249			Some(quote! {250				BuiltinParam::new(#name, #is_option),251			})252		}253		ArgInfo::Context => None,254		ArgInfo::Location => None,255		ArgInfo::This => None,256	});257258	let mut id = 0usize;259	let pass = args260		.iter()261		.map(|a| match a {262			ArgInfo::Normal { .. } | ArgInfo::Lazy { .. } => {263				let cid = id;264				id += 1;265				(quote! {#cid}, a)266			}267			ArgInfo::Context | ArgInfo::Location | ArgInfo::This => {268				(quote! {compile_error!("should not use id")}, a)269			}270		})271		.map(|(id, a)| match a {272			ArgInfo::Normal {273				ty,274				is_option,275				name,276				cfg_attrs,277			} => {278				let name = name.as_ref().map(|v| v.as_str()).unwrap_or("<unnamed>");279				let eval = quote! {jrsonnet_evaluator::State::push_description(280					|| format!("argument <{}> evaluation", #name),281					|| <#ty>::from_untyped(value.evaluate()?),282				)?};283				let value = if *is_option {284					quote! {if let Some(value) = &parsed[#id] {285						Some(#eval)286					} else {287						None288					},}289				} else {290					quote! {{291						let value = parsed[#id].as_ref().expect("args shape is checked");292						#eval293					},}294				};295				quote! {296					#(#cfg_attrs)*297					#value298				}299			}300			ArgInfo::Lazy { is_option, .. } => {301				if *is_option {302					quote! {if let Some(value) = &parsed[#id] {303						Some(value.clone())304					} else {305						None306					}}307				} else {308					quote! {309						parsed[#id].as_ref().expect("args shape is correct").clone(),310					}311				}312			}313			ArgInfo::Context => quote! {ctx.clone(),},314			ArgInfo::Location => quote! {location,},315			ArgInfo::This => quote! {self,},316		});317318	let fields = attr.fields.iter().map(|field| {319		let attrs = &field.attrs;320		let name = &field.name;321		let ty = &field.ty;322		quote! {323			#(#attrs)*324			pub #name: #ty,325		}326	});327328	let name = &fun.sig.ident;329	let vis = &fun.vis;330	let static_ext = if attr.fields.is_empty() {331		quote! {332			impl #name {333				pub const INST: &'static dyn StaticBuiltin = &#name {};334			}335			impl StaticBuiltin for #name {}336		}337	} else {338		quote! {}339	};340	let static_derive_copy = if attr.fields.is_empty() {341		quote! {, Copy}342	} else {343		quote! {}344	};345346	Ok(quote! {347		#item348349		#[doc(hidden)]350		#[allow(non_camel_case_types)]351		#[derive(Clone, jrsonnet_gcmodule::Trace #static_derive_copy)]352		#vis struct #name {353			#(#fields)*354		}355		const _: () = {356			use ::jrsonnet_evaluator::{357				State, Val,358				function::{builtin::{Builtin, StaticBuiltin, BuiltinParam, ParamName}, CallLocation, ArgsLike, parse::parse_builtin_call},359				error::Result, Context, typed::Typed,360				parser::ExprLocation,361			};362			const PARAMS: &'static [BuiltinParam] = &[363				#(#params_desc)*364			];365366			#static_ext367			impl Builtin for #name368			where369				Self: 'static370			{371				fn name(&self) -> &str {372					stringify!(#name)373				}374				fn params(&self) -> &[BuiltinParam] {375					PARAMS376				}377				fn call(&self, ctx: Context, location: CallLocation, args: &dyn ArgsLike) -> Result<Val> {378					let parsed = parse_builtin_call(ctx.clone(), &PARAMS, args, false)?;379380					let result: #result = #name(#(#pass)*);381					<_ as Typed>::into_result(result)382				}383				fn as_any(&self) -> &dyn ::std::any::Any {384					self385				}386			}387		};388	})389}390391#[derive(Default)]392struct TypedAttr {393	rename: Option<String>,394	flatten: bool,395	/// flatten(ok) strategy for flattened optionals396	/// field would be None in case of any parsing error (as in serde)397	flatten_ok: bool,398	// Should it be `field+:` instead of `field:`399	add: bool,400	// Should it be `field::` instead of `field:`401	hide: bool,402}403impl Parse for TypedAttr {404	fn parse(input: ParseStream) -> syn::Result<Self> {405		let mut out = Self::default();406		loop {407			let lookahead = input.lookahead1();408			if lookahead.peek(kw::rename) {409				input.parse::<kw::rename>()?;410				input.parse::<Token![=]>()?;411				let name = input.parse::<LitStr>()?;412				if out.rename.is_some() {413					return Err(Error::new(414						name.span(),415						"rename attribute may only be specified once",416					));417				}418				out.rename = Some(name.value());419			} else if lookahead.peek(kw::flatten) {420				input.parse::<kw::flatten>()?;421				out.flatten = true;422				if input.peek(token::Paren) {423					let content;424					parenthesized!(content in input);425					let lookahead = content.lookahead1();426					if lookahead.peek(kw::ok) {427						content.parse::<kw::ok>()?;428						out.flatten_ok = true;429					} else {430						return Err(lookahead.error());431					}432				}433			} else if lookahead.peek(kw::add) {434				input.parse::<kw::add>()?;435				out.add = true;436			} else if lookahead.peek(kw::hide) {437				input.parse::<kw::hide>()?;438				out.hide = true;439			} else if input.is_empty() {440				break;441			} else {442				return Err(lookahead.error());443			}444			if input.peek(Token![,]) {445				input.parse::<Token![,]>()?;446			} else {447				break;448			}449		}450		Ok(out)451	}452}453454struct TypedField {455	attr: TypedAttr,456	ident: Ident,457	ty: Type,458	is_option: bool,459}460impl TypedField {461	fn parse(field: &syn::Field) -> Result<Self> {462		let attr = parse_attr::<TypedAttr, _>(&field.attrs, "typed")?.unwrap_or_default();463		let Some(ident) = field.ident.clone() else {464			return Err(Error::new(465				field.span(),466				"this field should appear in output object, but it has no visible name",467			));468		};469		let (is_option, ty) = if let Some(ty) = extract_type_from_option(&field.ty)? {470			(true, ty.clone())471		} else {472			(false, field.ty.clone())473		};474		if is_option && attr.flatten {475			if !attr.flatten_ok {476				return Err(Error::new(477					field.span(),478					"strategy should be set when flattening Option",479				));480			}481		} else if attr.flatten_ok {482			return Err(Error::new(483				field.span(),484				"flatten(ok) is only useable on optional fields",485			));486		}487488		Ok(Self {489			attr,490			ident,491			ty,492			is_option,493		})494	}495	/// None if this field is flattened in jsonnet output496	fn name(&self) -> Option<String> {497		if self.attr.flatten {498			return None;499		}500		Some(501			self.attr502				.rename503				.clone()504				.unwrap_or_else(|| self.ident.to_string()),505		)506	}507508	fn expand_field(&self) -> Option<TokenStream> {509		if self.is_option {510			return None;511		}512		let name = self.name()?;513		let ty = &self.ty;514		Some(quote! {515			(#name, <#ty as Typed>::TYPE)516		})517	}518	fn expand_parse(&self) -> TokenStream {519		let ident = &self.ident;520		let ty = &self.ty;521		if self.attr.flatten {522			// optional flatten is handled in same way as serde523			return if self.is_option {524				quote! {525					#ident: <#ty as TypedObj>::parse(&obj).ok(),526				}527			} else {528				quote! {529					#ident: <#ty as TypedObj>::parse(&obj)?,530				}531			};532		};533534		let name = self.name().unwrap();535		let value = if self.is_option {536			quote! {537				if let Some(value) = obj.get(#name.into())? {538					Some(<#ty as Typed>::from_untyped(value)?)539				} else {540					None541				}542			}543		} else {544			quote! {545				<#ty as Typed>::from_untyped(obj.get(#name.into())?.ok_or_else(|| ErrorKind::NoSuchField(#name.into(), vec![]))?)?546			}547		};548549		quote! {550			#ident: #value,551		}552	}553	fn expand_serialize(&self) -> Result<TokenStream> {554		let ident = &self.ident;555		let ty = &self.ty;556		Ok(if let Some(name) = self.name() {557			let hide = if self.attr.hide {558				quote! {.hide()}559			} else {560				quote! {}561			};562			let add = if self.attr.add {563				quote! {.add()}564			} else {565				quote! {}566			};567			if self.is_option {568				quote! {569					if let Some(value) = self.#ident {570						out.member(#name.into())571							#hide572							#add573							.value(<#ty as Typed>::into_untyped(value)?)?;574					}575				}576			} else {577				quote! {578					out.member(#name.into())579						#hide580						#add581						.value(<#ty as Typed>::into_untyped(self.#ident)?)?;582				}583			}584		} else if self.is_option {585			quote! {586				if let Some(value) = self.#ident {587					<#ty as TypedObj>::serialize(value, out)?;588				}589			}590		} else {591			quote! {592				<#ty as TypedObj>::serialize(self.#ident, out)?;593			}594		})595	}596}597598#[proc_macro_derive(Typed, attributes(typed))]599pub fn derive_typed(item: proc_macro::TokenStream) -> proc_macro::TokenStream {600	let input = parse_macro_input!(item as DeriveInput);601602	match derive_typed_inner(input) {603		Ok(v) => v.into(),604		Err(e) => e.to_compile_error().into(),605	}606}607608fn derive_typed_inner(input: DeriveInput) -> Result<TokenStream> {609	let syn::Data::Struct(data) = &input.data else {610		return Err(Error::new(input.span(), "only structs supported"));611	};612613	let ident = &input.ident;614	let fields = data615		.fields616		.iter()617		.map(TypedField::parse)618		.collect::<Result<Vec<_>>>()?;619620	let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();621622	let typed = {623		let fields = fields624			.iter()625			.flat_map(TypedField::expand_field)626			.collect::<Vec<_>>();627		quote! {628			impl #impl_generics Typed for #ident #ty_generics #where_clause {629				const TYPE: &'static ComplexValType = &ComplexValType::ObjectRef(&[630					#(#fields,)*631				]);632633				fn from_untyped(value: Val) -> JrResult<Self> {634					let obj = value.as_obj().expect("shape is correct");635					Self::parse(&obj)636				}637638				fn into_untyped(value: Self) -> JrResult<Val> {639					let mut out = ObjValueBuilder::new();640					value.serialize(&mut out)?;641					Ok(Val::Obj(out.build()))642				}643644			}645		}646	};647648	let fields_parse = fields.iter().map(TypedField::expand_parse);649	let fields_serialize = fields650		.iter()651		.map(TypedField::expand_serialize)652		.collect::<Result<Vec<_>>>()?;653654	Ok(quote! {655		const _: () = {656			use ::jrsonnet_evaluator::{657				typed::{ComplexValType, Typed, TypedObj, CheckType},658				Val, State,659				error::{ErrorKind, Result as JrResult},660				ObjValueBuilder, ObjValue,661			};662663			#typed664665			impl #impl_generics TypedObj for #ident #ty_generics #where_clause {666				fn serialize(self, out: &mut ObjValueBuilder) -> JrResult<()> {667					#(#fields_serialize)*668669					Ok(())670				}671				fn parse(obj: &ObjValue) -> JrResult<Self> {672					Ok(Self {673						#(#fields_parse)*674					})675				}676			}677		};678	})679}