From accaf45aa77099654f94319ed1fb12855dd568b4 Mon Sep 17 00:00:00 2001 From: Nadrieril Date: Mon, 9 Sep 2019 22:42:46 +0200 Subject: Move pest_consume macros into their own crate --- dhall_proc_macros/src/make_parser.rs | 334 ----------------------------------- 1 file changed, 334 deletions(-) delete mode 100644 dhall_proc_macros/src/make_parser.rs (limited to 'dhall_proc_macros/src/make_parser.rs') diff --git a/dhall_proc_macros/src/make_parser.rs b/dhall_proc_macros/src/make_parser.rs deleted file mode 100644 index c0594a5..0000000 --- a/dhall_proc_macros/src/make_parser.rs +++ /dev/null @@ -1,334 +0,0 @@ -use std::collections::HashMap; -use std::iter; - -use quote::quote; -use syn::parse::{Parse, ParseStream, Result}; -use syn::spanned::Spanned; -use syn::{ - parse_quote, Error, Expr, FnArg, Ident, ImplItem, ImplItemMethod, ItemImpl, - LitBool, Pat, Token, -}; - -mod kw { - syn::custom_keyword!(shortcut); -} - -struct AliasArgs { - target: Ident, - is_shortcut: bool, -} - -struct PrecClimbArgs { - child_rule: Ident, - climber: Expr, -} - -struct AliasSrc { - ident: Ident, - is_shortcut: bool, -} - -struct ParsedFn<'a> { - // Body of the function - function: &'a mut ImplItemMethod, - // Name of the function. - fn_name: Ident, - // Name of the first argument of the function, which should be of type `ParseInput`. - input_arg: Ident, - // List of aliases pointing to this function - alias_srcs: Vec, -} - -impl Parse for AliasArgs { - fn parse(input: ParseStream) -> Result { - let target = input.parse()?; - let is_shortcut = if input.peek(Token![,]) { - // #[alias(rule, shortcut = true)] - let _: Token![,] = input.parse()?; - let _: kw::shortcut = input.parse()?; - let _: Token![=] = input.parse()?; - let b: LitBool = input.parse()?; - b.value - } else { - // #[alias(rule)] - false - }; - Ok(AliasArgs { - target, - is_shortcut, - }) - } -} - -impl Parse for PrecClimbArgs { - fn parse(input: ParseStream) -> Result { - let child_rule = input.parse()?; - let _: Token![,] = input.parse()?; - let climber = input.parse()?; - Ok(PrecClimbArgs { - child_rule, - climber, - }) - } -} - -fn collect_aliases( - imp: &mut ItemImpl, -) -> Result>> { - let functions = imp.items.iter_mut().flat_map(|item| match item { - ImplItem::Method(m) => Some(m), - _ => None, - }); - - let mut alias_map = HashMap::new(); - for function in functions { - let fn_name = function.sig.ident.clone(); - let mut alias_attrs = function - .attrs - .drain_filter(|attr| attr.path.is_ident("alias")) - .collect::>() - .into_iter(); - - if let Some(attr) = alias_attrs.next() { - let args: AliasArgs = attr.parse_args()?; - alias_map.entry(args.target).or_insert_with(Vec::new).push( - AliasSrc { - ident: fn_name, - is_shortcut: args.is_shortcut, - }, - ); - } - if let Some(attr) = alias_attrs.next() { - return Err(Error::new( - attr.span(), - "expected at most one alias attribute", - )); - } - } - - Ok(alias_map) -} - -fn parse_fn<'a>( - function: &'a mut ImplItemMethod, - alias_map: &mut HashMap>, -) -> Result> { - let fn_name = function.sig.ident.clone(); - // Get the name of the first (`input`) function argument - let input_arg = function.sig.inputs.first().ok_or_else(|| { - Error::new( - function.sig.inputs.span(), - "a rule function needs an `input` argument", - ) - })?; - let input_arg = match &input_arg { - FnArg::Receiver(_) => return Err(Error::new( - input_arg.span(), - "a rule function should not have a `self` argument", - )), - FnArg::Typed(input_arg) => match &*input_arg.pat{ - Pat::Ident(ident) => ident.ident.clone(), - _ => return Err(Error::new( - input_arg.span(), - "this argument should be a plain identifier instead of a pattern", - )), - } - }; - - let alias_srcs = alias_map.remove(&fn_name).unwrap_or_else(Vec::new); - - Ok(ParsedFn { - function, - fn_name, - input_arg, - alias_srcs, - }) -} - -fn apply_special_attrs(f: &mut ParsedFn, rule_enum: &Ident) -> Result<()> { - let function = &mut *f.function; - let fn_name = &f.fn_name; - let input_arg = &f.input_arg; - - *function = parse_quote!( - #[allow(non_snake_case)] - #function - ); - - // `prec_climb` attr - let prec_climb_attrs: Vec<_> = function - .attrs - .drain_filter(|attr| attr.path.is_ident("prec_climb")) - .collect(); - - if prec_climb_attrs.len() > 1 { - return Err(Error::new( - prec_climb_attrs[1].span(), - "expected at most one prec_climb attribute", - )); - } else if prec_climb_attrs.is_empty() { - // do nothing - } else { - let attr = prec_climb_attrs.into_iter().next().unwrap(); - let PrecClimbArgs { - child_rule, - climber, - } = attr.parse_args()?; - - function.block = parse_quote!({ - #function - - #climber.climb( - #input_arg.as_pair().clone().into_inner(), - |p| Self::#child_rule(#input_arg.with_pair(p)), - |l, op, r| { - #fn_name(#input_arg.clone(), l?, op, r?) - }, - ) - }); - // Remove the 3 last arguments to keep only the `input` one - function.sig.inputs.pop(); - function.sig.inputs.pop(); - function.sig.inputs.pop(); - // Check that an argument remains - function.sig.inputs.first().ok_or_else(|| { - Error::new( - function.sig.inputs.span(), - "a prec_climb function needs 4 arguments", - ) - })?; - } - - // `alias` attr - if !f.alias_srcs.is_empty() { - let aliases = f.alias_srcs.iter().map(|src| &src.ident); - let block = &function.block; - function.block = parse_quote!({ - let mut #input_arg = #input_arg; - // While the current rule allows shortcutting, and there is a single child, and the - // child can still be parsed by the current function, then skip to that child. - while ::allows_shortcut(#input_arg.as_rule()) { - if let Some(child) = #input_arg.single_child() { - if &::rule_alias(child.as_rule()) - == stringify!(#fn_name) { - #input_arg = child; - continue; - } - } - break - } - - match #input_arg.as_rule() { - #(#rule_enum::#aliases => Self::#aliases(#input_arg),)* - #rule_enum::#fn_name => #block, - r => unreachable!( - "make_parser: called {} on {:?}", - stringify!(#fn_name), - r - ) - } - }); - } - - Ok(()) -} - -pub fn make_parser( - attrs: proc_macro::TokenStream, - input: proc_macro::TokenStream, -) -> Result { - let rule_enum: Ident = syn::parse(attrs)?; - let mut imp: ItemImpl = syn::parse(input)?; - - let mut alias_map = collect_aliases(&mut imp)?; - let rule_alias_branches: Vec<_> = alias_map - .iter() - .flat_map(|(tgt, srcs)| iter::repeat(tgt).zip(srcs)) - .map(|(tgt, src)| { - let ident = &src.ident; - quote!( - #rule_enum::#ident => stringify!(#tgt).to_string(), - ) - }) - .collect(); - let shortcut_branches: Vec<_> = alias_map - .iter() - .flat_map(|(_tgt, srcs)| srcs) - .map(|AliasSrc { ident, is_shortcut }| { - quote!( - #rule_enum::#ident => #is_shortcut, - ) - }) - .collect(); - - let fn_map: HashMap = imp - .items - .iter_mut() - .flat_map(|item| match item { - ImplItem::Method(m) => Some(m), - _ => None, - }) - .map(|method| { - let mut f = parse_fn(method, &mut alias_map)?; - apply_special_attrs(&mut f, &rule_enum)?; - Ok((f.fn_name.clone(), f)) - }) - .collect::>()?; - - // Entries that remain in the alias map don't have a matching method, so we create one. - let extra_fns: Vec<_> = alias_map - .iter() - .map(|(tgt, srcs)| { - // Get the signature of one of the functions that has this alias. They should all have - // essentially the same signature anyways. - let f = fn_map.get(&srcs.first().unwrap().ident).unwrap(); - let input_arg = f.input_arg.clone(); - let mut sig = f.function.sig.clone(); - sig.ident = tgt.clone(); - let srcs = srcs.iter().map(|src| &src.ident); - - Ok(parse_quote!( - #sig { - match #input_arg.as_rule() { - #(#rule_enum::#srcs => Self::#srcs(#input_arg),)* - // We can't match on #rule_enum::#tgt since `tgt` might be an arbitrary - // identifier. - r if &format!("{:?}", r) == stringify!(#tgt) => - return Err(#input_arg.error(format!( - "make_parser: missing method for rule {}", - stringify!(#tgt), - ))), - r => unreachable!( - "make_parser: called {} on {:?}", - stringify!(#tgt), - r - ) - } - } - )) - }) - .collect::>()?; - imp.items.extend(extra_fns); - - let ty = &imp.self_ty; - let (impl_generics, _, where_clause) = imp.generics.split_for_impl(); - Ok(quote!( - impl #impl_generics pest_consume::PestConsumer for #ty #where_clause { - type Rule = #rule_enum; - fn rule_alias(rule: Self::Rule) -> String { - match rule { - #(#rule_alias_branches)* - r => format!("{:?}", r), - } - } - fn allows_shortcut(rule: Self::Rule) -> bool { - match rule { - #(#shortcut_branches)* - _ => false, - } - } - } - - #imp - )) -} -- cgit v1.2.3