diff options
Diffstat (limited to 'dhall_proc_macros')
| -rw-r--r-- | dhall_proc_macros/src/make_parser.rs | 187 | ||||
| -rw-r--r-- | dhall_proc_macros/src/parse_children.rs | 11 |
2 files changed, 156 insertions, 42 deletions
diff --git a/dhall_proc_macros/src/make_parser.rs b/dhall_proc_macros/src/make_parser.rs index 268a639..3375c39 100644 --- a/dhall_proc_macros/src/make_parser.rs +++ b/dhall_proc_macros/src/make_parser.rs @@ -1,33 +1,101 @@ +use std::collections::HashMap; +use std::iter; + use quote::quote; use syn::parse::{ParseStream, Result}; use syn::spanned::Spanned; use syn::{ parse_quote, Error, Expr, FnArg, Ident, ImplItem, ImplItemMethod, ItemImpl, - Pat, Token, + Pat, Signature, Token, }; -fn apply_special_attrs(function: &mut ImplItemMethod) -> Result<()> { +fn collect_aliases( + imp: &mut ItemImpl, +) -> Result<HashMap<Ident, (Signature, Vec<Ident>)>> { + let mut alias_map = HashMap::new(); + + for item in &mut imp.items { + if let ImplItem::Method(function) = item { + let fn_name = function.sig.ident.clone(); + let mut alias_attrs = function + .attrs + .drain_filter(|attr| attr.path.is_ident("alias")) + .collect::<Vec<_>>() + .into_iter(); + + if let Some(attr) = alias_attrs.next() { + let tgt: Ident = attr.parse_args()?; + alias_map + .entry(tgt) + .or_insert_with(|| (function.sig.clone(), Vec::new())) + .1 + .push(fn_name); + } + if let Some(attr) = alias_attrs.next() { + return Err(Error::new( + attr.span(), + "expected at most one alias attribute", + )); + } + } + } + + Ok(alias_map) +} + +fn parse_rulefn_sig(sig: &Signature) -> Result<(Ident, Ident)> { + let fn_name = sig.ident.clone(); + // Get the name of the first (`input`) function argument + let input_arg = sig.inputs.first().ok_or_else(|| { + Error::new( + 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", + )), + } + }; + + Ok((fn_name, input_arg)) +} + +fn apply_special_attrs( + function: &mut ImplItemMethod, + alias_map: &mut HashMap<Ident, (Signature, Vec<Ident>)>, + rule_enum: &Ident, +) -> Result<()> { *function = parse_quote!( #[allow(non_snake_case, dead_code)] #function ); - let recognized_attrs: Vec<_> = function + let (fn_name, input_arg) = parse_rulefn_sig(&function.sig)?; + + // `prec_climb` attr + let prec_climb_attrs: Vec<_> = function .attrs .drain_filter(|attr| attr.path.is_ident("prec_climb")) .collect(); - let name = function.sig.ident.clone(); - - if recognized_attrs.is_empty() { - // do nothing - } else if recognized_attrs.len() > 1 { + if prec_climb_attrs.len() > 1 { return Err(Error::new( - recognized_attrs[1].span(), - "expected a single prec_climb attribute", + prec_climb_attrs[1].span(), + "expected at most one prec_climb attribute", )); + } else if prec_climb_attrs.is_empty() { + // do nothing } else { - let attr = recognized_attrs.into_iter().next().unwrap(); + let attr = prec_climb_attrs.into_iter().next().unwrap(); let (child_rule, climber) = attr.parse_args_with(|input: ParseStream| { let child_rule: Ident = input.parse()?; @@ -36,35 +104,14 @@ fn apply_special_attrs(function: &mut ImplItemMethod) -> Result<()> { Ok((child_rule, climber)) })?; - // Get the name of the first (`input`) function argument - let first_arg = function.sig.inputs.first().ok_or_else(|| { - Error::new( - function.sig.inputs.span(), - "a prec_climb function needs 4 arguments", - ) - })?; - let first_arg = match &first_arg { - FnArg::Receiver(_) => return Err(Error::new( - first_arg.span(), - "a prec_climb function should not have a `self` argument", - )), - FnArg::Typed(first_arg) => match &*first_arg.pat{ - Pat::Ident(ident) => &ident.ident, - _ => return Err(Error::new( - first_arg.span(), - "this argument should be a plain identifier instead of a pattern", - )), - } - }; - function.block = parse_quote!({ #function #climber.climb( - #first_arg.pair.clone().into_inner(), - |p| Self::#child_rule(#first_arg.with_pair(p)), + #input_arg.pair.clone().into_inner(), + |p| Self::#child_rule(#input_arg.with_pair(p)), |l, op, r| { - #name(#first_arg.clone(), l?, op, r?) + #fn_name(#input_arg.clone(), l?, op, r?) }, ) }); @@ -81,6 +128,22 @@ fn apply_special_attrs(function: &mut ImplItemMethod) -> Result<()> { })?; } + // `alias` attr + if let Some((_, aliases)) = alias_map.remove(&fn_name) { + let block = &function.block; + function.block = parse_quote!({ + 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(()) } @@ -89,21 +152,69 @@ pub fn make_parser( input: proc_macro::TokenStream, ) -> Result<proc_macro2::TokenStream> { 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)| { + quote!( + #rule_enum::#src => stringify!(#tgt).to_string(), + ) + }) + .collect(); + imp.items .iter_mut() .map(|item| match item { - ImplItem::Method(m) => apply_special_attrs(m), + ImplItem::Method(m) => { + apply_special_attrs(m, &mut alias_map, &rule_enum) + } _ => Ok(()), }) .collect::<Result<()>>()?; + // 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, (sig, srcs))| { + let mut sig = sig.clone(); + sig.ident = tgt.clone(); + + let (_, input_arg) = parse_rulefn_sig(&sig)?; + Ok(ImplItem::Method(parse_quote!( + #sig { + match #input_arg.as_rule() { + #(#rule_enum::#srcs => Self::#srcs(#input_arg),)* + 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::<Result<_>>()?; + 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 PestConsumer for #ty #where_clause { - type RuleEnum = #rule_enum; + type Rule = #rule_enum; + fn rule_alias(rule: Self::Rule) -> String { + match rule { + #(#rule_alias_branches)* + r => format!("{:?}", r), + } + } } #imp diff --git a/dhall_proc_macros/src/parse_children.rs b/dhall_proc_macros/src/parse_children.rs index b1d43fc..a35c03f 100644 --- a/dhall_proc_macros/src/parse_children.rs +++ b/dhall_proc_macros/src/parse_children.rs @@ -88,9 +88,7 @@ fn make_parser_branch( let i_variable_pattern = Ident::new("___variable_pattern", Span::call_site()); let match_pat = branch.pattern.iter().map(|item| match item { - Single { rule_name, .. } => { - quote!(<<Self as PestConsumer>::RuleEnum>::#rule_name) - } + Single { rule_name, .. } => quote!(stringify!(#rule_name)), Multiple { .. } => quote!(#i_variable_pattern @ ..), }); let match_filter = branch.pattern.iter().map(|item| match item { @@ -101,7 +99,7 @@ fn make_parser_branch( // https://github.com/rust-lang/rust/issues/59803. let all_match = |slice: &[_]| { slice.iter().all(|r| - r == &<<Self as PestConsumer>::RuleEnum>::#rule_name + *r == stringify!(#rule_name) ) }; all_match(#i_variable_pattern) @@ -192,6 +190,11 @@ pub fn parse_children( .clone() .into_inner() .map(|p| p.as_rule()) + .map(<Self as PestConsumer>::rule_alias) + .collect(); + let #i_children_rules: Vec<&str> = #i_children_rules + .iter() + .map(String::as_str) .collect(); #[allow(unused_mut)] |