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Diffstat (limited to 'dhall_proc_macros/src/make_parser.rs')
-rw-r--r--dhall_proc_macros/src/make_parser.rs334
1 files changed, 0 insertions, 334 deletions
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<AliasSrc>,
-}
-
-impl Parse for AliasArgs {
- fn parse(input: ParseStream) -> Result<Self> {
- 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<Self> {
- 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<HashMap<Ident, Vec<AliasSrc>>> {
- 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::<Vec<_>>()
- .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<Ident, Vec<AliasSrc>>,
-) -> Result<ParsedFn<'a>> {
- 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 <Self as pest_consume::PestConsumer>::allows_shortcut(#input_arg.as_rule()) {
- if let Some(child) = #input_arg.single_child() {
- if &<Self as pest_consume::PestConsumer>::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<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)| {
- 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<Ident, ParsedFn> = 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::<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, 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::<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 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
- ))
-}
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