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-rw-r--r--dhall_proc_macros/Cargo.toml6
-rw-r--r--dhall_proc_macros/src/lib.rs19
-rw-r--r--dhall_proc_macros/src/make_parser.rs111
-rw-r--r--dhall_proc_macros/src/parse_children.rs212
4 files changed, 345 insertions, 3 deletions
diff --git a/dhall_proc_macros/Cargo.toml b/dhall_proc_macros/Cargo.toml
index df1eda8..b641a39 100644
--- a/dhall_proc_macros/Cargo.toml
+++ b/dhall_proc_macros/Cargo.toml
@@ -11,6 +11,6 @@ doctest = false
[dependencies]
itertools = "0.8.0"
-quote = "0.6.11"
-proc-macro2 = "0.4.27"
-syn = "0.15.29"
+quote = "1.0.2"
+proc-macro2 = "1.0.2"
+syn = { version = "1.0.5", features = ["full", "extra-traits"] }
diff --git a/dhall_proc_macros/src/lib.rs b/dhall_proc_macros/src/lib.rs
index 5304429..37e8f9f 100644
--- a/dhall_proc_macros/src/lib.rs
+++ b/dhall_proc_macros/src/lib.rs
@@ -1,3 +1,4 @@
+#![feature(drain_filter)]
//! This crate contains the code-generation primitives for the [dhall-rust][dhall-rust] crate.
//! This is highly unstable and breaks regularly; use at your own risk.
//!
@@ -6,6 +7,8 @@
extern crate proc_macro;
mod derive;
+mod make_parser;
+mod parse_children;
use proc_macro::TokenStream;
@@ -13,3 +16,19 @@ use proc_macro::TokenStream;
pub fn derive_static_type(input: TokenStream) -> TokenStream {
derive::derive_static_type(input)
}
+
+#[proc_macro_attribute]
+pub fn make_parser(attrs: TokenStream, input: TokenStream) -> TokenStream {
+ TokenStream::from(match make_parser::make_parser(attrs, input) {
+ Ok(tokens) => tokens,
+ Err(err) => err.to_compile_error(),
+ })
+}
+
+#[proc_macro]
+pub fn parse_children(input: TokenStream) -> TokenStream {
+ TokenStream::from(match parse_children::parse_children(input) {
+ Ok(tokens) => tokens,
+ Err(err) => err.to_compile_error(),
+ })
+}
diff --git a/dhall_proc_macros/src/make_parser.rs b/dhall_proc_macros/src/make_parser.rs
new file mode 100644
index 0000000..268a639
--- /dev/null
+++ b/dhall_proc_macros/src/make_parser.rs
@@ -0,0 +1,111 @@
+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,
+};
+
+fn apply_special_attrs(function: &mut ImplItemMethod) -> Result<()> {
+ *function = parse_quote!(
+ #[allow(non_snake_case, dead_code)]
+ #function
+ );
+
+ let recognized_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 {
+ return Err(Error::new(
+ recognized_attrs[1].span(),
+ "expected a single prec_climb attribute",
+ ));
+ } else {
+ let attr = recognized_attrs.into_iter().next().unwrap();
+ let (child_rule, climber) =
+ attr.parse_args_with(|input: ParseStream| {
+ let child_rule: Ident = input.parse()?;
+ let _: Token![,] = input.parse()?;
+ let climber: Expr = input.parse()?;
+ 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)),
+ |l, op, r| {
+ #name(#first_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",
+ )
+ })?;
+ }
+
+ 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)?;
+ imp.items
+ .iter_mut()
+ .map(|item| match item {
+ ImplItem::Method(m) => apply_special_attrs(m),
+ _ => Ok(()),
+ })
+ .collect::<Result<()>>()?;
+
+ 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;
+ }
+
+ #imp
+ ))
+}
diff --git a/dhall_proc_macros/src/parse_children.rs b/dhall_proc_macros/src/parse_children.rs
new file mode 100644
index 0000000..c78adbc
--- /dev/null
+++ b/dhall_proc_macros/src/parse_children.rs
@@ -0,0 +1,212 @@
+use proc_macro2::{Span, TokenStream};
+use quote::quote;
+use syn::parse::{Parse, ParseStream, Result};
+use syn::punctuated::Punctuated;
+use syn::spanned::Spanned;
+use syn::{bracketed, parenthesized, token, Error, Expr, Ident, Pat, Token};
+
+#[derive(Debug, Clone)]
+struct ChildrenBranch {
+ pattern_span: Span,
+ pattern: Punctuated<ChildrenBranchPatternItem, Token![,]>,
+ body: Expr,
+}
+
+#[derive(Debug, Clone)]
+enum ChildrenBranchPatternItem {
+ Single { rule_name: Ident, binder: Pat },
+ Multiple { rule_name: Ident, binder: Ident },
+}
+
+#[derive(Debug, Clone)]
+struct ParseChildrenInput {
+ input_expr: Expr,
+ branches: Punctuated<ChildrenBranch, Token![,]>,
+}
+
+impl Parse for ChildrenBranch {
+ fn parse(input: ParseStream) -> Result<Self> {
+ let contents;
+ let _: token::Bracket = bracketed!(contents in input);
+ let pattern_unparsed: TokenStream = contents.fork().parse()?;
+ let pattern_span = pattern_unparsed.span();
+ let pattern = Punctuated::parse_terminated(&contents)?;
+ let _: Token![=>] = input.parse()?;
+ let body = input.parse()?;
+
+ Ok(ChildrenBranch {
+ pattern_span,
+ pattern,
+ body,
+ })
+ }
+}
+
+impl Parse for ChildrenBranchPatternItem {
+ fn parse(input: ParseStream) -> Result<Self> {
+ let contents;
+ let rule_name = input.parse()?;
+ parenthesized!(contents in input);
+ if input.peek(Token![..]) {
+ let binder = contents.parse()?;
+ let _: Token![..] = input.parse()?;
+ Ok(ChildrenBranchPatternItem::Multiple { rule_name, binder })
+ } else if input.is_empty() || input.peek(Token![,]) {
+ let binder = contents.parse()?;
+ Ok(ChildrenBranchPatternItem::Single { rule_name, binder })
+ } else {
+ Err(input.error("expected `..` or nothing"))
+ }
+ }
+}
+
+impl Parse for ParseChildrenInput {
+ fn parse(input: ParseStream) -> Result<Self> {
+ let input_expr = input.parse()?;
+ let _: Token![;] = input.parse()?;
+ let branches = Punctuated::parse_terminated(input)?;
+
+ Ok(ParseChildrenInput {
+ input_expr,
+ branches,
+ })
+ }
+}
+
+fn make_parser_branch(
+ branch: &ChildrenBranch,
+ i_inputs: &Ident,
+) -> Result<TokenStream> {
+ use ChildrenBranchPatternItem::{Multiple, Single};
+
+ let body = &branch.body;
+
+ // Convert the input pattern into a pattern-match on the Rules of the children. This uses
+ // slice_patterns.
+ // A single pattern just checks that the rule matches; a variable-length pattern binds the
+ // subslice and checks, in the if-guard, that its elements all match the chosen Rule.
+ 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)
+ }
+ Multiple { .. } => quote!(#i_variable_pattern..),
+ });
+ let match_filter = branch.pattern.iter().map(|item| match item {
+ Single { .. } => quote!(),
+ Multiple { rule_name, .. } => quote!(
+ {
+ // We can't use .all() directly in the pattern guard; see
+ // https://github.com/rust-lang/rust/issues/59803.
+ let all_match = |slice: &[_]| {
+ slice.iter().all(|r|
+ r == &<<Self as PestConsumer>::RuleEnum>::#rule_name
+ )
+ };
+ all_match(#i_variable_pattern)
+ } &&
+ ),
+ });
+
+ // Once we have found a branch that matches, we need to parse the children.
+ let mut singles_before_multiple = Vec::new();
+ let mut multiple = None;
+ let mut singles_after_multiple = Vec::new();
+ for item in &branch.pattern {
+ match item {
+ Single {
+ rule_name, binder, ..
+ } => {
+ if multiple.is_none() {
+ singles_before_multiple.push((rule_name, binder))
+ } else {
+ singles_after_multiple.push((rule_name, binder))
+ }
+ }
+ Multiple {
+ rule_name, binder, ..
+ } => {
+ if multiple.is_none() {
+ multiple = Some((rule_name, binder))
+ } else {
+ return Err(Error::new(
+ branch.pattern_span.clone(),
+ "multiple variable-length patterns are not allowed",
+ ));
+ }
+ }
+ }
+ }
+ let mut parses = Vec::new();
+ for (rule_name, binder) in singles_before_multiple.into_iter() {
+ parses.push(quote!(
+ let #binder = Self::#rule_name(
+ #i_inputs.next().unwrap()
+ )?;
+ ))
+ }
+ // Note the `rev()`: we are taking inputs from the end of the iterator in reverse order, so that
+ // only the unmatched inputs are left for the variable-length pattern, if any.
+ for (rule_name, binder) in singles_after_multiple.into_iter().rev() {
+ parses.push(quote!(
+ let #binder = Self::#rule_name(
+ #i_inputs.next_back().unwrap()
+ )?;
+ ))
+ }
+ if let Some((rule_name, binder)) = multiple {
+ parses.push(quote!(
+ let #binder = #i_inputs
+ .map(|i| Self::#rule_name(i))
+ .collect::<Result<Vec<_>, _>>()?
+ .into_iter();
+ ))
+ }
+
+ Ok(quote!(
+ [#(#match_pat),*] if #(#match_filter)* true => {
+ #(#parses)*
+ #body
+ }
+ ))
+}
+
+pub fn parse_children(
+ input: proc_macro::TokenStream,
+) -> Result<proc_macro2::TokenStream> {
+ let input: ParseChildrenInput = syn::parse(input)?;
+
+ let i_children_rules = Ident::new("___children_rules", Span::call_site());
+ let i_inputs = Ident::new("___inputs", Span::call_site());
+
+ let input_expr = &input.input_expr;
+ let branches = input
+ .branches
+ .iter()
+ .map(|br| make_parser_branch(br, &i_inputs))
+ .collect::<Result<Vec<_>>>()?;
+
+ Ok(quote!({
+ let #i_children_rules: Vec<_> = #input_expr.pair
+ .clone()
+ .into_inner()
+ .map(|p| p.as_rule())
+ .collect();
+
+ #[allow(unused_mut)]
+ let mut #i_inputs = #input_expr
+ .pair
+ .clone()
+ .into_inner()
+ .map(|p| #input_expr.with_pair(p));
+
+ #[allow(unreachable_code)]
+ match #i_children_rules.as_slice() {
+ #(#branches,)*
+ [..] => return Err(#input_expr.error(
+ format!("Unexpected children: {:?}", #i_children_rules)
+ )),
+ }
+ }))
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-22 20:31:08 +0000