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-rw-r--r--pest_consume_macros/src/match_nodes.rs248
1 files changed, 0 insertions, 248 deletions
diff --git a/pest_consume_macros/src/match_nodes.rs b/pest_consume_macros/src/match_nodes.rs
deleted file mode 100644
index a91d1f4..0000000
--- a/pest_consume_macros/src/match_nodes.rs
+++ /dev/null
@@ -1,248 +0,0 @@
-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, parse_quote, token, Error, Expr, Ident, Pat,
- Token, Type,
-};
-
-#[derive(Clone)]
-struct MatchBranch {
- // Patterns all have the form [a, b, c.., d], with a bunch of simple patterns,
- // optionally a multiple pattern, and then some more simple patterns.
- singles_before_multiple: Vec<(Ident, Pat)>,
- multiple: Option<(Ident, Ident)>,
- singles_after_multiple: Vec<(Ident, Pat)>,
-
- body: Expr,
-}
-
-#[derive(Clone)]
-enum MatchBranchPatternItem {
- Single {
- rule_name: Ident,
- binder: Pat,
- },
- Multiple {
- rule_name: Ident,
- binder: Ident,
- slice_token: Token![..],
- },
-}
-
-#[derive(Clone)]
-struct MacroInput {
- parser: Type,
- input_expr: Expr,
- branches: Punctuated<MatchBranch, Token![,]>,
-}
-
-impl Parse for MatchBranch {
- fn parse(input: ParseStream) -> Result<Self> {
- let contents;
- let _: token::Bracket = bracketed!(contents in input);
-
- let pattern: Punctuated<MatchBranchPatternItem, Token![,]> =
- Punctuated::parse_terminated(&contents)?;
- use MatchBranchPatternItem::{Multiple, Single};
- let mut singles_before_multiple = Vec::new();
- let mut multiple = None;
- let mut singles_after_multiple = Vec::new();
- for item in pattern.clone() {
- 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,
- slice_token,
- } => {
- if multiple.is_none() {
- multiple = Some((rule_name, binder))
- } else {
- return Err(Error::new(
- slice_token.span(),
- "multiple variable-length patterns are not allowed",
- ));
- }
- }
- }
- }
-
- let _: Token![=>] = input.parse()?;
- let body = input.parse()?;
-
- Ok(MatchBranch {
- singles_before_multiple,
- multiple,
- singles_after_multiple,
- body,
- })
- }
-}
-
-impl Parse for MatchBranchPatternItem {
- 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 slice_token = input.parse()?;
- Ok(MatchBranchPatternItem::Multiple {
- rule_name,
- binder,
- slice_token,
- })
- } else if input.is_empty() || input.peek(Token![,]) {
- let binder = contents.parse()?;
- Ok(MatchBranchPatternItem::Single { rule_name, binder })
- } else {
- Err(input.error("expected `..` or nothing"))
- }
- }
-}
-
-impl Parse for MacroInput {
- fn parse(input: ParseStream) -> Result<Self> {
- let parser = if input.peek(token::Lt) {
- let _: token::Lt = input.parse()?;
- let parser = input.parse()?;
- let _: token::Gt = input.parse()?;
- let _: Token![;] = input.parse()?;
- parser
- } else {
- parse_quote!(Self)
- };
- let input_expr = input.parse()?;
- let _: Token![;] = input.parse()?;
- let branches = Punctuated::parse_terminated(input)?;
-
- Ok(MacroInput {
- parser,
- input_expr,
- branches,
- })
- }
-}
-
-fn make_branch(
- branch: &MatchBranch,
- i_nodes: &Ident,
- i_node_rules: &Ident,
- parser: &Type,
-) -> Result<TokenStream> {
- let aliased_rule = quote!(<#parser as ::pest_consume::Parser>::AliasedRule);
-
- // Find which branch to take
- let mut conditions = Vec::new();
- let start = branch.singles_before_multiple.len();
- let end = branch.singles_after_multiple.len();
- conditions.push(quote!(
- #start + #end <= #i_node_rules.len()
- ));
- for (i, (rule_name, _)) in branch.singles_before_multiple.iter().enumerate()
- {
- conditions.push(quote!(
- #i_node_rules[#i] == #aliased_rule::#rule_name
- ))
- }
- for (i, (rule_name, _)) in branch.singles_after_multiple.iter().enumerate()
- {
- conditions.push(quote!(
- #i_node_rules[#i_node_rules.len()-1 - #i] == #aliased_rule::#rule_name
- ))
- }
- if let Some((rule_name, _)) = &branch.multiple {
- conditions.push(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 == #aliased_rule::#rule_name
- )
- };
- all_match(&#i_node_rules[#start..#i_node_rules.len() - #end])
- }
- ))
- } else {
- // No variable-length pattern, so the size must be exactly the number of patterns
- conditions.push(quote!(
- #start + #end == #i_node_rules.len()
- ))
- }
-
- // Once we have found a branch that matches, we need to parse the nodes.
- let mut parses = Vec::new();
- for (rule_name, binder) in branch.singles_before_multiple.iter() {
- parses.push(quote!(
- let #binder = #parser::#rule_name(
- #i_nodes.next().unwrap()
- )?;
- ))
- }
- // Note the `rev()`: we are taking nodes from the end of the iterator in reverse order, so that
- // only the unmatched nodes are left in the iterator for the variable-length pattern, if any.
- for (rule_name, binder) in branch.singles_after_multiple.iter().rev() {
- parses.push(quote!(
- let #binder = #parser::#rule_name(
- #i_nodes.next_back().unwrap()
- )?;
- ))
- }
- if let Some((rule_name, binder)) = &branch.multiple {
- parses.push(quote!(
- let #binder = #i_nodes
- .map(|i| #parser::#rule_name(i))
- .collect::<::std::result::Result<::std::vec::Vec<_>, _>>()?
- .into_iter();
- ))
- }
-
- let body = &branch.body;
- Ok(quote!(
- _ if #(#conditions &&)* true => {
- #(#parses)*
- #body
- }
- ))
-}
-
-pub fn match_nodes(
- input: proc_macro::TokenStream,
-) -> Result<proc_macro2::TokenStream> {
- let input: MacroInput = syn::parse(input)?;
-
- let i_nodes = Ident::new("___nodes", input.input_expr.span());
- let i_node_rules = Ident::new("___node_rules", Span::call_site());
-
- let input_expr = &input.input_expr;
- let parser = &input.parser;
- let branches = input
- .branches
- .iter()
- .map(|br| make_branch(br, &i_nodes, &i_node_rules, parser))
- .collect::<Result<Vec<_>>>()?;
-
- Ok(quote!({
- #[allow(unused_mut)]
- let mut #i_nodes = #input_expr;
- let #i_node_rules = #i_nodes.aliased_rules::<#parser>();
-
- #[allow(unreachable_code)]
- match () {
- #(#branches,)*
- _ => return ::std::result::Result::Err(#i_nodes.error(
- std::format!("Nodes didn't match any pattern: {:?}", #i_node_rules)
- )),
- }
- }))
-}
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