Vendor things

third-party/vendor/proc-macro-hack/src/parse.rs

@@ -0,0 +1,254 @@
+use crate::iter::{self, Iter, IterImpl};
+use crate::{Define, Error, Export, ExportArgs, FakeCallSite, Input, Macro, Visibility};
+use proc_macro::Delimiter::{Brace, Bracket, Parenthesis};
+use proc_macro::{Delimiter, Ident, Span, TokenStream, TokenTree};
+
+pub(crate) fn parse_input(tokens: Iter) -> Result<Input, Error> {
+    let attrs = parse_attributes(tokens)?;
+    let vis = parse_visibility(tokens);
+    let kw = parse_ident(tokens)?;
+    if kw.to_string() == "use" {
+        parse_export(attrs, vis, tokens).map(Input::Export)
+    } else if kw.to_string() == "fn" {
+        parse_define(attrs, vis, kw.span(), tokens).map(Input::Define)
+    } else {
+        Err(Error::new(
+            kw.span(),
+            "unexpected input to #[proc_macro_hack]",
+        ))
+    }
+}
+
+fn parse_export(attrs: TokenStream, vis: Visibility, tokens: Iter) -> Result<Export, Error> {
+    let _ = parse_punct(tokens, ':');
+    let _ = parse_punct(tokens, ':');
+    let from = parse_ident(tokens)?;
+    parse_punct(tokens, ':')?;
+    parse_punct(tokens, ':')?;
+
+    let mut macros = Vec::new();
+    match tokens.peek() {
+        Some(TokenTree::Group(group)) if group.delimiter() == Brace => {
+            let ref mut content = iter::new(group.stream());
+            loop {
+                macros.push(parse_macro(content)?);
+                if content.peek().is_none() {
+                    break;
+                }
+                parse_punct(content, ',')?;
+                if content.peek().is_none() {
+                    break;
+                }
+            }
+            tokens.next().unwrap();
+        }
+        _ => macros.push(parse_macro(tokens)?),
+    }
+
+    parse_punct(tokens, ';')?;
+    Ok(Export {
+        attrs,
+        vis,
+        from,
+        macros,
+    })
+}
+
+fn parse_punct(tokens: Iter, ch: char) -> Result<(), Error> {
+    match tokens.peek() {
+        Some(TokenTree::Punct(punct)) if punct.as_char() == ch => {
+            tokens.next().unwrap();
+            Ok(())
+        }
+        tt => Err(Error::new(
+            tt.map_or_else(Span::call_site, TokenTree::span),
+            format!("expected `{}`", ch),
+        )),
+    }
+}
+
+fn parse_define(
+    attrs: TokenStream,
+    vis: Visibility,
+    fn_token: Span,
+    tokens: Iter,
+) -> Result<Define, Error> {
+    if vis.is_none() {
+        return Err(Error::new(
+            fn_token,
+            "functions tagged with `#[proc_macro_hack]` must be `pub`",
+        ));
+    }
+    let name = parse_ident(tokens)?;
+    let body = tokens.collect();
+    Ok(Define { attrs, name, body })
+}
+
+fn parse_macro(tokens: Iter) -> Result<Macro, Error> {
+    let name = parse_ident(tokens)?;
+    let export_as = match tokens.peek() {
+        Some(TokenTree::Ident(ident)) if ident.to_string() == "as" => {
+            tokens.next().unwrap();
+            parse_ident(tokens)?
+        }
+        _ => name.clone(),
+    };
+    Ok(Macro { name, export_as })
+}
+
+fn parse_ident(tokens: Iter) -> Result<Ident, Error> {
+    match tokens.next() {
+        Some(TokenTree::Ident(ident)) => Ok(ident),
+        tt => Err(Error::new(
+            tt.as_ref().map_or_else(Span::call_site, TokenTree::span),
+            "expected identifier",
+        )),
+    }
+}
+
+fn parse_keyword(tokens: Iter, kw: &'static str) -> Result<(), Error> {
+    match &tokens.next() {
+        Some(TokenTree::Ident(ident)) if ident.to_string() == kw => Ok(()),
+        tt => Err(Error::new(
+            tt.as_ref().map_or_else(Span::call_site, TokenTree::span),
+            format!("expected `{}`", kw),
+        )),
+    }
+}
+
+fn parse_int(tokens: Iter) -> Result<u16, Span> {
+    match tokens.next() {
+        Some(TokenTree::Literal(lit)) => lit.to_string().parse().map_err(|_| lit.span()),
+        Some(tt) => Err(tt.span()),
+        None => Err(Span::call_site()),
+    }
+}
+
+fn parse_group(tokens: Iter, delimiter: Delimiter) -> Result<IterImpl, Error> {
+    match &tokens.next() {
+        Some(TokenTree::Group(group)) if group.delimiter() == delimiter => {
+            Ok(iter::new(group.stream()))
+        }
+        tt => Err(Error::new(
+            tt.as_ref().map_or_else(Span::call_site, TokenTree::span),
+            "expected delimiter",
+        )),
+    }
+}
+
+fn parse_visibility(tokens: Iter) -> Visibility {
+    if let Some(TokenTree::Ident(ident)) = tokens.peek() {
+        if ident.to_string() == "pub" {
+            match tokens.next().unwrap() {
+                TokenTree::Ident(vis) => return Some(vis),
+                _ => unreachable!(),
+            }
+        }
+    }
+    None
+}
+
+fn parse_attributes(tokens: Iter) -> Result<TokenStream, Error> {
+    let mut attrs = TokenStream::new();
+    while let Some(TokenTree::Punct(punct)) = tokens.peek() {
+        if punct.as_char() != '#' {
+            break;
+        }
+        let span = punct.span();
+        attrs.extend(tokens.next());
+        match tokens.peek() {
+            Some(TokenTree::Group(group)) if group.delimiter() == Bracket => {
+                attrs.extend(tokens.next());
+            }
+            _ => return Err(Error::new(span, "unexpected input")),
+        }
+    }
+    Ok(attrs)
+}
+
+pub(crate) fn parse_export_args(tokens: Iter) -> Result<ExportArgs, Error> {
+    let mut args = ExportArgs {
+        support_nested: false,
+        internal_macro_calls: 0,
+        fake_call_site: false,
+        only_hack_old_rustc: false,
+    };
+
+    while let Some(tt) = tokens.next() {
+        match &tt {
+            TokenTree::Ident(ident) if ident.to_string() == "support_nested" => {
+                args.support_nested = true;
+            }
+            TokenTree::Ident(ident) if ident.to_string() == "internal_macro_calls" => {
+                parse_punct(tokens, '=')?;
+                let calls = parse_int(tokens).map_err(|span| {
+                    Error::new(span, "expected integer value for internal_macro_calls")
+                })?;
+                args.internal_macro_calls = calls;
+            }
+            TokenTree::Ident(ident) if ident.to_string() == "fake_call_site" => {
+                args.fake_call_site = true;
+            }
+            TokenTree::Ident(ident) if ident.to_string() == "only_hack_old_rustc" => {
+                args.only_hack_old_rustc = true;
+            }
+            _ => {
+                return Err(Error::new(
+                    tt.span(),
+                    "expected one of: `support_nested`, `internal_macro_calls`, `fake_call_site`, `only_hack_old_rustc`",
+                ));
+            }
+        }
+        if tokens.peek().is_none() {
+            break;
+        }
+        parse_punct(tokens, ',')?;
+    }
+
+    Ok(args)
+}
+
+pub(crate) fn parse_define_args(tokens: Iter) -> Result<(), Error> {
+    match tokens.peek() {
+        None => Ok(()),
+        Some(token) => Err(Error::new(
+            token.span(),
+            "unexpected argument to proc_macro_hack macro implementation; args are only accepted on the macro declaration (the `pub use`)",
+        )),
+    }
+}
+
+pub(crate) fn parse_enum_hack(tokens: Iter) -> Result<TokenStream, Error> {
+    parse_keyword(tokens, "enum")?;
+    parse_ident(tokens)?;
+
+    let ref mut braces = parse_group(tokens, Brace)?;
+    parse_ident(braces)?;
+    parse_punct(braces, '=')?;
+
+    let ref mut parens = parse_group(braces, Parenthesis)?;
+    parse_ident(parens)?;
+    parse_punct(parens, '!')?;
+
+    let ref mut inner = parse_group(parens, Brace)?;
+    let token_stream = inner.collect();
+
+    parse_punct(parens, ',')?;
+    let _ = parens.next();
+    parse_punct(braces, '.')?;
+    let _ = braces.next();
+    parse_punct(braces, ',')?;
+
+    Ok(token_stream)
+}
+
+pub(crate) fn parse_fake_call_site(tokens: Iter) -> Result<FakeCallSite, Error> {
+    parse_punct(tokens, '#')?;
+    let ref mut attr = parse_group(tokens, Bracket)?;
+    parse_keyword(attr, "derive")?;
+    let ref mut path = parse_group(attr, Parenthesis)?;
+    Ok(FakeCallSite {
+        derive: parse_ident(path)?,
+        rest: tokens.collect(),
+    })
+}