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    use super::*;
    use crate::token::{Brace, Bracket, Paren};
    use proc_macro2::TokenStream;
    #[cfg(feature = "parsing")]
    use proc_macro2::{Delimiter, Group, Span, TokenTree};

    #[cfg(feature = "parsing")]
    use crate::parse::{Parse, ParseStream, Parser, Result};

    ast_struct! {
        /// A macro invocation: `println!("{}", mac)`.
        ///
        /// *This type is available only if Syn is built with the `"derive"` or `"full"`
        /// feature.*
        #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
        pub struct Macro {
            pub path: Path,
            pub bang_token: Token![!],
            pub delimiter: MacroDelimiter,
            pub tokens: TokenStream,
        }
    }

    ast_enum! {
        /// A grouping token that surrounds a macro body: `m!(...)` or `m!{...}` or `m![...]`.
        ///
        /// *This type is available only if Syn is built with the `"derive"` or `"full"`
        /// feature.*
        #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
        pub enum MacroDelimiter {
            Paren(Paren),
            Brace(Brace),
            Bracket(Bracket),
        }
    }

    #[cfg(feature = "parsing")]
    fn delimiter_span_close(macro_delimiter: &MacroDelimiter) -> Span {
        let delimiter = match macro_delimiter {
            MacroDelimiter::Paren(_) => Delimiter::Parenthesis,
            MacroDelimiter::Brace(_) => Delimiter::Brace,
            MacroDelimiter::Bracket(_) => Delimiter::Bracket,
        };
        let mut group = Group::new(delimiter, TokenStream::new());
        group.set_span(match macro_delimiter {
            MacroDelimiter::Paren(token) => token.span,
            MacroDelimiter::Brace(token) => token.span,
            MacroDelimiter::Bracket(token) => token.span,
        });
        group.span_close()
    }

    impl Macro {
        /// Parse the tokens within the macro invocation's delimiters into a syntax
        /// tree.
        ///
        /// This is equivalent to `syn::parse2::<T>(mac.tokens)` except that it
        /// produces a more useful span when `tokens` is empty.
        ///
        /// # Example
        ///
        /// ```
        /// use syn::{parse_quote, Expr, ExprLit, Ident, Lit, LitStr, Macro, Token};
        /// use syn::ext::IdentExt;
        /// use syn::parse::{Error, Parse, ParseStream, Result};
        /// use syn::punctuated::Punctuated;
        ///
        /// // The arguments expected by libcore's format_args macro, and as a
        /// // result most other formatting and printing macros like println.
        /// //
        /// //     println!("{} is {number:.prec$}", "x", prec=5, number=0.01)
        /// struct FormatArgs {
        ///     format_string: Expr,
        ///     positional_args: Vec<Expr>,
        ///     named_args: Vec<(Ident, Expr)>,
        /// }
        ///
        /// impl Parse for FormatArgs {
        ///     fn parse(input: ParseStream) -> Result<Self> {
        ///         let format_string: Expr;
        ///         let mut positional_args = Vec::new();
        ///         let mut named_args = Vec::new();
        ///
        ///         format_string = input.parse()?;
        ///         while !input.is_empty() {
        ///             input.parse::<Token![,]>()?;
        ///             if input.is_empty() {
        ///                 break;
        ///             }
        ///             if input.peek(Ident::peek_any) && input.peek2(Token![=]) {
        ///                 while !input.is_empty() {
        ///                     let name: Ident = input.call(Ident::parse_any)?;
        ///                     input.parse::<Token![=]>()?;
        ///                     let value: Expr = input.parse()?;
        ///                     named_args.push((name, value));
        ///                     if input.is_empty() {
        ///                         break;
        ///                     }
        ///                     input.parse::<Token![,]>()?;
        ///                 }
        ///                 break;
        ///             }
        ///             positional_args.push(input.parse()?);
        ///         }
        ///
        ///         Ok(FormatArgs {
        ///             format_string,
        ///             positional_args,
        ///             named_args,
        ///         })
        ///     }
        /// }
        ///
        /// // Extract the first argument, the format string literal, from an
        /// // invocation of a formatting or printing macro.
        /// fn get_format_string(m: &Macro) -> Result<LitStr> {
        ///     let args: FormatArgs = m.parse_body()?;
        ///     match args.format_string {
        ///         Expr::Lit(ExprLit { lit: Lit::Str(lit), .. }) => Ok(lit),
        ///         other => {
        ///             // First argument was not a string literal expression.
        ///             // Maybe something like: println!(concat!(...), ...)
        ///             Err(Error::new_spanned(other, "format string must be a string literal"))
        ///         }
        ///     }
        /// }
        ///
        /// fn main() {
        ///     let invocation = parse_quote! {
        ///         println!("{:?}", Instant::now())
        ///     };
        ///     let lit = get_format_string(&invocation).unwrap();
        ///     assert_eq!(lit.value(), "{:?}");
        /// }
        /// ```
        #[cfg(feature = "parsing")]
        #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
        pub fn parse_body<T: Parse>(&self) -> Result<T> {
            self.parse_body_with(T::parse)
        }

        /// Parse the tokens within the macro invocation's delimiters using the
        /// given parser.
        #[cfg(feature = "parsing")]
        #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
        pub fn parse_body_with<F: Parser>(&self, parser: F) -> Result<F::Output> {
            let scope = delimiter_span_close(&self.delimiter);
            crate::parse::parse_scoped(parser, scope, self.tokens.clone())
        }
    }

    #[cfg(feature = "parsing")]
    pub fn parse_delimiter(input: ParseStream) -> Result<(MacroDelimiter, TokenStream)> {
        input.step(|cursor| {
            if let Some((TokenTree::Group(g), rest)) = cursor.token_tree() {
                let span = g.span();
                let delimiter = match g.delimiter() {
                    Delimiter::Parenthesis => MacroDelimiter::Paren(Paren(span)),
                    Delimiter::Brace => MacroDelimiter::Brace(Brace(span)),
                    Delimiter::Bracket => MacroDelimiter::Bracket(Bracket(span)),
                    Delimiter::None => {
                        return Err(cursor.error("expected delimiter"));
                    }
                };
                Ok(((delimiter, g.stream()), rest))
            } else {
                Err(cursor.error("expected delimiter"))
            }
        })
    }

    #[cfg(feature = "parsing")]
    pub mod parsing {
        use super::*;
        use crate::parse::{Parse, ParseStream, Result};

        #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
        impl Parse for Macro {
            fn parse(input: ParseStream) -> Result<Self> {
                let tokens;
                Ok(Macro {
                    path: input.call(Path::parse_mod_style)?,
                    bang_token: input.parse()?,
                    delimiter: {
                        let (delimiter, content) = parse_delimiter(input)?;
                        tokens = content;
                        delimiter
                    },
                    tokens,
                })
            }
        }
    }

    #[cfg(feature = "printing")]
    mod printing {
        use super::*;
        use proc_macro2::TokenStream;
        use quote::ToTokens;

        #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
        impl ToTokens for Macro {
            fn to_tokens(&self, tokens: &mut TokenStream) {
                self.path.to_tokens(tokens);
                self.bang_token.to_tokens(tokens);
                match &self.delimiter {
                    MacroDelimiter::Paren(paren) => {
                        paren.surround(tokens, |tokens| self.tokens.to_tokens(tokens));
                    }
                    MacroDelimiter::Brace(brace) => {
                        brace.surround(tokens, |tokens| self.tokens.to_tokens(tokens));
                    }
                    MacroDelimiter::Bracket(bracket) => {
                        bracket.surround(tokens, |tokens| self.tokens.to_tokens(tokens));
                    }
                }
            }
        }
    }