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//! <div align="center">
//!     <img alt="Rune Logo" src="https://raw.githubusercontent.com/rune-rs/rune/main/assets/icon.png" />
//! </div>
//!
//! <br>
//!
//! <div align="center">
//! <a href="https://rune-rs.github.io">
//!     <b>Visit the site 🌐</b>
//! </a>
//! -
//! <a href="https://rune-rs.github.io/book/">
//!     <b>Read the book 📖</b>
//! </a>
//! </div>
//!
//! <br>
//!
//! <div align="center">
//! <a href="https://github.com/rune-rs/rune/actions">
//!     <img alt="Build Status" src="https://github.com/rune-rs/rune/workflows/Build/badge.svg">
//! </a>
//!
//! <a href="https://github.com/rune-rs/rune/actions">
//!     <img alt="Site Status" src="https://github.com/rune-rs/rune/workflows/Site/badge.svg">
//! </a>
//!
//! <a href="https://crates.io/crates/rune">
//!     <img alt="crates.io" src="https://img.shields.io/crates/v/rune.svg">
//! </a>
//!
//! <a href="https://docs.rs/rune">
//!     <img alt="docs.rs" src="https://docs.rs/rune/badge.svg">
//! </a>
//!
//! <a href="https://discord.gg/v5AeNkT">
//!     <img alt="Chat on Discord" src="https://img.shields.io/discord/558644981137670144.svg?logo=discord&style=flat-square">
//! </a>
//! </div>
//!
//! <br>
//!
//! Macros for Rune.
//!
//! This is part of the [Rune Language](https://rune-rs.github.io).

extern crate proc_macro;

mod context;
mod internals;
mod option_spanned;
mod parse;
mod quote;
mod spanned;
mod to_tokens;

/// Helper derive to implement `ToTokens`.
#[proc_macro_derive(ToTokens, attributes(rune))]
#[doc(hidden)]
pub fn to_tokens(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
    let derive = syn::parse_macro_input!(input as to_tokens::Derive);
    derive.expand().unwrap_or_else(to_compile_errors).into()
}

/// Helper derive to implement `Parse`.
#[proc_macro_derive(Parse, attributes(rune))]
#[doc(hidden)]
pub fn parse(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
    let derive = syn::parse_macro_input!(input as parse::Derive);
    derive.expand().unwrap_or_else(to_compile_errors).into()
}

/// Helper derive to implement `Spanned`.
#[proc_macro_derive(Spanned, attributes(rune))]
#[doc(hidden)]
pub fn spanned(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
    let derive = syn::parse_macro_input!(input as spanned::Derive);
    derive.expand().unwrap_or_else(to_compile_errors).into()
}

/// Helper derive to implement `OptionSpanned`.
#[proc_macro_derive(OptionSpanned, attributes(rune))]
#[doc(hidden)]
pub fn option_spanned(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
    let derive = syn::parse_macro_input!(input as option_spanned::Derive);
    derive.expand().unwrap_or_else(to_compile_errors).into()
}

/// Macro helper function for quoting the token stream as macro output.
///
/// Is capable of quoting everything in Rune, except for the following:
/// * Labels, which must be created using `Label::new`.
/// * Dynamic quoted strings and other literals, which must be created using
///   `Lit::new`.
///
/// # Panics
///
/// Calling this macro will panic if called outside of a macro context. A macro
/// context can be setup using `with_context`.
///
/// ```rust
/// use rune::macros::{with_context, MacroContext};
/// let ctx = MacroContext::empty();
///
/// with_context(ctx, || {
///     rune::quote!(hello self);
/// });
/// ```
///
/// # Interpolating values
///
/// Values are interpolated with `#value`, or `#(value + 1)` for expressions.
///
/// # Iterators
///
/// Anything that can be used as an iterator can be iterated over with
/// `#(iter)*`. A token can also be used to join inbetween each iteration, like
/// `#(iter),*`.
#[proc_macro]
pub fn quote(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
    let input = proc_macro2::TokenStream::from(input);
    let parser = crate::quote::Quote::new();

    let output = match parser.parse(input) {
        Ok(output) => output,
        Err(e) => return proc_macro::TokenStream::from(e.to_compile_error()),
    };

    output.into()
}

fn to_compile_errors(errors: Vec<syn::Error>) -> proc_macro2::TokenStream {
    let compile_errors = errors.iter().map(syn::Error::to_compile_error);
    ::quote::quote!(#(#compile_errors)*)
}