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extern crate proc_macro;
extern crate proc_macro2;
extern crate quote;

use peg::Parse;
use quote::quote_spanned;

// This can't use the `peg` crate as it would be a circular dependency, but the generated code in grammar.rs
// requires `::peg` paths.
extern crate peg_runtime as peg;

mod analysis;
mod ast;
mod grammar;
mod tokens;
mod translate;

/// The main macro for creating a PEG parser.
///
/// For the grammar syntax, see the `peg` crate documentation.
#[proc_macro]
pub fn parser(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
    let tokens = tokens::FlatTokenStream::new(input.into());
    let grammar = match grammar::peg::peg_grammar(&tokens) {
        Ok(g) => g,
        Err(err) => {
            let msg = if tokens.is_eof(err.location.1) {
                format!("expected {} at end of input", err.expected)
            } else {
                format!("expected {}", err.expected)
            };
            return quote_spanned!(err.location.0=> compile_error!(#msg);).into();
        }
    };

    translate::compile_grammar(&grammar).into()
}