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use std::env;
use std::fs::File;
use std::io::{BufRead, BufReader, Read, Write};
use std::path::Path;
use abnf_to_pest::render_rules_to_pest;
fn main() -> std::io::Result<()> {
// TODO: upstream changes to grammar
// let abnf_path = "../dhall-lang/standard/dhall.abnf";
let abnf_path = "src/dhall.abnf";
let visibility_path = "src/dhall.pest.visibility";
let pest_path = "src/dhall.pest";
println!("cargo:rerun-if-changed={}", abnf_path);
println!("cargo:rerun-if-changed={}", visibility_path);
let mut file = File::open(abnf_path)?;
let mut data = Vec::new();
file.read_to_end(&mut data)?;
data.push('\n' as u8);
let mut rules = abnf_to_pest::parse_abnf(&data)?;
for line in BufReader::new(File::open(visibility_path)?).lines() {
let line = line?;
if line.len() >= 2 && &line[0..2] == "# " {
rules.get_mut(&line[2..]).map(|x| x.silent = true);
}
}
let mut file = File::create(pest_path)?;
writeln!(&mut file, "// AUTO-GENERATED FILE. See build.rs.")?;
// TODO: this is a cheat; properly support RFC3986 URLs instead
rules.remove("url_path");
writeln!(&mut file, "url_path = _{{ path }}")?;
rules.remove("simple_label");
writeln!(
&mut file,
"simple_label = {{
keyword ~ simple_label_next_char+
| !keyword ~ simple_label_first_char ~ simple_label_next_char*
}}"
)?;
rules.remove("nonreserved_label");
writeln!(
&mut file,
"nonreserved_label = _{{
!(builtin ~ !simple_label_next_char) ~ label
}}"
)?;
// Setup grammar for precedence climbing
rules.remove("operator_expression");
writeln!(&mut file, r##"
import_alt = {{ "?" ~ whsp1 }}
bool_or = {{ "||" }}
natural_plus = {{ "+" ~ whsp1 }}
text_append = {{ "++" }}
list_append = {{ "#" }}
bool_and = {{ "&&" }}
natural_times = {{ "*" }}
bool_eq = {{ "==" }}
bool_ne = {{ "!=" }}
operator = _{{
equivalent |
bool_ne |
bool_eq |
natural_times |
combine_types |
prefer |
combine |
bool_and |
list_append |
text_append |
natural_plus |
bool_or |
import_alt
}}
operator_expression = {{ application_expression ~ (whsp ~ operator ~ whsp ~ application_expression)* }}
"##)?;
writeln!(
&mut file,
"final_expression = ${{ SOI ~ complete_expression ~ EOI }}"
)?;
writeln!(&mut file)?;
writeln!(&mut file, "{}", render_rules_to_pest(rules).pretty(80))?;
// Generate pest parser manually to avoid spurious recompilations
let derived = {
let pest_path = "dhall.pest";
let pest = quote::quote! {
#[grammar = #pest_path]
pub struct DhallParser;
};
pest_generator::derive_parser(pest, false)
};
let out_dir = env::var("OUT_DIR").unwrap();
let grammar_path = Path::new(&out_dir).join("grammar.rs");
let mut file = File::create(grammar_path)?;
writeln!(file, "pub struct DhallParser;\n{}", derived,)?;
Ok(())
}
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