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use std::fs::File;
use std::io::{Read,Write,BufReader,BufRead};
use std::collections::HashMap;
use itertools::Itertools;
use lalrpop;
struct PestRuleSettings {
visible: bool,
replace: Option<String>,
}
impl Default for PestRuleSettings {
fn default() -> Self { PestRuleSettings { visible: true, replace: None } }
}
fn abnf_to_pest(data: &Vec<u8>, rule_settings: &HashMap<String, PestRuleSettings>) -> std::io::Result<String> {
use abnf::abnf::*;
use pretty::{Doc, BoxDoc};
fn format_rule(x: Rule, rule_settings: &HashMap<String, PestRuleSettings>) -> Doc<BoxDoc<()>> {
let rulename = format_rulename(x.name);
let default = Default::default();
let setting = rule_settings.get(&rulename).unwrap_or(&default);
let visible = if setting.visible { "" } else { "_" };
let contents = match setting.replace {
None => format_alternation(x.elements),
Some(ref x) => Doc::text(x.clone()),
};
Doc::nil()
.append(Doc::text(rulename))
.append(Doc::text(" = "))
.append(Doc::text(visible))
.append(Doc::text("{"))
.append(Doc::space().append(contents).nest(2))
.append(Doc::space())
.append(Doc::text("}"))
.group()
}
fn format_rulename(x: String) -> String {
let x = x.replace("-", "_");
if x == "if" || x == "else" || x == "as" || x == "let" || x == "in" || x == "fn" {
x + "_"
} else {
x
}
}
fn format_alternation(x: Alternation) -> Doc<'static, BoxDoc<'static, ()>> {
Doc::intersperse(
x.concatenations.into_iter().map(format_concatenation),
Doc::space().append(Doc::text("| "))
)
}
fn format_concatenation(x: Concatenation) -> Doc<'static, BoxDoc<'static, ()>> {
Doc::intersperse(
x.repetitions.into_iter().map(format_repetition),
Doc::text(" ~ ")
)
}
fn format_repetition(x: Repetition) -> Doc<'static, BoxDoc<'static, ()>> {
format_element(x.element)
.append(x.repeat.map(format_repeat).map(Doc::text).unwrap_or(Doc::nil()))
}
fn format_repeat(x: Repeat) -> String {
match (x.min.unwrap_or(0), x.max) {
(0, None) => "*".into(),
(1, None) => "+".into(),
(0, Some(1)) => "?".into(),
(min, None) => format!("{{{},}}", min),
(min, Some(max)) if min == max => format!("{{{}}}", min),
(min, Some(max)) => format!("{{{},{}}}", min, max),
}
}
fn format_element(x: Element) -> Doc<'static, BoxDoc<'static, ()>> {
use abnf::abnf::Element::*;
match x {
Rulename(s) => Doc::text(format_rulename(s)),
Group(g) =>
Doc::text("(")
.append(format_alternation(g.alternation).nest(4).group())
.append(Doc::text(")")),
Option(o) =>
Doc::text("(")
.append(format_alternation(o.alternation).nest(4).group())
.append(Doc::text(")?")),
CharVal(s) => Doc::text(format!("^\"{}\"", s.replace("\"", "\\\"").replace("\\", "\\\\"))),
NumVal(r) => Doc::text(format_range(r)),
ProseVal(_) => unimplemented!(),
}
}
fn format_range(x: Range) -> String {
use abnf::abnf::Range::*;
match x {
Range(x, y) => format!("'{}'..'{}'", format_char(x), format_char(y)),
OneOf(v) => format!("\"{}\"", v.into_iter().map(format_char).join("")),
}
}
fn format_char(x: u64) -> String {
if x <= (u8::max_value() as u64) {
let x: u8 = x as u8;
if x.is_ascii_graphic() {
let x: char = x as char;
if x != '"' && x != '\'' && x != '\\' {
return x.to_string();
}
}
}
format!("\\u{{{:02X}}}", x)
}
let make_err = |e| std::io::Error::new(std::io::ErrorKind::Other, format!("{}", e));
let rules = rulelist_comp(&data).map_err(make_err)?.1;
let formatted_rules = rules.into_iter().map(|x| format_rule(x, rule_settings));
let doc: Doc<_> = Doc::intersperse(formatted_rules, Doc::newline());
Ok(format!("{}", doc.pretty(80)))
}
fn main() -> std::io::Result<()> {
lalrpop::process_root().unwrap();
println!("cargo:rerun-if-changed=src/grammar.lalrpop");
let abnf_path = "dhall-lang/standard/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 rule_settings: HashMap<String, PestRuleSettings> = HashMap::new();
for line in BufReader::new(File::open(visibility_path)?).lines() {
let line = line?;
if line.len() >= 2 && &line[0..2] == "# " {
rule_settings.insert(line[2..].into(), PestRuleSettings { visible: false, ..Default::default() });
} else {
rule_settings.insert(line, PestRuleSettings { visible: true, ..Default::default() });
}
}
let mut file = File::create(pest_path)?;
writeln!(&mut file, "{}", abnf_to_pest(&data, &rule_settings)?)?;
writeln!(&mut file, "final_expression = _{{ SOI ~ complete_expression ~ EOI }}")?;
Ok(())
}
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