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|
use itertools::Itertools;
use std::collections::HashMap;
pub struct PestRuleSettings {
pub visible: bool,
pub replace: Option<String>,
}
impl Default for PestRuleSettings {
fn default() -> Self {
PestRuleSettings {
visible: true,
replace: None,
}
}
}
pub fn abnf_to_pest(
data: &Vec<u8>,
rule_settings: &HashMap<String, PestRuleSettings>,
) -> std::io::Result<String> {
use abnf::abnf::*;
use pretty::{BoxDoc, Doc};
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"
// TODO: remove when https://github.com/pest-parser/pest/pull/375 gets into a release
|| x == "whitespace"
{
x + "_"
} else {
x
}
}
fn format_alternation(x: Alternation) -> Doc<'static, BoxDoc<'static, ()>> {
Doc::intersperse(
x.concatenations
.into_iter()
.map(|x| format_concatenation(x).nest(2).group()),
Doc::space().append(Doc::text("| ")),
)
}
fn format_concatenation(
x: Concatenation,
) -> Doc<'static, BoxDoc<'static, ()>> {
Doc::intersperse(
x.repetitions.into_iter().map(format_repetition),
Doc::space().append(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)))
}
|
