2 files changed, 124 insertions, 0 deletions
diff --git a/abnf_to_pest/Cargo.toml b/abnf_to_pest/Cargo.toml
new file mode 100644
index 0000000..bfa6b6d
--- /dev/null
+++ b/abnf_to_pest/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "abnf_to_pest"
+version = "0.1.0"
+authors = ["Nadrieril <nadrieril@users.noreply.github.com>"]
+edition = "2018"
+
+[dependencies]
+abnf = { git = "https://github.com/Nadrieril/abnf" }
+itertools = "0.8.0"
+pretty = "0.5.2"
diff --git a/abnf_to_pest/src/lib.rs b/abnf_to_pest/src/lib.rs
new file mode 100644
index 0000000..cb7ba99
--- /dev/null
+++ b/abnf_to_pest/src/lib.rs
@@ -0,0 +1,114 @@
+use std::collections::HashMap;
+use itertools::Itertools;
+
+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::{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)))
+}
+