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use pest::iterators::{Pair, Pairs};
use pest::Parser;
use crate::parser::{RhizParser, Rule};
#[derive(Debug, PartialEq)]
pub enum RhizValue {
Program(Vec<RhizValue>),
SExpr(Vec<RhizValue>),
Symbol(String),
String(String),
}
impl std::convert::From<&RhizValue> for String {
fn from(v: &RhizValue) -> String {
match v {
RhizValue::String(s) => format!("\"{}\"", s),
RhizValue::Symbol(s) => s.to_owned(),
RhizValue::SExpr(contents) => {
let mut outp = String::new();
let items = contents.iter();
for i in items {
let s: String = i.into();
outp.push_str(&s);
outp.push(' ');
}
outp
}
RhizValue::Program(sexprs) => {
let mut outp = String::new();
let items = sexprs.iter();
for i in items {
let s: String = i.into();
outp.push_str(&s);
outp.push(' ');
}
outp
}
}
}
}
fn collect_or_first_error(pairs: Pairs<Rule>) -> Result<Vec<RhizValue>, String> {
let mut result = Vec::new();
for p in pairs {
match parse_value(p) {
Ok(v) => result.push(v),
Err(e) => return Err(e),
}
}
Ok(result)
}
fn parse_value(pair: Pair<Rule>) -> Result<RhizValue, String> {
match pair.as_rule() {
Rule::program => {
let exprs = collect_or_first_error(pair.into_inner())?;
Ok(RhizValue::Program(exprs))
}
Rule::sexpr => {
let exprs = collect_or_first_error(pair.into_inner())?;
Ok(RhizValue::SExpr(exprs))
}
Rule::symbol => {
let raw = pair.as_str().to_owned();
Ok(RhizValue::Symbol(raw))
}
Rule::string => {
let raw = pair.as_str();
let contents = raw[1..raw.len() - 1].to_owned();
Ok(RhizValue::String(contents))
}
_ => unreachable!("{:?}", pair),
}
}
pub fn parse_rhiz_program(src: &str) -> Result<RhizValue, String> {
let mut parse_tree =
RhizParser::parse(Rule::file, src).map_err(|e| format!("Parsing error: {}", e))?;
let prog = parse_tree.next().expect("Expected a program");
parse_value(prog)
}
#[test]
fn test_parse_values() {
let example_src = r#"(Once there was) (a "way" to get "back home")"#;
assert!(parse_rhiz_program(example_src).is_ok())
}