sunflower/src/pest_parser.rs

use pest::{iterators::Pair, Parser};
use pest_derive::Parser;

use crate::{
    expression::{BinaryOperation, Expression},
    statement::Statement,
    value::Value,
};

#[derive(Parser)]
#[grammar = "grammar.pest"]
pub struct LangParser;

pub fn parse<S: ToString>(source: S) -> Statement {
    let source = source.to_string();
    let pairs = LangParser::parse(Rule::root_statement, &source).unwrap();
    handle_rules(pairs)
}

pub fn parser_test() {
    // let p = LangParser::parse(Rule::number, "-273.15").unwrap();
    // println!("{:?}", p);
    // let p = LangParser::parse(Rule::number, "25565");
    // println!("{:?}", p);

    // let str_test = LangParser::parse(Rule::string, "\"hello\"").unwrap();
    // println!("{:?}", str_test);

    // let str_test = LangParser::parse(Rule::char, "'a'").unwrap();
    // println!("{:?}", str_test);

    // let foo = LangParser::parse(Rule::statement, "10 + foo + bar(20) * 40;").unwrap();
    // println!("{:?}", foo);

    // let bar = "
    //     let x = 10;
    //     let y = 20;
    //     let z = x + y;
    //     print(z);
    //     while (x < y) {
    //         x = x + 1;
    //     }
    //     let x = x + \"lmao\";
    // ";
    // let bar = LangParser::parse(Rule::root_statement, bar);
    // println!("{:?}", bar);

    let baz = "
    if x {
        a;
    } else if y {
        b;
    } else {
        c;
    }";

    let baz = LangParser::parse(Rule::root_statement, baz);
    println!("{:?}", baz);

    let x = "x == 10;";
    let x = LangParser::parse(Rule::statement, x);
    handle_rules(x.unwrap());
}
fn handle_rules(mut p: pest::iterators::Pairs<Rule>) -> Statement {
    fn parse_statement(pair: Pair<Rule>) -> Statement {
        match pair.as_rule() {
            Rule::root_statement => {
                Statement::Body(pair.into_inner().map(parse_statement).collect())
            }
            Rule::while_block => {
                let mut inner = pair.into_inner();
                let expr = inner.next().unwrap();
                let body = inner.next().unwrap();
                Statement::While(parse_expression(expr), Box::new(parse_statement(body)))
            }
            Rule::if_block => {
                let mut inner = pair.into_inner().into_iter();
                let mut the_list = vec![];
                let mut the_else = None;
                while let Some(expr) = inner.next() {
                    if expr.as_rule() == Rule::expression {
                        let body = inner.next().unwrap();
                        the_list.push((parse_expression(expr), parse_statement(body)));
                    } else {
                        the_else = Some(Box::new(parse_statement(expr)));
                    }
                }
                Statement::If(the_list, the_else)
            }
            Rule::assignment => {
                let mut inner = pair.into_inner();
                let name = inner.next().unwrap();
                let expr = inner.next().unwrap();
                Statement::Assignment(name.as_str().to_string(), parse_expression(expr), false)
            }
            Rule::assignment_let => {
                let mut inner = pair.into_inner();
                let name = inner.next().unwrap();
                let expr = inner.next().unwrap();
                Statement::Assignment(name.as_str().to_string(), parse_expression(expr), true)
            }
            Rule::expression => Statement::Expression(parse_expression(pair)),
            Rule::statement => {
                let inner = pair.into_inner().next().unwrap();
                parse_statement(inner)
            }
            Rule::EOI => Statement::Body(vec![]),
            x => unreachable!("How did we get to {:?}", x),
        }
    }

    fn parse_expression(pair: Pair<Rule>) -> Expression {
        match pair.as_rule() {
            Rule::expression => {
                let mut inner = pair.into_inner();
                parse_expression(inner.next().unwrap())
            }
            Rule::equality => {
                let mut inner = pair.into_inner();
                let lhs = parse_expression(inner.next().unwrap());
                if let Some(op) = inner.next() {
                    let rhs = parse_expression(inner.next().unwrap());
                    Expression::Binary(Box::new(lhs), op.as_str().parse().unwrap(), Box::new(rhs))
                } else {
                    lhs
                }
            }
            Rule::inequality => {
                let mut inner = pair.into_inner();
                let lhs = parse_expression(inner.next().unwrap());
                if let Some(op) = inner.next() {
                    let rhs = parse_expression(inner.next().unwrap());
                    Expression::Binary(Box::new(lhs), op.as_str().parse().unwrap(), Box::new(rhs))
                } else {
                    lhs
                }
            }
            Rule::sum => {
                let mut inner = pair.into_inner();
                let lhs = parse_expression(inner.next().unwrap());
                if let Some(op) = inner.next() {
                    let rhs = parse_expression(inner.next().unwrap());
                    Expression::Binary(Box::new(lhs), op.as_str().parse().unwrap(), Box::new(rhs))
                } else {
                    lhs
                }
            }
            Rule::product => {
                let mut inner = pair.into_inner();
                let lhs = parse_expression(inner.next().unwrap());
                if let Some(op) = inner.next() {
                    let rhs = parse_expression(inner.next().unwrap());
                    Expression::Binary(Box::new(lhs), op.as_str().parse().unwrap(), Box::new(rhs))
                } else {
                    lhs
                }
            }
            Rule::value => {
                let inner = pair.into_inner().next().unwrap();
                parse_value(inner)
            }
            _ => unreachable!(),
        }
    }

    fn parse_value(pair: Pair<Rule>) -> Expression {
        match pair.as_rule() {
            Rule::const_value => {
                Expression::Constant(parse_const_value(pair.into_inner().next().unwrap()))
            }
            Rule::identifier => Expression::Variable(pair.as_str().to_string()),
            Rule::call => {
                let mut inner = pair.into_inner();
                let name = inner.next().unwrap();
                let args = inner
                    .next()
                    .unwrap()
                    .into_inner()
                    .map(parse_expression)
                    .collect();
                Expression::Call(name.as_str().to_string(), args)
            }
            Rule::parens => {
                let mut inner = pair.into_inner();
                parse_expression(inner.next().unwrap())
            }
            _ => unreachable!(),
        }
    }

    fn parse_const_value(pair: Pair<Rule>) -> Value {
        match pair.as_rule() {
            Rule::number => {
                if let Ok(f) = pair.as_str().parse::<i32>() {
                    Value::Int(f)
                } else if let Ok(f) = pair.as_str().parse::<f32>() {
                    Value::Float(f)
                } else {
                    unreachable!()
                }
            }
            Rule::string => Value::String(pair.as_str().to_string()),
            Rule::boolean => Value::Bool(pair.as_str() == "true"),
            Rule::char => Value::Char(pair.as_str().chars().next().unwrap()),
            _ => unreachable!(),
        }
    }

    let z = p.next().unwrap();
    parse_statement(z)
}

#[cfg(test)]
mod tests {
    use pest::Parser;

    use super::{LangParser, Rule};

    #[test]
    fn foo() {}
}