schala/schala-lang/src/util.rs

use std::{cmp::Eq, collections::HashMap, fmt::Write, hash::Hash};

/// Utility function for printing a comma-delimited list of things
pub(crate) fn delim_wrapped(lhs: char, rhs: char, terms: impl Iterator<Item = String>) -> String {
    let mut buf = String::new();
    write!(buf, "{}", lhs).unwrap();
    for term in terms.map(Some).intersperse(None) {
        match term {
            Some(e) => write!(buf, "{}", e).unwrap(),
            None => write!(buf, ", ").unwrap(),
        };
    }
    write!(buf, "{}", rhs).unwrap();
    buf
}

#[derive(Default, Debug)]
pub struct ScopeStack<'a, T: 'a, V: 'a, N = String>
where T: Hash + Eq
{
    parent: Option<&'a ScopeStack<'a, T, V, N>>,
    values: HashMap<T, V>,
    scope_name: Option<N>,
}

impl<'a, T, V, N> ScopeStack<'a, T, V, N>
where T: Hash + Eq
{
    pub fn new(scope_name: Option<N>) -> Self
    where T: Hash + Eq {
        ScopeStack { parent: None, values: HashMap::new(), scope_name }
    }
    pub fn insert(&mut self, key: T, value: V)
    where T: Hash + Eq {
        self.values.insert(key, value);
    }
    pub fn lookup(&self, key: &T) -> Option<&V>
    where T: Hash + Eq {
        match (self.values.get(key), self.parent) {
            (None, None) => None,
            (None, Some(parent)) => parent.lookup(key),
            (Some(value), _) => Some(value),
        }
    }

    pub fn new_scope(&'a self, scope_name: Option<N>) -> Self
    where T: Hash + Eq {
        ScopeStack { parent: Some(self), values: HashMap::default(), scope_name }
    }

    #[allow(dead_code)]
    pub fn lookup_with_scope(&self, key: &T) -> Option<(&V, Option<&N>)>
    where T: Hash + Eq {
        match (self.values.get(key), self.parent) {
            (None, None) => None,
            (None, Some(parent)) => parent.lookup_with_scope(key),
            (Some(value), _) => Some((value, self.scope_name.as_ref())),
        }
    }

    pub fn get_name(&self) -> Option<&N> {
        self.scope_name.as_ref()
    }
}

/// Quickly create an AST from a string, with no error checking. For test use only
#[cfg(test)]
pub fn quick_ast(input: &str) -> crate::ast::AST {
    let mut parser = crate::parsing::Parser::new();
    let output = parser.parse(input);
    match output {
        Ok(output) => output,
        Err(err) => {
            println!("Parse error: {}", err.msg);
            panic!();
        }
    }
}

#[allow(unused_macros)]
macro_rules! rc {
    ($string:tt) => {
        Rc::new(stringify!($string).to_string())
    };
}