hiko-syntax 0.5.0

hiko-syntax: part of the hiko ML-family scripting language
Documentation 
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use std::collections::HashMap;
use std::fmt;

#[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
pub struct Symbol(u32);

impl fmt::Debug for Symbol {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "Symbol({})", self.0)
    }
}

#[derive(Clone)]
pub struct StringInterner {
    map: HashMap<String, Symbol>,
    strings: Vec<String>,
}

impl Default for StringInterner {
    fn default() -> Self {
        Self::new()
    }
}

impl StringInterner {
    pub fn new() -> Self {
        Self {
            map: HashMap::new(),
            strings: Vec::new(),
        }
    }

    pub fn intern(&mut self, s: &str) -> Symbol {
        if let Some(&sym) = self.map.get(s) {
            return sym;
        }
        let sym = Symbol(self.strings.len() as u32);
        self.strings.push(s.to_string());
        self.map.insert(s.to_string(), sym);
        sym
    }

    pub fn resolve(&self, sym: Symbol) -> &str {
        &self.strings[sym.0 as usize]
    }
}