stringtab.rs

use serde::{Deserialize, Serialize};

use std::collections::HashMap;

// Map strings to unique identifiers and counts uids
#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct StringTable {
    count: usize,
    string_to_index: HashMap<String, usize>,
    index_to_string: HashMap<usize, String>,
}

impl StringTable {
    pub fn new() -> StringTable {
        StringTable {
            count: 0,
            string_to_index: HashMap::new(),
            index_to_string: HashMap::new(),
        }
    }

    // Produce the UID for a string
    pub fn lookup_string(&mut self, s: String) -> usize {
        match self.string_to_index.get(&s) {
            Some(n) => *n,
            None => {
                let n = self.count;
                self.count += 1;
                self.string_to_index.insert(s.clone(), n);
                self.index_to_string.insert(n, s);
                n
            }
        }
    }

    // Identify the string corresponding to a UID
    pub fn lookup_id(&self, n: usize) -> Option<String> {
        self.index_to_string.get(&n).cloned()
    }
}

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