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use std::fmt;
pub struct StringTable {
data: Vec<u8>,
}
impl StringTable {
pub fn with_null() -> Self {
StringTable { data: vec![0] }
}
pub fn get(&self, idx: usize) -> &str {
let bytes = self.data[idx..].split(|n| *n == 0).next().unwrap();
std::str::from_utf8(bytes).unwrap()
}
pub fn push_with_null(&mut self, s: &str) {
for c in s.chars() {
if !c.is_ascii() {
panic!("could not push non-ascii char");
}
self.data.push(c as u8);
}
self.data.push(0);
}
pub fn len(&self) -> usize {
self.data.len()
}
pub fn iter(&self) -> impl Iterator<Item = &str> {
self.as_ref()
.split(|b| *b == 0)
.skip(1)
.map(|bytes| std::str::from_utf8(bytes).unwrap())
}
}
impl AsRef<[u8]> for StringTable {
fn as_ref(&self) -> &[u8] {
self.data.as_ref()
}
}
impl From<Vec<u8>> for StringTable {
fn from(data: Vec<u8>) -> Self {
assert!(data.starts_with(&[0]));
assert!(data.ends_with(&[0]));
assert!(data.iter().all(|n| *n == 0 || n.is_ascii()));
StringTable { data }
}
}
impl fmt::Debug for StringTable {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
let mut debug = fmt.debug_list();
for n in self.data.iter() {
match n {
0 => {
debug.entry(&"");
}
_ => {
debug.entry(&char::from(*n));
}
}
}
debug.finish()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn get_index_0_always_return_empty_string() {
let data = vec![0x00, 0x5f, 0x6d, 0x61, 0x69, 0x6e, 0x00];
let table = StringTable::from(data);
assert_eq!(table.get(0), "");
let mut table = StringTable::with_null();
table.push_with_null("hoge");
assert_eq!(table.get(0), "");
}
#[test]
fn get_string_from_vec() {
let data = vec![0x00, 0x5f, 0x6d, 0x61, 0x69, 0x6e, 0x00];
let table = StringTable::from(data);
assert_eq!(table.get(1), "_main");
assert_eq!(table.get(2), "main");
}
#[test]
fn get_string() {
let mut table = StringTable::with_null();
table.push_with_null("hoge");
assert_eq!(table.get(1), "hoge");
}
}