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use std::fmt;
use std::fs;
use crate::config::*;
const fn build_lookup_table() -> [usize; 128] {
let mut result = [0; 128];
let mut i = 0;
while i < NUM_KEYS {
result[KEY_CHARS[i] as usize] = i;
i += 1;
}
return result;
}
const CHAR_TO_INDEX: [usize; 128] = build_lookup_table();
const NUM_BIGRAMS: usize = NUM_KEYS * NUM_KEYS;
pub struct Corpus {
bigram_count: [u32; NUM_BIGRAMS],
character_count: [u32; 128],
total_count: u32,
index_threshold: u32,
}
fn pair_to_index(x: u8, y: u8) -> usize {
let xi = CHAR_TO_INDEX[x as usize];
let yi = CHAR_TO_INDEX[y as usize];
xi + NUM_KEYS * yi
}
impl Corpus {
pub fn get_character_count(&self, c: u8) -> u32 {
self.character_count[c as usize]
}
pub fn get_bigram_count(&self, x: u8, y: u8) -> u32 {
self.bigram_count[pair_to_index(x, y)]
}
pub fn get_index_threshold(&self) -> u32 {
self.index_threshold
}
pub fn get_total_count(&self) -> u32 {
self.total_count
}
pub fn load(path: &str) -> Result<Corpus, std::io::Error> {
let contents = fs::read_to_string(path)?;
let mut bigram_count = [0; NUM_BIGRAMS];
let mut character_count = [0; 128];
let mut total_count = 0;
let mut last_char: Option<u8> = None;
for c in contents.chars() {
if let Some(c) = canonicalise(c) {
if let Some(lc) = last_char {
// We don't count these anyway
if lc != c {
bigram_count[pair_to_index(c, lc)] += 1;
bigram_count[pair_to_index(lc, c)] += 1;
}
}
last_char = Some(c);
character_count[c as usize] += 1;
total_count += 1;
} else {
last_char = None;
}
}
let index_threshold = (total_count as f32 * DESIRED_INDEX_USAGE_PERCENT) as u32;
return Ok(Corpus {
bigram_count,
character_count,
total_count,
index_threshold,
});
}
}
fn dump_bigrams(corpus: &Corpus) -> Vec<(String, u32)> {
let mut result: Vec<(String, u32)> = Vec::new();
for (i, &x) in KEY_CHARS.iter().enumerate() {
for &y in &KEY_CHARS[i..] {
let mut pair = String::from(x);
pair.push(y);
result.push((pair, corpus.bigram_count[pair_to_index(x as u8, y as u8)]));
}
}
result.sort_by(|(_, c1), (_, c2)| c1.cmp(c2).reverse());
return result;
}
impl fmt::Display for Corpus {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str(&format!(
"Counted {} characters, top 5 bigrams {:?}",
self.total_count,
&dump_bigrams(self)[0..5]
))
}
}
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