implement caching spellcheck results & other stuff

asklyphe-frontend/src/spellcheck.rs

@@ -1,36 +1,37 @@
+use once_cell::sync::Lazy;
 use tracing::{debug, error};
 use std::{cmp, mem};
+use std::collections::BTreeMap;
+use std::sync::Mutex;
 // TODO: cache distances of strings/substrings
 // TODO: use binary search to find direct matches, and if that fails, calculate and cache the result in BTreeMap<word: String, closest_match: String>
-// TODO: limit by number of words and word length, not max chars, and use code more like this for better readability & async:
-/*
-	let words = prepare(query).split_whitespace()
-		.filter(|qword| qword.len() > 0)
-		.map(|qword| qword.to_lowercase());
-	for word in words { // it might need to be while let Some(word) = words.next()
-		tokio::spawn(levenshtein_distance(...))
-	}
- */
 
 include!("./words.txt");
 
+// a cache of misspelled words and the closest match in the database
+static MATCH_CACHE: Lazy<Mutex<BTreeMap<String, Option<&str>>>> = Lazy::new(|| Mutex::new(BTreeMap::new()));
+
 // max distance before no alternatives are considered
 const MAX_DISTANCE: usize = 6;
 // max input text size before spellcheck is not run. on my laptop 13,000 chars of input takes around 4 seconds so this should be fine
 // update: got a larger word database and it doesn't take 4 seconds anymore lmao
-const MAX_QUERY_SIZE: usize = 1024;
+// update 2: added binary search & caching and now 50000 chars takes ~2-4 seconds
+const MAX_QUERY_WORDS: usize = 512;
+// Not really a huge issue, just used to hopefully reduce the allocations made in levenshtein_distance & provide minor performance improvements
+// not needed for now
+// const MAX_WORD_SIZE: usize = 64;
 
 pub type SpellCheckResults = Vec<SpellCheckResult>;
 
 #[derive(Debug)]
 pub struct SpellCheckResult {
 	pub orig: String,
-	pub correction: String,
+	pub correction: &'static str,
 }
 
 pub fn check(query: &String) -> Option<SpellCheckResults> {
 	error!("Query: {}", query);
-	let query: &str = {
+	/*let query: &str = {
 		if query.len() > MAX_QUERY_SIZE {
 			error!("Query is too large to be spell checked, only checking first {} chars", MAX_QUERY_SIZE);
 			query.get(0..MAX_QUERY_SIZE).unwrap()
@@ -38,9 +39,66 @@ pub fn check(query: &String) -> Option<SpellCheckResults> {
 		} else {
 			query
 		}
-	};
+	};*/
 
-	let distances = prepare(query).split_whitespace()
+	// TODO: look into how 'wc -w' counts words and copy how it splits things
+	let query_flattened = prepare(query);
+	let words = query_flattened
+		.split_whitespace()
+		.filter(|word| word.len() > 0)
+		// .filter(|word|)
+		.collect::<Vec<_>>();
+
+	error!("Words in query: {}", words.len());
+
+	if (words.len() > MAX_QUERY_WORDS) {
+		error!("{} is too many words in query to spell check", words.len());
+		// return None;
+	}
+
+	let mut distances: SpellCheckResults = vec![];
+	for qword in words {
+		// error!("Word: {}", qword);
+		// error!("is known: {:?}", KNOWN_WORDS.binary_search(&qword));
+		if KNOWN_WORDS.binary_search(&qword).is_ok() {
+			// error!("Exact word match: {}", qword);
+		} else {
+			let mut cache = MATCH_CACHE.lock().unwrap();
+			if cache.contains_key(qword) {
+				// We don't need to tell the user if there is no suggestion for an unknown word
+				if (cache.get(qword).unwrap().is_some()) {
+					// TODO: don't push duplicate misspelled words
+					distances.push(SpellCheckResult{orig: qword.to_owned(), correction: cache.get(qword).unwrap().unwrap()});
+				}
+			} else {
+				let closest_match = KNOWN_WORDS.iter()
+					.map(|kword| (kword, levenshtein_distance(&qword, &kword)))
+					.min_by(|a, b| a.1.cmp(&b.1)).unwrap();
+
+				assert!(closest_match.1 > 0, "Found exact match not caught by binary search, is the word database properly sorted?");
+
+				if closest_match.1 <= MAX_DISTANCE {
+					cache.insert(qword.to_owned(), Some(*closest_match.0));
+				} else {
+					// even though there is no close enough match, cache it anyway so that it doesn't have to be looked up every time
+					cache.insert(qword.to_owned(), None);
+				}
+			}
+		}
+		// error!("End");
+	}
+	error!("Spell check results:");
+	for word in &distances {
+		debug!("instead of '{}' did you mean '{}'?", word.orig, word.correction);
+	}
+
+	if distances.len() > 0 {
+		Some(distances)
+	} else {
+		None
+	}
+
+/*	let distances = prepare(query).split_whitespace()
 		.filter(|qword| qword.len() > 0)
 		.map(|qword| qword.to_lowercase())
 		.map(
@@ -69,7 +127,8 @@ pub fn check(query: &String) -> Option<SpellCheckResults> {
 		Some(distances)
 	} else {
 		None
-	}
+	}*/
+	// None
 	// vec![]
 }
 
@@ -94,11 +153,15 @@ fn prepare(s: &str) -> String {
 		.replace("7", "")
 		.replace("8", "")
 		.replace("9", "")
+		.to_lowercase()
 }
 
 // cost of 2 for add/remove, cost of 1 for replace
 fn levenshtein_distance(a: &str, other: &str) -> usize {
 	// debug!("Self: '{}', Other: '{}'", a, other);
+	// let mut dist: &mut [usize; MAX_WORD_SIZE] = &mut [0usize; MAX_WORD_SIZE];
+	// let mut dist_prev: &mut [usize; MAX_WORD_SIZE] = &mut [0usize; MAX_WORD_SIZE];
+
 	let mut dist = vec![0usize; other.len() + 1];
 	let mut dist_prev = vec![0usize; other.len() + 1];
 
@@ -113,6 +176,8 @@ fn levenshtein_distance(a: &str, other: &str) -> usize {
 			if a.get(i - 1..i).unwrap() == other.get(j - 1..j).unwrap() {
 				dist[j] = dist_prev[j - 1];
 			} else {
+				// TODO: make addition/subtraction 1 more expensive than replacement, presumably by adding '+ 1' to 2/3 of these
+				// motivation: honex from bee movie script is turned into hone instead of honey, this will also generally improve results & is what wikipedia says to do (best reason)
 				dist[j] = 1 + cmp::min(
 					dist.get(j - 1).unwrap(),
 					cmp::min(dist_prev.get(j).unwrap(), dist_prev.get(j - 1).unwrap()));