refactor(dict): Allow 0..n corrections in BuiltIn

The main use case is taking `ther` -> `there` and adding `the` and
`their`.

Cargo.lock

@@ -1526,6 +1526,7 @@ version = "1.2.0"
 dependencies = [
  "codegenrs",
  "csv",
+ "itertools 0.10.0",
  "phf",
  "phf_codegen",
  "structopt",

crates/typos-dict/codegen/Cargo.toml

@@ -18,6 +18,7 @@ codecov = { repository = "crate-ci/typos" }
 phf = { version = "0.8", features = ["unicase"] }
 phf_codegen = "0.8"
 csv = "1.1"
+itertools = "0.10"
 unicase = "2.5"
 codegenrs = "1.0"
 structopt = "0.3"

crates/typos-dict/codegen/src/main.rs

@@ -18,20 +18,26 @@ fn generate<W: std::io::Write>(file: &mut W) {
 
     writeln!(
         file,
-        "pub static WORD_DICTIONARY: phf::Map<unicase::UniCase<&'static str>, &'static str> = "
+        "pub static WORD_DICTIONARY: phf::Map<unicase::UniCase<&'static str>, &'static [&'static str]> = "
     )
     .unwrap();
     let mut builder = phf_codegen::Map::new();
     let records: Vec<_> = csv::ReaderBuilder::new()
         .has_headers(false)
+        .flexible(true)
         .from_reader(DICT)
         .records()
         .map(|r| r.unwrap())
         .collect();
     for record in &records {
-        smallest = std::cmp::min(smallest, record[0].len());
-        largest = std::cmp::max(largest, record[0].len());
-        let value = format!(r#""{}""#, &record[1]);
+        let mut record_fields = record.iter();
+        let key = record_fields.next().unwrap();
+        smallest = std::cmp::min(smallest, key.len());
+        largest = std::cmp::max(largest, key.len());
+        let value = format!(
+            "&[{}]",
+            itertools::join(record_fields.map(|field| format!(r#""{}""#, field)), ", ")
+        );
         builder.entry(unicase::UniCase::new(&record[0]), &value);
     }
     let codegenned = builder.build();

crates/typos-dict/verify/src/main.rs

@@ -4,26 +4,32 @@ use std::collections::HashSet;
 use structopt::StructOpt;
 
 fn generate<W: std::io::Write>(file: &mut W, dict: &[u8]) {
-    let mut wtr = csv::Writer::from_writer(file);
+    let mut wtr = csv::WriterBuilder::new().flexible(true).from_writer(file);
 
     let disallowed_typos = varcon_words();
     let word_variants = proper_word_variants();
 
     let mut reader = csv::ReaderBuilder::new()
         .has_headers(false)
+        .flexible(true)
         .from_reader(dict);
     for record in reader.records() {
         let record = record.unwrap();
-        let typo = &record[0];
-        let correction = &record[1];
+        let mut record_fields = record.iter();
+        let typo = record_fields.next().unwrap();
         if disallowed_typos.contains(&unicase::UniCase::new(typo)) {
             continue;
         }
+
+        let mut row = vec![typo];
+        for correction in record_fields {
             let correction = word_variants
                 .get(correction)
                 .and_then(|words| find_best_match(typo, correction, words))
                 .unwrap_or(correction);
-        wtr.write_record(&[typo, correction]).unwrap();
+            row.push(correction);
+        }
+        wtr.write_record(&row).unwrap();
     }
     wtr.flush().unwrap();
 }

src/dict.rs

@@ -34,14 +34,11 @@ impl BuiltIn {
         }
 
         let word = word_token.token();
-        let mut corrections = if let Some(correction) = self.correct_with_dict(word) {
-            match self.correct_with_vars(correction) {
-                Some(Status::Valid) => Status::Corrections(vec![Cow::Borrowed(correction)]),
-                Some(correction @ Status::Corrections(_)) => correction,
-                Some(Status::Invalid) => {
-                    unreachable!("correct_with_vars should always have valid suggestions")
-                }
-                None => Status::Corrections(vec![Cow::Borrowed(correction)]),
+        let mut corrections = if let Some(corrections) = self.correct_with_dict(word) {
+            if corrections.is_empty() {
+                Status::Invalid
+            } else {
+                self.chain_with_vars(corrections)?
             }
         } else {
             self.correct_with_vars(word)?
@@ -54,7 +51,7 @@ impl BuiltIn {
 
     #[cfg(feature = "dict")]
     // Not using `Status` to avoid the allocations
-    fn correct_with_dict(&self, word: &str) -> Option<&'static str> {
+    fn correct_with_dict(&self, word: &str) -> Option<&'static [&'static str]> {
         if typos_dict::WORD_RANGE.contains(&word.len()) {
             map_lookup(&typos_dict::WORD_DICTIONARY, word)
         } else {
@@ -63,10 +60,35 @@ impl BuiltIn {
     }
 
     #[cfg(not(feature = "dict"))]
-    fn correct_with_dict(&self, _word: &str) -> Option<&'static str> {
+    fn correct_with_dict(&self, _word: &str) -> Option<&'static [&'static str]> {
         None
     }
 
+    #[cfg(feature = "vars")]
+    fn chain_with_vars(&self, corrections: &'static [&'static str]) -> Option<Status<'static>> {
+        let mut chained: Vec<_> = corrections
+            .iter()
+            .flat_map(|c| match self.correct_with_vars(c) {
+                Some(Status::Valid) | None => vec![Cow::Borrowed(*c)],
+                Some(Status::Corrections(vars)) => vars,
+                Some(Status::Invalid) => {
+                    unreachable!("correct_with_vars should always have valid suggestions")
+                }
+            })
+            .collect();
+        if chained.len() != 1 {
+            chained.sort_unstable();
+            chained.dedup();
+        }
+        debug_assert!(!chained.is_empty());
+        Some(Status::Corrections(chained))
+    }
+
+    #[cfg(not(feature = "vars"))]
+    fn chain_with_vars(&self, corrections: &[&str]) -> Option<Status<'static>> {
+        Status::Corrections(corrections.map(|c| Cow::Borrowed(correction).collect()))
+    }
+
     #[cfg(feature = "vars")]
     fn correct_with_vars(&self, word: &str) -> Option<Status<'static>> {
         if typos_vars::WORD_RANGE.contains(&word.len()) {