feat: tantivy lexical index over Alpha-ID texts

tests/lexical_tests.rs

@@ -0,0 +1,23 @@
+use alpha_id::lexical::LexicalIndex;
+use alpha_id::model::AlphaIdEntry;
+
+fn entry(id: &str, code: &str, text: &str) -> AlphaIdEntry {
+    AlphaIdEntry {
+        alpha_id: id.into(), valid: true,
+        icd_primary: code.into(), icd_star: "".into(), icd_addon: "".into(),
+        icd_primary2: "".into(), orpha: "".into(), text: text.into(),
+    }
+}
+
+#[test]
+fn finds_entry_by_fuzzy_query() {
+    let entries = vec![
+        entry("I1", "E11.9", "Diabetes mellitus Typ 2"),
+        entry("I2", "I10.90", "Arterielle essentielle Hypertonie"),
+    ];
+    let idx = LexicalIndex::build_in_ram(&entries).unwrap();
+    let hits = idx.search("diabetes typ 2", 5).unwrap();
+    assert!(!hits.is_empty());
+    assert_eq!(hits[0].0, 0); // entry index 0
+    assert!(hits[0].1 > 0.0); // bm25 score
+}