lsp-completion: better ranking for case mismatch, it will be pushed to near next rank (#2234)

Author: kiennq

lsp-completion.el

@@ -561,11 +561,9 @@ Others: TRIGGER-CHARS CANDIDATES"
                      (format "\\(%s\\)" (regexp-quote (char-to-string c))))
                    str))))
 
-(defvar lsp-completion--fuz-case-sensitiveness 20
-  "Case sensitiveness, can be in range of [0, inf).")
-
 (defun lsp-completion--fuz-score (query str)
-  "Calculate fuzzy score for STR with query QUERY."
+  "Calculate fuzzy score for STR with query QUERY.
+The return is nil or in range of (0, inf)."
   (-when-let* ((md (cddr (or (get-text-property 0 'match-data str)
                              (let ((re (lsp-completion--regex-fuz query)))
                                (when (string-match re str)
@@ -610,21 +608,23 @@ Others: TRIGGER-CHARS CANDIDATES"
                   "Update score variables given match range (A B)."
                   (setq score-numerator (+ score-numerator (- b a)))
                   (unless (= a len)
+                    ;; case mis-match will be pushed to near next rank
+                    (unless (equal (aref query q-ind) (aref str a))
+                      (cl-incf a 0.9))
                     (setq score-denominator
                           (+ score-denominator
                              (if (= a last-b) 0
-                               ;; Give a higher score for match near start
-                               (+ 1 (expt (- a last-b 1) (if (eq last-b -1) 0.75 0.25))))
-                             (if (equal (aref query q-ind) (aref str a)) 0
-                               lsp-completion--fuz-case-sensitiveness))))
+                               (+ 1 (* (if (< 0 (- a last-b 1)) 1 -1)
+                                       (expt (abs (- a last-b 1))
+                                             ;; Give a higher score for match near start
+                                             (if (eq last-b -1) 0.75 0.25))))))))
                   (setq last-b b))))
-    (funcall update-score start start)
     (while md
       (funcall update-score start (cl-first md))
+      ;; Due to the way completion regex is constructed, `(eq end (+ start 1))`
+      (cl-incf q-ind)
       (pop md)
-      (setq start (pop md))
-      (cl-incf q-ind))
-    (funcall update-score len len)
+      (setq start (pop md)))
     (unless (zerop len)
       (/ score-numerator (1+ score-denominator) 1.0))))
 

test/lsp-completion-test.el

@@ -49,32 +49,35 @@
              '("hash-map"
                "as-definition"
                "as-def"
-               "aS-selection"
+               "As-selection"
                "To-as-expected"
                "amused"
                "subclass-1"
                "superand-sort")
              '("as-definition"    ; Prefix match
                "as-def"           ; Also prefix match (stable)
+               "As-selection"     ; case mismatch, rank lower to near next rank
                "hash-map"         ; middle match
                "amused"           ; partial match with prefix match
                "To-as-expected"   ; more in middle match
                "subclass-1"       ; more in middle match
                "superand-sort"    ; partial match without prefix match
-               "aS-selection"     ; case mismatch
                ))
+    (do-test "f"
+             '("f" "foo" "Foo" "aFoo" "afoo")
+             '("f" "foo" "Foo" "afoo" "aFoo"))
+    (do-test "foo"
+             '("foo" "afoo" "aafoo" "aaafoo" "Foo" "aFoo" "aaFoo" "aaaFoo")
+             '("foo" "Foo" "afoo" "aFoo" "aafoo" "aaFoo" "aaafoo" "aaaFoo"))
     (do-test "F"
-             '("F" "foo" "Foo")
-             '("F" "Foo" "foo"))
+             '("F" "foo" "Foo" "aFoo" "afoo")
+             '("F" "Foo" "foo" "aFoo" "afoo"))
     (do-test "Fo"
              '("Fo" "daFo" "safo")
              '("Fo" "daFo" "safo"))
     (do-test "F"
              '("F" "daFo" "safo")
-             '("F" "daFo" "safo"))
-    (do-test "foo"
-             '("foo" "afoo" "aafoo" "aaafoo")
-             '("foo" "afoo" "aafoo" "aaafoo"))))
+             '("F" "daFo" "safo"))))
 
 (provide 'lsp-completion-test)
 ;;; lsp-completion-test.el ends here