branch: externals/trie
commit 53146c1373c270fa60f240018bf058bd412de560
Author: Toby S. Cubitt <toby-predict...@dr-qubit.org>
Commit: Toby S. Cubitt <toby-predict...@dr-qubit.org>
Implement fuzzy match and completion on dict-trees.
Also, simplify dict-tree cache parameters to a single cache-threshold
setting
instead of one per query type.
Note: Breaks backwards-compatibility of dicts saved to file!
---
trie.el | 68 +++++++++++++++++++++++++++++++++++++++++++++--------------------
1 file changed, 47 insertions(+), 21 deletions(-)
diff --git a/trie.el b/trie.el
index 86b86ac..69abe6f 100644
--- a/trie.el
+++ b/trie.el
@@ -1382,8 +1382,8 @@ element stored in the trie.)"
;; MAXNUM. The remaining arguments have the usual meanings, and should be
;; passed straight through from the query function's arguments.
- ;; rename functions to help avoid dynamic-scoping bugs FIXME: not needed
- ;; with lexical scoping
+ ;; rename functions to help avoid dynamic-scoping bugs
+ ;; FIXME: not needed with lexical scoping
`(let* ((--trie-accumulate--rankfun ,rankfun)
(--trie-accumulate--filter ,filter)
(--trie-accumulate--resultfun ,resultfun)
@@ -1930,6 +1930,47 @@ elements that matched the corresponding groups, in
order."
;; ================================================================
;; Fuzzy matching
+
+;; Basic Lewenstein distance (edit distance) functions
+;; ---------------------------------------------------
+
+(defun* Lewenstein-distance (str1 str2 &key (test 'equal))
+ "Return the Lewenstein distance between strings STR1 and STR2
+\(a.k.a. edit distance\).
+
+The Lewenstein distance is the minimum number of single-character
+insertions, deletions or substitutions required to transform STR1
+into STR2.
+
+More generally, STR1 and STR2 can be sequences of elements all of
+the same type. The optional keyword argument :test specifies the
+function to use to test equality of sequence elements, defaulting
+to `equal'."
+ (let ((row (apply #'vector (number-sequence 0 (length str2)))))
+ (dotimes (i (length str1))
+ (setq row (Lewenstein--next-row row str2 (elt str1 i) test)))
+ (aref row (1- (length row)))))
+
+
+(defalias 'edit-distance 'Lewenstein-distance)
+
+
+(defun Lewenstein--next-row (row string chr equalfun)
+ ;; Compute next row of Lewenstein distance matrix.
+ (let ((next-row (make-vector (length row) nil))
+ (i 0) inscost delcost subcost)
+ (aset next-row 0 (1+ (aref row 0)))
+ (while (< (incf i) (length row))
+ (setq inscost (1+ (aref next-row (1- i)))
+ delcost (1+ (aref row i))
+ subcost (if (funcall equalfun chr (elt string (1- i)))
+ (aref row (1- i))
+ (1+ (aref row (1- i)))))
+ (aset next-row i (min inscost delcost subcost)))
+ next-row))
+
+
+
;; Implementation Note
;; -------------------
;; The standard dynamical-programming solution to computing Lewenstein
@@ -2054,7 +2095,7 @@ of the default key-dist-data list."
(trie--node-data node))))
;; build next row of Lewenstein table
- (setq row (trie--Lewenstein-next-row
+ (setq row (Lewenstein--next-row
row string (trie--node-split node) equalfun)
seq (trie--seq-append seq (trie--node-split node)))
@@ -2069,21 +2110,6 @@ of the default key-dist-data list."
reverse))))
-(defun trie--Lewenstein-next-row (row string chr equalfun)
- ;; Compute next row of Lewenstein distance matrix.
- (let ((next-row (make-vector (length row) nil))
- (i 0) inscost delcost subcost)
- (aset next-row 0 (1+ (aref row 0)))
- (while (< (incf i) (length row))
- (setq inscost (1+ (aref next-row (1- i)))
- delcost (1+ (aref row i))
- subcost (if (funcall equalfun chr (elt string (1- i)))
- (aref row (1- i))
- (1+ (aref row (1- i)))))
- (aset next-row i (min inscost delcost subcost)))
- next-row))
-
-
(defun trie-fuzzy-match-stack (trie string distance &optional reverse)
"Return an object that allows fuzzy matches to be accessed
@@ -2166,7 +2192,7 @@ within Lewenstein distance \(edit distance\) DISTANCE of
STRING."
(<= (aref row (1- (length row))) distance))))
;; drop data nodes whose SEQ is greater than DISTANCE
(unless (trie--node-data-p node)
- (setq nextrow (trie--Lewenstein-next-row
+ (setq nextrow (Lewenstein--next-row
row string (trie--node-split node) equalfun))
;; push children of non-data nodes whose SEQ is less than DISTANCE
;; onto stack
@@ -2308,7 +2334,7 @@ of the default key-dist-data list."
(trie--node-data node))))
;; build next row of Lewenstein table
- (setq row (trie--Lewenstein-next-row
+ (setq row (Lewenstein--next-row
row prefix (trie--node-split node) equalfun)
seq (trie--seq-append seq (trie--node-split node))
pfxcost (min pfxcost (aref row (1- (length row)))))
@@ -2421,7 +2447,7 @@ DISTANCE of PREFIX."
;; drop data nodes whose SEQ is greater than DISTANCE
(unless (trie--node-data-p node)
;; build next row of Lewenstein table
- (setq row (trie--Lewenstein-next-row
+ (setq row (Lewenstein--next-row
row prefix (trie--node-split node) equalfun)
seq (trie--seq-append seq (trie--node-split node))
pfxcost (min pfxcost (aref row (1- (length row)))))
