From bb00063f540ce9ac4a1b4957cbe8ab546e33e9ae Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Fri, 24 Jun 2016 07:03:15 -0700
Subject: [PATCH] avoid a list operation

---
 hyphenate/hyphenate/private/core.rkt | 61 ++++++++++++++--------------
 1 file changed, 31 insertions(+), 30 deletions(-)

diff --git a/hyphenate/hyphenate/private/core.rkt b/hyphenate/hyphenate/private/core.rkt
index f43efc25..b38ae474 100644
--- a/hyphenate/hyphenate/private/core.rkt
+++ b/hyphenate/hyphenate/private/core.rkt
@@ -12,19 +12,29 @@
 (define default-joiner #\u00AD)
 
 
+(define (trim-points points)
+  ;; for point list generated from a pattern,
+  ;; drop first two elements because they represent hyphenation weight
+  ;; before the starting "." and between "." and the first letter.
+  ;; drop last element because it represents hyphen after last "."
+  ;; after you drop these two, then each number corresponds to
+  ;; whether a hyphen goes after that letter.
+  (drop-right (drop points 2) 1))
+
+
 ;; Convert the hyphenated pattern into a point array for use later.
 (define (convert-exception-word exception)
   (define (make-key x) (format ".~a." (string-replace x "-" "")))
   (define (make-value x)
     (append (list 0) (map (λ(x) (if (equal? x "-") 1 0)) (regexp-split #px"\\p{L}" x)) (list 0)))
   ;; use list instead of cons because value is itself a list, and consing will muddy the waters
-  (list (make-key exception) (make-value exception)))
+  (list (make-key exception) (trim-points (make-value exception))))
 
 
 (module+ test
-  (check-equal? (convert-exception-word "snôw-man") '(".snôwman." (0 0 0 0 0 1 0 0 0 0)))
-  (check-equal? (convert-exception-word "snôwman") '(".snôwman." (0 0 0 0 0 0 0 0 0 0)))
-  (check-equal? (convert-exception-word "sn-ôw-ma-n") '(".snôwman." (0 0 0 1 0 1 0 1 0 0))))
+  (check-equal? (convert-exception-word "snôw-man") '(".snôwman." (0 0 0 1 0 0 0)))
+  (check-equal? (convert-exception-word "snôwman") '(".snôwman." (0 0 0 0 0 0 0)))
+  (check-equal? (convert-exception-word "sn-ôw-ma-n") '(".snôwman." (0 1 0 1 0 1 0))))
 
 
 (define (add-exception-word word)
@@ -90,32 +100,23 @@
 
 (define (make-points word)
   (define word-with-dots (format ".~a." (string-downcase word)))
-  (define max-pattern
-    (hash-ref! (current-word-cache) word-with-dots 
-               (λ () ; compute pattern when missing from cache
-                 (define word-length (string-length word-with-dots))
-                 (define default-zero-pattern (make-list (add1 word-length) 0))
-                 ;; walk through all the substrings and see if there's a matching pattern.
-                 (define matching-patterns
-                   (for*/list ([start (in-range word-length)] 
-                               [end (in-range start word-length)]
-                               [substr (in-value (substring word-with-dots start (add1 end)))]
-                               [partial-pattern (in-value (hash-ref (current-patterns) substr #f))]
-                               #:when partial-pattern)
-                              ;; pad out partial-pattern to full length
-                              ;; (so we can compare patterns to find max value for each slot)
-                              (define left-zeroes (make-list start 0))
-                              (define right-zeroes (make-list (- (add1 word-length) (length partial-pattern) start) 0))
-                              (append left-zeroes partial-pattern right-zeroes)))
-                 (calculate-max-pattern (cons default-zero-pattern matching-patterns)))))
-  
-  ;; for point list,
-  ;; drop first two elements because they represent hyphenation weight
-  ;; before the starting "." and between "." and the first letter.
-  ;; drop last element because it represents hyphen after last "."
-  ;; after you drop these two, then each number corresponds to
-  ;; whether a hyphen goes after that letter.
-  (drop-right (drop max-pattern 2) 1))
+  (hash-ref! (current-word-cache) word-with-dots 
+             (λ () ; compute pattern when missing from cache
+               (define word-length (string-length word-with-dots))
+               (define default-zero-pattern (make-list (add1 word-length) 0))
+               ;; walk through all the substrings and see if there's a matching pattern.
+               (define matching-patterns
+                 (for*/list ([start (in-range word-length)] 
+                             [end (in-range start word-length)]
+                             [substr (in-value (substring word-with-dots start (add1 end)))]
+                             [partial-pattern (in-value (hash-ref (current-patterns) substr #f))]
+                             #:when partial-pattern)
+                            ;; pad out partial-pattern to full length
+                            ;; (so we can compare patterns to find max value for each slot)
+                            (define left-zeroes (make-list start 0))
+                            (define right-zeroes (make-list (- (add1 word-length) (length partial-pattern) start) 0))
+                            (append left-zeroes partial-pattern right-zeroes)))
+               (trim-points (calculate-max-pattern (cons default-zero-pattern matching-patterns))))))
 
 
 ;; Find hyphenation points in a word. This is not quite synonymous with syllables.