feat(tazjin/russian): Exclude known words from random display r/3108

Adds a set of words that I consider "known" (but that should be in the
most frequent word list anyways). This set can be populated by
invoking `mark-last-russian-word-as-known` after display, and is
automatically persisted.

Right now there's nothing automatically loading it back in, just as
there is nothing loading any of this automatically, that's for the
future.

Change-Id: I51ee4f37114c6b95925e8ad5bdc5dc9b8657bdad

1 files changed, 29 insertions, 1 deletions

diff --git a/users/tazjin/russian/russian.el b/users/tazjin/russian/russian.el
index 94245f07c1..5871b180b5 100644
--- a/users/tazjin/russian/russian.el
+++ b/users/tazjin/russian/russian.el
@@ -82,11 +82,39 @@
 
 (defun display-random-russian-word ()
   (interactive)
-  (let ((word (seq-random-elt (ht-values russian-words))))
+  (let* ((word (seq-random-elt (ht-values russian-words))))
+    (while (ht-contains? russian--known-words (russian-word-word word))
+      (setq word (seq-random-elt (ht-values russian-words))))
     (setq russian--last-word word)
     (message (russian--format-word word))))
 
 (defvar russian--display-timer
   (run-with-idle-timer 5 t #'display-random-russian-word))
 
+;; Ability to filter out known words
+
+(defvar russian--known-words (make-hash-table)
+  "Table of words that are already known.")
+
+(defun persist-known-russian-words ()
+  "Persist all known Russian words."
+  (let ((file "/persist/tazjin/known-russian-words.el"))
+    (with-temp-file file
+      (insert (prin1-to-string russian--known-words)))))
+
+(defun load-known-russian-words ()
+  "Load all known Russian words."
+  (let ((file "/persist/tazjin/known-russian-words.el"))
+    (with-temp-buffer
+      (insert-file-contents file)
+      (setq russian--known-words (read (current-buffer))))))
+
+(defun mark-last-russian-word-known ()
+  "Mark the last Russian word that appeared as known."
+  (interactive)
+  (let ((word (russian-word-word russian--last-word)))
+    (ht-set russian--known-words word t)
+    (persist-known-russian-words)
+    (message "Marked '%s' as known" word)))
+
 (provide 'russian)